TY - JOUR

T1 - Computer simulation of the oxygen mobility in CaMnO3-x

AU - Petrov, A. V.

AU - Parker, S. C.

AU - Reller, A.

PY - 1995/12/1

Y1 - 1995/12/1

N2 - The perovskite-type metal oxide CaMnO3-xis known to accommodate substantial amounts of oxygen vacancies. High-resolution electron microscope investigations give evidence for ordering of the vacancies, i.e. well-defined structures in the compositional range of CaMnO2.5< CaMnO3-x< CaMnO. Within this range the metal cation positions do not change, i.e. perovskitic framework is conserved while a remarkably high oxygen anion mobility is recorded. In addition, the electronic and magnetic structure, and thus the physical properties, depend directly on the oxygen stoichiometry. This contribution focusses on the oxygen mobility in different CaMnO3-xphases exhibiting oxygen vacancy ordered structures, i.e. CaMnO.0, CaMnO2.80, CaMnO2.75, CaMnO2.66, CaMnO2.55and CaMnO2.50-In these compounds the formal oxidation state of manganese changes from Mn4+(x=0) to Mn3+(x=0.5). For the computer simulation of the defect structure and for the mobility of the oxygen anions within these defect structures we applied the method of interatomic potentials in a simple rigid-ion approximation. The parameters of interaction were calibrated on the basis of empirical data, i.e. equilibrium geometry and cohesive energies of the binary oxides CaO, MnO2and Mn2O were taken into account for the present calculations. Stabilities, oxygen migration barriers and dielectric constants of selected representants of CaMnO3-x are presented.

AB - The perovskite-type metal oxide CaMnO3-xis known to accommodate substantial amounts of oxygen vacancies. High-resolution electron microscope investigations give evidence for ordering of the vacancies, i.e. well-defined structures in the compositional range of CaMnO2.5< CaMnO3-x< CaMnO. Within this range the metal cation positions do not change, i.e. perovskitic framework is conserved while a remarkably high oxygen anion mobility is recorded. In addition, the electronic and magnetic structure, and thus the physical properties, depend directly on the oxygen stoichiometry. This contribution focusses on the oxygen mobility in different CaMnO3-xphases exhibiting oxygen vacancy ordered structures, i.e. CaMnO.0, CaMnO2.80, CaMnO2.75, CaMnO2.66, CaMnO2.55and CaMnO2.50-In these compounds the formal oxidation state of manganese changes from Mn4+(x=0) to Mn3+(x=0.5). For the computer simulation of the defect structure and for the mobility of the oxygen anions within these defect structures we applied the method of interatomic potentials in a simple rigid-ion approximation. The parameters of interaction were calibrated on the basis of empirical data, i.e. equilibrium geometry and cohesive energies of the binary oxides CaO, MnO2and Mn2O were taken into account for the present calculations. Stabilities, oxygen migration barriers and dielectric constants of selected representants of CaMnO3-x are presented.

KW - anion deficient structures

KW - computer simulation

KW - dielectric constants

KW - oxygen migration barriers

KW - oxygen mobility

KW - Perovskitic calcium manganese oxides

UR - http://www.scopus.com/inward/record.url?scp=0029484894&partnerID=8YFLogxK

U2 - 10.1080/01411599508200436

DO - 10.1080/01411599508200436

M3 - Article

AN - SCOPUS:0029484894

VL - 55

SP - 229

EP - 244

JO - Phase Transitions

JF - Phase Transitions

SN - 0141-1594

IS - 1-4

ER -