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钙钛矿型稀土锰氧化物RE_(1-x)T_xMnO_3(RE=La,Pr,Nd,Gd;T=Ca,Sr,Ba,Pb等)因其特殊的巨磁电阻效应,引起人们广泛的关注.用非晶态的分子合金为前驱体,制备了一系列具有纳米尺寸的La-Ca-Mn-O复合氧化物颗粒.研究表明,前驱体的晶化温度对纳米颗粒的形貌和大小均有影响.当晶化温度为450℃~600℃时,从透射电子显微镜观察到的颗粒大小约为25nm~100nm.该纳米材料的磁及磁电阻行为不同于其体相体系,其交流磁化率表现出较强的尺寸依赖性,而磁电阻具有本征型和自旋隧穿型的巨磁电阻行为.
Due to its special GMR effect, RE_ (1-x) T_xMnO_3 (RE = La, Pr, Nd, Gd; T = Ca, Sr, Ba, Pb etc.) Concerned about the use of amorphous molecular alloys as precursors, a series of nano-sized La-Ca-Mn-O composite oxide particles were prepared.Research shows that the crystallization temperature of precursors on the morphology and size of the nanoparticles When the crystallization temperature is 450 ℃ ~ 600 ℃, the size of the particles observed by transmission electron microscopy is about 25nm ~ 100nm.The magnetic and magneto-resistive behavior of the nanomaterials is different from the bulk system, the AC magnetization The rate shows a strong dimensional dependence, while the magnetoresistance has the properties of intrinsic magnetoresistance and spin-tunneling giant magnetoresistance.