静电场作用下电介质电热效应的热力学机理

摘要

The promising solid-state refrigerator based on the electrocaloric effect plays an important role in the cooling of microelectronic devices.In this paper, a fundamental thermodynamic differential equation considering the polar energy was proposed, and the thermodynamic expressions of heat capacity, temperature, entropy and heat flux in electrostatic field were derived.Then, a verification of the expressions was conducted by using the experimental data of barium titanate, and a good accordance was found.It is concluded that the electrocaloric effect owes itself to the variation of electric dipole moment with temperature and becomes obvious with the increase of temperature sensitivity of permittivity.Thus, the research on giant electrocaloric effect in the future should focus on the drastic change region of permittivity with temperature.%以电热效应为基础的固体制冷技术在微电子器件散热等方面有重要的应用.文中将极化能引入热力学基本微分方程,导出了静电场作用下系统的热容、温度、熵和热流量等随外场变化的计算公式,并选用钛酸钡的实验数据验证热力学理论公式,发现这些热力学理论计算式与文献资料提供的实验结果相符.研究表明,电偶极矩随外界温度发生变化是产生电热效应的基础,且介电常数的温度变化率越大,电热效应越明显,因此巨电热效应的研究方向应该是寻找介电常数随温度的剧烈变化区域.