Email: jan.filip@upol.cz
Location: Šlechtitelů 11, Olomouc
Phone: (+420) 58 563 1406
Fax: (+420) 58 563 4958
Oblast výzkumu:
Spectroscopic and X-ray methods applied in mineral characterization and processes
Natural & synthetic nanoparticles
Environmental & applied mineralogy
Geochemistry and mineralogy of acid mine drainage
Trace hydrogen in nominally anhydrous minerals
Kvalifikace:
Mgr.: Mineralogy, petrology and geochemistry, Masaryk University
Ph.D.: Mineralogy, Masaryk University
Publications
2011
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![[DOI]](http://www.rcptm.com/wp-content/plugins/papercite/img/external.png)
J. Cuda, T. Kohout, J. Tucek, J. Haloda, J. Filip, R. Prucek, and R. Zboril, “Low-temperature magnetic transition in troilite: A simple marker for
highly stoichiometric FeS systems,” JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, vol. 116, 2011.
[Bibtex]@article ISI:000297257000001, Author = Cuda, J. and Kohout, T. and Tucek, J. and Haloda, J. and Filip, J. and Prucek, R. and Zboril, R., Title = Low-temperature magnetic transition in troilite: A simple marker for highly stoichiometric FeS systems, Journal = JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Year = 2011, Volume = 116, Month = NOV 15, Abstract = Low-temperature magnetic evolution of troilite sample, extracted from the Cape York IIIA octahedrite meteorite, was investigated by employing macroscopic magnetic measurement, Mssbauer spectroscopy, scanning electron microscopy (SEM) and backscattered electrons (BSE) microscopy, X-ray diffraction (XRD), electron microprobe analysis (EMA), and atomic absorption spectrometry (AAS). The study identified a magnetic transition at approximate to 70 K manifested itself in a similar manner as previously reported for troilite from the Bruderheim L6 chondrite meteorite. The data show that this transition is unlikely driven by impurity such as chromite and seems to be rather an intrinsic property of troilite. In this study, we unambiguously exclude the relation of this transition to the structural rearrangement like the Morin transition in hematite. Similarly, in-field Mssbauer data do not support the change of the canting angle in the spin structure of FeS above and below the transition. Mssbauer, XRD, and magnetic data, newly measured also for troilite from the Bruderheim L6 chondrite, demonstrate that both studied troilite samples exhibit nearly the same magnetic and structural characteristics. Thus, the nature of the transition occurring at approximate to 70 K in both samples has identical characteristics and its detection can be used as a simple general marker for highly stoichiometric FeS systems., DOI = 10.1029/2011JB008232, Article-Number = B11205, ISSN = 0148-0227, Unique-ID = ISI:000297257000001, - O. Schneeweiss, J. Filip, B. David, R. Zboril, and M. Maslan, “Iron nanoparticles prepared from natural ferrihydrite precursors:
kinetics and properties,” JOURNAL OF NANOPARTICLE RESEARCH, vol. 13, iss. 11, SI, pp. 5677-5684, 2011.
[Bibtex]@article ISI:000297351600012, Author = Schneeweiss, O. and Filip, J. and David, B. and Zboril, R. and Maslan, M., Title = Iron nanoparticles prepared from natural ferrihydrite precursors: kinetics and properties, Journal = JOURNAL OF NANOPARTICLE RESEARCH, Year = 2011, Volume = 13, Number = 11, SI, Pages = 5677-5684, Month = NOV, Note = 10th International Conference on Nanostructured Materials (NANO), Rome, ITALY, SEP 13-17, 2010, Organization = Int Comm Nanostruct Mat, Abstract = Natural ferrihydrite was used as the precursors for the preparation of the nanocrystalline alpha-Fe powder using heat treatment in hydrogen atmosphere. Transformation temperatures were estimated from the temperature dependences of magnetic moment. Structure and phase composition of the precursors and the final powders were characterized by X-ray diffraction and Mossbauer spectroscopy. Magnetic properties were characterized according to hysteresis loop parameters. The kinetics of the transformation was described using Avrami relation applied on the data of the isothermal time dependence of magnetic moment measurements and subsequently the activation enthalpy of transformation was estimated using Arrhenius plots of their parameters. Comparison of the changes of activation enthalpies derived from a different temperature ranges indicates effects of different processes on formation of alpha-Fe nanoparticles., DOI = 10.1007/s11051-011-0383-2, ISSN = 1388-0764, Unique-ID = ISI:000297351600012, - M. Novak, P. Gadas, J. Filip, T. Vaculovic, J. Prikryl, and B. Fojt, “Blue, complexly zoned, (Na,Mg,Fe,Li)-rich beryl from quartz-calcite
veins in low-grade metamorphosed Fe-deposit Skaly near Rymarov, Czech
Republic,” MINERALOGY AND PETROLOGY, vol. 102, iss. 1-4, pp. 3-14, 2011.
[Bibtex]@article ISI:000297118700002, Author = Novak, Milan and Gadas, Petr and Filip, Jan and Vaculovic, Tomas and Prikryl, Jan and Fojt, Bohuslav, Title = Blue, complexly zoned, (Na,Mg,Fe,Li)-rich beryl from quartz-calcite veins in low-grade metamorphosed Fe-deposit Skaly near Rymarov, Czech Republic, Journal = MINERALOGY AND PETROLOGY, Year = 2011, Volume = 102, Number = 1-4, Pages = 3-14, Month = OCT, Abstract = Syn-tectonic quartz-calcite veins containing blue beryl are enclosed in hematite > magnetite-rich portions of the low-grade metamorphosed Fe-deposit Skaly near Rymarov, Czech Republic. Aggregates of pale to deep blue beryl, up to 2 cm in diameter, are associated with euclase, clinochlore, hematite, albite and dravite. Complexly zoned beryl crystals consist of skeletal aggregates of beryl I randomly distributed within volumetrically dominant beryl II with narrow rims of beryl III. All types of beryl have similar contents of Na (0.32-0.49 apfu) and Mg (0.31-0.41 apfu) but variable contents of Fe(tot) (0.05-0.34 apfu) and Al (1.20-1.62 apfu). The LA-ICP-MS study yielded elevated contents of Li, up 1,314 ppm (0.28 wt.\% Li(2)O) in beryl I. The quartz-calcite veins represent an unusual type of low-T metamorphic-hydrothermal vein related to Fe-ore deposit characterized by single-stage fracturing and mobilization in a closed system at T similar to 200-300 degrees C and CO(3)(2-) as a major complexing agent for the mobility of Be., DOI = 10.1007/s00710-011-0157-7, ISSN = 0930-0708, Unique-ID = ISI:000297118700002, - J. Filip, R. A. Yngard, K. Siskova, Z. Marusak, V. Ettler, P. Sajdl, V. K. Sharma, and R. Zboril, “Mechanisms and Efficiency of the Simultaneous Removal of Metals and
Cyanides by Using Ferrate(VI): Crucial Roles of Nanocrystalline
Iron(III) Oxyhydroxides and Metal Carbonates,” CHEMISTRY-A EUROPEAN JOURNAL, vol. 17, iss. 36, pp. 10097-10105, 2011.
[Bibtex]@article ISI:000295357800031, Author = Filip, Jan and Yngard, Ria A. and Siskova, Karolina and Marusak, Zdenek and Ettler, Vojtech and Sajdl, Petr and Sharma, Virender K. and Zboril, Radek, Title = Mechanisms and Efficiency of the Simultaneous Removal of Metals and Cyanides by Using Ferrate(VI): Crucial Roles of Nanocrystalline Iron(III) Oxyhydroxides and Metal Carbonates, Journal = CHEMISTRY-A EUROPEAN JOURNAL, Year = 2011, Volume = 17, Number = 36, Pages = 10097-10105, Month = AUG, Abstract = The reaction of potassium ferrate(VI), K(2)FeO(4), with weak-acid dissociable cyanides-namely, K(2)[Zn(CN)(4)], K(2)[Cd(CN)(4)], K(2)[Ni(CN)(4)], and K(3)[Cu(CN)(4)]-results in the formation of iron(III) oxyhydroxide nanoparticles that differ in size, crystal structure, and surface area. During cyanide oxidation and the simultaneous reduction of iron(VI), zinc(II), copper(II), and cadmium(II), metallic ions are almost completely removed from solution due to their co-precipitation with the iron(III) oxyhydroxides including 2-line ferrihydrite, 7-line ferrihydrite, and/or goethite. Based on the results of XRD, Mossbauer and IR spectroscopies, as well as TEM, X-ray photoelectron emission spectroscopy, and Brunauer-Emmett-Teller measurements, we suggest three scavenging mechanisms for the removal of metals including their incorporation into the ferrihydrite crystal structure, the formation of a separate phase, and their adsorption onto the precipitate surface. Zn and Cu are preferentially and almost completely incorporated into the crystal structure of the iron(III) oxyhydroxides; the formation of the Cd-bearing, X-ray amorphous phase, together with Cd carbonate is the principal mechanism of Cd removal. Interestingly, Ni remains predominantly in solution due to the key role of nickel(II) carbonate, which exhibits a solubility product constant several orders of magnitude higher than the carbonates of the other metals. Traces of Ni, identified in the iron(III) precipitate, are exclusively adsorbed onto the large surface area of nanoparticles. We discuss the relationship between the crystal structure of iron(III) oxyhydroxides and the mechanism of metal removal, as well as the linear relationship observed between the rate constant and the surface area of precipitates., DOI = 10.1002/chem.201100711, ISSN = 0947-6539, Unique-ID = ISI:000295357800031, - E. Kocourkova, O. Sracek, S. Houzar, J. Cempirek, Z. Losos, J. Filip, and P. Hrselova, “Geochemical and mineralogical control on the mobility of arsenic in a
waste rock pile at Dlouha Ves, Czech Republic,” JOURNAL OF GEOCHEMICAL EXPLORATION, vol. 110, iss. 2, pp. 61-73, 2011.
[Bibtex]@article ISI:000294238400002, Author = Kocourkova, E. and Sracek, O. and Houzar, S. and Cempirek, J. and Losos, Z. and Filip, J. and Hrselova, P., Title = Geochemical and mineralogical control on the mobility of arsenic in a waste rock pile at Dlouha Ves, Czech Republic, Journal = JOURNAL OF GEOCHEMICAL EXPLORATION, Year = 2011, Volume = 110, Number = 2, Pages = 61-73, Month = AUG, Abstract = A waste rock pile with initial high sulfide (10-20 wt.\%) and low carbonate content (1-2 wt.\%) located at Dlouha yes in the Czech Republic has been investigated in two profiles (excavation and outcrop) using powder X-ray diffraction, electron microprobe analysis, bulk composition analysis and Mossbauer spectroscopy. The mobility of arsenic and other contaminants was evaluated by leaching experiments. The primary source of the arsenic was arsenopyrite, which was significantly oxidized in both profiles. The principal As-bearing phase at the excavation profile was goethite, located at the top of the profile, and minerals of the jarosite group which were found down to its base. Melanterite, rich in copper and zinc, was found in a sulfide-rich, lower part of the profile together with anglesite. At the outcrop profile, minerals of the jarosite-beudantite group, scorodite and kankite prevail and no Fe(II)-minerals were found. The paste pH was lower at the excavation profile (minimum about 1.9) than at the outcrop profile (minimum of about 2.8). Processes in the pile are affected by the pyrite/arsenopyrite ratio, where high pyrite content decreases the As/S ratio and results in the formation of jarosite group minerals and low pH conditions. Where arsenopyrite predominates, sulphides are coated by scorodite and other Fe-As phases like schwertmannite, which limit their further oxidation. Arsenic concentrations released during the leaching experiments were generally low; maximum amounts (up to 0.56 ppm) were released from horizons with jarosite and arsenopyrite. In contrast, minimum amounts of arsenic were released from horizons with beudantite and scorodite. Melanterite found at the excavation profile was fully soluble, releasing copper and zinc into the solution. Differences between both profiles are caused especially by the different degrees of water flow through the pile material and the limited penetration of oxygen into the deep parts of the excavation profile. It seems that beudantite and scorodite represent a long-term option for immobilization of arsenic, but arsenic stored in jarosite can be mobilized relatively easily. Highly soluble Fe( II) minerals such as melanterite may represent an environmental problem. However, potential mineralogical transformations and stability of arsenic in beudantite group minerals have yet to be evaluated. (C) 2011 Elsevier B.V. All rights reserved., DOI = 10.1016/j.gexplo.2011.02.009, ISSN = 0375-6742, Unique-ID = ISI:000294238400002, - R. Prucek, J. Tucek, M. Kilianova, A. Panacek, L. Kvitek, J. Filip, M. Kolar, K. Tomankova, and R. Zboril, “The targeted antibacterial and antifungal properties of magnetic
nanocomposite of iron oxide and silver nanoparticles,” BIOMATERIALS, vol. 32, iss. 21, pp. 4704-4713, 2011.
[Bibtex]@article ISI:000291571400003, Author = Prucek, Robert and Tucek, Jiri and Kilianova, Martina and Panacek, Ales and Kvitek, Libor and Filip, Jan and Kolar, Milan and Tomankova, Katerina and Zboril, Radek, Title = The targeted antibacterial and antifungal properties of magnetic nanocomposite of iron oxide and silver nanoparticles, Journal = BIOMATERIALS, Year = 2011, Volume = 32, Number = 21, Pages = 4704-4713, Month = JUL, Abstract = Two types of magnetic binary nanocomposites, Ag@Fe(3)O(4) and gamma-Fe(2)O(3)@Ag, were synthesized and characterized and their antibacterial activities were tested. As a magnetic component, Fe(3)O(4) (magnetite) nanoparticles with an average size of about 70 nm and monodisperse gamma-Fe(2)O(3) (maghemite) nanoparticles with an average size of 5 nm were used. Nanocomposites were prepared via in situ chemical reduction of silver ions by maltose in the presence of particular magnetic phase and molecules of polyacrylate serving as a spacer among iron oxide and silver nanoparticles. In the case of the Ag@Fe(3)O(4) nanocomposite, silver nanoparticles, caught at the surfaces of Fe(3)O(4) nanocrystals, were around 5 nm in a size. On the contrary, in the case of the gamma-Fe(2)O(3)@Ag nanocomposite, ultrafine gamma-Fe(2)O(3) nanoparticles surrounded silver nanoparticles ranging in a size between 20 and 40 nm. In addition, the molecules of polyacrylate in this nanocomposite type suppress considerably interparticle magnetic interactions as proved by magnetization measurements. Both synthesized nanocomposites exhibited very significant antibacterial and antifungal activities against ten tested bacterial strains (minimum inhibition concentrations (MIC) from 15.6 mg/L to 125 mg/L) and four candida species (MIC from 1.9 mg/L to 31.3 mg/L). Moreover, acute nanocomposite cytotoxicity against mice embryonal fibroblasts was observed at concentrations of higher than 430 mg/L (Ag@Fe(3)O(4)) and 292 mg/L (gamma-Fe(2)O(3)@Ag). With respect to the non-cytotoxic nature of the polyacrylate linker, both kinds of silver nanocomposites are well applicable for a targeted magnetic delivery of silver nanoparticles in medicinal and disinfection applications. (C) 2011 Elsevier Ltd. All rights reserved., DOI = 10.1016/j.biomaterials.2011.03.039, ISSN = 0142-9612, Unique-ID = ISI:000291571400003, - V. Prochazka, H. Stepankova, V. Chlan, J. Tucek, J. Cuda, K. Kouril, J. Filip, and R. Zboril, “Electric field gradient in FeTiO(3) by nuclear magnetic resonance and ab
initio calculations,” JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 23, iss. 20, 2011.
[Bibtex]@article ISI:000290212300014, Author = Prochazka, V. and Stepankova, H. and Chlan, V. and Tucek, J. and Cuda, J. and Kouril, K. and Filip, J. and Zboril, R., Title = Electric field gradient in FeTiO(3) by nuclear magnetic resonance and ab initio calculations, Journal = JOURNAL OF PHYSICS-CONDENSED MATTER, Year = 2011, Volume = 23, Number = 20, Month = MAY 25, Abstract = Temperature dependence of nuclear magnetic resonance (NMR) spectra of (47)Ti and (49)Ti in polycrystalline ilmenite FeTiO(3) was measured in the range from 5 to 300 K under an external magnetic field of 9.401 T. NMR spectra collected between 300 and 77 K exhibit a resolved quadrupole splitting. The electric field gradient (EFG) tensor was evaluated for Ti nuclei and the ratio of (47)Ti and (49)Ti nuclear quadrupole moments was refined during the fitting procedure. Below 77 K, the fine structure of quadrupole splitting disappears due to the enormous increase of anisotropy. As a counterpart, ab initio calculations were performed using full potential augmented plane waves + local orbitals. The calculated EFG tensors for Ti and Fe were compared to the experimental ones evaluated from NMR and the Mossbauer spectroscopy experiments., DOI = 10.1088/0953-8984/23/20/205503, Article-Number = 205503, ISSN = 0953-8984, Unique-ID = ISI:000290212300014, - M. Novak, R. Skoda, J. Filip, I. Macek, and T. Vaculovic, “COMPOSITIONAL TRENDS IN TOURMALINE FROM INTRAGRANITIC NYF PEGMATITES OF
THE TREBIC PLUTON, CZECH REPUBLIC: AN ELECTRON MICROPROBE, MOSSBAUER AND
LA-ICP-MS STUDY,” CANADIAN MINERALOGIST, vol. 49, iss. 1, pp. 359-380, 2011.
[Bibtex]@article ISI:000288240400023, Author = Novak, Milan and Skoda, Radek and Filip, Jan and Macek, Ivo and Vaculovic, Tomas, Title = COMPOSITIONAL TRENDS IN TOURMALINE FROM INTRAGRANITIC NYF PEGMATITES OF THE TREBIC PLUTON, CZECH REPUBLIC: AN ELECTRON MICROPROBE, MOSSBAUER AND LA-ICP-MS STUDY, Journal = CANADIAN MINERALOGIST, Year = 2011, Volume = 49, Number = 1, Pages = 359-380, Month = FEB, Abstract = Tourmalines (dravite - schorl - uvite - povondraite) from intragranitic pegmatites of the Trebic Pluton (porphyritic, amphibole-biotite melasyenite to quartz melasyenite - melagranite), in the Czech Republic, were examined using an electron microprobe, Mossbauer spectroscopy and LA-ICP-MS analyses. Pegmatites with the common assemblage Kfs + qtz + pl (An(0-13)) + Fe-rich phlogopite (0.49 < X(Mg) < 0.70) and accessory allanite-(Ce), ilmenite, tourmaline and titanite, were divided into three types generally related to the NYF (REL-REE) pegmatites: allanite- type, euxenite-type (+ euxenite, aeschynite, pyrochlore, beryl, niobian rutile, zircon), and the most evolved euxenite-type pegmatite, Klucov I ( with annite, X(Mg) 0.09), cassiterite, herzenbergite, and abundant graphic intergrowths of quartz + feldspars and quartz + tourmaline). Black tourmaline occurs in several distinct morphological, paragenetic and textural types with very high variability in zoning; however, the morphological types of tourmaline do not differ chemically. They generally show two distinct trends: Fe(tot)/(Fe(tot) + Mg) = 0.243-0.882, 0.657-0.978; Al(tot) = 5.039-6.464, 5.040-7.030 apfu; Ca <= 0.508, <= 0.174 apfu; Mn <= 0.079, <= 0.445, respectively. High concentrations of Ti <= 0.490, <= 0.361 apfu are typical, as well as low F, <= 0.288, 0.046-0.508 apfu, and low vacancy at the X site, 0.152, 0.348 pfu, respectively. Mossbauer spectroscopy revealed similar to 21\% of the Fe as Fe(3+) for allanite- type, 17 to 26\% for euxenite-type, and 22\% for tourmaline from the pegmatite Klucov I, respectively, values that are high relative to ordinary granitic pegmatites. Our LA-ICP-MS study revealed highly variable concentrations of the individual trace elements within single grains and within the individual types of pegmatites. Explicit compositional evolution from less to highly evolved pegmatites was revealed only rarely, e. g., increase in Ni, Co, Zn, Ga, Sc and Ce from less to more evolved pegmatites. Two distinct sets of substitutions are dominant: R(3+)O R(2+) (-1)(OH)(-1) and square R(3+) Na(-1)R(2+) (-1). In addition, there are minor substitutions, CaR(2+) Na(-1)Al(-1), Fe(2+) Mg(-1) and MnF Fe(2+) (-1)(OH)(-1), the latter exclusively at Klucov I. They are similar to those from ordinary Li-poor to slightly Li-enriched granitic pegmatites. Tourmalines from allanite- type and euxenite-type pegmatites exhibit less convincing plots, with the dominant substitutions CaR(2+) (3)O(2) Na(-1)R(3+) (-3)(OH)(-2) and Fe(2+) Mg(-1), and minor Al Fe(3+) (-1). High contents of Ti(4+) imply the presence of the component (X)Ca(2+) (Y)R(2+) (1.5) (Y)Ti(1.5) (Z)R(3+) (5) (Z)Mg(2+) Si(6)O(18) (BO(3))(3)O(3)(OH). These substitutions are different from those normally encountered in granitic pegmatites, but show some features of non-pegmatitic Fe(3+)-enriched tourmalines. Textural relations suggest very late solidus to early subsolidus origin of the tourmaline. Discussions of a tourmaline's stability in moderately aluminous granitic systems is shifted to the role of tourmaline composition along with the melt's composiion., DOI = 10.3749/canmin.49.1.359, ISSN = 0008-4476, Unique-ID = ISI:000288240400023, - S. Klimkova, M. Cernik, L. Lacinova, J. Filip, D. Jancik, and R. Zboril, "Zero-valent iron nanoparticles in treatment of acid mine water from in
situ uranium leaching," CHEMOSPHERE, vol. 82, iss. 8, pp. 1178-1184, 2011.
[Bibtex]@article ISI:000287432100016, Author = Klimkova, Stepanka and Cernik, Miroslav and Lacinova, Lenka and Filip, Jan and Jancik, Dalibor and Zboril, Radek, Title = Zero-valent iron nanoparticles in treatment of acid mine water from in situ uranium leaching, Journal = CHEMOSPHERE, Year = 2011, Volume = 82, Number = 8, Pages = 1178-1184, Month = FEB, Abstract = Acid mine water from in situ chemical leaching of uranium (Straz pod Ralskem, Czech Republic) was treated in laboratory scale experiments by zero-valent iron nanoparticles (nZVI). For the first time, nZVI were applied for the treatment of the real acid water system containing the miscellaneous mixture of pollutants, where the various removal mechanisms occur simultaneously. Toxicity of the treated saline acid water is caused by major contaminants represented by aluminum and sulphates in a high concentration, as well as by microcontaminants like As, Be, Cd, Cr, Cu, Ni, U, V. and Zn. Laboratory batch experiments proved a significant decrease in concentrations of all the monitored pollutants due to an increase in pH and a decrease in oxidation-reduction potential related to an application of nZVI. The assumed mechanisms of contaminants removal include precipitation of cations in a lower oxidation state, precipitation caused by a simple pH increase and co-precipitation with the formed iron oxyhydroxides. The possibility to control the reaction kinetics through the nature of the surface stabilizing shell (polymer vs. FeO nano-layer) is discussed as an important practical aspect. (C) 2010 Elsevier Ltd. All rights reserved., DOI = 10.1016/j.chemosphere.2010.11.075, ISSN = 0045-6535, Unique-ID = ISI:000287432100016, - O. Sracek, J. Filip, M. Mihaljevic, B. Kribek, V. Majer, and F. Veselovsky, "Attenuation of dissolved metals in neutral mine drainage in the Zambian
Copperbelt," ENVIRONMENTAL MONITORING AND ASSESSMENT, vol. 172, iss. 1-4, pp. 287-299, 2011.
[Bibtex]@article ISI:000284959400021, Author = Sracek, Ondra and Filip, Jan and Mihaljevic, Martin and Kribek, Bohdan and Majer, Vladimir and Veselovsky, Frantisek, Title = Attenuation of dissolved metals in neutral mine drainage in the Zambian Copperbelt, Journal = ENVIRONMENTAL MONITORING AND ASSESSMENT, Year = 2011, Volume = 172, Number = 1-4, Pages = 287-299, Month = JAN, Abstract = Behaviour of metals like Cu and Co was studied in nearly neutral (pH a parts per thousand yen 6.4) mine drainage seepage in a stream downgradient of a tailing dam at Chambishi site in the Copperbelt of Zambia. They are attenuated by precipitation of ferruginous ochres that incorporate significant quantities of metals. Using chemical analysis, X-ray powder diffraction and Mossbauer spectroscopy, we show that the ochres are composed mostly of amorphous ferric hydroxide. Close to the seepage face, the total Fe content of ochres increases due to precipitation of amorphous ferric hydroxide, but total Fe in sediment decreases further downstream. The stream then flows through wetland (dambo) where the remaining fraction of metals is removed. During rainy periods, increased flow rate may result in re-suspension of ochres, increasing thus the mobility of metals. Major ions like sulphate are conservative at the start of the dry period (May), but gypsum may probably precipitate later at the end of the dry period. Sequential extractions of bulk sediments indicate that Mn behaves differently to Fe, with a trend of increasing Mn with distance from the tailing dam. There is much more Fe than Mn in residual (Aqua Regia) fraction, indicating that amorphous ferric hydroxides are transformed to more crystalline phases deeper in sediment. Environmental impact of mine drainage is relatively limited due to its neutral character., DOI = 10.1007/s10661-010-1334-6, ISSN = 0167-6369, Unique-ID = ISI:000284959400021,
2010
- O. Schneeweiss, B. David, T. Zak, J. Filip, J. Tucek, R. Zboril, and M. Maslan, "Magnetic Interactions between Nanoparticles Formed during Calcination of
Ferrihydrite," ACTA PHYSICA POLONICA A, vol. 118, iss. 5, pp. 749-750, 2010.
[Bibtex]@article ISI:000285797100015, Author = Schneeweiss, O. and David, B. and Zak, T. and Filip, J. and Tucek, J. and Zboril, R. and Maslan, M., Title = Magnetic Interactions between Nanoparticles Formed during Calcination of Ferrihydrite, Journal = ACTA PHYSICA POLONICA A, Year = 2010, Volume = 118, Number = 5, Pages = 749-750, Month = NOV, Note = 14th Czech and Slovak Conference on Magnetism, Kosice, SLOVAKIA, JUN 06-09, 2010, Organization = Safarik Univ, Fac Sci; Inst Phys, Slovak Acad Sci; Slovak Phys Soc, Abstract = Magnetic interactions between nanoparticles of magnetite Fe(3)O(4) and alpha-Fe Formed during calcination of ferrihydrite in H(2) at temperatures 533 - 713 K were studied The detailed phase analysis describes evolution of contents of magnetite and alpha-Fe Explanation of an anomalous course of magnetic moment characterized by a local maximum at an early stage of formation of nanoparticles is discussed, ISSN = 0587-4246, Unique-ID = ISI:000285797100015, - M. Novak and J. Filip, "UNUSUAL (Na,Mg)-ENRICHED BERYL AND ITS BREAKDOWN PRODUCTS (BERYL II,
BAZZITE, BAVENITE) FROM EUXENITE-TYPE NYF PEGMATITE RELATED TO THE
OROGENIC ULTRAPOTASSIC TREBIC PLUTON, CZECH REPUBLIC," CANADIAN MINERALOGIST, vol. 48, iss. 3, pp. 615-628, 2010.
[Bibtex]@article ISI:000280414600012, Author = Novak, Milan and Filip, Jan, Title = UNUSUAL (Na,Mg)-ENRICHED BERYL AND ITS BREAKDOWN PRODUCTS (BERYL II, BAZZITE, BAVENITE) FROM EUXENITE-TYPE NYF PEGMATITE RELATED TO THE OROGENIC ULTRAPOTASSIC TREBIC PLUTON, CZECH REPUBLIC, Journal = CANADIAN MINERALOGIST, Year = 2010, Volume = 48, Number = 3, Pages = 615-628, Month = JUN, Abstract = An intragranitic, euxenite-type NYF pegmatite, Kozichovice II, derived from the ultrapotassic orogenic Trebic syenogranite pluton, contains pale green prismatic crystals of primary beryl I, up to 3 cm long, arranged in radial aggregates. They are typically enclosed in massive quartz at the contact with albite or K-feldspar. Beryl I is locally altered to the secondary mineral assemblage beryl II + bavenite + bazzite + smectite. Electron-microprobe and LA-ICP-MS data yielded: slight indications of heterogeneity in beryl I, with high Na (0.20-0.32 apfu), Mg (0.24-0.38 apfu), moderate Fe(tot) (0.06-0.14 apfu), Sc (<= 0.06 apfu, 0.05-0.68 wt.\% Sc(2)O(3)), Cs (0.01-0.15 apfu, 0.23-3.65 wt.\% Cs(2)O), and very low Li (<= 80 ppm); secondary beryl II with high Na (0.24-0.34 apfu), low Fe(tot) (0.03-0.05 apfu), Sc (<= 0.02 apfu, <= 0.22 wt.\% Sc(2)O(3)), and Cs (<= 0.005 apfu; <= 0.14 wt.\% Cs(2)O); bazzite with high Na (0.38-0.48 apfu), Mg (0.41-0.64 apfu), Fe(tot) (0.09-0.33 apfu), Sc (1.13-1.22 apfu, 12.79-13.80 wt.\% Sc(2)O(3)), and moderate Ca (0.10-0.16 apfu, 0.91-1.53 wt.\% CaO). Low-temperature measurements (25 K) of (57)Fe Mossbauer spectra of beryl I yielded: (O,CH)Fe(2+) similar to 80\%, (T)Fe(2+) similar to 10\% and (O)Fe(3+) similar to 10\%. The substitutions: (1) (CH)square (O)R(3+) = (CH)R(+) (O)R(2+) where R(+) = Na, Cs, K, Rb; R(2+) = Mg, Fe(2+), Mn, Ca; R(3+) = Al, Sc, Fe(3+), and (2) (CH)square 2(O)R(3+) = (CH)Ca 2(O)R(2+) [or modified (CH)square (2)OR(3+) = (CH)(Ca,Fe(2+))2(O)R(2+)] were revealed. A sum of Na + K + Rb + Cs > 0.5 apfu found in bazzite from Kozichovice, Kazakhstan and Tordal, Telemark, Norway, suggests the existence of new phases related to bazzite via the substitution (1) with the general formula R(+)Be(3)R(3+)R(2+)Si(6)O(18) and idealized formulas Na(+)Be(3)ScMg(2+)Si(6)O(18) (Kozichovice) and Na(+)Be(3)ScFe(2+)Si(6)O(18) (Kazakhstan, Norway). Low Fe/(Fe + Mg) values, in the range 0.14-0.29 in beryl I, are similar to those in the other Fe, Mg minerals (biotite, tourmaline, amphibole) from the pegmatites of the Trebic pluton. The (Na, Mg, Fe)-enriched crystals of beryl examined are similar to various, but mostly non-pegmatitic environments rather than to NYF pegmatites, and support a rather unique bulk-composition and compositional evolution of minerals from granitic pegmatites of the Trebic pluton. The assemblage of secondary minerals after beryl I, including common bavenite and elevated Ca in bazzite, suggest a high activity of Ca in the late fluids, which is perhaps enhanced by very low contents of P and F in pegmatites of the Trebic pluton. We suggest a temperature slightly below 250-350 degrees C and neutral to slightly alkaline conditions for the formation of the secondary assemblage beryl II + bavenite + bazzite + smectite., DOI = 10.3749/canmin.48.3.615, ISSN = 0008-4476, Unique-ID = ISI:000280414600012, - C. Gregor, M. Hermanek, D. Jancik, J. Pechousek, J. Filip, J. Hrbac, and R. Zboril, "The Effect of Surface Area and Crystal Structure on the Catalytic
Efficiency of Iron(III) Oxide Nanoparticles in Hydrogen Peroxide
Decomposition," EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, iss. 16, pp. 2343-2351, 2010.
[Bibtex]@article ISI:000278888300003, Author = Gregor, Cenek and Hermanek, Martin and Jancik, Dalibor and Pechousek, Jiri and Filip, Jan and Hrbac, Jan and Zboril, Radek, Title = The Effect of Surface Area and Crystal Structure on the Catalytic Efficiency of Iron(III) Oxide Nanoparticles in Hydrogen Peroxide Decomposition, Journal = EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Year = 2010, Number = 16, Pages = 2343-2351, Month = JUN, Abstract = Iron(II) oxalate dihydrate has been used as a readily decomposable substance for the controlled synthesis of nanosized iron(III) oxides. The polymorphous composition, particle size and surface area of these iron oxide nanoparticles were controlled by varying the reaction temperature between 185 and 500 degrees C. As-prepared samples were characterized by XRD, low-temperature and in-field Mossbauer spectroscopy, BET surface area and the TEM technique. They were also tested as heterogeneous catalysts in hydrogen peroxide decomposition. At the selected temperatures, the formed nanomaterials did not contain any traces of amorphous phase, which is known to considerably reduce the catalytic efficiency of iron(III) oxide catalysts. As the thickness of the sample (approximate to 2 mm) was above the critical value, a temporary temperature increase (''exo effect'') was observed during all quasi-isothermal decompositions studied, irrespective of the reaction temperature. Increasing the reaction temperature resulted in a shift of the exo effect towards shorter times and an increased content of maghemite phase. The maghemite content decreases above 350 degrees C as a result of a thermally induced polymorphous transition into hematite. The catalytic data demonstrate that the crystal structure of iron(III) oxide (i.e. the relative contents of maghemite and hematite) does not influence the rate of hydrogen peroxide decomposition. However, the rate constant increases monotonously with increasing sample surface area (and decreasing thermolysis temperature), reaching a maximum of 27 x 10(-3) min(-1)(g/L)(-1) for the sample with a surface area of 285 m(2)g(-1). This rate constant is currently the highest reported value of all known iron oxide catalytic systems and is even slightly higher than that observed for the most efficient catalyst reported to date, which has a significantly larger surface area of 337 m(2)g(-1). This surprisingly high catalytic activity at relatively low surface area can be ascribed to the absence of a amorphous phase in the samples prepared in this study. Taking into account these new findings, the contributions of the key factors highlighted above (surface area, particle size, crystal structure, crystallinity) to the overall activity of iron oxides for hydrogen peroxide decomposition are discussed., DOI = 10.1002/ejic.200901066, ISSN = 1434-1948, Unique-ID = ISI:000278888300003, - C. Aparicio, J. Filip, and M. Mashlan, "High Temperature Decomposition of Almandine and Pyrope in Reducing
Atmosphere," in MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE - 2010, 2010, pp. 47-54.
[Bibtex]@inproceedings ISI:000281606200007, Author = Aparicio, C. and Filip, J. and Mashlan, M., Editor = Tucek, J and Miglierini, M, Title = High Temperature Decomposition of Almandine and Pyrope in Reducing Atmosphere, Booktitle = MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE - 2010, Series = AIP Conference Proceedings, Year = 2010, Volume = 1258, Pages = 47-54, Note = International Conference on Mossbauer Spectroscopy in Materials Science, Liptovsky Jan, SLOVAKIA, JAN 31-FEB 05, 2010, Abstract = Thermal decomposition of two garnets of near end-member composition - almandine (Fe(2.85)Mg(0.15))(Al(1.99))Si(2.99)O(12) and pyrope (Mg(2.22)Fe(0.47)Ca(0.33))(Cr(0.11)Fe(0.06)Al(1.81))Si(2.98)O(12) has been carried out in reducing atmosphere (forming gas: 10\% of H(2) in N(2)). High-temperature behavior of both samples was monitored using simultaneous thermogravimetry and differential scanning calorimetry. The decomposition of almandine and pyrope turned out to proceed at slightly different temperatures above 1000 C. Therefore, two series of samples were prepared based on the results of thermal analysis: almandine heated up to 950 degrees C, 1070 degrees C and 1200 degrees C, and pyrope heated up to 1000 degrees C, 1100 degrees C, 1125 degrees C and 1200 degrees C. The identification of the decomposition products was performed by X-ray powder diffraction and Mossbauer spectroscopy. The common feature of the decomposition of both garnets is the presence of metallic iron and spinet phase, while the other products include fayalite, cristobalite, and cordierite for almandine; and enstatite and anorthite for pyrope. The formation of this last component was enabled due to Ca content in pyrope., DOI = 10.1063/1.3473898, ISSN = 0094-243X, ISBN = 978-0-7354-0806-7, Unique-ID = ISI:000281606200007,
2009
- L. Machala, R. Zboril, V. K. Sharma, J. Filip, D. Jancik, and Z. Homonnay, "Transformation of Solid Potassium Ferrate(VI) (K(2)FeO(4)): Mechanism
and Kinetic Effect of Air Humidity," EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, iss. 8, pp. 1060-1067, 2009.
[Bibtex]@article ISI:000264683200010, Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Filip, Jan and Jancik, Dalibor and Homonnay, Zoltan, Title = Transformation of Solid Potassium Ferrate(VI) (K(2)FeO(4)): Mechanism and Kinetic Effect of Air Humidity, Journal = EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Year = 2009, Number = 8, Pages = 1060-1067, Month = MAR, Abstract = The kinetics of solid-state transformation (aging) of potassium ferrate(VI) (K(2)FeO(4)) under various air-humidity conditions (55-95\% relative humidity) at room temperature were studied by in-situ Mossbauer spectroscopy. The kinetic data showed a significant increase in the decomposition rate with increasing air humidity. The decomposition kinetics is very unusual with two almost linear decay steps. The first slow decay was observable at rather lower humidity levels (55-70\%) probably due to the formation of the narrow compact layer of nanoparticulate Fe(OH)(3) reaction product. This layer limits the access of both H(2)O and CO(2) participating in the reaction as the gaseous reactants. The second decay with much faster rate showed a nearly positive linear relationship with the humidity. The identification and characterization of the final products of aging were conducted by using X-ray diffraction (XRD), variable-temperature and in-field Mossbauer spectroscopy, magnetic measurements, thermogravimetry (TG) and differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) techniques. The reaction mechanism, assuming formation of KHCO(3) and Fe(OH)(3) in the molar ratio of 2:1 per 1 mol of solid K(2)FeO(4) was suggested. The SEM images revealed the formation of large KHCO(3) crystallites whose surface was covered by ultrasmall X-ray amorphous iron(III) hydroxide nanoparticles in a high degree of agglomeration. The obtained results of aging under humid conditions are important for the possible storage of K(2)FeO(4) and thus for its environmental and industrial applications. ((C) Wiley-VCH Verlag GmbH \& Co. KGaA, 69451 Weinheim, Germany, 2009), DOI = 10.1002/ejic.200801068, ISSN = 1434-1948, Unique-ID = ISI:000264683200010,
2008
- R. A. Yngard, V. K. Sharma, J. Filip, and R. Zboril, "Ferrate(VI) oxidation of weak-acid dissociable cyanides," ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 42, iss. 8, pp. 3005-3010, 2008.
[Bibtex]@article ISI:000254890400054, Author = Yngard, Ria A. and Sharma, Virender K. and Filip, Jan and Zboril, Radek, Title = Ferrate(VI) oxidation of weak-acid dissociable cyanides, Journal = ENVIRONMENTAL SCIENCE \& TECHNOLOGY, Year = 2008, Volume = 42, Number = 8, Pages = 3005-3010, Month = APR 15, Abstract = Cyanide is commonly found in electroplating, mining, coal gasification, and petroleum refining effluents, which require treatment before being discharged. Cyanide in effluents exists either as free cyanide or as a metal complex. The kinetics of the oxidation of weak-acid dissociable cyanides by an environmentally friendly oxidant, ferrate(VI) ((FeO42-)-O-VI , Fe(Vl)), were studied as a function of pH (9.1-10.5) and temperature (15-45 degrees C) using a stopped-flow technique. The weak-acid dissociable cyanides were Cd(CN)(4)(2-) and Ni(CN)(4)(2-), and the rate-laws for the oxidation maybe -d[Fe(Vl)]/dt=k[Fe(VI)][M(CN)(4)(2-)](n) where n = 0.5 and 1 for Cd(CN)(4)(2-) and Ni(CN)(4)(2-), respectively. The rates decreased with increasing pH and were mostly related to a decrease in concentration of the reactive protonated Fe(VI) species, HFeO4-. The stoichiometries with Fe(VI) were determined to be: 4HFeO(4-) + M(CN)(4)(2-) + 6H(2)O -> 4Fe(OH)(3) + M2+ + 4NCO(-) + O-2 + 40H(-). Mechanisms are proposed that agree with the observed reaction rate-laws and stoichiometries of the oxidation of weak-acid dissociable cyanides by Fe(VI). Results indicate that Fe(VI) is effective in removing cyanide in coke oven plant effluent, where organics are also present., DOI = 10.1021/es0720816, ISSN = 0013-936X, Unique-ID = ISI:000254890400054, - J. Filip, E. Dachs, J. Tucek, M. Novak, and P. Bezdicka, "Low-temperature calorimetric and magnetic data for natural end-members
of the axinite group," AMERICAN MINERALOGIST, vol. 93, iss. 4, pp. 548-557, 2008.
[Bibtex]@article ISI:000254657600007, Author = Filip, Jan and Dachs, Edgar and Tucek, Jiri and Novak, Milan and Bezdicka, Petr, Title = Low-temperature calorimetric and magnetic data for natural end-members of the axinite group, Journal = AMERICAN MINERALOGIST, Year = 2008, Volume = 93, Number = 4, Pages = 548-557, Month = APR, Abstract = The low-temperature heat capacities of natural near end-member minerals (about 95 mol\%, except tinzenite of about 34 mol\% on average) of the axinite group, previously characterized in detail by means of powder and single-crystal X-ray diffraction, electron microprobe, and Mossbauer spectroscopy, were measured by heat-pulse calorimetry using the Physical Properties Measurement System (Quantum Design) at temperatures between 5(2) and 300 K. From these data, the following entropy values [in J/(mol center dot K)] of the natural samples at 298.15 K were derived: S-298,S-magnesioaxinite = 696.3 +/- 1.1, S-298,S-ferroaxinite = 743.5 +/- 3.5, S-298,S-manganaxinite = 737.5 +/- 2.6, and S-298,S-tinzenite = 758.1 +/- 2.8. For the end-memeber compositions, the corrected heat capacities at 298.15 K and standard third-law entropies of the axinites are [all in J/(mol center dot K)]: C-Pmagnesioaxinite degrees = 827.5 +/- 1.5 and S-magnesioaxinite degrees = 693.7 +/- 1.1, C-Pferroaxinite degrees = 841.8 +/- 3.3 and S-ferroaxinite degrees = 749.6 +/- 3.5, C-Pmanganaxinite degrees (=) 849.1 +/- 2.5 and S-manganaxinite degrees = 737.8 +/- 2.6, and C-Ptinzenite degrees = 841.6 +/- 2.6, S-tinzenite degrees = 754.0 +/- 2.8. The standard entropies of manganaxinite and tinzenite include contributions of 1.9 and 4.3 J/(mol center dot K) for the range 0-5 K evaluated based on a Schottky anomaly fitted to the low-T C-P values of these axinites. The lowest measured heat capacities of ferroaxinite indicate that a lambda-type C-P anomaly should exist between 0 and 2 K. Its likely contribution to the standard entropy was estimated as similar to 5.2 J/(mol center dot K). A low-temperature C-P anomaly below 15 K for ferroaxinite is well-explained by ferromagnetic ordering, whereas for manganaxinite by uncompensated antiferromagnetic ordering, and ferromagnetic by pure antiferromagnetic ordering., DOI = 10.2138/am.2008.2680, ISSN = 0003-004X, Unique-ID = ISI:000254657600007,
2007
- J. Filip, R. Zboril, O. Schneeweiss, J. Zeman, M. Cernik, P. Kvapil, and M. Otyepka, "Environmental applications of chemically pure natural ferrihydrite," ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 41, iss. 12, pp. 4367-4374, 2007.
[Bibtex]@article ISI:000247187600026, Author = Filip, Jan and Zboril, Radek and Schneeweiss, Oldrich and Zeman, Josef and Cernik, Miroslav and Kvapil, Petr and Otyepka, Michal, Title = Environmental applications of chemically pure natural ferrihydrite, Journal = ENVIRONMENTAL SCIENCE \& TECHNOLOGY, Year = 2007, Volume = 41, Number = 12, Pages = 4367-4374, Month = JUN 15, Abstract = Fresh precipitates, deposited from seepage waters of complex-ore mine-tailing impoundment at Zlate Hory, Czech Republic, were characterized by means of X-ray diffraction, transmission electron microscopy, low temperature and in-field Mossbauer spectroscopy, and Brunauer-Emmett-Teller surface area measurements. The prevailing phases (similar to 96 wt \%) found in precipitates are poorly crystalline, 2-6 nm sized two-line ferrihydrite, forming globular aggregates of about 150 nm in diameter, rimmed by acicular irregular nanocrystals of goethite. These nanocrystalline ferrihydrite-goethite precipitates are of a relatively high chemical purity (similar to 3\% SiO2, Zn similar to 1300 ppm, trace and rare earth elements < 100 ppm) and thus applicable in various nanotechnologies. With a surface area of 270 m(2) g(-1), precipitate possesses a high catalytic activity in the decomposition of hydrogen peroxide, which is comparable with that found for commercially accessible FeO(OH) catalyst. Another superior aspect of such natural nanoparticles presents a cheap and suitable precursor for a thermally induced solid-state synthesis of the stable core-shell alpha-Fe-FeO nanoparticles that are well applicable in reductive technologies of groundwater treatment. Just the possibility of using the undesirable waste contaminating the environment in further environmental technologies is the key practical benefit discussed in this paper., DOI = 10.1021/es062312t, ISSN = 0013-936X, Unique-ID = ISI:000247187600026, - L. Machala, R. Zboril, V. K. Sharma, J. Filip, O. Schneeweiss, and Z. Homonnay, "Mossbauer characterization and in situ monitoring of thermal
decomposition of potassium ferrate(VI), K(2)FeO(4) in static air
conditions," JOURNAL OF PHYSICAL CHEMISTRY B, vol. 111, iss. 16, pp. 4280-4286, 2007.
[Bibtex]@article ISI:000245797700035, Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Filip, Jan and Schneeweiss, Oldrich and Homonnay, Zoltan, Title = Mossbauer characterization and in situ monitoring of thermal decomposition of potassium ferrate(VI), K(2)FeO(4) in static air conditions, Journal = JOURNAL OF PHYSICAL CHEMISTRY B, Year = 2007, Volume = 111, Number = 16, Pages = 4280-4286, Month = APR 26, Abstract = Solid orthorhombic crystals of potassium ferrate(VI) (K(2)FeO(4)) of a high-chemical purity (> 99.0\%) were characterized by low-temperature (1.5-5 K), high-temperature (463-863 K), and in-field (1.5 K/3 T) Mossbauer spectroscopy. Potassium ferrate(VI) reveals a Neel magnetic transition temperature (T(N)) of similar to 3.8 K and a saturation hyperfine magnetic field of 13.8 T at 1.5 K. Spectral line intensities recorded below T(N) in an external magnetic field of 3 T manifest a perfect antiferromagnetic ordering. For the in situ monitoring of the thermal behavior of K(2)FeO(4), high-temperature Mossbauer data were combined with those obtained from thermogravimetry, differential scanning calorimetry, and variable-temperature X-ray diffraction measurements. Such in situ approach allowed the identification of the reaction products and intermediates and yielded the first experimental evidence for the participation of CO(2) in the decomposition process. As the primary conversion products, KFeO(2) and two potassium oxides in equivalent molar ratio, KO(2) and K(2)O, were suggested. However, the KO(2) phase is detectable with difficulty as it reacts very quickly with CO(2) from air resulting in the formation of K(2)CO(3). The presented decomposition model is consistent with thermogravimetric data giving the mass loss of 8.0\%, which corresponds to the participation of (1)/(6) mol of CO(2) and liberation of (3)/(4) mol of O(2) per 1 mol of K(2)FeO(4) (K(2)FeO(4) + (1)/(6)CO(2) -> KFeO(2) + (1)/(3)K(2)O + (1)/(6)K(2)CO(3) + (3)/(4)O(2)). An explanation of the multistage reaction mechanism has an important practical impact for the optimization of the solid-state synthesis of potassium ferrate(VI)., DOI = 10.1021/jp068272x, ISSN = 1520-6106, Unique-ID = ISI:000245797700035,
2006
- K. Barcova, M. Mashlan, R. Zboril, J. Filip, J. Podjuklova, K. Hrabovska, and P. Schaaf, "Phase composition of steel-enamel interfaces: Effects of chemical
pre-treatment," SURFACE & COATINGS TECHNOLOGY, vol. 201, iss. 3-4, pp. 1836-1844, 2006.
[Bibtex]@article ISI:000244477300181, Author = Barcova, K. and Mashlan, M. and Zboril, R. and Filip, J. and Podjuklova, J. and Hrabovska, K. and Schaaf, P., Title = Phase composition of steel-enamel interfaces: Effects of chemical pre-treatment, Journal = SURFACE \& COATINGS TECHNOLOGY, Year = 2006, Volume = 201, Number = 3-4, Pages = 1836-1844, Month = OCT 5, Abstract = Mossbauer spectroscopy in transmission geometry, performed simultaneously with conversion X-ray, and conversion electron Mossbauer spectroscopy, X-ray powder diffraction and electron microprobe analysis (EMPA), have been used to monitor the effects of a chemical pretreatment on the phase composition of a ``steel-enamel interface'' of a hot-rolled steel surface formed during a thermally induced coating process. In this comparative study, we have analysed both an untreated sample and a treated sample of a steel sheet with the surface pickled by dilute H2SO4 and passivated in Na2CO3 solution. A continuous magnetite layer covering the steel surface as a result of the chemical pre-treatment was identified by backscattering Mossbauer spectroscopy and EMPA. During a fusion process, well crystalline fayalite (Fe2SiO4) is formed at the phase boundary by the solid-state reaction of magnetite with the SiO2-based enamel matrix. Wustite (FeO) was detected as a product of oxidation of iron under the magnetite layer of the chemically pre-treated sample, whereas hematite represents a product of oxidation of magnetite. This wustite-magnetite-(hematite)-fayalite layered interface is rimmed by isometric metallic intricate network-forming particles with a composition of about Fe0.95Ni0.05 and which are related to a diffusion-reduction process of iron and/or to a reduction of Fe3+ in glass. In the case of chemically untreated steel, EMPA revealed a sharp phase boundary, rimmed again by Fe-based metallic particles. Magnetite covered by fayalite was occasionally observed in a few areas of the phase boundary. The presence of magnetite at the interface of the chemically untreated sample is due to a thermally induced air-oxidation of the alpha-Fe steel surface during an enamelling procedure. The surprising effect of the chemical pre-treatment, resulting in a lowering of adhesion of enamel on the steel surface, is discussed. (c) 2006 Elsevier B.V. All rights reserved., DOI = 10.1016/j.surfcoat.2006.03.015, ISSN = 0257-8972, Unique-ID = ISI:000244477300181, - J. Filip, U. Kolitsch, M. Novak, and O. Schneeweiss, "The crystal structure of near-end-member ferroaxinite from an
iron-contaminated pegmatite at Malesov, Czech Republic," CANADIAN MINERALOGIST, vol. 44, iss. Part 5, pp. 1159-1170, 2006.
[Bibtex]@article ISI:000241882100013, Author = Filip, Jan and Kolitsch, Uwe and Novak, Milan and Schneeweiss, Oldrich, Title = The crystal structure of near-end-member ferroaxinite from an iron-contaminated pegmatite at Malesov, Czech Republic, Journal = CANADIAN MINERALOGIST, Year = 2006, Volume = 44, Number = Part 5, Pages = 1159-1170, Month = OCT, Abstract = We have characterized ferroaxinite (up to 95 mol.\% of end-member composition) from a contaminated granitic pegmatite cutting the magnetite-rich portion of an Fe-skarn body near Malesov, Czech Republic, by means of electron-microprobe analysis, single-crystal X-ray diffraction, infrared spectroscopy and temperature-dependent Fe-57 Mossbauer spectroscopy. The following crystal-chemical formula was obtained: (VI)[Ca-2.00 Ca-2.00 (Fe1.832+Mn0.10Mg0.06)(Sigma 1.99) (Al1.97Fe0.043+)(Sigma 2.00) Al-2.00] (IV)[B2.00Si8.00] O-30 OH2.00. The crystal structure was refined to R(F) = 0.0184 for 4667 observed reflections with F-o > 4 sigma(F-o). We obtained the following Unit-cell parameters: a 7.152(1), b 9.206(2), c 8.962(2) angstrom, alpha 91.84(3), beta 99.17(3), gamma 77.33(3)degrees, V 569.86(19) angstrom(3). Relative to the other end-members of axinite group, the only significant differences of structural parameters occur at the Y site, where Fe2+ atoms predominate; the mean Y-O bond length is 2.229 angstrom. The unusually long Fe-O(14) bond (2.704 angstrom) of the distorted Y site suggests a [5 + 1] coordination rather than the previously reported distorted [6] coordination for the group. The scarcity of near-end-member ferroaxinite in nature is due to preferred incorporation of Mn into the structure. The formation of near-end-member ferroaxinite in the late stage of pegmatite evolution at Malesov was favored by high activity of Fe, and lack of Mn and Mg in parent low-temperature fluids., DOI = 10.2113/gscanmin.44.5.1159, ISSN = 0008-4476, Unique-ID = ISI:000241882100013, - L. Machala, R. Zboril, V. K. Sharma, J. Filip, and O. Schneeweiss, "New view on thermal behavior of K(2)FeO(4) in static air," ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 232, pp. 42-ENVR, 2006.
[Bibtex]@article ISI:000207781604643, Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Filip, Jan and Schneeweiss, Oldrich, Title = New view on thermal behavior of K(2)FeO(4) in static air, Journal = ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Year = 2006, Volume = 232, Pages = 42-ENVR, Month = SEP 10, ISSN = 0065-7727, Unique-ID = ISI:000207781604643, - K. Barcova, R. Zboril, M. Mashlan, Y. Jiraskova, J. Filip, J. Lunacek, and K. Hrabovska, "Influence of enamel ageing on mechanical properties and phase
composition of the steel-enamel system," SURFACE AND INTERFACE ANALYSIS, vol. 38, iss. 4, pp. 413-416, 2006.
[Bibtex]@article ISI:000237437100059, Author = Barcova, K and Zboril, R and Mashlan, M and Jiraskova, Y and Filip, J and Lunacek, J and Hrabovska, K, Title = Influence of enamel ageing on mechanical properties and phase composition of the steel-enamel system, Journal = SURFACE AND INTERFACE ANALYSIS, Year = 2006, Volume = 38, Number = 4, Pages = 413-416, Month = APR, Note = 11th European Conference on Applications of Surface and Interface Analysis, Vienna, AUSTRIA, SEP 25-30, 2005, Abstract = An effect of the enamel ageing on the mechanical properties and composition of the steel-enamel system was monitored by means of conversion electron and transmission Mossbauer spectroscopy, electron-microprobe analysis, thermogravimetry and microhardness measurement. Two enamels differing in the time delay between their preparation and application on the steel surface (1 day vs 30 days) were used for this comparative study. After the enamelling procedure, the qualitative phase composition of both samples is similar, including alpha-Fe, FeO, Fe(3)O(4), alpha-Fe(2)O(3), Fe(2)SiO(4) and the Fe-Ni particles. Despite this similar qualitative phase composition of differently aged enamels, the mechanical properties of the samples are significantly different. Copyright (C) 2006 John Wiley \& Sons, Ltd., DOI = 10.1002/sia.2288, ISSN = 0142-2421, Unique-ID = ISI:000237437100059, - B. David, N. Pizurova, O. Schneeweiss, P. Bezdicka, M. Klementova, J. Filip, R. Alexandrescu, F. Dumitrache, C. T. Fleaca, I. Voicu, and I. Morjan, "Multi-walled carbon nanotubes formed by condensed-phase conversions of
Fe-C-based nanopowder in vacuum," CZECHOSLOVAK JOURNAL OF PHYSICS, vol. 56, iss. E, pp. E51-E61, 2006.
[Bibtex]@article ISI:000249124100007, Author = David, B. and Pizurova, N. and Schneeweiss, O. and Bezdicka, P. and Klementova, M. and Filip, J. and Alexandrescu, R. and Dumitrache, F. and Fleaca, C. T. and Voicu, I. and Morjan, I., Title = Multi-walled carbon nanotubes formed by condensed-phase conversions of Fe-C-based nanopowder in vacuum, Journal = CZECHOSLOVAK JOURNAL OF PHYSICS, Year = 2006, Volume = 56, Number = E, Pages = E51-E61, Note = International Colloquium on Mossbauer Spectroscopy in Materials Science, Kocovce, SLOVAKIA, JUN 11-15, 2006, Abstract = We describe the formation of multi-walled carbon nanotubes (MWCNTs) which have grown during annealing at 800 degrees C of Fe-C-based nanopowder in vacuum. The Fe-C-based nanopowder was produced by a laser pyrolysis of gas-phase reactants. The as-synthesized and annealed samples were characterised by TEM, XRD, Mossbauer spectroscopy, Raman spectroscopy, and magnetic measurements. Under the TEM, MWCNTs were observed in the annealed sample. In addition, larger particles with the graphitic shells and various graphitic structures were found. XRD and Mossbauer analysis confirmed that only two iron phases were present in the annealed sample: alpha-Fe and Fe3C. Phase transformations taking place during the thermal treatment of the sample are discussed., DOI = 10.1007/s10582-006-0471-1, ISSN = 0011-4626, Unique-ID = ISI:000249124100007, - J. Filip, M. Novak, A. Beran, and R. Zboril, "Crystal chemistry and OH defect concentrations in spodumene from
different granitic pegmatites," PHYSICS AND CHEMISTRY OF MINERALS, vol. 32, iss. 10, pp. 733-746, 2006.
[Bibtex]@article ISI:000234687100009, Author = Filip, J and Novak, M and Beran, A and Zboril, R, Title = Crystal chemistry and OH defect concentrations in spodumene from different granitic pegmatites, Journal = PHYSICS AND CHEMISTRY OF MINERALS, Year = 2006, Volume = 32, Number = 10, Pages = 733-746, Month = JAN, Abstract = Thirty spodumene samples of distinct paragenetic types ( primary magmatic, secondary after petalite and hydrothermal) from variety of granitic pegmatites were characterized by electron microprobe, polarized FTIR spectroscopy and Mossbauer spectroscopy. The FTIR spectra of OH ( weak sharp pleochroic bands at 3,425, 3,410, 3,395 cm(-1) and in the 3,500 - 3,470 spectral region) are strongly polarized with maximum absorption parallel to n(gamma). The majority of OH dipoles are presumably generated by a partial replacement of O2 oxygen atoms with an orientation pointing above the Li vacancy site. The separation of the bands probably resulted from a replacement of the coordinating Al by Fe and Si by Al. Homogeneous spodumene mostly close to its ideal formula LiAlSi(2)O(6) shows Fe (0.00 - 0.10 apfu as Fe(3+); Fe(3+) >> Fe(2+)) and Na (0.00 - 0.04 apfu) as the only minor cations and Fe(3+) Al(-1) substitution up to 10 mol\% of the LiFe(3+) Si(2)O(6) component. Hydrogen concentrations (from 0.1 up to < 5 ppm H(2)O by weight) vary as a function of genetic type with the highest amounts in high-temperature magmatic spodumene. Differences among particular genetic types of spodumene are related to maximum solubility of OH in spodumene structure at given P - T conditions and at actual chemical composition of spodumene. OH defect concentrations in spodumene follow a trend, LT/LP pyroxenes containing lower hydrogen contents compared to HT/HP ones. The hydrogen contents in particular genetic types of spodumene and their decrease with decreasing T and P are consistent with petrologic models of the pegmatite ( sub) types formations., DOI = 10.1007/s00269-005-0051-0, ISSN = 0342-1791, Unique-ID = ISI:000234687100009,