【摘要】 采用溶胶-凝胶方法在Si(111)上制备了LSMO(x=0.17)薄膜.研究了块体材料和不同厚度薄膜R-T曲线、红外光谱和X射线衍射.结果表明,LSMO薄膜属于正交晶体结构,薄膜取向与膜厚度有关,当膜厚度为450nm或680nm时,主要取向〈200〉,而膜厚度为900nm时取向为〈020〉:根据离子对相互作用能和谐振子模型,得到了红外吸收与Mn—O—Mn键长和键角关系式,600cm-1附近红外吸收与晶格常数b的变化有关;块体与薄膜的金属—绝缘体转变温度(TMI)存在较大差别,薄膜转变温度显著低于块体,并与厚度有一定关系.认为是LSMO薄膜中的应力诱导了晶格常数变化,引起键角改变及JT效应是转变温度变化的主要原因.更多还原

【Abstract】 The LSMO (x=0.17) film on the Si (111) substrate was fabricated by the sol-gel method.The R-T curves, the infrared spectra and XRD results of the block and the film with different thickness show that the crystals of the LSMO films are orthogonal, and the film orientation has some relation with the film thickness. When the film thickness lies between the 450nm to 680 nm, the orientation is 〈200〉, but when the film thickness equals to 900 nm, the orientation is 〈020〉. According to the reactive energy and the harmonic oscillator model, the relational expressions, between the infrared absorption and the Mn-O-Mn bond length and bond angel were studied. The infrared absorption near 600cm~ -1 relates to the different lattice constant b, and the metal-insulator transformation temperatures (T- MI ) of the block material and the films differ much, those of the films being much lower than that of the block material and, at the same time, has something to do with the film thickness. The paper indicates that the stress in the LSMO films inducing the lattice constant change and then arousing the change of bond angel and JT effect is the main reason for the change of the transformation temperature.更多还原