Browsing by Author "Shiva Kumar Singh"

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Impact of sintering temperature on room temperature magneto-resistive and magneto-caloric properties of Pr2/3Sr1/3MnO3
(Elsevier Ltd, 2013) Ramesh Chandra Bhatt; Shiva Kumar Singh; P.C. Srivastava; S.K. Agarwal; V.P.S. Awana
Magneto-resistive and magneto-caloric properties of polycrystalline Pr 2/3Sr1/3MnO3 have been studied as a function of sintering temperature (Ts) between 1260 and 1450 °C. Reitveld refinement of their X-ray diffraction (XRD) patterns confirms their single phase crystalline structure with orthorhombic Pbnm space group. The point of maximum value of temperature coefficient of resistance (TCRmax) and Curie temperature (Tc) decreased slightly with Ts. Magneto-resistance (MR) and magnetic entropy (DSM) increased markedly with sintering temperature. This could be attributed to the observed sharpness of both the magnetic and resistive transitions due to better grain connectivity. Optimum results are obtained for the sample with Ts = 1400 °C. MR at Tc of the same is found to be as large as 32% at 1T and 58% at 5T magnetic fields. The maximum entropy change (DSMmax) near its Tc is 2.3 J kg-1 K-1 and 7.8 J kg--1 K-1 upon 1T and 5T fields change respectively. These characteristics [MR (32% 1T, 58% 5T) and reasonable change in magnetic entropy (7.8 J kg-1 K-1, 5T)] generate possibility that the optimized compound can be used as a potential magnetic refrigerant close to room temperature. © 2013 Elsevier B.V. All rights reserved.