Colossal magnetoresistance of La0.67Ca0.33Mn1-xAx)3 [A=V, Dy and Zr] perovskite

Koh, Song Foo (2001) Colossal magnetoresistance of La0.67Ca0.33Mn1-xAx)3 [A=V, Dy and Zr] perovskite. Masters thesis, Universiti Putra Malaysia.

[img] PDF
1354Kb

Abstract

The colossal magnetoresistive of Lao.67Cao.33Mnl-x V x03 (LCMVO), to x=O.30, ceramics have been studied. X-ray diffraction (XRD) patterns show single-phase perovskite structure with the presence of some minor impurities for all the samples. The systems exhibit tetragonal and orthorhombic distorted perovskite structures, which resulted from the Jahn Teller distortion. Paramagnetic - Ferromagnetic phase transitions were observed in the X'-temperature curves for all the samples. The Curie temperature, Tc shifts to lower temperature as vanadium, dysprosium and zirconium doping increases respectively, which indicate the loss of ferromagnetic order. Zirconium doping is observed to decrease the Te more than the effect of other dopants. For LCMVO system, samples with x=0.0l, 0.02, 0.03 and 0.30 show an enhancement of volume susceptibility as the temperature increases from 110 K- 140 K, 120 K- 142 K, 123 K-140 K and 77 K-94 K respectively. These enhancements are due to the formation of magnetic clusters m the samples. For LCMDO system, all the samples show the typical ferromagnetic-paramagnetic transition and no spin glass behaviour was detected. However, in LCMZO system, the samples with x>0.05 show ferromagnetic onset followed by a cusp when cooling from room temperature. The anomalies were due to the formation of spin glass in the sample. The transport properties show the transition of semiconducting to metallic conductivity at T p. The existence of T p and T c was found correlated.

Item Type:Thesis (Masters)
Subject:Magnetoresistance
Subject:Perovskite - Structure-activity relationships
Chairman Supervisor:Professor Abdul Halim bin Shaari, PhD
Call Number:FSAS 2001 20
Faculty or Institute:Faculty of Science and Environmental Studies
ID Code:9244
Deposited By: Tuan Norasiah Tuan Yaacob
Deposited On:17 Jan 2011 04:08
Last Modified:27 Sep 2013 07:37

Repository Staff Only: Edit item detail

Document Download Statistics

This item has been downloaded for since 17 Jan 2011 04:08.

View statistics for "Colossal magnetoresistance of La0.67Ca0.33Mn1-xAx)3 [A=V, Dy and Zr] perovskite"


Universiti Putra Malaysia Institutional Repository

Universiti Putra Malaysia Institutional Repository is an on-line digital archive that serves as a central collection and storage of scientific information and research at the Universiti Putra Malaysia.

Currently, the collections deposited in the IR consists of Master and PhD theses, Master and PhD Project Report, Journal Articles, Journal Bulletins, Conference Papers, UPM News, Newspaper Cuttings, Patents and Inaugural Lectures.

As the policy of the university does not permit users to view thesis in full text, access is only given to the first 24 pages only.