Effect of oxygen nonstoichiometry on magnetic phase transitions in frustrated cobaltites YBaCo4O7+x (x = 0.0, 0.1, 0.2)статья
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Дата последнего поиска статьи во внешних источниках: 26 декабря 2018 г.
Аннотация:The structural and elastic characteristics of YBaCo4O7 + x (x = 0, 0.1, 0.2) cobaltites synthesized by various technologies and having various excess oxygen contents x are experimentally studied. The distortion of the crystal structure in stoichiometric samples is found to remove frustrations and to bring about a longrange magnetic order in the cobalt subsystem, which is accompanied by well-pronounced anomalies in the elastic properties in the temperature range of a magnetic phase transition TN. At a weak deviation from oxygen
stoichiometry, the structural distortion disappears, frustrations are retained, and the further development of a long-range magnetic order is hindered. As a result of an absent long-range magnetic order, the anomalies of the elastic characteristics at TN diffuse rapidly and disappear. This finding points to the suppression of structural and magnetic transitions in nonstoichiometric samples and to the conservation of only short-range order parameter correlations. It is found that nonstoichiometric samples can be separated into two phases
depending on the ceramic synthesis conditions.