"

Cookies ussage consent

Our site saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing our site without changing the browser settings you grant us permission to store that information on your device.

I agree, do not show this message again.

Influence of the microstructure on extrinsic magnetoresistance in Sr2Fe0.9Gd0.1Mo1-xWxO6 double perovskites

M.-L. CRAUS1,2, C. NECULIŢA3, L. BÎLTEANU4, M. LOZOVAN2,*

Affiliation

  1. LNF – JINR, Dubna Russia, Joliot-Curie 6, 141980 Dubna, Mosk.Obl, Russia
  2. National Institute of R & D for Technical Physics, 47 D. Mangeron Blvd., 700050 Iasi, Romania
  3. Faculty of Physics, University of Bucharest, 405 Fizicienilor Street, RO 077125 Bucharest-Mǎgurele, Romania
  4. Faculty of Physics,”Al. I. Cuza” University, 11 Carol I Blvd., RO 700506 Iasi, Romania

Abstract

We have prepared by an improved standard ceramic technology Sr2Fe0.9Gd0.1Mo1-xWxO6 double perovskites. As precursors were used oxides and carbonates, mixed in stoechiometric ratios, corresponding to the expected chemical composition. The final treatment was performed in vacuum at 1190°C. The sintered/treated samples were investigated by means of XRD by using a DRON 2.0 diffractometer, with an acquisition data system. Transport measurements were performed between room temperature and 700 K. The samples contain small quantities of foreign phases as Sr2Fe2O5, SrFeO3-x, SrMoO3 or similar. The crystalline structure of the main phase can be identified as Fm3m (GS 225) or a cubic phase with a low tetragonal distortion, identified by FullProf@ tests as having an I4/mmm structure. The lattice constant, volume unit and the microstrains level have a minimum value for x = 0.4. We attributed this minimum to corroboration of two processed: (1) a general increase of the concentration of B’ cations in the low valence state, and (2) an increase of the W concentration in the samples. The Mott mechanism seems to dominate around room temperature, while at higher temperature the transport is similar to that of the semiconductors..

Keywords

Double perovskites, Rare earth, Extrinsic magnetoresistance, Activation energy.

Submitted at: Sept. 6, 2006
Accepted at: Sept. 13, 2006

Citation

M.-L. CRAUS, C. NECULIŢA, L. BÎLTEANU, M. LOZOVAN, Influence of the microstructure on extrinsic magnetoresistance in Sr2Fe0.9Gd0.1Mo1-xWxO6 double perovskites, Journal of Optoelectronics and Advanced Materials Vol. 8, Iss. 5, pp. 1723-1726 (2006)