TY - JOUR
T1 - Electronic structure and crystal chemistry of niobium oxide phases
AU - Turzhevsky, S. A.
AU - Novikov, D. L.
AU - Gubanov, V. A.
AU - Freeman, Arthur J
PY - 1994/1/1
Y1 - 1994/1/1
N2 - Results of local-density linear muffin-tin orbital (LMTO) electronic-structure calculations for both known and recently obtained niobium oxide phases with different crystal lattices and different coordination of Nb atoms are presented. Perovskite-like compounds with one- or two-dimensional Nb-O condensed clusters, as well as hexagonal layered structures with trigonal-prismatic coordination of Nb atoms, are used. For SrNbO3, BaNb5O8, BaNb4O6, and Sr2Nb5O9, the Fermi level is located at the shoulder of the Nb d conduction band with a low density of oxygen states. For hexagonal MxNbO2 (M=Li,Na) compounds, oxygen contributions definitely appear at EF, but remain small compared with those of the high-Tc superconducting cuprates. Pair-interaction energies and superexchange-interaction parameters were calculated using the LMTO Green-function method. Typical for high-Tc superconductors, antiferromagnetic coupling between metal atoms in the Nb-O planes is shown to exist, but not the ferromagnetic exchange between metal d and oxygen p states. The calculations show that perovskite niobium oxide systems are not good candidates in the search for new high-Tc superconducting materials, but that hexagonal layered niobium oxide phases of the type considered in this paper might be of interest in studies of low Tc superconducting oxides.
AB - Results of local-density linear muffin-tin orbital (LMTO) electronic-structure calculations for both known and recently obtained niobium oxide phases with different crystal lattices and different coordination of Nb atoms are presented. Perovskite-like compounds with one- or two-dimensional Nb-O condensed clusters, as well as hexagonal layered structures with trigonal-prismatic coordination of Nb atoms, are used. For SrNbO3, BaNb5O8, BaNb4O6, and Sr2Nb5O9, the Fermi level is located at the shoulder of the Nb d conduction band with a low density of oxygen states. For hexagonal MxNbO2 (M=Li,Na) compounds, oxygen contributions definitely appear at EF, but remain small compared with those of the high-Tc superconducting cuprates. Pair-interaction energies and superexchange-interaction parameters were calculated using the LMTO Green-function method. Typical for high-Tc superconductors, antiferromagnetic coupling between metal atoms in the Nb-O planes is shown to exist, but not the ferromagnetic exchange between metal d and oxygen p states. The calculations show that perovskite niobium oxide systems are not good candidates in the search for new high-Tc superconducting materials, but that hexagonal layered niobium oxide phases of the type considered in this paper might be of interest in studies of low Tc superconducting oxides.
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U2 - 10.1103/PhysRevB.50.3200
DO - 10.1103/PhysRevB.50.3200
M3 - Article
AN - SCOPUS:4243944480
SN - 0163-1829
VL - 50
SP - 3200
EP - 3208
JO - Physical Review B
JF - Physical Review B
IS - 5
ER -