Phase transitions in double tungstate in extremely low-dimensional and low-symmetry compounds with cooperative Jahn-Teller effect

2001 ◽  
Author(s):  
Mieczyslaw T. Borowiec
Keyword(s):  
Phase Transitions ◽  
Teller Effect ◽  
Double Tungstate ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Low Dimensional ◽  
Low Symmetry

Local structure and excitations in systems with CuF64− units: lack of Jahn–Teller effect in the low symmetry compound Na2CuF4

2020 ◽  
Vol 22 (15) ◽  
pp. 7875-7887
Author(s):  
I. Sanchez-Movellan ◽  
J. A. Aramburu ◽  
M. Moreno
Keyword(s):  
Local Structure ◽  
Teller Effect ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Low Symmetry

The lack of a Jahn–Teller effect in Na2CuF4 is illustrated by the anisotropy of the Na2ZnF4 parent lattice.

Phase diagrams of Ni2+xMn1-xGa Heusler alloys from Hubbard Hamiltonian with account of Jahn-Teller effect

2011 ◽  
Vol 1310 ◽  
Author(s):  
Mikhail A. Zagrebin ◽  
Vasiliy D. Buchelnikov ◽  
Sergey V. Taskaev ◽  
Natal’ya Yu. Fedulova
Keyword(s):  
Phase Diagram ◽  
Free Energy ◽  
Phase Transitions ◽  
Phase Diagrams ◽  
Density Of States ◽  
Heusler Alloys ◽  
Teller Effect ◽  
Hubbard Hamiltonian ◽  
Jahn Teller ◽  
Jahn Teller Effect

ABSTRACTIn this work a microscopic Hamiltonian is investigated using the Hubbard model for a ferromagnet with two degenerate bands, taking into account the Jahn-Teller effect. A macroscopic free energy is obtained from the microscopic Hubbard Hamiltonian. All free energy coefficients depend on microscopic parameters: temperature T and composition x. As a result of analytical minimization of free energy, phase diagrams are numerically constructed. It is shown that at certain values of parameters on the phase diagrams there are thermodynamic paths which correspond to experimentally observed sequences of phase transitions. Using density of states spectra for different compositions x the T-x phase diagram is numerically constructed. This phase diagram can theoretically explain experimentally observed behavior of the temperatures of phase transitions.

DFT Analysis of the Indium-Antimony-Vacancy Cluster in Silicon

2005 ◽  
Vol 245-246 ◽  
pp. 29-38 ◽  
Author(s):  
M.M. De Souza ◽  
Jonathan P. Goss
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Vacancy Cluster ◽  
Antimony Atom ◽  
Teller Effect ◽  
High Temperature Anneal ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Low Symmetry ◽  
Strong Binding Energy

A cluster comprising of indium, antimony and a vacancy in silicon is analysed using the planewave pseudopotential technique. This cluster has a strong binding energy that inhibits indium diffusion after high temperature anneal cycles. Difficulties associated with the simulation of a vacancy using the supercell approach are initially highlighted. In comparison, the indium-antimony-vacancy cluster reveals stronger distortions and reduction in relaxation volume. The indium atom in the relaxed cluster shows nearly six-fold coordination whereas the antimony atom acquires four neighbours. Due to the low symmetry of the centre, in constrast to the isolated vacancy there is no propensity for a Jahn-Teller effect. It gives rise to two defect levels in the bandgap.

Jahn-Teller effect induced phase transitions in CsCuCl3

1979 ◽  
Vol 70 (1) ◽  
pp. 44-46 ◽  
Author(s):  
S. Vasudevan ◽  
A.M. Shaikh ◽  
C.N.R. Rao
Keyword(s):  
Phase Transitions ◽  
Teller Effect ◽  
Jahn Teller ◽  
Jahn Teller Effect
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