Low temperature synthesis of ferromagnetic (LaK)MnO3 from KCl, KBr and KI fluxes

Potassium doped lanthanum manganites have been synthesized from KCl, KBr an d KI fluxes at 900, 850 and 750 degreesC respectively. While all the flux-g rown oxides are ferromagnetic metals (T-c = 290-330 K), the oxides grown fr om KCl and KBr fluxes crystallize in the rhombohedral structure and that sy nthesized from KI flux adopts the cubic structure. The enhancement in T-c c orrelates with the increasing tendency of the flux to get oxidized and decr easing melting points of the flux. Nearly stoichiometric (LaK)MnO3 with 33 % of Mn4+ concentration could be prepared at temperature as low as 750 degr eesC. Composition of all the phases have been obtained from the chemical an alysis of the elements present. (C) 2001 Editions scientifiques et medicale s Elsevier SAS. All rights reserved.