【摘要】 采用溶胶-凝胶(sol-gel)法制备了名义组分为La0.67Sr0.20Cu0.10□0.03MnO3(□代表阳离子空位)的多晶母体粉体材料,在不同温度(200℃,250℃,300℃)的氢气环境中对母体粉体材料还原15分钟后,在1100℃氩气环境中烧结12小时得到系列块体样品。研究了块体样品的相结构,导电性质、磁学性质以及磁电阻效应。实验结果表明,在适当温度的氢气环境中对粉体材料还原,可减少乃至消除粉体样品中的Mn3O4杂相,从而可以使块体样品电阻率降低,磁电阻峰值提高。在1.8T外磁场下,La0.67Sr0.20Cu0.10□0.03MnO3母体样品的磁电阻在319K出现峰值,其峰值为24.6%;在250℃还原15分钟样品,其磁电阻峰值达到31.5%。更多还原

【Abstract】 La_0.67Sr_0.20Cu_0.10□_0.03MnO₃（"□" representing cation vacancy） poly-crystalline manganite powder was synthesized by sol-gel method,after reduced in hydrogen atmosphere for 15 minutes at different temperature（200℃,250℃,300℃）,the series bulk samples were obtained by sintering in argon atmosphere for 12 hrs at 1100℃.The structure,electrical and magnetic properties as well as colossal magnetoresistance（MR） of the bulk samples were researched in detail.Experiment results indicate that: the Mn₃O₄ impurity phase in the samples could decrease or disappear by reducing treatment in a hydrogen atmosphere at proper temperature;and resulting in the decrease of resistivity and increase of magnetoresistance peak value for the bulk samples.Under an applied magnetic filed of 1.8T,for La_0.67Sr_0.20Cu_0.10□_0.03MnO₃ non-reduced materials,the maximum value of MR is 24.6% at 319K;for the sample reduced for 15 minutes at 250℃,its peak value of MR reached 31.5%.更多还原