Temperature-Dependent Structure of Epitaxial （Ba,Sr）TiOa Films Grown on SrRuO3-Covered SrTiO3 Substrates

Growth dynamics of epitaxiai （Ba, Sr）TiO3 thin films deposited at different temperatures on SrRuO3/SrTiO3 substrates by pulsed laser deposition is investigated by transmission electron microscopy. The films exhibit a layered structure comprising sublayers with distinctive features in regard to the remaining strain, density of misfit dislocations and/or lattice defects, and growth habit. We correlate these temperature-dependent features with the predominant misfit-strain relaxation mechanisms for each one of the detected growth regimes. The thickness dependence of the film structure is discussed within the framework of the predictions for a kineticaily modified Stranski-Krastanov growth mode.     

热电材料与发电器件的进展和挑战

热电/温差电效应是一种能够实现热能和电能直接相互转换的环境友好型能源技术,基于该技术的热电发电器件的应用,有望成为缓解能源问题的可行方案.文章主要介绍了中高温区p型和n型热电材料的最新研究进展,重点论述了可能应用于热电发电器件的几种典型热电材料体系的相关优缺点.此外,还回顾了目前中高温区热电发电器件的研究现状,尝试给出...     

La1/2Sr3/2MnO4 的制备以及非公度电荷有序和轨道电子有序

用固态反应法制备了La1/2Sr3／2MnO4相X射线能谱分析证实了样品的平均成分为La0.45Sr1.49-MnO4，且有一定的微观成分不均匀性，用透射电镜在100K低温下观察到了[001]带轴电子衍射花样中出现的超衍射五点，它来源于非公度电荷有序和轨道电子有邓，其非公有制调制矢量K＝δ[110]T^*，其中δ＝0．19，经分析，这种δ＝0．19的非公度调制是δ＝1／4和δ＝1／6的公度调制无规分布的结果。