کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1296447 973781 2011 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Antiferroelectric phase transition in pyrochlore-like (Dy1− xCax)2Ti2O7 − δ (x = 0, 0.1) high temperature conductors
موضوعات مرتبط
مهندسی و علوم پایه شیمی الکتروشیمی
پیش نمایش صفحه اول مقاله
Antiferroelectric phase transition in pyrochlore-like (Dy1− xCax)2Ti2O7 − δ (x = 0, 0.1) high temperature conductors
چکیده انگلیسی
Low-temperature ordering transitions in polycrystalline high temperature conductors (Dy1 − xCax)2Ti2O7 − δ (x = 0, 0.1) prepared using co-precipitation, mechanical activation and solid-state reactions at 1400 or 1600 °C have been studied by impedance spectroscopy at low frequencies and thermal mechanical analysis (TMA). The dielectric permittivity and loss tangent of the ceramics obtained have been measured as a function of temperature at low frequencies (0.5−500 Hz). The results provide evidence for the relaxation of point defects, most likely oxygen vacancies, at 500−600 °C and an antiferroelectric low-temperature phase transition of the second order, associated with re-arrangement process in the oxygen sublattice of pyrochlore structure. The temperature of the antiferroelectric transition is 700 to 800 °C, depending on the synthesis procedure and ceramic composition. Calcium doping of Dy2Ti2O7 leads to the formation of additional oxygen vacancies and, in the case of the samples prepared via co-precipitation, increases the peaks in permittivity due to the relaxation process and ordering transition by three or six times, respectively.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Solid State Ionics - Volume 192, Issue 1, 16 June 2011, Pages 188-194
نویسندگان
, , , , , , ,