The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in ...The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in air followed by annealing in a reducing atmosphere.XRD and SEM analyses show that the rutile TiO_(2 i)n Sr_(0.95)TiO_(3) formed after sintering becomes Magneli phase of TinO_(2n-1) after annealing.Moreover,Bi resolves from Sr1-xBixTiO_(3 )after annealing,resulting in the formation of Sr1-xBixTiO_(3-δ)/Bi/TinO_(2n-1) composites.With increasing Bi content in Sr1-xBixTiO_(3-δ),the electrical conductivity increases while the absolute values of the Seebeck coefficient decrease as a result of increasing carrier concentration.The thermal conductivity of SrTiO_(3-δ) is reduced by doping Bi up to x=0.07.Highest ZT~0.13 is obtained in Sr0.93Bi0.07TiO_(3-δ) at 1000 K.展开更多
In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering...In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering. Structural properties of La1-xBaxCoO3 were systematically investigated and thermoelectric properties were measured in the temperature range of 330–1000 K. The results show that the thermoelectric properties of Ba-substituted LaCoO3 depend on x. Indeed, at 330 K, electrical conductivity presents an optimum value for x = 0.25 with a value of σmax ≈ 2.2×105 S·m–1 whereas the Seebeck coefficient decreases when x and/or the temperature increases. The Ba-substituted LaCoO3 samples exhibit p-type semiconducting behaviour. The best power factor value found is 3.4×10–4 W·m–1·K–2 at 330 K for x = 0.075, which is 10% higher than the optimum value measured in La1–xSrxCoO3 for x = 0.05. The thermal diffusivity and thermal conductivity increase with increasing temperature and Ba concentration. La1-xBaxCoO3 shows a maximum figure of merit(ZT = 0.048) for x = 0.05 at 330 K, 25% higher than the best value in La1–xSrxCoO3 compounds.展开更多
文摘The thermoelectric properties of Sr1-xBixTiO_(3-δ)(0≤x≤0.07)have been investigated.Dense ceramics of Sr1-xBixTiO_(3-δ) and Sr0.95TiO_(3-δ) have been prepared by solid-state reaction and conventional sintering in air followed by annealing in a reducing atmosphere.XRD and SEM analyses show that the rutile TiO_(2 i)n Sr_(0.95)TiO_(3) formed after sintering becomes Magneli phase of TinO_(2n-1) after annealing.Moreover,Bi resolves from Sr1-xBixTiO_(3 )after annealing,resulting in the formation of Sr1-xBixTiO_(3-δ)/Bi/TinO_(2n-1) composites.With increasing Bi content in Sr1-xBixTiO_(3-δ),the electrical conductivity increases while the absolute values of the Seebeck coefficient decrease as a result of increasing carrier concentration.The thermal conductivity of SrTiO_(3-δ) is reduced by doping Bi up to x=0.07.Highest ZT~0.13 is obtained in Sr0.93Bi0.07TiO_(3-δ) at 1000 K.
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文摘In the present work, dense perovskite ceramics were successfully prepared from a series of La1-xBaxCoO3 solid solutions in the range of substitution 0 ≤ x ≤ 0.75 using solid state reaction and conventional sintering. Structural properties of La1-xBaxCoO3 were systematically investigated and thermoelectric properties were measured in the temperature range of 330–1000 K. The results show that the thermoelectric properties of Ba-substituted LaCoO3 depend on x. Indeed, at 330 K, electrical conductivity presents an optimum value for x = 0.25 with a value of σmax ≈ 2.2×105 S·m–1 whereas the Seebeck coefficient decreases when x and/or the temperature increases. The Ba-substituted LaCoO3 samples exhibit p-type semiconducting behaviour. The best power factor value found is 3.4×10–4 W·m–1·K–2 at 330 K for x = 0.075, which is 10% higher than the optimum value measured in La1–xSrxCoO3 for x = 0.05. The thermal diffusivity and thermal conductivity increase with increasing temperature and Ba concentration. La1-xBaxCoO3 shows a maximum figure of merit(ZT = 0.048) for x = 0.05 at 330 K, 25% higher than the best value in La1–xSrxCoO3 compounds.
