Yoo H-I
School of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Korea.
Phys Chem Chem Phys. 2005 Nov 21;7(22):3888-93. doi: 10.1039/b508998k. Epub 2005 Sep 26.
The effect of hole-trapping on the thermopower of a mixed ionic electronic conductor, e.g., BaTiO3, is analyzed in terms of irreversible thermodynamics by taking trapped holes as a fourth kind of electronic charge carrier in addition to free electrons, free holes and mobile oxide ions. It is found that the effect manifests itself in two ways: thermostatically in the ionic thermopower via the thermodynamic factor and dynamically in the electronic thermopower via the electrical conductivity contribution of the trapped holes. The thermopowers of both 99.995% pure, undoped and 1.8 m/o Al-doped BaTiO3, that were measured against oxygen activity in the range of -18 < log aO2 < or = 0 at elevated temperatures of 800 degrees to 1100 degrees C [H.-I. Yoo and C. R. Song, J. Electroceram., 2001, 6, 61, ref. 6], are reanalyzed by taking into account the hole-trapping for the doped case. It is found that while the reduced heats-of-transport of free electrons and holes are, respectively, close to their thermal energy k(B)T (k(B) being the Boltzmann constant), that of trapped holes is close to their migration energy that is essentially the same as the trapping energy onto the acceptors doped, 1.04 eV.
通过不可逆热力学，将捕获的空穴视为除自由电子、自由空穴和可移动氧离子之外的第四种电子电荷载流子，分析了空穴捕获对混合离子电子导体（如BaTiO₃）热功率的影响。研究发现，这种影响以两种方式表现出来：通过热力学因子在离子热功率中表现为恒温效应，通过捕获空穴的电导率贡献在电子热功率中表现为动态效应。在800℃至1100℃的高温下，针对氧活度在-18＜log aO₂≤0范围内测量的99.995%纯的未掺杂和1.8 m/o铝掺杂BaTiO₃的热功率[H.-I. Yoo和C. R. Song，《J. Electroceram.》，2001，6，61，参考文献6]，在考虑掺杂情况下的空穴捕获后进行了重新分析。研究发现，虽然自由电子和空穴的约化输运热分别接近它们的热能k(B)T（k(B)为玻尔兹曼常数），但捕获空穴的约化输运热接近它们的迁移能，该迁移能与掺杂到受体上的捕获能基本相同，为1.04 eV。
