Electron microscopy, XRD, dielectric, and Mossbauer studies of Li-doped Pb(Fe_0.5Nb_0.5)O₃ ceramics sintered from mechanically activated powders

ABSTRACT

X-ray diffraction (XRD) studies of the phases formed on the surface of the Li-doped PbFe_0.5Nb_0.5O₃ (PFN) ceramics sintered under different conditions from the mechanically activated mixture of oxides and Li₂CO₃ have been carried out. At sintering temperatures exceeding 800°C a partial evaporation of PbO leads to the formation of pyrochlore Pb₂Fe₄Nb₄O₂₁ and lithium ferrites LiFeO₂ and LiFe₅O₈ phases in the surface layer about 100 μm thick. An increase of the Neel temperature by more than 40 K, as compared to single crystal, was achieved in the mechanically activated PFN powder sintered at 600°C.

KEYWORDS:

• Li-doped lead iron niobate
• ferroelectric
• mechanical activation
• phase transition

Funding

This study is partially supported by the Russian Foundation for Basic Research (RFBR) project 13–03-00869_a, Ministry of education and science of the Russian Federation (research projects 2132 and 3.1137. 2014K), Southern Federal University (grant 213.01–2014/012-VG), and Research Committee of the University of Macau under Research & Development Grant for Chair Professor No RDG007/FST-CHD/2012.