Polycrystalline samples of Bi 1.5 Pb 0.5 Sr 2-x La x Co 2 O y （x = 0.1, 0.2, 0.3） with a layered structure were prepared by solid-state reaction method. All samples are p-type semiconductors. The thermoelectric prop...Polycrystalline samples of Bi 1.5 Pb 0.5 Sr 2-x La x Co 2 O y （x = 0.1, 0.2, 0.3） with a layered structure were prepared by solid-state reaction method. All samples are p-type semiconductors. The thermoelectric properties, namely, the electric resistivity （ρ）, Seebeck coefficient （S）, and power factor （S 2 /ρ） of the samples are dependent on chemical composition. The values of ρ, S, and S 2 /ρ increase with an increase in temperature for all samples. The substitution of Pb 2＋ for Bi 3＋ and La 3＋ for Sr 2＋ improves the thermoelectric properties of the Bi 2 Sr 2 Co 2 O y system owing to the simultaneous decrease of electric resistivity and increase of Seebeck coefficient. As a result, the optimal thermoelectric property has been obtained in Bi 1.5 Pb 0.5 Sr 1.7 La 0.3 Co 2 O y and the power factor can reach 2.1 × 10-4 W·m-1 K-2 at 998 K.展开更多
Layered cobalt oxides （Ca0.85–xYxOH）1.16CoO2 （x=0, 0.05, 0.1） were prepared by hydrothermal process and were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The electrical con...Layered cobalt oxides （Ca0.85–xYxOH）1.16CoO2 （x=0, 0.05, 0.1） were prepared by hydrothermal process and were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The electrical conductivity and Seebeck coefficient were measured from 323 to 573 K. The XRD and SEM analysis showed that all samples were single phase with plate-like morphology. The substitution of trivalent Y for divalent Ca had a remarkable effect on the enhancement of electrical properties. The maximum PF value, 9.17×10–5 W/（m？K2）, was obtained for （Ca0.75Y0.1OH）1.16CoO2 at 573 K, indicating that they are promising thermoelectric materials for middle-temperature usage.展开更多
Ca3Co409/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co409 film on the lwt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition...Ca3Co409/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co409 film on the lwt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition technique. A large open-circuit voltage signal with the response time of tens of nanosecond was observed at room temperature when the Ca3Co409 layer of the heterojunction was illuminated under the 308 nm irradiation and no voltage signal was detected under the 10.6 gun irradiation. A mechanism based on the photovoltaic effect of a p-n junction was proposed to explain the experimental results. The present work shows a great potential of this new heterojunction as photoelectric devices.展开更多
基金supported by the Program for Innovative Research Team (in Science and Technology) (No. 2009IRTHNIE05) in Henan Institute of Engineeringthe Foundation for University Key Teachers of Henan Province (No. 2008136)+1 种基金the Natural Science Fund of Henan Education Department, China (No. 2010C140001)the Youth Fund of Henan Institute of Engineering (No. Y10021)
文摘Polycrystalline samples of Bi 1.5 Pb 0.5 Sr 2-x La x Co 2 O y （x = 0.1, 0.2, 0.3） with a layered structure were prepared by solid-state reaction method. All samples are p-type semiconductors. The thermoelectric properties, namely, the electric resistivity （ρ）, Seebeck coefficient （S）, and power factor （S 2 /ρ） of the samples are dependent on chemical composition. The values of ρ, S, and S 2 /ρ increase with an increase in temperature for all samples. The substitution of Pb 2＋ for Bi 3＋ and La 3＋ for Sr 2＋ improves the thermoelectric properties of the Bi 2 Sr 2 Co 2 O y system owing to the simultaneous decrease of electric resistivity and increase of Seebeck coefficient. As a result, the optimal thermoelectric property has been obtained in Bi 1.5 Pb 0.5 Sr 1.7 La 0.3 Co 2 O y and the power factor can reach 2.1 × 10-4 W·m-1 K-2 at 998 K.
基金supported by National Natural Science Foundation of China(21201050,21271055)China Postdoctoral Science Foundation(2012M510086)
文摘Layered cobalt oxides （Ca0.85–xYxOH）1.16CoO2 （x=0, 0.05, 0.1） were prepared by hydrothermal process and were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The electrical conductivity and Seebeck coefficient were measured from 323 to 573 K. The XRD and SEM analysis showed that all samples were single phase with plate-like morphology. The substitution of trivalent Y for divalent Ca had a remarkable effect on the enhancement of electrical properties. The maximum PF value, 9.17×10–5 W/（m？K2）, was obtained for （Ca0.75Y0.1OH）1.16CoO2 at 573 K, indicating that they are promising thermoelectric materials for middle-temperature usage.
基金supported by the National Natural Science Foundation of China (Grant No.10904030)the Key Project of Hebei Education Department (Grant No.ZD200909)
文摘Ca3Co409/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co409 film on the lwt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition technique. A large open-circuit voltage signal with the response time of tens of nanosecond was observed at room temperature when the Ca3Co409 layer of the heterojunction was illuminated under the 308 nm irradiation and no voltage signal was detected under the 10.6 gun irradiation. A mechanism based on the photovoltaic effect of a p-n junction was proposed to explain the experimental results. The present work shows a great potential of this new heterojunction as photoelectric devices.
