由廣東工業大學的唐新桂教授團隊發表了這篇基於鈦酸鋇基鐵電陶瓷的氧空位的介電弛豫行為的最近進展文章:採用常規的固相反應法合成無鉛鐵電陶瓷(1-x)BaTiO3-Bi(Mg1/2Ti1/2)O3(x=0.0-0.07),研究了其結構、介電、鐵電和阻抗性能的相關性。發現隨著BMT含量的增加,Tm和εm呈下降趨勢。所有樣品中都觀察到了高溫介電弛豫行為。由阻抗(EA)和電導率(Econd)計算的活化能表明,弛豫行為與氧空位的遷移有關。所有的結果表明,氧空位的短程跳躍有助於雙電離氧空位的介電弛豫和長距離的運動。 隨著BMT含量的增加,P-E曲線變得更收腰狹窄,表明鬆弛行為的增加。 相關研究成果發表在Journal of Materiomics第4卷第3期,題目為Oxygen-vacancy-related dielectric relaxation behaviours andimpedance spectroscopy of Bi(Mg1/2Ti1/2)O3 modified BaTiO3ferroelectric ceramics. 您可以點擊文末「閱讀全文」免費下載!
Ming-Ding Li, Xin-Gui Tang, Si-Ming Zeng, Yan-Ping Jiang, Qiu-Xiang Liu,Tian-Fu Zhang, Wen-Hua Li, Oxygen-vacancy-related dielectric relaxation behaviours andimpedance spectroscopy of Bi(Mg1/2Ti1/2)O3 modified BaTiO3ferroelectric ceramics. Journal of Materiomics 2018; 4 (3): 194-201.
近幾十年來,無鉛BaTiO3(BT)基鐵電陶瓷因其在多層陶瓷電容器、壓電致動器和電調微波器件等方面的廣泛應用而得到了廣泛的研究。以往對BT-BMT固溶體的研究主要集中在介電性能的溫度依賴性、穩定性、相變行為和弛豫特性等方面。最近,對改性BaTiO3陶瓷進行了儲能應用研究,如:BaTiO3-Bi(Mg0.5Ti0.5)O3、BaTiO3-Bi(Zn0.5Zr0.5)O3,BaTiO3-Bi(Mg2/3Nb1/3)3和BaTiO3-(Bi1-xNdx)FeO3等。但在Bi(Mg1/2Ti1/2)O3微量摻雜的BaTiO3體系中,氧空位相關的高溫介電弛豫行為還沒有得到很大的研究。此外,在過去的幾十年中,反常高溫介電弛豫行為在各種鐵電陶瓷中得到了廣泛的研究。例如CaCu3Ti4O12,(Pb1-xBax)ZrO3和BiFeO3陶瓷等。提出了晶粒內部和跨越邊界的不同電輸運行為,這是由於晶粒與邊界之間的氧含量不同所致。理論和實驗已經證明,氧空位對鐵電材料的物理性能有很大的影響。氧空位作為一種自摻雜元素,是所有氧化物材料不可忽視的最重要的改性因素之一。基於上述原因,這篇文章系統地研究了(BiMg1/2Ti1/2)O3摻雜含量對BaTiO3陶瓷結構、介電性能、弛豫行為和鐵電性能的影響。從阻抗和傳導計算的活化能表明,弛豫行為與氧空位的遷移有關。此外,隨著BMT含量的增加,P-E環變得更細和更細,這表明鬆弛行為的增加。
Fig. 1. Room-temperature XRD patterns of (1-x)BT–xBMT pellets with (a) x = 0.0–0.07, (b) the (002)/(200) diffraction patterns of all samples in the range 43°–48°.
Fig. 2. SEM images of (1-x) BT–x BMT ceramics: (a) x = 0, (b) x = 0.02, (c) x = 0.04, (d) x = 0.05, (e) x = 0.06, (f) x = 0.07.
Fig. 3. Element mapping of the (1-x) BT–x BMT (x = 0.04) ceramic sample. (a) Scanning area. Element distributions of (b) O, (c) Mg, (d) Ba, (e) Ti, (f) Bi.
Fig. 4. Dielectric permittivity and dielectric loss tanδ as a function of temperature (25 °C ≤ T ≤ 600 °C) at frequencies from 1 kHz to 500 kHz for (1-x)BT–xBMT ceramics (a) x = 0, (b) x = 0.02, (c) x = 0.04, (d) x = 0.05, (e) x = 0.06, (e) x = 0.07.
Fig. 5. (a) Dielectric permittivity εγ and loss tanδ as a function of temperature for (1-x)BT–xBMT ceramics at 10 kHz; (b)The temperature Tm of the maximum Dielectric Permittivity and maximum dielectric constant εm as functions of BMT-doping content x at 10 kHz for (1-x)BT–xBMT ceramics.
Fig. 6. Complex impedance plots of Z′ versus Z″ (Cole-Cole plots) at different temperatures. The insets show the normalized imaginary parts Z″/Z″max of impedance as a function of frequency for (1-x)BT–xBMT ceramics.
Fig. 7. (a) ln(ω) and (b) ln(σ) versus 1000/T curves of grain boundaries for(1-x)BT–xBMT ceramics, the inset shows (a) ln(ω) and (b) ln(σ) of grains versus 1000/T curves for pure BT and x = 0.02. The straight lines are a fit to the Arrhenius law.
Fig. 8. (a) P-E loops for (1-x)BT–xBMT ceramics; the inset shows Pmax and Pr Values as a function of x. (b) The temperature dependence of P-E loops for 0.98BT–0.02BMT ceramics at 55 kV cm−1; the inset presents the temperature dependence of Pmax, Pr and EC for the ceramic at electric field 55 kV cm−1.
The structure, dielectric, ferroelectric and impedance properties was first investigated in the (1-)BaTiO3–x(BiMg1/2Ti1/2)O3 ceramics.
The high-temperature dielectric relaxation behaviour was observed in all ceramic samples.
The activation energy calculated from impedance (Ea) and conductivity (Econd) revealed that the relaxation behaviour was due to the short-range hopping of the OVs.
Mr. Ming Ding Li is currently a MS student at School of Physics and Optoelectric Engineering, Guangdong University of Technology. He graduated from School of Materials and Environmental Engineering, Hunan University of Humanities, Science and Technology in June 2016. His current research interests are focused on ferroelectric and relaxor ferroelectric materials, and ceramic processing.
Dr. Xin Gui Tang is currently a Professor at School of Physics and Optoelectric Engineering, Guangdong University of Technology. He received his B.S. in Physics (1986) from Xiangtan University (Xiangtan, China), and awarded MS degree and PhD degree in Condensed Matter Physics, Sun Yat-sen University (Guangzhou, China) in 1995 and 1999, respectively. He worked as a postdoctoral fellow at Shanghai Institute of Ceramics, Chinese Academy of Sciences from September, 1999 to December, 2012, and worked as a postdoctoral fellow at Department of Applied Physics, The Hong Kong Polytechnic University from August, 2012 to August, 2014. He has authored and/or co-authored more than 160 papers in the pier-reviewed journals. His primary scientific interests cover the fields of ferroelectric and relxor ferroelectric materials, and ceramic and thin films processing.
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