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Phase transitions and electrical properties of Bi2W1–xNbxO6–y and Bi2W1–xTaxO6–yстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Kharitonova E.P., Voronkova V.I., Gagor A.B., Pietraszko A.P., Alekseeva O.A.
- Журнал: Journal of Alloys and Compounds
- Том: 573
- Год издания: 2013
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- Первая страница: 90
- Последняя страница: 95
- DOI: 10.1016/j.jallcom.2013.04.009
- Аннотация: Polycrystalline samples of Bi2W1–xMexO6–y (Me = Nb, Ta) solid solutions have been prepared by solid-state reactions, and the influence of Nb and Ta substitutions for W on the polymorphism and electrical properties of Bi2WO6 has been studied. The limit of the solid solutions is at x = 0.1 for Me = Nb and at x = 0.15 for Me = Ta. The distinctive features of the polymorphism of the Nb- and Ta-doped materials have been identified. According to differential scanning calorimetry data, tantalum and niobium substitutions for tungsten increase the temperature of the high-temperature, orthorhombic-to-monoclinic reconstructive phase transition and suppress the transition starting at x = 0.05 for Me = Nb and x = 0.10 for Me = Ta. As a result, the Bi2W1–xNbxO6–y samples have an orthorhombic Aurivillius-type structure up to their melting point. The Bi2W1–xTaxO6–y solid solutions at high temperatures consist of a mixture of an orthorhombic and a monoclinic phase. Nb and Ta doping shifts the ferroelectric phase transition to lower temperatures by more than 200 °C, thus markedly extending the stability range of the nonpolar orthorhombic paraelectric phase, which exists in a temperature range as narrow as 930–960 °C in the case of undoped Bi2WO6. The increase in oxygen vacancy concentration due to heterovalent substitutions of Nb5+ and Ta5+ for W6+ leads to an increase in conductivity by two orders of magnitude relative to the unsubstituted compound.
- Добавил в систему: Харитонова Елена Петровна