The solid solution between platinum and palladium in nature

2013 ◽  
Vol 77 (3) ◽  
pp. 269-274 ◽  
Author(s):  
L. Bindi ◽  
F. Zaccarini ◽  
G. Garuti ◽  
N. Angeli
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
Structural Data ◽  
Micro Hardness ◽  
Metallic Elements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complete Solid Solution ◽  
Hardness Values ◽  
Palladium Platinum

AbstractChemical and structural data are reported for platinum–palladium intermediates from two nuggets found at Córrego Bom Sucesso, Minas Gerais, Brazil. Three grains with simple stoichiometries (i.e. PtxPd1−x with x ∼0.67, ∼0.5 and ∼0.33, which correspond to Pt2Pd, PtPd and PtPd2, respectively) were characterized by single-crystal X-ray diffraction and electron-probe microanalysis. In the absence of single-crystal data it might be tempting to hypothesize that such simple stoichiometries represent distinct mineral species, however structural analyses show that all of the phases are cubic and crystallize in space group Fmm. They are, therefore, natural intermediates in the palladium–platinum solid solution. Reflectance and micro-hardness values are reported for the samples and a comparison with the pure metallic elements made. On the basis of information gained from the chemical and structural characterization it can be concluded that there is a complete solid solution between Pt and Pd in nature. These findings corroborate results from experiments on synthetic compounds.

Crystal chemistry of lamprophyllite-group minerals from the Murun alkaline complex (Russia) and pegmatites of Rocky Boy and Gordon Butte (USA): single crystal X-ray diffraction and Raman spectroscopy study

2021 ◽  
Vol 77 (2) ◽  
Author(s):  
Sergey M. Aksenov ◽  
Anastasia D. Ryanskaya ◽  
Yuliya V. Shchapova ◽  
Nikita V. Chukanov ◽  
Nikolay V. Vladykin ◽  
...  
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
Raman Spectra ◽  
Crystal Chemistry ◽  
Solid Solution Series ◽  
X Ray Diffraction ◽  
Alkaline Complex ◽  
Oh Groups ◽  
X Ray ◽  
Solution Series

Specific features of the crystal chemistry of lamprophyllite-group minerals (LGMs) are discussed using the available literature data and the results of the single-crystal X-ray diffraction and a Raman spectroscopic studies of several samples taken from the Murun alkaline complex (Russia), and Rocky Boy and Gordon Butte pegmatites (USA) presented here. The studied samples are unique in their chemical features and the distribution of cations over structural sites. In particular, the sample from the Gordon Butte pegmatite is a member of the barytolamprophyllite–emmerichite solid solution series, whereas the samples from the Murun alkaline complex and from the Rocky Boy pegmatite are intermediate members of the solid solution series formed by lamprophyllite and a hypothetical Sr analogue of emmerichite. The predominance of O2− over OH− and F− at the X site is a specific feature of sample Cha-192 from the Murun alkaline complex. New data on the Raman spectra of LGMs obtained in this work show that the wavenumbers of the O—H stretching vibrations depend on the occupancies of the M2 and M3 sites coordinating with (OH)− groups. Cations other than Na+ and Ti4+ (mainly, Mg and Fe3+) can play a significant role in the coordination of the X site occupied by (OH)−. Data on polarized Raman spectra of an oriented sample indicate that the OH groups having different local coordinations have similar orientations with respect to the crystal. The calculated measures of similarity (Δ) for lamprophyllite and ericssonite are identical (0.157 and 0.077 for the 2M- and 2O-polytypes, respectively), which indicates that these minerals are crystal-chemically isotypic and probably should be considered within the same mineral group by analogy to the other mineralogical groups which combine isotypic minerals.

Thermal and X-Ray Diffraction Studies of Doped and Undoped Single Crystal and Polycrystalline BaTiO3

1994 ◽  
Vol 360 ◽  
Author(s):  
L.G. Carreiro ◽  
J.V. Marzik ◽  
K.K Deb
Keyword(s):  
Solid Solution ◽  
Curie Temperature ◽  
Single Crystal ◽  
Dopant Concentration ◽  
Infrared Detection ◽  
Thermal Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Mole Percent ◽  
X Ray

AbstractCalorimetric changes in a series of pure and doped single crystal and polycrystalline BaTiO3 were studied using differential scanning calorimetry over the temperature range of-110°C to 200°BC. The dopants, oxides of niobium and iron were varied from 0.5 to 8 mole percent, and strontium was varied from 5 to 35 mole percent. Endotherms were observed corresponding to three crystallographic transitions. The highest observed thermal transition corresponds to a tetragonal to cubic crystallographic transition and is also associated with the Curie temperature in these materals. Two additional endothermic transitions were also observed, an intermediatetemperature orthorhombic to tetragonal transition, and a low-temperature rhombohedral to orthorhombic transition. The three dopants decreased the crystallographic transition temperatures and Curie temperature as the dopant concentration was increased. X-ray diffraction was used to identify phases present and to determine the extent of solid solution. It is expected that these materials will display improved infrared detection as well as opto-electronic properties.

scholarly journals Caracterização metalúrgica de ligas de Ni-Cr para metalocerimica

2021 ◽  
Vol 40 (1) ◽  
pp. 57-59
Author(s):  
Carlos Ariel Samudio Perez ◽  
Cezar Augusto Garbin
Keyword(s):  
Solid Solution ◽  
Diffraction Analysis ◽  
The Other ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardness Tests ◽  
Density Values ◽  
Cubic Structure ◽  
Hardness Values

Alternative Ni-Cr alloys applied in dentistry of two commercial brands for ceramometal restoration were evaluated. The alloys were analyzed in the commercial and after casting conditions using experimental techniques of metallography, X-ray diffraction, superficial hardness and density. The metalografics and X-ray diffraction analysis showed that, the alloys microstructure is marked with the presence of a solid solution having an ordered face- centred cubic structure, Ni-rich austenitic (y phase) matrix, and with fine precipitates particles of secondary phases. The Vicker hardness tests showed a decrease in hardness values of the studied alloys aer casting. The alloys density values, on the other hand, did not manifest changes.

Single crystal x-ray diffraction: optical and micro hardness studies on chalcone derivative single crystal

2005 ◽  
Author(s):  
Vincent Crasta ◽  
V. Ravindrachary ◽  
R. F. Bhajantri ◽  
S. Naveen ◽  
M. A. Shridar ◽  
...  
Keyword(s):  
Single Crystal ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chalcone Derivative

On the Precipitation Behavior at 250 and 300 °C of WE54 Supersaturated Solid Solution

2012 ◽  
Vol 629 ◽  
pp. 85-89 ◽  
Author(s):  
S. Tighiouaret ◽  
H. Azzeddine ◽  
A. Sam ◽  
A. Sari ◽  
B. Alili ◽  
...  
Keyword(s):  
Solid Solution ◽  
Supersaturated Solid Solution ◽  
Precipitation Sequence ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Precipitation Behavior ◽  
X Ray ◽  
The Mean ◽  
Kinetics Of

The current study seeks to further understand the precipitation sequence in a WE54 Mg alloy using in situ X-ray diffraction, micro-hardness and electrical resistivity during ageing at 250 and 300 °C. We show that the mean hardening effect is due to the precipitation of β' and β1metastable phases. The analysis of the kinetics of the precipitation shows that both phases nucleate at grain boundaries and within grains in the form of plates.

scholarly journals Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate

2020 ◽  
Vol 53 (1) ◽  
pp. 51-57
Author(s):  
Melissa Tan ◽  
Alexander T. Martin ◽  
Alexander G. Shtukenberg ◽  
Bart Kahr
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
Mueller Matrix ◽  
Mixed Crystals ◽  
Refractive Indices ◽  
Linear Birefringence ◽  
Solid Solution Series ◽  
X Ray Diffraction ◽  
X Ray ◽  
Isotropic Point

In anisotropic crystals, optical isotropic points are wavelengths where linear birefringence disappears because the refractive indices for both eigenmodes are accidentally equivalent. Here, the optical isotropic point of ethylenediammonium selenate (EDSe) is tuned by generating a solid-solution series of EDSe doped with sulfate. Mueller matrix polarimetry and single-crystal X-ray diffraction are used to correlate changes in linear birefringence with the crystal composition of EDS x Se1−x . A scheme for using mixed crystals with isotropic points as tunable birefringent optical bandpass filters is proposed and their performance is modeled.

scholarly journals Mg65Ni20Y15–XAgX (X = 1, 2, 3, 5) alloys prepared via atmosphere controlled induction system

2018 ◽  
Vol 96 (7) ◽  
pp. 810-815 ◽  
Author(s):  
Celal Kursun ◽  
Musa Gogebakan ◽  
Yunus Azakli ◽  
Sezgin Cengiz ◽  
Hasan Eskalen ◽  
...  
Keyword(s):  
Hardness Measurement ◽  
Microstructural Properties ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Induction System ◽  
Quantitative Results ◽  
Hardness Values ◽  
Vickers Micro Hardness ◽  
Scanning Electron

In this work, Mg65Ni20Y15–XAgX (X = 1, 2, 3, 5) alloys were manufactured by atmosphere controlled induction system. The effect of Ag ratio on the microstructural properties, micro-hardness, density, and homogeneity of the Mg–Ni–Y alloys were investigated. These alloys were characterized by X-ray diffraction (XRD), optical microscopy, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and Vickers micro-hardness measurement. According to XRD results, Ni3Y and Mg6Ni phases were observed as well as AgY and Ag17Mg54 phases, which were obtained in alloys. The quantitative results of EDX analysis confirm that the chemical composition of the obtained phases is very close and their homogeneities are so high. The average micro-hardness values of the ingot alloys were measured between 208 and 266 HV for matrix. The elastic modulus and densities of the Mg65Ni20Y15–XAgX (X = 1, 2, 3, 5) alloys increased by increasing Ag in the alloys and they were determined in the range of 58.18–68.12 GPa and 3.14–3.53 g/cm3, respectively.

Study of Aluminium-Titanate Based Ceramics in Fe2O3-Al2O3-TiO2 System

2010 ◽  
Vol 659 ◽  
pp. 31-36
Author(s):  
Támas Korim
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Lattice Parameter ◽  
Self Healing ◽  
X Ray Diffraction ◽  
Repeated Heating ◽  
X Ray ◽  
Aluminium Titanate ◽  
Complete Solid Solution ◽  
Constructed Self

Solid solutions formed within the Al2O3-TiO2-Fe2O3 (Fe2xAl2(1-x)TiO5) system upon heat treatment were investigated by adjusting the substituting Fe3+ content in the range of x=0.0 to 1.0. X-ray diffraction phase analyses and lattice parameter determinations confirmed that substitution of Fe3+ ions within the aluminium titanate lattice was complete. For this complete solid solution, however, the trends observed for changes in d-spacing values indicated that there were certain discrete compositions to identify with Fe3+ substitution. Within these, Fe0.4Al1.6TiO5 and Fe1.6Al0.4TiO5 crystalline phases were investigated in detail and their X-ray diffraction cards were constructed. Self-healing effect occurring in repeated heating-cooling cycles in Fe3+ doped AT ceramics were proved; it was demonstrated that Fe3+ doped AT ceramics do not decompose even if exposed to repeated thermal shock.

The Solid Solution Lu2–xScxSiO5

2011 ◽  
Vol 66 (11) ◽  
pp. 1183-1187
Author(s):  
Hamdi Ben Yahia ◽  
Ute Ch. Rodewald ◽  
Birgit Heying ◽  
Sarkarainadar Balamurugan ◽  
Rainer Pöttgen
Keyword(s):  
Solid Solution ◽  
Rare Earth ◽  
Single Crystal ◽  
Diffraction Data ◽  
Strong Preference ◽  
X Ray Diffraction ◽  
X Ray ◽  
Type Space ◽  
Coordination Numbers ◽  
Oxygen Coordination

The monoclinic silicates Lu2SiO5 and Sc2SiO5 (Y2SiO5 type, space groupC2/c) forma solid solution Lu2−xScxSiO5. Samples with x = 0.5, 0.8, 1.0 were synthesized ceramically from Lu2O3, Sc2O3, and SiO2. The structures of three crystals with x = 0.88, 0.77, and 0.50 were refined on the basis of single-crystal X-ray diffraction data. The rare earth (RE) atoms occupy two crystallographically different 8ƒ sites with oxygen coordination numbers (CN) of 6 (RE2) and 7 (RE1). Refinements of the occupancy parameters showed Lu/Sc mixing for both sites with a strong preference of the smaller scandium atoms for CN6

Re-investigation of the structure and crystal chemistry of the Bi2O3–W2O6 `type (Ib)' solid solution using single-crystal neutron and synchrotron X-ray diffraction

2010 ◽  
Vol 66 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Neeraj Sharma ◽  
Rene B. Macquart ◽  
Maxim Avdeev ◽  
Mogens Christensen ◽  
Garry J. McIntyre ◽  
...  
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Cation Site ◽  
X Ray ◽  
Oxide Ion Conductivity ◽  
Solid Solution Region ◽  
Solution Region ◽  
First Time ◽  
Oxide Ion

Single crystals of composition Bi35.66W4.34O66.51 (or Bi8.2WO15.3, bismuth tungsten oxide), within the type (Ib) solid-solution region of the Bi2O3–WO3 system, were synthesized using the floating-zone furnace method. Synchrotron X-ray and neutron single-crystal diffraction data were used to confirm the previously tentative assignment of the room-temperature space group as I41. Fourier analysis of the combined X-ray and neutron datasets was used to elucidate and refine fully the cation and anion arrays for the first time. The mixed cation site M1 is shown to be coordinated by eight O atoms in an irregular cube when M = Bi, and by six O atoms in an octahedron when M = W. The resulting disorder in the average structure around M1 is discussed in the context of experimentally observed oxide-ion conductivity.

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