Year

2001

Degree Name

Master of Engineering (Hons.)

Department

Institute for Superconducting and Electronic Materials

Abstract

The La0.8Sr0.2Mn1-xZnxO3 system with x = 0, 0.01, 0,03, 0.05, 0.1,0.15, 0,3, 0.5 and 0.75 was prepared by the solid state reaction and investigated by structural, transport and magnetic properties measurements. X-ray powder diffraction results indicate a single orthorhombic phase over the whole range of x values and an increase in the lattice parameters (a, b, c) with an increase in zinc doping concentration in the studied system. Single phase is retained for x < = 0.3. SEM investigation shows that the average grain size of the La0.8Sr0.2Mn1-xZnxO3 system decreases from 3 um to less than 1 um with increases in the zinc doping level in the system. Results of transport measurements performed by the four-probe technique indicate that the insulator to metal transition temperature, Ti-m, decreases with an increase in the zinc substitution in the Mn site, while the resistivity of the La0.8Sr0.2Mn1-xZnxO3 system increases with an increase in the doping concentration for all doping levels.

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