Nax Co2 O4陶瓷的力学弛豫和阻抗弛豫研究

 采用溶胶－凝胶法制备得到了γ-Na_x Co₂ O₄陶瓷,利用动态力学分析仪（DMA）在120～370 K和1～20 Hz的温度、频率范围内测量其内耗－温度谱,首次观测到γ-Na_x Co₂ O₄陶瓷在150 K附近的弛豫内耗峰,激活能为0.39 eV。采用高精度阻抗测量仪 (TH2816) 测量了γ-Na_x Co₂ O₄陶瓷在100～300 K,2 kHz～100 kHz的温度、频率范围内的阻抗－温度谱,观测到室温以下的阻抗弛豫峰,其激活能为0.13 eV,阻抗弛豫峰在外加磁场(1kGs)下向低温方向移动。这些结果表明:γ- Na_x Co₂ O₄陶瓷具有不同的力学和电学弛豫机制。

Mechanical and Impedance Relaxations Study in NaxCo2O4

Thermoelectric oxide γ-Na_x Co₂ O₄ ceramics are successfully synthesized with Sol-Gel method,and the internal friction temperature spectrum is measured by Dynamic Mechanical Analysis (DMA) in the temperature range of 120～370 K with the frequencies of 1～20 Hz. A relaxation-type internal friction peak around 150 K with an activation energy of 0.39 eV is observed for the first time. The temperature dependence of impendence is obtained via LCR meter (TH2816) in the temperature range of 100～300 K at the frequencies of 2 kHz～100 kHz. A relaxation type impedance peak with an activation energy of 0.13 eV is observed below room temperature, which moves to lower temperature when the sample is under a magnetic field of 1 kGs. Our results show that γ-Na_x Co₂ O₄ thermoelectric oxide has different relaxation mechanisms for the mechanical and impendence relaxations.