Computational design and fabrication of novel functional materials based on tin oxide

采用理论与实验相结合的方法研究了二氧化锡（SnO_2）的新型气敏和p型导电性能。将基于第一性原理的投影增强波法、团簇展开技术和蒙特卡罗模拟相结合，提出了一种预测给定气体压力和温度下声子性质的计算方法。结果表明，采用这种方法可以很好地再现二元和三元氧化物体系的相变行为和相边界。应用于SnO_2表面的分子吸附，发现吸附能与表面平面和原子结构有显著的关系。它对环境气氛和温度也有很强的依赖性。在此基础上，提出了设计具有优异传感性能的表面结构的指导方针。并对SnO_2中各种掺杂物进行了计算，以考察其潜在的p型电导率。大量掺杂与锡尺寸不匹配的杂质会导致在带隙中形成杂质诱导带。表明可以通过控制杂质带来改变电导率。在理论预测的基础上，实现了掺杂SnO_2薄膜的脉冲激光沉积。

Novel gas sensing and p-type conducting properties of tin dioxide (SnO_2) have been explored using a combined theoretical and experimental approach. A computational method to predict the properties under a given gas pressure and temperature has been developed, by combining phonon calculation based on first-principles projector augmented wave method, cluster expansion technique, and Monte Carlo simulation. It is demonstrated that using this approach phase transition behaviors and phase boundaries are well reproduced for binary and ternary oxide systems. Appling to molecule adsorption on SnO_2 surfaces, adsorption energy is shown to significantly depend on surface planes and atomic structures. It also has a strong dependence on ambient atmosphere and temperature. Based on the results, a guideline for the design of surface structures with superb sensing properties is suggested.Calculations have been conducted as well for various dopants in SnO_2 in order to examine its potential p-type conductivity. A heavy doping of impurities having a large size mismatch with Sn results in the formation of impurity-induced bands in the band gap. It is suggested that the conductivity can be altered by controlling the impurity bands. Pulsed laser deposition of doped SnO_2 films has been made on the basis of the theoretical prediction.