scholarly journals Using high-pressure X-ray powder diffraction to explore plastic and elastic deformations in ultra-hard transition metal borides

2019 ◽  
Vol 75 (a1) ◽  
pp. a399-a399
Author(s):  
Sarah H. Tolbert
Keyword(s):  
High Pressure ◽  
Transition Metal ◽  
Powder Diffraction ◽  
Elastic Deformations ◽  
X Ray ◽  
Metal Borides ◽  
Hard Transition

Synthesis and characterisation of transition metal substituted barium hollandite ceramics

2006 ◽  
Vol 932 ◽  
Author(s):  
Neil C. Hyatt ◽  
Martin C. Stennett ◽  
Steven G. Fiddy ◽  
Jayne S. Wellings ◽  
Sian S. Dutton ◽  
...  
Keyword(s):  
Transition Metal ◽  
Oxidation State ◽  
Powder Diffraction ◽  
Single Phase ◽  
Maximum Density ◽  
Processing Conditions ◽  
Metal Oxidation ◽  
Exafs Data ◽  
X Ray ◽  
Oxygen Atoms

ABSTRACTA range of transition metal bearing hollandite phases, formulated Ba1.2B1.2Ti6.8O16 (B2+ = Mg, Co, Ni, Zn, Mn) and Ba1.2B2.4Ti5.6O16 (B3+ = Al, Cr, Fe) were prepared using an alkoxide - nitrate route. X-ray powder diffraction demonstrated the synthesis of single phase materials for all compositions except B = Mn. The processing conditions required to produce > 95 % dense ceramics were determined for all compositions, except B = Mg for which the maximum density obtained was > 93 %. Analysis of transition metal K-edge XANES data confirmed the presence of the targeted transition metal oxidation state for all compositions except B = Mn, where the overall oxidation state was found to be Mn3+. The K-edge EXAFS data of Ba1.2B1.2Ti6.8O16 (B = Ni and Co) were successfully analysed using a crystallographic model of the hollandite structure, with six oxygen atoms present in the first co-ordination shell at a distance of ca. 2.02Å. Analysis of Fe K-edge EXAFS data of Ba1.2B2.4Ti5.4O16 revealed a reduced co-ordination shell of five oxygens at ca. 1.99Å.

Phase transitions in ReO3studied by high-pressure X-ray diffraction

2000 ◽  
Vol 33 (2) ◽  
pp. 279-284 ◽  
Author(s):  
J.-E. Jørgensen ◽  
J. Staun Olsen ◽  
L. Gerward
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Powder Diffraction ◽  
Ambient Pressure ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ions ◽  
Pressure Phase ◽  
Related Phase

ReO3has been studied at pressures up to 52 GPa by X-ray powder diffraction. The previously observed cubicIm3¯ high-pressure phase was shown to transform to a monoclinic MnF3-related phase at about 3 GPa. All patterns recorded above 12 GPa could be indexed on rhombohedral cells. The compressibility was observed to decrease abruptly at 38 GPa. It is therefore proposed that the oxygen ions are hexagonally close packed above this pressure, giving rise to two rhombohedral phases labelled I and II. The zero-pressure bulk moduliBoof the observed phases were determined and the rhombohedral phase II was found to have an extremely large value of 617 (10) GPa. It was found that ReO3transforms back to thePm3¯mphase found at ambient pressure.

scholarly journals Radial X‐Ray Diffraction Study of Superhard Early Transition Metal Dodecaborides under High Pressure

2019 ◽  
Vol 29 (22) ◽  
pp. 1900293 ◽  
Author(s):  
Jialin Lei ◽  
Georgiy Akopov ◽  
Michael T. Yeung ◽  
Jinyuan Yan ◽  
Richard B. Kaner ◽  
...  
Keyword(s):  
High Pressure ◽  
Transition Metal ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Early Transition Metal ◽  
Early Transition

Ternary transition metal gallides with TiNiSi, ZrBeSi and MgZn2-type structure

2019 ◽  
Vol 74 (3) ◽  
pp. 297-306 ◽  
Author(s):  
Lukas Heletta ◽  
Theresa Block ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Transition Metal ◽  
Powder Diffraction ◽  
Metallic Iron ◽  
Site Occupancy ◽  
Laves Phase ◽  
Structural Motif ◽  
Equiatomic Composition ◽  
Laves Phases ◽  
X Ray ◽  
Arc Melting

AbstractA series of ternary transition metal gallides around the equiatomic composition have been synthesized from the elements by arc-melting and subsequent annealing. The compounds crystallize with site occupancy variants of the hexagonal Laves phase MgZn2, with the hexagonal ZrBeSi or the orthorhombic TiNiSi type. All samples have been characterized on the basis of their lattice parameters, determined by X-ray powder diffraction (Guinier technique). The structures of NbCr1.58Ga0.42 and NbFe1.51Ga0.49 (MgZn2 type, P63/mmc), NbRhGa (ZrBeSi type, P63/mmc), and ScNiGa, ScPtGa and ScAuGa (TiNiSi type, Pnma) were refined from single crystal X-ray diffractometer data. The ScPtGa and ScAuGa crystals showed trilling formation. Mixed site occupancies were only observed in the Laves phases while all other crystals were well ordered. A striking structural motif of NbRhGa is the formation of niobium chains (264 pm Nb–Nb) along the c axis. Several gallides were magnetically characterized. They are Pauli paramagnets. The two crystallographically independent iron sites in the Laves phase TaFeGa could be distinguished in the 57Fe Mössbauer spectrum. The isomer shifts of 0.06(3) (Fe1) and –0.02(3) (Fe2) mm s−1 indicate metallic iron.

Bulk moduli and high-pressure crystal structures of minium, Pb3O4, determined by X-ray powder diffraction

2003 ◽  
Vol 88 (7) ◽  
pp. 996-1002 ◽  
Author(s):  
Robert E. Dinnebier ◽  
Stefan Carlson ◽  
Michael Hanfland ◽  
Martin Jansen
Keyword(s):  
High Pressure ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
X Ray

scholarly journals Polymorphism of 1,3-X-adamantanes (X = Br, OH, CH3) and the crystal plastic phase formation ability

CrystEngComm ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 1230-1238 ◽  
Author(s):  
Philippe Negrier ◽  
Bacem Ben Hassine ◽  
Maria Barrio ◽  
Michela Romanini ◽  
Denise Mondieig ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
High Pressure ◽  
Phase Formation ◽  
Powder Diffraction ◽  
Scanning Calorimetry ◽  
Density Measurements ◽  
X Ray ◽  
Plastic Phase

The polymorphism of 1,3-dimethyladamantane (13DMA), 1,3-adamantanediol (13DOHA) and 1,3-dibromoadamantane (13DBrA) has been studied by X-ray powder diffraction, density measurements and differential scanning calorimetry at normal and high-pressure.

Transition Metal Pnictide Synthesis: Self Propagating Reactions Involving Sodium Arsenide, Antimonide and Bismuthide

1994 ◽  
Vol 49 (4) ◽  
pp. 477-482 ◽  
Author(s):  
Andrew L. Hector ◽  
Ivan P. Parkin
Keyword(s):  
Transition Metal ◽  
Powder Diffraction ◽  
Metal Halides ◽  
X Ray ◽  
Ft Ir ◽  
Cu And Zn

Initiation of the reaction between Na 3E (E = As, Sb, Bi) and anhydrous metal halides at 25 to 550 °C produces metal arsenides MxAsy (M=Y,La, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Pt ,Cu and Zn) and antimonides MxSby (M=Ti, V, Nb, Ta, Cr, Fe, Co, Ni, Pt, Cu and Zn) via an exothermic selfpropagating reaction. The metal arsenides were characterized by X-ray powder diffraction, SEM/EDAX , microanalysis and FT-IR.

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