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首页> 外文会议>7th Biennial Conference on Engineering Systems Design and Analysis 2004(ESDA 2004) vol.1: Advanced Energy Systems; Advanced Heat Transfer in Engineering Systems; ... >STRUCTURAL, ELECTRICAL TRANSPORT AND MAGNETORESISTIVE STUDIES OF PR AND ND SUBSTITUTED ON LA_(2/3)BA_(1/3)MNO_3 PEROVSKITE
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STRUCTURAL, ELECTRICAL TRANSPORT AND MAGNETORESISTIVE STUDIES OF PR AND ND SUBSTITUTED ON LA_(2/3)BA_(1/3)MNO_3 PEROVSKITE

机译：LA_（2/3）BA_（1/3）MNO_3钙钛矿上PR和ND的结构，电输运和磁致电阻研究

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Colossal magnetoresistance (CMR), as the name implies, is the phenomenon of dramatic changes in resistance attendant upon application of a magnetic field. The typical CMR material is derived from perovskite manganites with the chemical formula Ln_(1-x)A_xMnO_3, where Ln is the rare earth (Ln = La, Pr, Nd, Sm) and A is the divalent metal (A = Ca, Ba, Sr). The objective of this paper is to study the effects of the doping Nd and Pr at La site on La-Ba-Mn-O ceramics using solid state reaction. The characteristics and magnetotransport properties of CMR materials are investigated. Polycrystalline (La_(1-x) Pr_x)_(0.67)Ba_(0.33)MnO_3 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, 1) and (La_(1-x)Pr_x)_(0.67)Ba_(0.33)MnO_3 (x = 0, 1/6, 1/3, 1/2, 2/3, 5/6, 1), are doped with Pr and Nd site based manganites, calcined at 900℃ for 12 hours, pelletized and sintered at 1300℃ for 24 hours have been synthesized and investigated. The magnetoresistance (MR) effects are measured using the four point probe technique. The magnetoresistance defined as MR% = (R_o - R_H)/R_H x 100 was measured at a magnetic field of H ≤ 1T at room temperature. The MR values were increased from 7.9 - 12.7% and from 7.9 - 12.3% for doping with Nd (x = 0.17) and Pr (x = 0.33) respectively. The electrical property, T_p was determined by using standard four-point probe resistivity measurement in a temperature range of 20 K to 300 K. The result shows that Pr and Nd dopants shift the value of T_p to a lower temperature. In this paper the structural pattern and microstructure property of bulk samples have been investigated via XRD, AFM and SEM. XRD patterns show that these systems are in single- phase with orthorhombic distorted perovskite structures. The rms roughness for the AFM images has obtained for undoped and doped samples. SEM micrographs have shown that undoped samples are observed to be more compact than the doped samples doped due to the existence of pores. The potential of this research is to produce magnetoresistive read head such as read/write heads in computer disc-drives, position sensor, magnetoresistive random access memory (MRAM), biomagnetic sensor and magnetic accelerometers.
机译：顾名思义，巨大的磁阻（CMR）是施加磁场后电阻急剧变化的现象。典型的CMR材料来自化学通式为Ln_（1-x）A_xMnO_3的钙钛矿锰矿，其中Ln为稀土（Ln = La，Pr，Nd，Sm），A为二价金属（A = Ca，Ba ，Sr）。本文的目的是通过固态反应研究La位点掺杂Nd和Pr对La-Ba-Mn-O陶瓷的影响。研究了CMR材料的特性和磁传输性能。多晶硅（La_（1-x）Pr_x）_（0.67）Ba_（0.33）MnO_3（x = 0，1/6，1/3，1/2，2/3，5/6，1）和（La_（ 1-x）Pr_x）_（0.67）Ba_（0.33）MnO_3（x = 0、1 / 6、1 / 3、1 / 2、2 / 3、5 / 6、1）掺杂有Pr和Nd部位合成并研究了在900℃下煅烧12小时，在1300℃下造粒并烧结24小时的三氧化二锰。使用四点探针技术测量磁阻（MR）效应。室温下在H≤1T的磁场下测量的磁阻定义为MR％=（R_o-R_H）/ R_H x 100。掺杂Nd（x = 0.17）和Pr（x = 0.33）的MR值分别从7.9-12.7％和7.9-12.3％提高。通过使用标准的四点探针电阻率测量在20 K至300 K的温度范围内确定电性能T_p。结果表明，Pr和Nd掺杂剂将T_p的值移至较低的温度。本文通过X射线衍射，原子力显微镜和扫描电镜研究了大块样品的结构特征和微观结构。 XRD图谱表明这些系统为单相，具有正交畸变的钙钛矿结构。对于未掺杂和掺杂的样品，已经获得了AFM图像的均方根粗糙度。 SEM显微照片表明，由于存在孔，未掺杂样品比掺杂样品更致密。这项研究的潜力是生产磁阻读头，例如计算机磁盘驱动器中的读/写头，位置传感器，磁阻随机存取存储器（MRAM），生物磁传感器和磁加速度计。

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