کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10624029 | 989583 | 2016 | 39 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Dielectric properties and defect chemistry of barium titanate ceramics co-doped R and Dy ions (R=Eu, Gd, Tb)
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The structure, microstructure, dielectric behavior, point defects, mixed valence states, site occupations, and defect chemistry of nominal (Ba1âxRx)(Ti1âxDyx)O3 (x=0.06, R=Eu, Gd, Tb) (BRTD) ceramics were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, electron paramagnetic resonance (EPR), dielectric and resistivity measurements. BRTD exhibited a tetragonal perovskite structure, a higher ceramic density of Ïr=91% of theoretical density, a diffuse phase transition (DPT) behavior, and a nonlinear shift in dielectric-peak temperature (Tm) with the kind of doping ions. The feature of mixed valence states associated with site occupation is responsible for this abnormal Tm-shift rate. BRTD with R=Tb exhibited a lowest dielectric loss of tan δ=0.025 at 1 kHz and a nearly frequency-independent stability up to 107 Hz at room temperature. A double-site compensation mode of GdBa
- -DyTi' could be formed and led to a rapid Tm-shift rate of approximately â10 °C/%(Gd-Dy). A symmetrical EPR signal at g=1.985 was designated as Gd3+ (4f7) Kramers ions. The mixed valence states of Ba-site Eu3+/Eu2+ (4f7) and Ba-site Tb3+/Ti-site Tb4+ (4f7) appeared in BRTD owing to the metastable nature of the 4f7 electron configuration. The Raman spectra in a high-wavenumber region of 1500-6700 cmâ1 were discovered and might be likely linked to the 4f7 doping ions, such as Eu2+, Gd3+, and Tb4+ ions. The defect chemistry is discussed.
- -DyTi' could be formed and led to a rapid Tm-shift rate of approximately â10 °C/%(Gd-Dy). A symmetrical EPR signal at g=1.985 was designated as Gd3+ (4f7) Kramers ions. The mixed valence states of Ba-site Eu3+/Eu2+ (4f7) and Ba-site Tb3+/Ti-site Tb4+ (4f7) appeared in BRTD owing to the metastable nature of the 4f7 electron configuration. The Raman spectra in a high-wavenumber region of 1500-6700 cmâ1 were discovered and might be likely linked to the 4f7 doping ions, such as Eu2+, Gd3+, and Tb4+ ions. The defect chemistry is discussed.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Ceramics International - Volume 42, Issue 13, October 2016, Pages 14364-14373
Journal: Ceramics International - Volume 42, Issue 13, October 2016, Pages 14364-14373
نویسندگان
Da-Yong Lu, Shu-Zhen Cui, Qiao-Li Liu, Xiu-Yun Sun,