Hydroxyl-bastnaesite-(Nd), a new mineral from Montenegro, Yugoslavia

1985 ◽  
Vol 49 (354) ◽  
pp. 717-720 ◽  
Author(s):  
Zoran Maksimović ◽  
György Pantó
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Electron Probe ◽  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
New Mineral ◽  
Electron Probe Analysis ◽  
Evolved Gas ◽  
X Ray ◽  
Cell Dimensions

AbstractHydroxyl-bastnaesite-(Nd), the Nd- and OH-dominant new member of the bastnaesite group, has been found in the red karstic bauxites near Nikšić, Montenegro. It occurs as whitish, irregular aggregates of crystals usually 100–200 µm in diameter. Hexagonal with the cell dimensions a = 7.191 and c = 9.921 Å, with Z = 6. The strongest lines of the X-ray powder diffraction pattern (d, I, hkl) are: 4.95 80(002); 3.596 79(110); 2.911 100(112); 2.077 29(300); 2.042 51(114); 1.914 30(302). The mineral is uniaxial positive, ω 1.715, ɛ 1.81; Dcalc 4.89 g/cm3.Electron probe analysis, using garnet, apatite and synthetic glass standards, combined with thermogravimetric and evolved gas analysis, gave Y2O3 0.2, La2O3 27.1, Ce2O3 0.3, Pr2O3 8.5, Nd2O3 31.5, Sm2O3 4.4, Eu2O3 1.3, Gd2O3 1.4, CaO 0.3, F 3.3, H2O 2.26, CO2 20.63, sum 101.19, less O = F 1.39, total 99.80%. This analysis calculates to (Nd0.41La0.36Pr0.11Sm0.06Gd0.02 Eu0.02Ca0.01)Σ0.99(CO3)1.03[(OH)0.55F0.38]Σ0.93, or ideally, (Nd,La)CO3(OH,F), with Nd > La and OH > F.

Plumbian tennantite from Sark, Channel Islands

1977 ◽  
Vol 41 (317) ◽  
pp. 59-63 ◽  
Author(s):  
A. C. Bishop ◽  
A. J. Criddle ◽  
A. M. Clark
Keyword(s):  
Powder Diffraction ◽  
Electron Probe ◽  
Visible Spectrum ◽  
Channel Islands ◽  
Electron Probe Analysis ◽  
X Ray ◽  
Probe Analysis ◽  
Cell Dimensions ◽  
Reflectance Data

SummaryAn unusual tennantite, containing 4·64% Pb, has been found on a mineral specimen from Sark's Hope Mine collected in 1843. An electron-probe analysis is given, together with visible spectrum reflectance data, quantitative colour values, VHN, and cell dimensions determined from X-ray powder diffraction photographs.

Basic halides and related species of molybdenum(III). I. The empirical formulae and unit cell dimensions of the basic halides

1976 ◽  
Vol 29 (4) ◽  
pp. 711 ◽  
Author(s):  
DJ Stabb
Keyword(s):  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
Unit Cell ◽  
Water Molecules ◽  
Orthorhombic Unit Cell ◽  
Evolved Gas ◽  
X Ray ◽  
Cell Parameters ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The basic halides MoOX(H2O), (X = F, Cl) were examined by vacuogravimetric and evolved gas analysis and by X-ray and electron diffraction techniques. The basic chloride prepared by slow crystallization had y = 3.08, with an orthorhombic unit cell 0.723 by 0.820 by 1.805 nm. Basic chlorides produced by rapid precipitation were less crystalline, of slightly larger unit cell dimensions and had 3.0 < y < 4.3. The water in excess of y = 3 was loosely held, while three water molecules per molybdenum were more strongly held. The fluoride, which could not be obtained with the perfect MoOF(H2O)3 stoichiometry, was isomorphous (cell parameters 0.710 by 0.823 by 1.824 nm for [MoOF0.96(OH)0.04(H2O)3] (H2O)0.28). It is concluded that the only hydrate of MoOX existing under normal conditions is MoOX(H2O)3, not the previously reported tetrahydrate.

X-Ray and Optical Data for a Vanadium-rich Dravite from Silver Knob, Mariposa County, California, U.S.A.

1992 ◽  
Vol 7 (4) ◽  
pp. 236-238 ◽  
Author(s):  
Franklin F. Foit
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Divalent Cation ◽  
Optical Data ◽  
Cation Substitution ◽  
X Ray ◽  
Octahedral Sites ◽  
Cell Dimensions ◽  
Compositional Variability ◽  
Unit Cell Dimensions

AbstractX-ray powder diffraction and optical data are presented for a vanadium-rich dravite from Silver Knob, Mariposa County, California, U.S.A. The limited compositional variability observed for vanadium-rich dravite is due to the presence of a Tschermaks substitution whereby the substitution of Al for Si in the tetrahedral ring is charge balanced by trivalent for divalent cation substitution in the octahedral sites in the structure. Vanadium-rich dravite is uniaxial negative with ε = 1.646(2) and ω = 1.676(2). Refined unit cell dimensions are a = 15.9599(10) and c = 7.1889(2); F30 = 111(0.009; 30); M20 = 80; and Dx = 3.07. An indexed X-ray powder diffraction pattern is also presented.

Hydroniumpharmacosiderite, a new member of the pharmacosiderite supergroup from Cornwall, UK: structure and description

2010 ◽  
Vol 74 (5) ◽  
pp. 863-869 ◽  
Author(s):  
S. J. Mills ◽  
A. R. Kampf ◽  
P. A. Williams ◽  
P. Leverett ◽  
G. Poirier ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Empirical Formula ◽  
Direct Methods ◽  
Structure Type ◽  
New Mineral ◽  
Calculated Density ◽  
X Ray ◽  
Mohs Hardness

AbstractHydroniumpharmacosiderite, ideally (H3O)Fe4(AsO4)3(OH)4·4H2O, is a new mineral from Cornwall, UK, probably from the St. Day group of mines. It occurs as a single yellowish green, slightly elongated cube, measuring 0.17 mm ×0.14 mm ×0.14 mm. The mineral is transparent with a vitreous lustre. It is brittle with a cleavage on {001}, has an irregular fracture, a white streak and a Mohs hardness of 2–3 (determined on H3O-exchanged pharmacosiderite). Hydroniumpharmacosiderite has a calculated density of 2.559 g cm–3 for the empirical formula. The empirical formula, based upon 20.5 oxygen atoms, is: [(H3O)0.50K0.48Na0.06]1.04(Fe3.79Al0.22)4.01[(As2.73P0.15)2.88O12](OH)4·4H2.14O. The five strongest lines in the X-ray powder diffraction pattern are [dobs(Å),Iobs,(hkl)]: 8.050,100,(001); 3.265,35,(112); 2.412,30,(113); 2.830,23,(202); 4.628,22,(111). Hydroniumpharmacosiderite is cubic, space group with a = 7.9587(2) Å, V = 504.11(2) Å3 and Z = 1. The crystal structure was solved by direct methods and refined to R1 = 0.0481 for 520 reflections with I > 2σ(I). The structure is consistent with determinations for H3O-exhchanged pharmacosiderite and the general pharmacosiderite structure type.

Munirite, naturally occurring sodium vanadium oxide hydrate, a new mineral

1983 ◽  
Vol 47 (344) ◽  
pp. 391-392 ◽  
Author(s):  
K. A. Butt ◽  
K. Mahmood
Keyword(s):  
Vanadium Oxide ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Globular Clusters ◽  
New Mineral ◽  
Synthetic Compound ◽  
Remarkable Similarity ◽  
X Ray ◽  
Oxide Hydrate ◽  
Naturally Occurring

AbstractMunirite was found in the sandstones of Siwaliks formation of mid-Miocene to Pleistocene age. It occurs as small globular clusters of acicular crystals (2 to 3 mm long). Analysis gave V2O5 67.46, N2O 22.91, and H2O 10.26%. The X-ray powder diffraction pattern shows remarkable similarity to a synthetic compound NaVO3 · 1.9H2O (Lukacs and Strausievici, 1962).

Irreversible hydrogenation of solid C60 with and without catalytic metals

1999 ◽  
Vol 14 (5) ◽  
pp. 2138-2146 ◽  
Author(s):  
Eric L. Brosha ◽  
John Davey ◽  
Fernando H. Garzon ◽  
Shimshon Gottesfeld
Keyword(s):  
Diffraction Analysis ◽  
Volume Fraction ◽  
Evolved Gas Analysis ◽  
Amorphous Material ◽  
Single Layer ◽  
Gas Analysis ◽  
X Ray Diffraction ◽  
Evolved Gas ◽  
X Ray ◽  
Graphite Sheets

The dehydrogenation of C60 · H18.7 was studied using thermogravimetric and powder x-ray diffraction analysis. C60 · H18.7 was found to be stable up to 430 °C in Ar at which point the release of hydrogen initiated the collapse of a fraction of fullerene molecules. X-ray diffraction analysis performed on C60 · H18.7 samples dehydrogenated at 454, 475, and 600 °C displayed an increasing volume fraction of amorphous material. The decomposition product comprises randomly oriented, single-layer graphite sheets. Evolved gas analysis using gas chromatograph (GC) mass spectroscopy confirmed the presence of both H2 and methane upon dehydrogenation. Attempts to improve reversibility or reduce hydrogenation/ dehydrogenation temperatures by addition of Ru and Pt catalysts were unsuccessful.

scholarly journals Structural Properties and Catalytic Behaviour of CrOx/TiO2 Systems

2017 ◽  
Vol 6 (2) ◽  
pp. 79
Author(s):  
P. Wilson ◽  
P.M. Rao ◽  
R.P. Viswanath
Keyword(s):  
Evolved Gas Analysis ◽  
Anatase Phase ◽  
Active Phase ◽  
Molecular State ◽  
Gas Analysis ◽  
Spectroscopic Techniques ◽  
Evolved Gas ◽  
X Ray ◽  
Dehydrogenation Of Cyclohexane ◽  
Ft Raman

<p>The present investigation comprises of an attempt to investigate the titania supported chromia catalysts using X-ray diffraction measurements (XRD), evolved gas analysis (EGA), FT infrared spectroscopy (FTIR) and FT-Raman spectroscopic techniques with catalytic evaluation by dehydrogenation of cyclohexane. Evolved Gas Analysis shows a modified decomposition pattern than that of bulk chromia and presence of surface heterogeneity owing to the modified surface anchored chromia species formed as a result of interaction between chromia and titania. Above 773 K, Cr<sup>6+</sup> is not stable over TiO<sub>2</sub> surface and the reduction of the Cr<sup>6+</sup> to intermediate chemical states take place. XRD investigations illustrate the significance of X-ray source in examining supported chromia catalysts to study the morphological modifications of the active phase when crystalline supports are employed. FT Raman spectra reveals that on calcining the sample at 573 K, for 2 hours, the chromia phase assumes a monomerically anchored molecular state. Longer calcination time (6 hours) at the same temperature, leads to the diffusion of <em>in</em><em> </em><em>situ </em>formed Cr<sup>3+</sup> ions into the anatase lattice. On calcination at 973 K for 6 hours, amorphous chromia phase is no more stable on TiO<sub>2</sub> support resulting inagglomeration leading to the germination of microcrystalline α–Cr<sub>2</sub>O<sub>3</sub>. Evaluation of catalytic performance of above catalysts by dehydrogenation of cyclohexane confirms the fact that diffusion of part of Cr<sup>3+</sup> species into the bulk of anatase phase occurs under reaction conditions.</p>

Analysis of the X-Ray Powder Diffraction Pattern of Neodymium Ammonium Hydroxynitrate: Nd(OH)2NO3.(NH4NO3)0.5.H2O

1988 ◽  
Vol 3 (2) ◽  
pp. 110-112
Author(s):  
D. Louër ◽  
F. Deneuve ◽  
N. Ouillon ◽  
C. David
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Unit Cell ◽  
Line Broadening ◽  
X Ray ◽  
Cell Dimensions ◽  
Orthorhombic Cell ◽  
Unit Cell Dimensions

AbstractNeodymium ammonium hydroxynitrate, Nd(OH)2NO3.(NH4NO3)0.5.H2O, has been investigated by means of X-ray powder diffraction. Unit cell dimensions were determined by indexing programs, from diffractometer data obtained with strictly monochromatic CuKα1 radiation. An I orthorhombic cell was found: a = 24.577 (4) Å, b = 7.1488 (16) Å, c = 3.8211 (9) Å. It is shown that the h 1 1 reflections present a selective line broadening.

scholarly journals Retzian-(La), a new mineral from Sterling Hill, Sussex County, New Jersey

1984 ◽  
Vol 48 (349) ◽  
pp. 533-535 ◽  
Author(s):  
Pete J. Dunn ◽  
Donald R. Peacor ◽  
William B. Simmons
Keyword(s):  
Rare Earth ◽  
New Jersey ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Microprobe Analysis ◽  
New Mineral ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Sussex County ◽  
Dominant Member

AbstractRetzian-(La), ideally, Mn2La(AsO4)(OH)4, is a new rare-earth analogue of retzian and retzian-(Nd). It was found associated with willemite, calcite, and franklinite, in the Stealing Hill Mine, Ogdensburg, Sussex County, New Jersey, USA. Retzian-(La) is orthorhombic, space group Pban, with a = 5.670(7), b = 12.01(1), and c = 4.869(8) Å. The strongest lines in the X-ray powder diffraction pattern are (d,I/I0,hkl): 3.51 80 111, 2.715 100 131, 1.848 50 061, 1.456 40. Microprobe analysis yielded MnO 25.2, MgO 3.7, ZnO 1.2, As2O5 26.5, La2O3 10.6, Ce2O3 8.8, Nd2O3 8.2, Pr2O3 5.1, Sm2O3 2.2, Y2O3 2.5, H2O [7.7], sum = 101.7 wt. %, corresponding to an La-dominant member of the retzian series.Retzian-(La) forms 0.5 mm euhedral crystals composed of the forms {001}, {010}, {110}, and {150}; the crystals have pseudohexagonal habit. It is reddish-brown, with vitreous luster, no cleavage, density > 4.2 g/cm3. Optically, it is biaxial, positive, 2V = 82° with α = 1.766, β = 1.773, and γ = 1.788. Dispersion is strong, r > v; pleochroism is very weak; orientation is X = c, Y= b, Z = a; absorption is Z > Y > X.

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