Na{sub 0.5}La{sub 0.5}RuO{sub 3}: Structure and electronic properties

Journal Article · Sat Mar 01 04:00:00 EST 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.6888· OSTI ID:535940

Chen, X L ^[1]; Bauernfeind, L; Braun, H F ^[1]

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1. Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany)

A compound Na{sub 0.5}La{sub 0.5}RuO{sub 3} has been synthesized by the solid-state reaction method. It crystallizes in the perovskite structure with a lattice parameter a=3.8874(1) {Angstrom} and space group Pm3m. The large cations Na{sup +} and La{sup 3+} are randomly distributed at the A sites, and no structural ordering has been found. All samples, prepared at different post-treatment conditions, exhibit good conduction over the temperature range from 4.2 K to room temperature, with a resistivity {approximately}2{endash}7 m{Omega} cm. A crossover from metallic transport to a semiconductinglike transport with decreasing temperatures, characterized by a minimum resistivity {rho}{sub min} in the {rho}-T curves, was observed for some samples. The temperature dependence of resistivity at T{gt}50 K is very weak, {vert_bar}d{rho}/dT{vert_bar}{lt}5{times}10{sup {minus}3} m{Omega} cm/K, regardless of the metallic or the semiconductinglike transport. At low temperatures, the temperature dependence of resistivity for all samples can be described by a three-dimensional variable-range-hopping conduction due to the hopping between localized states near the Fermi energy in an inhomogeneous medium. The measurement of the magnetization indicates that there is no magnetic order in Na{sub 0.5}La{sub 0.5}RuO{sub 3} from 250 K down to 5 K. Instead, the magnetic susceptibilities obey well the Curie-Weiss law. The fitted effective moment and Weiss temperature are p{sub eff}=2.93(1){mu}{sub B} and {Theta}={minus}243.5(1) K. The Pauli paramagnetic susceptibility {chi}{sub pauli} is estimated to be {approximately}1.43{times}10{sup {minus}4} emu/mole Ru. Moreover, at low temperatures the susceptibility still obeys the Curie-Weiss law, but with a reduced Curie constant. The observed transport and magnetic data can be understood based on a qualitative density-of-states model, combined with the Anderson localization. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 535940
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 11 Vol. 55; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
HEAT TREATMENTS
LANTHANUM OXIDES
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
RUTHENIUM OXIDES
SODIUM OXIDES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K