Based on the Boltzmann transport equation of electrons and taking the scattering effect of electrons in the grain boundary as the boundary conditions of electrons transport in the grain, we presented a theoretical mod...Based on the Boltzmann transport equation of electrons and taking the scattering effect of electrons in the grain boundary as the boundary conditions of electrons transport in the grain, we presented a theoretical model for the Seebeck coefficient of bulk poly- crystalline thermoelectric materials, and applied it to studying the grain size effect on the Seebeck coefficient. Then we discussed the effects of transmissivity, temperature and the mean free path of electrons on the size effect. The results show that the proposed theoretical model is reasonable and effective and the predicted results for the Seebeck coefficient are in good agreement with the experimental data reported in literature. The bulk polycrystalline materials have notable (big) grain size effects on the Seebeck coefficient, and the influences of transmissivity, temperature and the mean free path of electrons on the Seebeck coefficient are also significant.展开更多
Exploiting the thermal insulation properties of glass fiber and excellent conductivity of conducting polymer, a novel one-dimensional (1D) composite thermoelectric material, based on poly(3,4-ethylenedioxythiophene): ...Exploiting the thermal insulation properties of glass fiber and excellent conductivity of conducting polymer, a novel one-dimensional (1D) composite thermoelectric material, based on poly(3,4-ethylenedioxythiophene): p-toluenesulfonic acid (PEDOT: p-TSA)/glass fiber, is prepared by coating the PEDOT: p-TSA on the surface of glass fiber with in situ polymerization method. We hope the materials can bring out the performance of the “electron conductor, photon glass”. During the polymerization process, the effects of oxidant concentration and dopant mass fraction on thermoelectric properties of the materials are investigated. The group type of the polymer chain and the morphology of the samples were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), respectively. The maximal Seebeck coefficient (S) and electric conductivity (σ) of the pristine sample are 32 μVK-1 and 169 Sm-1, respectively. After further post-processing with methanol, the thermoelectric properties of materials were improved, and the maximum value of S and σ increased greatly to 48.5 μVK-1 and 3184 Sm-1, respectively. The maximal power factor (PF) of materials also increased from 0.12 μWm-1 K-2 to 6.74 μWm-1 K-2. Moreover, we have proposed a preliminary explanation on the carrier transport mechanism.展开更多
Silver (Ag) and silver antimonate (AgSbO3) composites with different amounts of Sb3+ were synthesized by normal sintering with the aim of realizing a thermoelectric material. The electrical conductivity (σ) increased...Silver (Ag) and silver antimonate (AgSbO3) composites with different amounts of Sb3+ were synthesized by normal sintering with the aim of realizing a thermoelectric material. The electrical conductivity (σ) increased in the sample containing larger amount of Sb3+, whereas Seebeck coefficient (S) decreased. Producing Sb3+ caused the generation of oxygen vacancies in the material, and thus the corresponding donor levels are created in the bandgap, providing more conduction electrons. The conductive Ag particles would contribute to the conduction path as bypasses for carrier transport. The thermal conductivity (κ) was slightly lower in the presence of Ag defects in AgSbO3.展开更多
Single-phase pristine and cation-substituted calcium manganite（Ca1-xBixMn1-yVyO3-δ） polycrystalline samples were synthesized by the solid state reaction technique. Their thermoelectric properties were measured by a...Single-phase pristine and cation-substituted calcium manganite（Ca1-xBixMn1-yVyO3-δ） polycrystalline samples were synthesized by the solid state reaction technique. Their thermoelectric properties were measured by a set up that was designed and assembled in the laboratory. The Ca1-x BixMn1-yVyO3-δsample with x = y = 0.04 has shown a power factor（S^2σ） of 176 μW/m/K^2 at 423 K, which is nearly two orders of magnitude higher than that of the pristine sample（2.1 μW/m/K2）. The power factor of the substituted oxide remains almost temperature independent as the Seebeck coefficient increases monotonically with temperature, along with the simultaneous decrease in electrical resistivity which is attributed to enhanced electron density due to co-doping of bismuth and vanadium and grain boundary scattering. These cation-substituted calcium manganites can be used as a potential candidate for an n-type leg in a thermoelectric generator（module）.展开更多
采用合金设计、真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料,采用XRD、SEM和ZEM-3热电测试系统等表征热电材料晶体结构、微观形貌和热电性能,研究Cu、S掺杂的n型Bi_(2)T...采用合金设计、真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料,采用XRD、SEM和ZEM-3热电测试系统等表征热电材料晶体结构、微观形貌和热电性能,研究Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料热电性能机理。结果表明:Cu_(y)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料晶体结构为R-3m空间群斜方晶系的六面体层状结构;掺杂Cu的Cu_(y)Bi_(2)Te_(2.7)Se_(0.3)热电材料,形成Cui间隙缺陷和Bi′Te反位缺陷,随着载流子(电子)浓度增加,载流子迁移率降低,电导率显著增大;掺杂S的Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料,生成化学键健能较Bi-Te强的Bi-S,抑制反位缺陷Bi′Te形成,少数(空穴)载流子浓度减小,同时增强声子对声子散射和点缺陷对声子散射,从而使晶格热导率和双极扩散热导率降低,总热导率明显降低,抑制塞贝克系数的减少;Cu、S共掺杂的协同作用,n型Cu_(y)Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料电导率增大,而热导率基本不变,由此ZT值和功率因子显著提高;在300~400 K温度范围内,Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)的电导率约为7.0×10^(4)S/m,塞贝克系数约为220μV/K,功率因子约为2.4 m W/(m·K^(2)),热电优值(ZT值)约为1.0。Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料可广泛应用于低温尤其室温条件下的热电制冷器件和温差发电电池。展开更多
基金supported by the National Basic Research Program of China (Grant No. 2007CB607506)National Natural Science Foundation of China (Grant No. 10672070)Program for New Century Talent of the Ministry of Education (Grant No. NCET06-0896)
文摘Based on the Boltzmann transport equation of electrons and taking the scattering effect of electrons in the grain boundary as the boundary conditions of electrons transport in the grain, we presented a theoretical model for the Seebeck coefficient of bulk poly- crystalline thermoelectric materials, and applied it to studying the grain size effect on the Seebeck coefficient. Then we discussed the effects of transmissivity, temperature and the mean free path of electrons on the size effect. The results show that the proposed theoretical model is reasonable and effective and the predicted results for the Seebeck coefficient are in good agreement with the experimental data reported in literature. The bulk polycrystalline materials have notable (big) grain size effects on the Seebeck coefficient, and the influences of transmissivity, temperature and the mean free path of electrons on the Seebeck coefficient are also significant.
文摘Exploiting the thermal insulation properties of glass fiber and excellent conductivity of conducting polymer, a novel one-dimensional (1D) composite thermoelectric material, based on poly(3,4-ethylenedioxythiophene): p-toluenesulfonic acid (PEDOT: p-TSA)/glass fiber, is prepared by coating the PEDOT: p-TSA on the surface of glass fiber with in situ polymerization method. We hope the materials can bring out the performance of the “electron conductor, photon glass”. During the polymerization process, the effects of oxidant concentration and dopant mass fraction on thermoelectric properties of the materials are investigated. The group type of the polymer chain and the morphology of the samples were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), respectively. The maximal Seebeck coefficient (S) and electric conductivity (σ) of the pristine sample are 32 μVK-1 and 169 Sm-1, respectively. After further post-processing with methanol, the thermoelectric properties of materials were improved, and the maximum value of S and σ increased greatly to 48.5 μVK-1 and 3184 Sm-1, respectively. The maximal power factor (PF) of materials also increased from 0.12 μWm-1 K-2 to 6.74 μWm-1 K-2. Moreover, we have proposed a preliminary explanation on the carrier transport mechanism.
文摘Silver (Ag) and silver antimonate (AgSbO3) composites with different amounts of Sb3+ were synthesized by normal sintering with the aim of realizing a thermoelectric material. The electrical conductivity (σ) increased in the sample containing larger amount of Sb3+, whereas Seebeck coefficient (S) decreased. Producing Sb3+ caused the generation of oxygen vacancies in the material, and thus the corresponding donor levels are created in the bandgap, providing more conduction electrons. The conductive Ag particles would contribute to the conduction path as bypasses for carrier transport. The thermal conductivity (κ) was slightly lower in the presence of Ag defects in AgSbO3.
文摘Single-phase pristine and cation-substituted calcium manganite（Ca1-xBixMn1-yVyO3-δ） polycrystalline samples were synthesized by the solid state reaction technique. Their thermoelectric properties were measured by a set up that was designed and assembled in the laboratory. The Ca1-x BixMn1-yVyO3-δsample with x = y = 0.04 has shown a power factor（S^2σ） of 176 μW/m/K^2 at 423 K, which is nearly two orders of magnitude higher than that of the pristine sample（2.1 μW/m/K2）. The power factor of the substituted oxide remains almost temperature independent as the Seebeck coefficient increases monotonically with temperature, along with the simultaneous decrease in electrical resistivity which is attributed to enhanced electron density due to co-doping of bismuth and vanadium and grain boundary scattering. These cation-substituted calcium manganites can be used as a potential candidate for an n-type leg in a thermoelectric generator（module）.
文摘采用合金设计、真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料,采用XRD、SEM和ZEM-3热电测试系统等表征热电材料晶体结构、微观形貌和热电性能,研究Cu、S掺杂的n型Bi_(2)Te_(2.7)Se_(0.3)热电材料热电性能机理。结果表明:Cu_(y)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料晶体结构为R-3m空间群斜方晶系的六面体层状结构;掺杂Cu的Cu_(y)Bi_(2)Te_(2.7)Se_(0.3)热电材料,形成Cui间隙缺陷和Bi′Te反位缺陷,随着载流子(电子)浓度增加,载流子迁移率降低,电导率显著增大;掺杂S的Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料,生成化学键健能较Bi-Te强的Bi-S,抑制反位缺陷Bi′Te形成,少数(空穴)载流子浓度减小,同时增强声子对声子散射和点缺陷对声子散射,从而使晶格热导率和双极扩散热导率降低,总热导率明显降低,抑制塞贝克系数的减少;Cu、S共掺杂的协同作用,n型Cu_(y)Bi_(2)Te_(2.62-z)SzSe_(0.3)热电材料电导率增大,而热导率基本不变,由此ZT值和功率因子显著提高;在300~400 K温度范围内,Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)的电导率约为7.0×10^(4)S/m,塞贝克系数约为220μV/K,功率因子约为2.4 m W/(m·K^(2)),热电优值(ZT值)约为1.0。Cu_(0.03)Bi_(2)Te_(2.62)S_(0.08)Se_(0.3)热电材料可广泛应用于低温尤其室温条件下的热电制冷器件和温差发电电池。
