La_(0.7)Ca_(0.3)MnO_3薄膜微观结构的HRTEM表征

Characterization of microstructure of La_(0.7)Ca_(0.3)MnO_3 film by high resolution transmission electron microscopy

利用透射电子显微镜研究了衬底温度600～800℃条件下采用脉冲激光法在(001)LaAlO3(LAO)衬底上制备的La0.7Ca0.3MnO3(LCMO)薄膜的微观结构。结果表明薄膜由大量柱状晶组成且与LAO衬底形成良好外延关系。LCMO薄膜与LAO衬底的取向关系可以描述为:(ⅰ)(100)f∥(001)s、[011]f∥[100]s;(ⅱ)(011)f∥(001)s、[100]f∥[100]s。LCMO显示层状畴结构,即在衬底上初始生长的薄膜为(ⅱ)型畴,在此之上生长的薄膜为(ⅰ)类和(ⅱ)类型畴的混合体。薄膜中可观察到一些反向畴与孪晶等缺陷。薄膜与衬底界面少见错配位错,薄膜以Stranski-Krastanov模式生长。

The La0.7Ca0.3MnO3 films were prepared by pulsed laser deposition on a（100） LaAlO3 substrate at the temperature between 600 and 800℃.The microstructure of these films was studied by high resolution electron microscopy.The results show that La0.7Ca0.3MnO3 films were epitaxially grown on LaAlO3 substrates at the temperatures chosen and were composed of a lot of columnar grains.The oriented relationship between film and substrate was identified as follows：（ⅰ）（100）f∥（001）s,f∥s,（ⅱ）（011）f∥（001）s,f∥s.The film has lamella domain structure,that is,the film close to the substrate shows（ⅱ）-domain and the upper lamella shows a complex of（ⅰ） and（ⅱ）-domains.Anti-phase domains and twins were also observed in these films.The misfit dislocations between films and substrates were seldom seen in these films.The films grow in a mode of Stranski-Krastanov.