【作者】 麻小明；

【导师】 熊永红；

【作者基本信息】 华中科技大学 ， 材料物理与化学， 2009， 硕士

【摘要】 2007年10月,瑞典皇家科学院颁发的诺贝尔奖揭晓,法国科学家阿尔贝·费尔（Albert Fert）和德国科学家彼得·格林贝格尔（Peter Grünberg）由于分别独立发现了巨磁电阻（GMR）效应共同获得了本届诺贝尔物理学奖。这是到目前为止,科学界对磁电阻效应及其应用的最大认可。在多年的磁电阻研究应用中,人们发现在钙钛矿型锰氧化物中有超大磁电阻效应,我们一般称它为庞磁电阻（CMR）效应。经过多年的研究发现,要使这类庞磁电阻化合物达到最大的磁电阻效应,绝大多数都需要加上一个很强的磁场,并且只有在转变温度附近一个很窄的温度范围内才有一个较大的磁电阻效应,由于此类化合物的转变温度一般远低于室温,所以大大的限制了它在实际生活生产中的应用。为了改变这种现状,研究者们研究发现,在锰基钙钛矿结构的氧化物中存在一种非本征磁电阻效应,此类效应可以通过一种“磁性金属/非磁性金属/磁性金属”的三明治夹层结构达到,通过这种方式使材料可以在一个接近室温的环境下得到一个较大的磁电阻效应。本论文中以La_0.7Ca_0.2Sr_0.1MnO₃颗粒作为磁性金属相,用化学镀的方式在其表面镀上铜或者银作为非磁性金属相当中间层,再做其表面镀上一层镍作为磁性金属相,从而形成上述的三明治夹层结构并对其进行磁电阻效应的研究。本论文主要包括以下几个方面的内容:（1）对磁电阻效应的发现和发展做简要介绍,并对锰基钙钛矿类氧化物的电子结构、本征磁电阻效应、非本征磁电阻效应等相关理论做简单介绍。并在此基础上提出本论文的选题目的和研究内容。（2）介绍了通过固相反应法制备La_0.7Ca_0.2Sr_0.1MnO₃样品基体的方法,并对制备出来的样品基体性能进行测试和分析。（3）介绍了化学镀技术的发展概况,着重介绍了化学镀铜、银、镍的方法,并对在La_0.7Ca_0.2Sr_0.1MnO₃样品基体粉体上做不同的化学镀要注意到的事项和粉体的前后处理做重点说明和分析。（4）将制备出来的La_0.7Ca_0.2Sr_0.1MnO₃-Cu-Ni和La_0.7Ca_0.2Sr_0.1MnO₃-Ag-Ni复合体系进行性能测试和分析。（5）结论总结部分。更多还原

【Abstract】 October 2007, the Nobel Prize,which is presented by Royal Swedish Academy ,have been announced, Albert Fert , who is from France, and Peter Grünberg, who is from Germany, share the Nobel Prize in Physics this time, because they found the giant magnetoresistance （GMR） effect as independent. This is the most recognized of the scientific community on the magnetoresistance effect and its application by far。fter years of research and application of magneto-resistance, it has been found in perovskite-type manganese oxides have very large magnetoresistance effect, we generally call it Colossal Magnetoresistance （CMR） effect. After years of study found that, for such compounds Colossal Magnetoresistance maximum magnetoresistance effect, the vast majority will need to add a strong magnetic field, and only near the transition temperature in a very narrow temperature range only a larger magnetoresistance effect, due to the transition temperature of these compounds generally much lower than room temperature, so greatly limited its production in real life applications. In order to change this situation, the researchers found that in the Mn-based perovskite oxides that exist in a non-intrinsic magnetoresistance, such effects may be through a "magnetic metal / non-magnetic metal / magnetic metals "sandwich sandwiches achieved in this way so that material can be at room temperature in an environment close to a large magnetoresistance effect. In this paper as the magnetic metal particles La_0.7Ca_0.2Sr_0.1MnO₃, by chemical plating in the plating on the surface of copper or silver as a fairly non-magnetic metal intermediate layer, another layer of its surface plated with nickel as the magnetic metals phase, forming the sandwich structure and researchs magnetoresistance .In this paper, include the following main aspects:（1） Have a brief introduction on the discovery and development of the magnetoresistance effect, introduce the perovskite-type manganese oxide-based electronic structure, intrinsic magnetoresistance, non-intrinsic magnetoresistance on the theory briefly. And, in this based on the purpose of this thesis and research content.（2） Introduced the preparation La_0.7Ca_0.2Sr_0.1MnO₃ samples by solid-state reaction method, analysis and test the capability of the sample.（3） Introduced the electroless plating technology development, focused on the chemical copper, silver, nickel, methods, and sample matrix in La_0.7Ca_0.2Sr_0.1MnO₃ powder electroless plating different matters and should be noted that powder before and after the processing and analysis focusing on it.（4）Test and analysis the La_0.7Ca_0.2Sr_0.1MnO₃-Cu-Ni and La_0.7Ca_0.2Sr_0.1MnO₃-Ag-Ni composite system which have been prepared .（5） The conclusion.更多还原