scholarly journals Pressure-induced order–disorder transition in Gd 1.5 Ce 0.5 Ti 2 O 7 pyrochlore

2019 ◽  
Vol 6 (9) ◽  
pp. 190842
Author(s):  
Jingjing Niu ◽  
Xiang Wu ◽  
Haibin Zhang ◽  
Shan Qin
Keyword(s):  
High Pressure ◽  
Unit Cell Volume ◽  
Pyrochlore Phase ◽  
X Ray Diffraction ◽  
Structure Transition ◽  
X Ray ◽  
Compression Behaviour ◽  
Cationic Radius ◽  
Pressure Stability ◽  
Induced Structure

An experimental study on ordered pyrochlore structured Gd 1.5 Ce 0.5 Ti 2 O 7 ( F d 3 ¯ m ) was carried out up to 45 GPa by synchrotron radiation X-ray diffraction and Raman spectroscopy. Experimental results show that Gd 1.5 Ce 0.5 Ti 2 O 7 transfers to a disordered cotunnite-like phase ( Pnma Z = 4) at approximately 42 GPa. Compared with the end member Gd 2 Ti 2 O 7 , the substitution of Ce 3+ for Gd 3+ increases the transition pressure and the high-pressure stability of the pyrochlore phase. This pressure-induced structure transition is mainly controlled by cationic order–disorder modification, and the cationic radius ratio r A / r B may also be effective for predicting the pyrochlore oxides' high-pressure stability. Two isostructural transitions are observed at 6.5 GPa and 13 GPa, and the unit-cell volume of Gd 1.5 Ce 0.5 Ti 2 O 7 as a function of pressure demonstrates its compression behaviour is rather complex.

Pressure-induced chemical decomposition of copper orthovanadate (α-Cu3V2O8)

2021 ◽  
Author(s):  
Daniel Diaz-Anichtchenko ◽  
Robin Turnbull ◽  
Enrico Bandiello ◽  
Simone Anzellini ◽  
Srungarpu N. Achary ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Theoretical Density ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Chemical Decomposition ◽  
X Ray ◽  
Pressure Stability

The high pressure stability of α-Cu3V2O8 has been investigated via complementary high pressure synchrotron X-ray diffraction experiments and theoretical density functional theory calculations. The results of both experiment and theory...

Effects of neodymium doping on the structural and magnetic properties of the double perovskite Sr2−yNdyFe1+xMo1−xO6 compound

2019 ◽  
Vol 33 (29) ◽  
pp. 1950344
Author(s):  
Y. Ruiz ◽  
B. Aguilar ◽  
C. Carvallo ◽  
J. de la Torre Medina ◽  
O. Navarro
Keyword(s):  
Unit Cell Volume ◽  
Double Perovskite ◽  
Double Perovskites ◽  
X Ray Diffraction ◽  
Charge Neutrality ◽  
Structure Transition ◽  
X Ray ◽  
Solid State Route ◽  
Neodymium Doping ◽  
Structural And Magnetic Properties

Curie temperature (TC) of the ferromagnetic compound Sr2FeMoO6 can be modified by increasing the itinerant electrons at the Fermi level. Nd doping increases the electron density but the charge neutrality should be taken into account. In this work, a series of double perovskites Sr[Formula: see text]Nd[Formula: see text]Fe[Formula: see text]Mo[Formula: see text]O6 ([Formula: see text]y[Formula: see text]=[Formula: see text]0.0, 0.25, 0.5, 0.75 and 1.0) for both cases, the off-stoichiometric ([Formula: see text]x[Formula: see text]=[Formula: see text]0) and the stoichiometric ([Formula: see text]x[Formula: see text][Formula: see text][Formula: see text]0 with x[Formula: see text]=[Formula: see text]y/2) one, were synthesized via solid state route and discussed in detail. A crystalline structure transition was confirmed by X-ray diffraction analysis, showing a change of the lattice parameters and the unit cell volume as a function of Nd doping. It was also found that the nominal valence in Fe is mainly Fe[Formula: see text] and in Mo is Mo[Formula: see text]. The TC increases continuously with Nd doping in the stoichiometric case. The increase of the TC follows a competition with the substitution of Sr[Formula: see text] ions by Nd[Formula: see text] ions and the charge neutrality considered in our system.

scholarly journals Thermodynamics by synchrotron X-ray diffraction: phase relationships and crystal structure of l-tyrosine ethyl ester form III

CrystEngComm ◽  
2015 ◽  
Vol 17 (21) ◽  
pp. 3974-3984 ◽  
Author(s):  
Béatrice Nicolaï ◽  
Jean-Paul Itié ◽  
Maria Barrio ◽  
Josep-Lluìs Tamarit ◽  
Ivo B. Rietveld
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Ethyl Ester ◽  
Equilibrium Curve ◽  
X Ray Diffraction ◽  
Structure Transition ◽  
X Ray ◽  
Transition Enthalpy ◽  
Pressure Form ◽  
Phase Relationships

Structure, transition enthalpy and equilibrium curve were obtained by X-ray diffraction for the commercial form and a new crystalline high-pressure form.

The study of the structure stability of hexagonal Bi(PO4)(H2O)0.67 under high pressure

2017 ◽  
Vol 31 (25) ◽  
pp. 1745020 ◽  
Author(s):  
Jun Zhang ◽  
Zhen Yuan ◽  
Jian-Fa Zhao ◽  
Wen-Min Li ◽  
Ya-Ting Jia ◽  
...  
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Unit Cell Volume ◽  
Ambient Pressure ◽  
Structure Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Experimental Pressure ◽  
Text Unit

In this work, the structure stability of hexagonal Bi(PO[Formula: see text](H2O)[Formula: see text] has been investigated by high-pressure synchrotron X-ray diffraction measurements. The results show that the structure is stable within the pressure up to 18.3 GPa. The diffraction data are refined and the lattice constants [Formula: see text] and [Formula: see text] are determined, which is compressed by 6.3(7)% and 3.5(0)% within the experimental pressure, respectively. By fitting the pressure dependence of [Formula: see text] (unit cell volume divided by that at ambient pressure) with the second-order Birch equation of state, the bulk modulus [Formula: see text] is given to be about 87.1(0) GPa.

FexCu1-xBa2YCu2O7+y SUPERCONDUCTORS SYNTHESIZED BY HIGH PRESSURE

2005 ◽  
Vol 19 (01n03) ◽  
pp. 221-223 ◽  
Author(s):  
Y. H. LIU ◽  
G. C. CHE ◽  
K. Q. LI ◽  
Z. X. ZHAO ◽  
Z. Q. KOU ◽  
...  
Keyword(s):  
High Pressure ◽  
Cell Volume ◽  
Oxygen Content ◽  
Unit Cell Volume ◽  
Ambient Pressure ◽  
Lattice Parameter ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Coordination

Systematic studies of x-ray diffraction(XRD), superconductivity and Mössbauer effect on Fe x Cu 1-x Ba 2 YCu 2 O 7+y ( x =0.00~0.70) superconductors synthesized by high pressure (HP) were summarized. All the HP-samples have tetragonal structure, smaller lattice parameter c and unit-cell volume than the AM-samples (synthesized by ambient pressure). The HP-samples have higher oxygen content than the AM-samples. Moreover, for the HP-sample with x =0.5, all of the Fe located in the CuO x chains have fivefold-oxygen coordination.

Effect of high pressure-temperature on silicon layered structures as determined by X-ray diffraction and electron microscopy

2004 ◽  
Vol 27 (1-3) ◽  
pp. 415-418
Author(s):  
J. Bak-Misiuk ◽  
A. Misiuk ◽  
J. Ratajczak ◽  
A. Shalimov ◽  
I. Antonova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Layered Structures ◽  
X Ray Diffraction ◽  
X Ray
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