DOCSLIB.ORG

Stabilization of Transition Metal Chromite Nanoparticles in Silica

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Stabilization of Transition Metal Chromite Nanoparticles in Silica World Academy of Science, Engineering and Technology International Journal of Chemical and Molecular Engineering Vol:8, No:11, 2014 6WDELOL]DWLRQ RI 7UDQVLWLRQ 0HWDO &KURPLWH1DQRSDUWLFOHV LQ 6LOLFD 0DWUL[ Jiri Plocek, Petr Holec, Simona Kubickova, Barbara Pacakova, Irena Matulkova, Alice Mantlikova, Ivan Nemec, Daniel NiznanskyJana Vejpravova Abstract—This article presents summary on preparation and temperature. The magnetic ordering is therefore characteristic characterization of zinc, copper, cadmium and cobalt chromite by a considerable spin frustration and strongly depend on nanocrystals, embedded in an amorphous silica matrix. The the chemical order (the spinel inversion, oxygen deficit etc.) ZnCr2O4/SiO2, CuCr2O4/SiO2, CdCr2O4/SiO2 and CoCr2O4/SiO2 nanocomposites were prepared by a conventional sol-gel method and on the cation site occupancy in the spinel structure [8] under acid catalysis. Final heat treatment of the samples was carried (diamagnetic, paramagnetic or JT active), respectively. ◦ out at temperatures in the range of 900 − 1200 C to adjust the The zinc chromite is known as a frustrated antiferromagnet phase composition and the crystallite size, respectively. The resulting with a complex coplanar spin structure below the Neel´ samples were characterized by Powder X-ray diffraction (PXRD), temperature, T = 12 K [9] and it is arguably the most High Resolution Transmission Electron Microscopy (HRTEM), N Raman/FTIR spectroscopy and magnetic measurements. Formation magnetically-frustrated system known so far. At room 3+ of the spinel phase was confirmed in all samples. The average size of temperature, it has a cubic crystal structure where Cr the nanocrystals was determined from the PXRD data and by direct ions form a network of pyrochlore-like lattice [10]. The particle size observation on HRTEM; both results were correlated. Curie-Weiss temperature is about 390 K, indicating strong The mean particle size (reviewed by HRTEM) was in the range from ∼ antiferromagnetic frustration, yet chromium spins remain in 4 to 46 nm. The results showed that the sol-gel method can be T effectively used for preparation of the spinel chromite nanoparticles a cooperative paramagnetic phase down to the N. There, embedded in the silica matrix and the particle size is driven by the a first-order phase transition from a cubic paramagnet to a type of the cation A2+ in the spinel structure and the temperature tetragonal antiferromagnet signals the end of distinct spin and of the final heat treatment. Magnetic properties of the nanocrystals lattice degrees of freedom. It is a unique example of the were found to be just moderately modified in comparison to the bulk so-called spin Jahn-Teller system [11]. phases. The other example with a diamagnetic cation, the cadmium Keywords—Chromite, Fourier transform infrared spectroscopy, chromite exhibits an elliptical spiral magnetic structure below agnetic properties, nanocomposites, Raman spectroscopy, Rietveld the T = 7.8 K and simultaneously reveals a dielectric anomaly refinement, sol-gel method, spinel. N at the TN [12]. The CdCr2O4 also undergoes a spin-Peierls-like lattice distortion at the TN [13], [14]. The lattice symmetry I. INTRODUCTION is lowered from cubic to tetragonal; the lattice is elongated 2+ 3+ along the c-axis, while it shrinks in the same direction in HROMITES with A Cr2 O4 formula are binary oxides, C where A2+ and Cr3+ are cations occupying tetrahedral the ZnCr2O4. It is also surprising that the magnitude of the (A) and octahedral (B) sites, respectively. The chromites are distortion is larger in the Zn compound with weaker magnetic considered as materials with variety of potential applications interactions. 2+ ranging from high-temperature ceramics [1], catalysis [2], While less common, tetrahedral Cu on the A site semiconductors [3]–[6] to electrochemical sensors [7]. of the spinel network also displays JT activity, with the T At high-enough temperatures, the chromites crystallize relatively high JT temperature, JT = 830 K, resulting in the in a cubic structure (space group Fd-3m), with 56 atoms tetragonal structure (space group I41/amd). This distortion per unit cell (Z = 8). The 3d3 electron configuration of lowers symmetry by compressing the tetrahedron and thereby 3+ breaking the degeneracy of the partially-occupied t2 energy Cr is very stable because each of the t2g energy level is singly occupied, so there is no tendency of site mixing or levels [15]. Magnetic properties of the copper chromite have mixed valence. In the chromites with Jahn-Teller (JT) active been rarely investigated, it is reported as a hard ferromagnet International Science Index, Chemical and Molecular Engineering Vol:8, No:11, 2014 waset.org/Publication/9999702 T A2+ cations, the collective JT distortions on the A-cations with the Curie temperature, C = 135 K. 2+ 7 results in a reduction in symmetry from cubic Fd-3m to Cobalt chromite samples with magnetic Co (d ) cations develop below TC = 94 K long-range ferrimagnetic order, and tetragonal I41/amd upon orbital ordering at the transition moreover exhibits a sharp phase transition at TS =27K to J.Plocek and P.Holec are with the Institute of Inorganic Chemistry, v.v.i., the onset of long-range spiral magnetic order [16], [17]. Academy of Sciences of the CR, 250 68 Rez, Czech Republic. Magneto-capacitive measurements show that the dielectric P.Holec, I.Matulkova, I.Nemec and D.Niznansky are with the Charles University Prague, Faculty of Science, Department of Inorganic Chemistry, constant of CoCr2O4 couples to the spiral magnetic order Hlavova 2030, 128 40, Prague 2, Czech Republic. parameter, but is insensitive to the ferrimagnetic spin S.Kubickova, B.Pacakova, A.Mantlikova and J.Vejpravova are with the component [18]. Institute of Physics, v.v.i., Academy of Sciences of the CR, Na Slovance 2, 18221 Prague, Czech Republic (corresponding author J.Vejpravova to provide phone: +420-266-052-325; fax: +420-286-890-527; e-mail: [email protected]). International Scholarly and Scientific Research & Innovation 8(11) 2014 1219 scholar.waset.org/1307-6892/9999702 World Academy of Science, Engineering and Technology International Journal of Chemical and Molecular Engineering Vol:8, No:11, 2014 As is known, the magnetic properties such as saturation The size and shape of prepared nanocomposites were magnetization, remanent magnetization and coercivity, analyzed on a HRTEM JEOL JEM 3010 (High-Resolution respectively, depend strongly on the particles size and Transmission Electron Microscope). Particle size distribution microstructure of the materials. In case of the spinel was obtained by manual measurement and statistical chromites, significant change of magnetic order and hence evaluation of large-scale projected images. Elemental dielectric response is expected upon reduction of the particle composition of nanoparticles was verified by EDS size below a coherence length of the spiral component of the (Energy-dispersive X-ray spectroscopy) analysis. magnetic structure [17], [19]. Therefore it is important to use The infrared spectra were recorded on a Thermo Scientific a proper technique by which both the size and the shape of Nicolet 6700 FTIR spectrometer (2 cm-1 resolution, KBr particles can be well controlled. One of the ways to prepare beamsplitter, DTGS detector, Happ-Genzel apodization) in the nanocrystals with the required properties represents the the 400 - 4000 cm-1 region using nujol mull (KBr windows) sol-gel method [20], [21]. The advantages of this method technique. The FAR IR spectra were recorded down to 50 cm-1 are namely a good homogeneity of the final materials, low (4 cm-1 resolution, Solid SubstrateTM beamsplitter, DTGS temperatures of the treatment, and control of the particle detector, Happ-Genzel apodization) in PE pellets. size by final heat treatment. On the other hand, to stabilize The Raman spectra were recorded on a Thermo a ternary spinel phase in silica matrix, which has an acidic Scientific DXR Raman Microscope interfaced to an nature, is a challenging task. Olympus microscope (objective 50x) in the 50 - 1900 cm-1 In this work we focused on optimization of the fabrication spectral region with ∼ 3cm-1 resolution. The power of procedure in order to obtain single phase transition metal frequency-stabilized single mode diode laser (780 nm) chromite nanoparticles, embedded in the silica matrix. The impinging on the sample was ranging from 1 to 4 mW. optimized samples were investigated by varied of experimental The spectrometer was calibrated by software-controlled techniques and results of structure characterization and calibration procedure using multiple neon emission lines magnetic properties are presented. Moreover, the impact of (wavelength calibration), multiple polystyrene Raman bands the size reduction on magnetic order in selected ACr2O4 is (laser frequency calibration) and standardized white light also discussed. sources (intensity calibration). Magnetic properties were measured using a commercial 7 T - SQUID magnetometer (MPMS by Quantum Design) in the II. EXPERIMENTAL temperature range 2 - 350 K. A. Materials Preparation The conventional sol-gel method using TEOS, HNO3 III. RESULTS AND DISCUSSION as an acid catalyst, formamide as a modifier, and A. Powder X-ray Diffraction Measurement methanol as a solvent, was used for preparation of the The PXRD measurements were carried out on all samples nanocomposites. The sol was prepared by dissolving of and are shown in Fig. 1. Phase compositions (of selected the corresponding amount of the Cr(NO ) ·9H O and 3 3 2 samples) are summarized in the Table I. All samples contained the Zn(NO ) ·6H O, Cu(NO ) ·3H O, Cd(NO ) ·4H O, or 3 2 2 3 2 2 3 2 2 spinel phase, together with the other impurity phases in some Co(NO ) ·6H O, respectively, in methanol. The Si/Cr molar 3 2 2 cases, as will be discussed further. In some samples, the ratio was 5/1, which corresponds to the SiO /ACr O (where 2 2 4 shape of the spinel phase diffraction peaks with the steep A = Zn, Cu, Cd, and Co) molar ratio of 10/1.
Load more

Recommended publications
  • Coulsonite Fev2o4—A Rare Vanadium Spinel Group Mineral in Metamorphosed Massive Sulfide Ores of the Kola Region, Russia
    minerals Article Coulsonite FeV2O4—A Rare Vanadium Spinel Group Mineral in Metamorphosed Massive Sulfide Ores of the Kola Region, Russia Alena A. Kompanchenko Geological Institute of the Federal Research Centre “Kola Science Centre of the Russian Academy of Sciences”, 14 Fersman Street, 184209 Apatity, Russia; [email protected]; Tel.: +7-921-048-8782 Received: 24 August 2020; Accepted: 21 September 2020; Published: 24 September 2020 Abstract: This work presents new data on a rare vanadium spinel group mineral, i.e., coulsonite FeV2O4 established in massive sulfide ores of the Bragino occurrence in the Kola region, Russia. Coulsonite in massive sulfide ores of the Bragino occurrence is one of the most common vanadium minerals. Three varieties of coulsonite were established based on its chemical composition, some physical properties, and mineral association: coulsonite-I, coulsonite-II, and coulsonite-III. Coulsonite-I forms octahedral crystal clusters of up to 500 µm, and has a uniformly high content of 2 Cr2O3 (20–30 wt.%), ZnO (up to 4.5 wt.%), and MnO (2.8 wt.%), high microhardness (743 kg/mm ) and coefficient of reflection. Coulsonite-II was found in relics of quartz–albite veins in association with other vanadium minerals. Its features are a thin tabular shape and enrichment in TiO2 of up to 18 wt.%. Coulsonite-III is the most common variety in massive sulfide ores of the Bragino occurrence. Coulsonite-III forms octahedral crystals of up to 150 µm, crystal clusters, and intergrowths with V-bearing ilmenite, W-V-bearing rutile, Sc-V-bearing senaite, etc. Chemical composition of coulsonite-III is characterized by wide variation of the major compounds—Fe, V, Cr.
    [Show full text]
  • Synthesis, Properties and Uses of Chromium-Based Pigments from The
    Synthesis, properties and uses of chromium-based pigments from the Manufacture de Sèvres Louisiane Verger, Olivier Dargaud, Mathieu Chassé, Nicolas Trcera, Gwenaëlle Rousse, Laurent Cormier To cite this version: Louisiane Verger, Olivier Dargaud, Mathieu Chassé, Nicolas Trcera, Gwenaëlle Rousse, et al.. Syn- thesis, properties and uses of chromium-based pigments from the Manufacture de Sèvres. Journal of Cultural Heritage, Elsevier, 2018, 30, pp.26 - 33. 10.1016/j.culher.2017.09.012. hal-01777923 HAL Id: hal-01777923 https://hal.sorbonne-universite.fr/hal-01777923 Submitted on 25 Apr 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Synthesis, Properties and Uses of Chromium-Based Pigments from the Manufacture de Sèvres Louisiane Verger1,2, Olivier Dargaud2, Mathieu Chassé1, Nicolas Trcera3, Gwenaëlle Rousse4,5, Laurent Cormier1 1. Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7590, Muséum national d'Histoire naturelle, IRD UMR 206, 4 place Jussieu, F-75005 Paris, France 2. Cité de la céramique - Sèvres et Limoges, 2 Place de la Manufacture, 92310 Sèvres, France 3. Synchrotron Soleil, 91190 Saint-Aubin 4 .Collège de France, Chimie du Solide et de l’Energie, UMR 8260, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France.
    [Show full text]
  • Chemistry, Geochemistry, and Geology of Chromium and Chromium Compounds
    L1608_C02.fm Page 23 Thursday, July 15, 2004 6:57 PM 2 Chemistry, Geochemistry, and Geology of Chromium and Chromium Compounds William E. Motzer and Todd Engineers CONTENTS 2.1 Chromium Chemistry .................................................................................24 2.1.1 Background ......................................................................................24 2.1.2 Elemental/Metallic Chromium Characteristics .........................25 2.1.3 Ionic Radii ........................................................................................29 2.1.4 Oxidation States...............................................................................30 2.1.5 Stable and Radioactive Isotopes ...................................................31 2.1.6 Characteristics of Chromium Compounds.................................34 2.2 Natural Chromium Concentrations..........................................................34 2.2.1 Mantle ...............................................................................................46 2.2.2 Chromium Minerals........................................................................46 2.2.3 Chromium Ore Deposits................................................................46 2.2.3.1 Stratiform Mafic-Ultramafic Chromite Deposits .........62 2.2.3.2 Podiform- or Alpine-Type Chromite Deposits ............63 2.2.4 Crude Oil, Tars and Pitch, Asphalts, and Coal..........................63 2.2.5 Rock ...................................................................................................64
    [Show full text]
  • Mineral Ecology and Network Analysis of Chromium, Platinum
    MINERAL ECOLOGY AND NETWORK ANALYSIS OF CHROMIUM, PLATINUM, GOLD AND PALLADIUM A THESIS IN ENVIRONMENTAL AND URBAN GEOSCIENCES Presented to the Faculty of the University Of Missouri-Kansas City in partial fulfillment of The requirements for the degree MASTER OF SCIENCE By CHARLES ANDENGENIE MWAIPOPO B.S., University of Missouri-Kansas City, 2018 Kansas City, Missouri 2020 MINERAL ECOLOGY AND NETWORK ANALYSIS OF CHROMIUM, PLATINUM, GOLD AND PALLADIUM Charles Andengenie Mwaipopo, Candidate for the Master of Science Degree University of Missouri-Kansas City, 2020 ABSTRACT Data collected on the location of mineral species and related minerals from the field have many great uses from mineral exploration to mineral analysis. Such data is useful for further exploration and discovery of other minerals as well as exploring relationships that were not as obvious even to a trained mineralogist. Two fields of mineral analysis are examined in the paper, namely mineral ecology and mineral network analysis through mineral co-existence. Mineral ecology explores spatial distribution and diversity of the earth’s minerals. Mineral network analysis uses mathematical functions to visualize and graph mineral relationships. Several functions such as the finite Zipf-Mandelbrot (fZM), chord diagrams and mineral network diagrams, processed data and provided information on the estimation of minerals at different localities and interrelationships between chromium, platinum, gold and palladium-bearing minerals. The results obtained are important in highlighting several connections that could prove useful in mineral exploration. The main objective of the study is to provide any insight into the relationship among chromium, platinum, palladium and gold that could prove useful in mapping out potential locations of either mineral in the future.
    [Show full text]
  • Linking Crystal Chemistry and Physical Properties of Natural and Synthetic Spinels: an UV-VIS-NIR and Raman Study
    Dottorato di ricerca in Scienze della Terra Ciclo XXVI Linking crystal chemistry and physical properties of natural and synthetic spinels: an UV-VIS-NIR and Raman study Settore Scientifico Disciplinare GEO/06 Candidato Docente guida: Veronica D’Ippolito Prof. Giovanni B. Andreozzi Anni 2010-2013 “La mineralogia è una scienza di elite, ha pochi sbocchi professionali. Ma, come in tutte le cose della vita, se ci metti passione e determinazione, una strada vedrai che te la crei” Prof. Sergio Lucchesi “Success is getting what you want. Happiness is liking what you get.” H. Jackson Brown Index Introduction………………………………………………………………....... 1 Chapter 1- The Spinel Group……………………….…………………... 5 1.1- Crystal chemistry……………………………………………………………. 5 1.2- Structure……………………………………………………………………... 8 1.3- Relevance of spinels in the geological field……………………………… 16 1.4- Relevance of spinels in the gemological field …………………………… 19 1.5- Relevance of spinels in the technological field …...…………………….. 20 Chapter 2- Spectroscopic methods…………….……………………. 22 2.1- Introduction to spectroscopy………………………………………………. 22 2.2- Raman spectroscopy...…………………………………………………….. 25 2.2.1- Symmetry, Group theory, Normal Modes and Selection rules … 30 2.2.2- Applications………………………………………………….……….. 33 2.2.3- Raman spectra of Spinel Group compounds…………………….. 36 2.2.4- Luminescence spectroscopy using Raman spectrometer…….… 40 2.3- Optical absorption spectroscopy………………………………………….. 42 2.3.1- Crystal Field Theory (CFT)…………………………….…………… 45 One-electron systems…………………………….……………... 45 Crystal field splitting…………………………….……………….. 47 Many-electron dN systems…………………………………….… 50 Tanabe-Sugano diagrams………………………….…………… 50 2.3.2- Qualitative measurements in optical absorption spectra……….. 52 Causes of color………………………….……………………….. 53 2.3.3- Quantitative analysis in optical absorption spectra……………… 56 Structural relaxation……………………………………………... 57 i Chapter 3- Materials and methods………………………………....... 60 3.1- Materials………………………………………………………………….….
    [Show full text]
  • Nomenclature and Classification of the Spinel Supergroup
    Eur. J. Mineral. 2019, 31, 183–192 Published online 12 September 2018 Nomenclature and classification of the spinel supergroup Ferdinando BOSI1,*, Cristian BIAGIONI2 and Marco PASERO2 1Department of Earth Sciences, Sapienza University of Rome, P. Aldo Moro 5, 00185 Roma, Italy *Corresponding author, e-mail: [email protected] 2Dipartimento di Scienze della Terra, Universita` di Pisa, Via S. Maria 53, 56126 Pisa, Italy Abstract: A new, IMA-approved classification scheme for the spinel-supergroup minerals is here reported. To belong to the spinel supergroup, a mineral must meet two criteria: (i) the ratio of cation to anion sites must be equal to 3:4, typically represented by the general formula AB2X4 where A and B represent cations (including vacancy) and X represents anions; (ii) its structure must comprise a heteropolyhedral framework of four-fold coordination polyhedra (TX4) isolated from each other and sharing corners with the neighboring six-fold coordination polyhedra (MX6), which, in turn, share six of their twelve X-X edges with nearest- neighbor MX6. Regardless of space group, the X anions form a cubic close-packing and each X anion is bonded to three M-cations and one T-cation. The fifty-six minerals of the spinel supergroup are divided into three groups on the basis of dominant X anion: O2– (oxyspinel), S2– (thiospinel), and Se2– (selenospinel). Each group is composed of subgroups identified according to the dominant valence and then the dominant constituent (or heterovalent pair of constituents) represented by the letter B in the formula AB2X4. 2þ 3þ The oxyspinel group (33 species) can be divided into the spinel subgroup 2-3 ðA B2 O4Þ and the ulvo¨spinel subgroup 4þ 2þ 1þ 3:5þ 4-2 ðA B2 O4Þ, the thiospinel group (20 species) into the carrollite subgroup 1-3.5 ðA B2 S4Þ and the linnaeite subgroup 2þ 3þ 2+ 3+ 2-3 ðA B2 S4Þ, finally, the selenospinel group (3 species) into the bornhardtite subgroup 2-3 (A B 2Se4) and the potential 1þ 3:5þ ‘‘tyrrellite subgroup’’ (A B2 S4, currently composed by only one species).
    [Show full text]
  • Zincochromite Zncr O4
    3+ Zincochromite ZnCr2 O4 c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Cubic. Point Group: 4/m 32/m. Crystals euhedral, showing hexagonal sections of dodecahedra, to 50 µm, strongly zoned. Physical Properties: Hardness = 5.8 VHN = 620 D(meas.) = n.d. D(calc.) = 5.434 Weakly paramagnetic. Optical Properties: Opaque, translucent in thin slivers. Color: Brownish black; brown in transmitted light; brownish gray in reflected light, with rare brown internal reflections. Streak: Brown. Luster: Semimetallic. Optical Class: Isotropic. R: (400) —, (420) —, (440) 13.0, (460) 12.4, (480) 12.1, (500) 12.0, (520) 11.9, (540) 11.8, (560) 11.7, (580) 11.6, (600) 11.6, (620) 11.6, (640) 11.6, (660) 11.6, (680) 11.6, (700) 11.6 Cell Data: Space Group: Fd3m (synthetic). a = 8.3271(2) Z = 8 X-ray Powder Pattern: Onega Lake, Russia. 2.519 (100), 2.954 (50), 1.476 (35), 1.607 (30), 2.088 (25), 4.822 (15), 1.705 (15) Chemistry: (1) (2) SiO2 2.82 TiO2 0.14 Al2O3 1.14 Fe2O3 2.03 V2O3 3.52 Cr2O3 53.30 65.13 ZnO 37.05 34.87 Total 100.00 100.00 (1) Onega Lake, Russia; by electron microprobe, weighted average of four zones in six grains; total Fe as Fe2O3, total Cr as Cr2O3, total V as V2O3; corresponding to Zn1.04(Cr1.61V0.11Si0.11 Fe0.06Al0.05)Σ=1.94O4. (2) ZnCr2O4. Mineral Group: Spinel group. Occurrence: Replacing chromian aegirine in micaceous metasomatites. Association: Quartz, chromian aegirine, and its amorphous breakdown products.
    [Show full text]
  • Chromium Mineral Ecology
    American Mineralogist, Volume 102, pages 612–619, 2017 Chromium mineral ecology CHAO LIU1,*, GRETHE HYSTAD2, JOSHUA J. GOLDEN3, DANIEL R. HUMMER4, ROBERT T. DOWNS3, SHAUNNA M. MORRISON3, JOLYON P. RALPH5, AND ROBERT M. HAZEN1 1Geophysical Laboratory, Carnegie Institution, 5251 Broad Branch Road NW, Washington, D.C. 20015, U.S.A. 2Department of Mathematics, Computer Science, and Statistics, Purdue University Northwest, Hammond, Indiana 46323, U.S.A. 3Department of Geosciences, University of Arizona, 1040 East 4th Street, Tucson, Arizona 85721-0077, U.S.A. 4Department of Geology, Southern Illinois University, Carbondale, Illinois 62901, U.S.A. 5Mindat.org, 128 Mullards Close, Mitcham, Surrey, CR4 4FD, U.K. ABSTRACT Minerals containing chromium (Cr) as an essential element display systematic trends in their diversity and distribution. We employ data for 72 approved terrestrial Cr mineral spe- cies (http://rruff.info/ima, as of 15 April 2016), representing 4089 mineral species-locality pairs (http://mindat.org and other sources, as of 15 April 2016). We find that Cr-containing mineral species, for which 30% are known at only one locality and more than half are known from three or fewer locali- ties, conform to a Large Number of Rare Events (LNRE) distribution. Our model predicts that at least 100 ± 13 (1σ) Cr minerals exist in Earth’s crust today, indicating that 28 ± 13 (1σ) species have yet to be discovered—a minimum estimate because our model assumes that new minerals will be found only using the same methods as in the past. Numerous additional Cr minerals likely await discovery using micro-analytical methods. We propose 117 compounds as plausible Cr minerals to be discovered, including 7 oxides, 11 sulfides, 7 silicates, 7 sulfates, and 82 chromates.
    [Show full text]
  • Comparative Crystal Chemistry of Orthosilicate and Dense Oxide
    Reviews in Mineralogy, Volume 40; Comparative Crystal Chemistry, in press 2000. Chapter 9 COMPARATIVE CRYSTAL CHEMISTRY OF DENSE OXIDE MINERALS Joseph R. Smyth, Steven D. Jacobsen Department of Geological Sciences, 2200 Colorado Avenue, University of Colorado, Boulder, CO 80309-0399 and Bayerisches Geoinstitut, Universität Bayreuth D95440 Bayreuth, Germany Robert M. Hazen Geophysical Laboratory, 5251 Broad Branch Road NW, Washington, DC 20015-1305 INTRODUCTION Oxygen is the most abundant element in the Earth, constituting about 43 percent by weight of the crust and mantle. While most of this mass is incorporated into silicates, the next most abundant mineral group in the planet is the oxides. The oxide minerals are generally considered to be those oxygen-based minerals that do not contain a distinct - 2- 2- 3- 4- polyanionic species such as OH , CO3 , SO4 PO4 , SiO4 , etc. The oxide structures are also of interest in mineral physics, because, at high pressure, many silicates are known to adopt structures similar to the dense oxides (see Hazen and Finger this volume). Oxide minerals, because of their compositional diversity and structural simplicity, have played a special role in the development of comparative crystal chemistry. Many of the systematic empirical relationships regarding the behavior of structures with changing temperature and pressure were first defined and illustrated with examples drawn from these phases. Oxides thus provide a standard for describing and interpreting the behavior of more complex compounds. Our principal objectives here are to review the mineral structures that have been studied at elevated temperatures and pressures, to compile thermal expansion and compression data for the various structural elements in a consistent fashion, and to explore systematic aspects of their structural behavior at nonambient conditions.
    [Show full text]
  • WTP-RPT-116 Rev 0
    PNWD-3499 WTP-RPT-116 Rev 0 Vitrification and Product Testing of AZ-101 Pretreated High-Level Waste Envelope D Glass P. Hrma D. J. Bates P. R. Bredt J. V. Crum L. R. Greenwood H. D. Smith September 2004 Prepared for Bechtel National Inc. By Battelle—Pacific Northwest Division under Contract 24590-101-TSA-W000-00004 LEGAL NOTICE This report was prepared by Battelle Memorial Institute (Battelle) as an account of sponsored research activities. Neither Client nor Battelle nor any person acting on behalf of either: MAKES ANY WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, process, or composition disclosed in this report may not infringe privately owned rights; or Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, process, or composition disclosed in this report. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by Battelle. The views and opinions of authors expressed herein do not necessarily state or reflect those of Battelle. This document was printed on recycled paper. (9/97) Contents Abbreviations and Acronyms ...................................................................................................................... xi References..................................................................................................................................................
    [Show full text]
  • The Systematics of the Spinel-Type Minerals: an Overview 22
    21 The systematics of the spinel-type minerals: an overview 22 1* 1 23 CRISTIAN BIAGIONI , MARCO PASERO 24 25 26 1 Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, I-56126 Pisa, Italy 27 *e-mail address: [email protected] 28 29 ABSTRACT 30 Compounds with a spinel-type structure include mineral species with the general formula 2- 2- 2- 31 AB2φ4, where φ can be O , S , or Se . Space group symmetry is Fd3m, even if lower symmetries 32 are reported owing to the off-centre displacement of metal ions. In oxide spinels (φ = O2-), A and B 33 cations can be divalent and trivalent (“2-3 spinels”) or, more rarely, tetravalent and divalent (“4-2 34 spinels”). From a chemical point of view, oxide spinels belong to the chemical classes of oxides, 35 germanates, and silicates. Up to now, 24 mineral species have been approved: ahrensite, 36 brunogeierite, chromite, cochromite, coulsonite, cuprospinel, filipstadite, franklinite, gahnite, 37 galaxite, hercynite, jacobsite, magnesiochromite, magnesiocoulsonite, magnesioferrite, magnetite, 38 manganochromite, qandilite, ringwoodite, spinel, trevorite, ülvospinel, vuorelainenite, and 39 zincochromite. Sulfospinels (φ = S2-) and selenospinels (φ = Se2-) are isostructural with oxide 40 spinels. Twenty-one different mineral species have been approved so far; of them, three are 41 selenospinels (bornhardtite, trüstedtite, and tyrrellite), whereas 18 are sulfospinels: cadmoindite, 42 carrollite, cuproiridsite, cuprokalininite, cuprorhodsite, daubréelite, ferrorhodsite, fletcherite, 43 florensovite, greigite, indite, kalininite, linnaeite, malanite, polydymite, siegenite, violarite, and 44 xingzhongite. The known mineral species with spinel-type structure are briefly reviewed, indicating 45 for each of them the type locality, the origin of the name, and a few more miscellaneous data.
    [Show full text]
  • Zinc Mobility and Speciation in Soil Covered by Contaminated Dredged Sediment Using Micrometer-Scale and Bulk-Averaging X-Ray Fl
    Geochimica et Cosmochimica Acta, Vol. 69, No. 5, pp. 1173–1198, 2005 Copyright © 2005 Elsevier Ltd Printed in the USA. All rights reserved 0016-7037/05 $30.00 ϩ .00 doi:10.1016/j.gca.2004.08.024 Zinc mobility and speciation in soil covered by contaminated dredged sediment using micrometer-scale and bulk-averaging X-ray fluorescence, absorption and diffraction techniques 1,2 1, 1 2 3 MARIE-PIERRE ISAURE, ALAIN MANCEAU, *NICOLAS GEOFFROY, AGNÈS LABOUDIGUE, NOBUMICHI TAMURA, 3 AND MATTHEW A. MARCUS 1Environmental Geochemistry Group, LGIT- Maison des Géosciences, University J. Fourier and CNRS, 38041 Grenoble cedex 9, France 2Centre National de Recherche sur les Sites et Sols Pollués, 930 Boulevard Lahure, BP537, 59505 Douai cedex, France 3Advanced Light Source, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA (Received May 6, 2004; accepted in revised form August 23, 2004) Abstract—The mobility and solid-state speciation of zinc in a pseudogley soil (pH ϭ 8.2–8.3) before and after contamination by land-disposition of a dredged sediment ([Zn] ϭ 6600 mg kgϪ1) affected by smelter operations were studied in a 50 m2 pilot-scale test site and the laboratory using state-of-the-art synchrotron- based techniques. Sediment disposition on land caused the migration of micrometer-sized, smelter-related, sphalerite (ZnS) and franklinite (ZnFe2O4) grains and dissolved Zn from the sediment downwards to a soil depth of 20 cm over a period of 18 months. Gravitational movement of fine-grained metal contaminants probably occurred continuously, while peaks of Zn leaching were observed in the summer when the oxidative dissolution of ZnS was favored by non-flooding conditions.
    [Show full text]