Phase transitions, dielectric, magnetic properties and valence of ions in AFe 2/3 W 1/3 O 3±σ (A = Ba, Sr) multiferroic ceramicsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 20 марта 2018 г.
Аннотация:The polycrystal multiferroic samples of BaFe2/3W1/3O3 (BFWO) and SrFe2/3W1/3O3 (SFWO) are synthesized by solid solution reaction route followed by sintering. The samples are analyzed using the methods of X-ray diffraction (XRD), dielectric, Mössbauer and X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). The XRD study reveals that BFWO possesses two crystal phases: cubic and hexagonal. SFWO is a single phase with a tetragonal symmetry. The VSM and Mössbauer spectroscopy show that both materials are ferrimagnets with magnetic phase transition temperatures TM ≈ 300 K for BFWO and TM ≈ 400 K for SFWO. The iron ions are in Fe3+ state. The XPS studies reveal the presence of the oxygen vacancies in the BFWO and SFWO samples which are responsible for the appearance of the tungsten ions with intermediate valences. BFWO is found to be paraelectric at room temperature. In the SFWO sample the phase transition from tetragonal (ferroelectric) to cubic (paraelectric) phase occurs in the range of 420 < T < 550 K