Transport and thermoelectric properties of Sr{sub 3}(Ti{sub 0.95}R{sub 0.05}){sub 2}O{sub 7} (R = Ta, Nb, W) oxides

Journal Article · Sat Dec 15 04:00:00 EST 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4769787· OSTI ID:22089664

Sun, R. R.; Qin, X. Y.; Li, L. L.; Li, D.; Wang, N. N.; Zhang, J.; Wang, Q. Q. ^[1]

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1. Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, 230031 Hefei (China)

The Sr{sub 3}(Ti{sub 0.95}R{sub 0.05}){sub 2}O{sub 7} (R = Ta, Nb, W) polycrystalline compounds were fabricated, and their transport and thermoelectric properties were investigated. The results indicate that at T > 300 K electrical resistivity {rho} for all the doped compounds increases monotonically with temperature, and basically can be described by a relation {rho}{proportional_to}T{sup M} at T > {approx}650 K, with M = 1.39, 1.66, and 1.77 for R = Ta, Nb, and W, respectively, implying that at the high temperatures the acoustic phonon scattering dominates the scattering process. Although the resistivity {rho} of Sr{sub 3}(Ti{sub 0.95}Ta{sub 0.05}){sub 2}O{sub 7} exhibits a metallic-like behavior at the temperature as low as 5 K, a transition from metallic state (d{rho}/dT > 0) to semiconductor-like state (d{rho}/dT < 0) was observed at a critical low temperature {approx}41 K and {approx}79 K for R = Nb and W, respectively. At T < {approx}22 K, {approx}57 K, and {approx}80 K, a relation of {sigma}{proportional_to}T{sup 1/2} (here conductivity {sigma} = 1/{rho}) holds for the doped compounds with R = Nb, Ta, and W, respectively, suggesting that at the low temperatures the main transport mechanism is electron-electron interaction due to the presence of disorder induced by the dopants. The thermoelectric figure of merit (ZT) for Ta-doped compound increases more steeply with increasing temperature among the three compounds and reaches 0.066 at 1000 K.

• OSTI ID: 22089664
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 112; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARRIER DENSITY
DOPED MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRON-ELECTRON INTERACTIONS
ELECTRON-PHONON COUPLING
METALS
NIOBIUM COMPOUNDS
OXYGEN COMPOUNDS
PHONONS
POLYCRYSTALS
SCATTERING
SEMICONDUCTOR MATERIALS
STRONTIUM COMPOUNDS
TANTALUM COMPOUNDS
THERMAL CONDUCTIVITY
THERMOELECTRIC PROPERTIES
THERMOELECTRICITY
TITANIUM COMPOUNDS
TUNGSTEN COMPOUNDS