Metastable nature of donor-doped BiFeO3 obtained by mechanochemical synthesis

[EN] Nb or W donor-doped powders were synthesized by applying a mechanochemical synthesis route, in an attempt to improve the multiferroic properties of BiFeO3 based materials. The as-synthesized samples evidence a highly efficient incorporation of Nb or W into the BiFeO perovskite lattice, together with a low presence of secondary phases. The relatively high purity of the mechanosynthetized products is even more appealing when it is compared with the multiphase scenario obtained by a mixed oxides route for these compositions. This confirms this technique as a good alternative to conventional solid state processing; however the thermal evolution of the as-prepared powders also reveals a metastable nature of the synthesized phases which upon an external energy input leads to an unwelcome multiphase system.This work was conducted in the frame of project MAT2013-40722-R. M. S. Bernardo acknowledges the Spanish Ministry of Education, Culture and Sport for the financial support (FPU scholarship program). M. Peiteado also acknowledges the Ramon y Cajal Program of MINECO for the financial funding