Structural and Electronic Transitions in AgReO4 Under Pressure

1990 ◽  
Vol 210 ◽  
Author(s):  
John K. Vassiliou ◽  
Jens W. Otto ◽  
Richard F. Porter ◽  
Arthur L. Ruoff
Keyword(s):  
Optical Transmission ◽  
Diamond Anvil Cell ◽  
Structural Transition ◽  
Energy Gap ◽  
Considerable Change ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
Diamond Anvil ◽  
First Order Phase

AbstractThe behavior of AgReO4 under pressure has been studied in a diamond anvil cell. The equation of state determined by synchrotron radiation shows considerable change in compressibility with increasing pressure. X-ray and Raman scattering show a first-order phase transition from the scheelite to an as yet undetermined structure at 13 GPa. Changes in both the internal and external Raman active modes suggest a change in Re coordination. Optical transmission experiments demonstrate that the energy gap in the scheelitephase decreases at the rate of 75 meV/GPa. There is a small jump in the energy gap at 13 GPa, probably related to the structural transition. AgReO4 remains aninsulator to at least 47 GPa.

Pressure buffering in a diamond anvil cell

2000 ◽  
Vol 64 (2) ◽  
pp. 241-245 ◽  
Author(s):  
T. Arlt ◽  
R. J. Angel
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
First Order ◽  
Diamond Anvil ◽  
First Order Phase

AbstractThe clinopyroxenes kanoite and spodumene were studied by single-crystal X-ray diffraction in a diamond anvil cell (DAC) at room temperature. At the displacive phase transitions between the C2/c and P21/c polymorphs both phases coexist within the same crystal. In this two-phase region the pressure in the DAC remains constant. The experimental results demonstrate that pressure buffering at first-order phase transitions can occur in the DAC.

Inorganic mixed phase templated by a fatty acid monolayer at the air–water interface: the Mn and Mg case

2018 ◽  
Vol 20 (9) ◽  
pp. 6629-6637 ◽  
Author(s):  
Alae El Haitami ◽  
Michel Goldmann ◽  
Philippe Fontaine ◽  
Marie-Claude Fauré ◽  
Sophie Cantin
Keyword(s):  
Grazing Incidence ◽  
Water Interface ◽  
X Ray Diffraction ◽  
Inorganic Layer ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
Air Water Interface ◽  
First Order Phase

A first-order phase transition with a peculiar feature is evidenced by means of in situ grazing incidence X-ray diffraction in the 2D organic phase-mediated nucleation of an inorganic layer.

OBSERVATION OF PHASE TRANSITIONS AT THE (100) SURFACE OF Al-3 at.% Ag

1995 ◽  
Vol 02 (02) ◽  
pp. 141-145 ◽  
Author(s):  
E. WETLI ◽  
M. HOCHSTRASSER ◽  
D. PESCIA ◽  
M. ERBUDAK
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Elevated Temperatures ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

In the bulk binary alloy Al-3 at.% Ag , Ag 2 Al precipitates are formed below 410°C which are reversibly dissolved at elevated temperatures. We have followed this phase transition at a (100) surface as a function of temperature by monitoring the bandwidth of the Ag 4d states in X-ray photoelectron spectroscopy. Since the bandwidth measures the coordination number of the emitting atoms, it directly reveals the short-range order of the Ag atoms at the surface. The measurements show that the dissolution of the Ag -rich clusters starts at temperatures at least 100 K below the bulk transition, and the observed hysteresis behavior is indicative of a first-order phase transition at the surface.

OPTICAL PROPERTIES OF UNDOPED AND Ni-DOPED SbSBr AND BiSBr SINGLE CRYSTALS

1995 ◽  
Vol 09 (03n04) ◽  
pp. 229-235
Author(s):  
MOON-SEOG JIN ◽  
HO-JUN SONG ◽  
YONG-GEUN KIM ◽  
HYUNG-GON KIM ◽  
JEONG-DAE KOH ◽  
...  
Keyword(s):  
Single Crystals ◽  
Energy Gap ◽  
Energy Levels ◽  
Bridgman Technique ◽  
Optical Energy Gap ◽  
Impurity Site ◽  
First Order ◽  
Electron Transitions ◽  
First Order Phase Transition ◽  
First Order Phase

SbSBr, BiSBr, SbSBr:Ni, and BiSBr:Ni single crystals were grown by the Bridgman technique. The grown single crystals crystallized in an orthorhombic structure and have an indirect band structure. The temperature dependence of their optical energy gap shows an anomalous property at the first order phase transition temperature and at the second order one. Nickel doped as an impurity site at the T d symmetry point in the host single crystals as Ni 2+ ion. The impurity optical absorption peaks appeared by the electron transitions between the energy levels of these ions.

Structural phase transition of CeAuGe at high pressure

2005 ◽  
Vol 220 (2/3) ◽  
Author(s):  
Valeri Brouskov ◽  
Michael Hanfland ◽  
Rainer Pöttgen ◽  
Ulrich Schwarz
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase ◽  
Lattice Parameter ◽  
First Order ◽  
First Order Phase Transition ◽  
Diamond Anvil ◽  
Ternary Intermetallic Compound ◽  
First Order Phase ◽  
Type Crystal

AbstractStructural properties of the ternary intermetallic compound CeAuGe were investigated at hydrostatic pressures up to 15 GPa with high-resolution angle dispersive X-ray powder diffraction using synchrotron radiation and the diamond anvil cell technique. At 8.7(7) GPa a first order phase transition is observed from a hexagonal NdPtSb-type arrangement into an orthorhombic high-pressure modification with a TiNiSi-type crystal structure. The transformation is associated with a 3% shortening of the lattice parameter perpendicular to the puckered layers [AuGe]

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