【作者】 陈克兵；

【导师】 姚凯伦；

【作者基本信息】 华中科技大学 ， 凝聚态物理， 2009， 硕士

【摘要】 在一定的温度变化范围之内,多铁材料既具有铁电性,又具有磁性,还具有铁电相和铁磁相耦合所生的一种新的效应-磁电效应。该材料可以分为单相的多铁材料和复合的多铁材料。复合的多铁材料除了具有单相的多铁材料所具有的优点之外,所产生的磁电耦合效应会更强,应用也会更广泛,因此,我们探索用纯相的铁电材料和纯相的铁磁材料来制备多铁复合材料。钛酸钡(BaTiO3)材料是一种典型的铁电材料,在BaTiO3里面掺Sr之后,并能调节Ba和Sr的比例就会得到比BaTiO3性能更好的钙钛矿结构的钛酸锶钡(Ba1-xSrxTiO3)铁电材料,而镧锶锰氧(La1-xSrxMnO3)也是一种钙钛矿结构的并具有较好铁磁性的材料。我们在本文中主要研究了利用溶胶-凝胶的方法制备Ba0.5Sr0.5TiO3(BST)铁电薄膜和多铁复合薄膜,并研究了薄膜的结构、厚度、铁电性、介电性、漏电流和磁性等性质。本文的主要内容如下:(1)利用溶胶-凝胶的方法在Si上制备出了不同退火温度的BST薄膜,经XRD和FSEM测试,发现薄膜在550℃退火温度下就已经结晶,薄膜的表面是很平整和均匀的,晶粒随着退火温度的升高而长大。(2)在LaNiO3/Si的底电极上制备了不同退火温度的BST薄膜,并研究了FSEM、铁电性、介电性和漏电流性质。其中,650℃退火温度下的BST薄膜在71.43 kV/cm的测试场下具有比较高的剩余极化强度为1.3129μC/cm2,而且介电特性也比较好。(3)利用溶胶-凝胶的方法在LaNiO3/Si的底电极上制备了BST/LSMO多铁薄膜。经XRD测试,可以看出多铁薄膜结晶良好;经磁性测试,发现多铁薄膜(LSMO5层)在750℃下退火时,当薄膜和磁场平行时饱和磁化强度达到了最大值为24.84 emu/cm3;经R-T测试,得到薄膜的电阻会随着退火温度的升高而增大;经铁电性质和漏电流性质的测试,可以看出多铁薄膜的剩余极化强度值比较大,700℃退火下的薄膜的漏电流比较小。更多还原

【Abstract】 In a certain range of temperature changes, the magnetoelectric material of both ferroelectric and magnetic, but also with ferroelectric and ferromagnetic coupling with a new-born effect-Magnetoelectric Effect, can be divided into single-phase magnetoelectric material and magnetoelectric composite materials.Magnetoelectric composite materials in addition to single-phase with the magnetic material other than the advantages, arising from the magnetic coupling effect will be stronger, the application will be more extensive, so we explore the pure phase of the ferroelectric material and the pure phase of the ferromagnetic material to prepare magnetoelectric composites. Barium titanate (BaTiO3) material is a typical ferroelectric material, in the Sr-doped BaTiO3 after it, and to adjust the ratio of Ba and Sr, we will get perovskite structure of BST ( Ba1-xSrxTiO3) ferroelectric material, it has better performance than the BaTiO3, and lanthanum strontium manganese oxide (La1-xSrxMnO3) is also a perovskite structure and has a good magnetic. In this article we study the use of modified sol - gel prepared Ba0.5Sr0.5TiO3 (BST) ferroelectric thin films and by the pure phase of the ferroelectric thin films (BST) and the pure phase of the ferromagnetic thin films (La0.67Sr0.33MnO3) posed by the magnetoelectric composite films and studying the properties of structure , thickness , ferroelectricity, dielectric , leakage current-electric field and magnetic . This article is divided into four chapters, are as follows:(1) The use of sol - gel method on Si prepared in different annealing temperature of the BST films by XRD and FSEM, found film annealed at 550℃temperature has been the crystallization, films’surface is very smooth and uniform, grain With the annealing temperature up;(2) At the end of the LaNiO3/Si electrodes prepared in different annealing temperature of the BST films, and studied the FSEM, ferroelectric, dielectric properties and leakage current. Of which, 650℃annealing temperature of the BST films under the 71.43 kV / cm field test with a relatively high intensity of the remanent polarization 1.3129μC/cm2, dielectric properties and also better. (3) On the LaNiO3/Si electrodes were prepared BST / LSMO magnetoelectric films by sol-gel. Through the XRD test, we can see that we get a good multi- crystalline magnetoelectric films; Through the magnetic test, we found that BST/LSMO films (LSMO5 layers) annealed at 750℃, when the films and the magnetic field parallel to the saturation magnetization reached a maximum of 24.84 emu/cm3 ;Through R-T test,we get films’resistance increased with the annealing temperature gradually increasing; Through ferroelectric and Leakage current test, films’value of remanent polarization relatively large, the relatively small leakage current at 700℃annealed .更多还原