共查询到19条相似文献,搜索用时 109 毫秒
1.
2.
采用改进的Sol-gel工艺和传统烧结技术制备了晶粒尺寸在0.15~10μm的Ba0.6Sr0.4TiO3(BST)陶瓷,观察了样品的显微结构,并对样品的介电性能进行了测试,分析了晶粒尺寸对材料介电性能的影响.实验结果表明:改进的Sol-gel工艺和两步烧结法可以有效地控制Ba0.6Sr0.4TiO3(BST)陶瓷的晶粒尺寸.晶粒尺寸的降低,材料的介电常数也随之下降,介电峰呈现明显的铁电-顺电弥散相变;但当陶瓷的晶粒尺寸<1 μm,介电常数出现峰值,铁电相变温区变窄. 相似文献
3.
4.
聚合物基复合介电材料的研究进展 总被引:1,自引:1,他引:0
聚合物基复合介电材料是以有机聚合物为基体,将具有高介电常数或易极化的微纳米尺寸的无机颗粒或其它有机物作为填充物复合而成,综合了无机材料的高介电性能,同时还兼备聚合物的粘结性、韧性、易加工性,在信息和微电子工业等领域具有广泛应用.该领域的研究与应用的关键是材料合成路线的设计与性能的有机结合,聚合物基体与表面修饰无机颗粒界面的良好作用,使其具有优良的介电特性.将聚合物基复合介电材料的填料颗粒分为铁电陶瓷、氧化物、碳纳米管类、金属导电颗粒、全有机高分子等几种类型,并概述了各种类型的聚合物基复合介电材料的研究状况,着重分析了聚合物与无机颗粒界面的相互作用,展望了聚合物基复合介电材料未来的发展趋势. 相似文献
5.
6.
7.
驰豫型铁电体是很重要的功能材料,其介电性能和极化机制一直是研究的热点。作者通过对掺钛铌镁酸铅系列铁电陶瓷介电、铁电、热电等宏观性能和微观结构详细、系统的实验研究,提出铁电微畴为三方相畸变结构散布于立方钙钛矿母相中,通过类马氏体预相变的位移型形核过程,实现顺电—驰豫型铁电态的弥散相变,进一步通过类马氏体相变,完成驰豫型铁电态无序态分布的微畴向正常铁电态长程序铁电宏畴转变;提出T_1可调整A(B′B″)O_3型复合钙钛矿铁电体B′和B″离子价态和离子半径等不同所产生的内电场和弹性场,使立方母相所承受切应力发生变化,诱发极性微区、铁电微畴随组成变化表现不同活性。对弛豫型铁电体介电谱分析与计算表明,其在介电常数峰值温度Tm附近的介电弛豫过程连续变化,不对应结构突变的相变过程,较接近偶极介质。通过铌锌酸铅基系列铁电陶瓷在准同型相界附近异常特性的研究,进一步揭示弛豫型铁电体中结构特征决定宏观行为的必要性,反映出铁电材料由微观到介观、再到宏观的有趣规律性。在此基础上,对复合钙钛矿弛豫型铁电体偏压介电行为、电致伸缩特性、介电老化行为等进行了系统研究,合理解释了一系列新的实验现象和结果;并对钨青铜结构铌酸锶钡弛豫型铁电陶瓷复介电响应进行了详细的对比分析和讨 相似文献
8.
铁电薄膜及铁电存储器的研究进展 总被引:1,自引:0,他引:1
铁电薄膜是具有铁电性且厚度尺寸为数纳米到数微米的薄膜材料,因其在非挥发性铁电随机存储器方面的潜在应用而受到广泛关注.综述了新型无铅、无疲劳Bi4Ti3O12(BIT)基铁电薄膜材料的制备和改性及性能表征方法,阐述了铁电薄膜的3种失效机制及铁电薄膜存储器的研究现状,最后提出了铁电薄膜及存储器今后可能的研究方向. 相似文献
9.
10.
11.
12.
铁电陶瓷/铁氧体叠层共烧体的介电特性 总被引:3,自引:0,他引:3
采用电介质物理学等效电路分析方法研究了Pb(Ni1/3Nb2/3)O3基铁电陶瓷与NiZnCu铁氧体叠层共烧体的介电频率响应,探讨了共烧体界面对介电性能的影响.结果表明,叠层共烧体的介电常数随频率的增加而减小,介电损耗随着频率的增加先增大后减小,有明显的损耗峰出现;界面扩散层对叠层共烧体电学响应有影响,叠层共烧体等效电路可视为介电材料层、铁氧体材料层和界面扩散层C re-R re等效电路的串联,并且界面扩散层会对叠层共烧体低频部分的介电响应起作用. 相似文献
13.
Xiaoli WANG Xi YAO Electronic Materials Research Laboratory Xi''an Jiaotong University Xi''an China 《材料科学技术学报》1993,9(6):461-463
A very strong dielectric relaxation was observed in Bi_2BaNb_2O_9 ceramic.The temperature differencebetween the maximum dielectric constant temperatures T_m measured at 1 kHz and 100 kHz is 65℃.which is about 2-4 times that of relaxor ferroelectrics.The possible mechanism of the anomalousdielectric relaxation was discussed. 相似文献
14.
Vopsaroiu M Weaver PM Cain MG Reece M Chong KB 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(9):1867-1873
Time- and temperature-dependent effects are critical for the operation of non-volatile memories based on ferroelectrics. In this paper, we assume a domain nucleation process of the polarization reversal and we discuss the polarization dynamics in the framework of a non-equilibrium statistical model. This approach yields analytical expressions which can be used to explain a wide range of time- and temperature-dependent effects in ferroelectrics. Domain wall velocity derived in this work is consistent with a domain wall creep behavior in ferroelectrics. In the limiting case of para-electric equilibrium, the model yields the well-known Curie law. We also present experimental P-E loops data obtained for soft ferroelectrics at various temperatures. The experimental coercive fields at various temperatures are well predicted by the coercive field formula derived in our theory. 相似文献
15.
16.
Fu DW Zhang W Cai HL Ge JZ Zhang Y Xiong RG 《Advanced materials (Deerfield Beach, Fla.)》2011,23(47):5658-5662
A simple organic salt, diisopropylammonium chloride, shows the highest ferroelectric phase transition temperature among molecule-based ferroelectrics with a large spontaneous polarization, making it a candidate for practical technological applications. 相似文献
17.
18.
Nanostructured ferroelectrics are important objects for studies on ferroelectric size effects as well as for applications
to memory devices with ultra-high memory density. In the present article, we introduce several approaches for the synthesis
of confined ferroelectrics with sizes in and below the hundreds of nanometer range, including top-down processes like e-beam
lithography, self-assembly methods like chemical solution deposition, and growth by pulsed laser deposition using stencil
masks. Furthermore, the ferroelectric domain structure of part of these nanostructures is investigated by means of synchrotron
X-ray diffraction, and its contribution to the ferroelectric properties is discussed. 相似文献
19.
Energy functions (or characteristic functions) and basic equations for ferroelectrics in use today are given by those for ordinary dielectrics in the physical and mechanical communications. Based on these basic equations and energy functions, the finite element computation of the nonlinear behavior of the ferroelectrics has been carried out by several research groups. However, it is difficult to process the finite element computation further after domain switching, and the computation results are remarkably deviating from the experimental results. For the crack problem, the iterative solution of the finite element calculation could not converge and the solutions for fields near the crack tip oscillate. In order to finish the calculation smoothly, the finite element formulation should be modified to neglect the equivalent nodal load produced by spontaneous polarization gradient. Meanwhile, certain energy functions for ferroelectrics in use today are not compatible with the constitutive equations of ferroelectrics and need to be modified. This paper proposes a set of new formulae of the energy functions for ferroelectrics. With regard to the new formulae of the energy functions, the new basic equations for ferroelectrics are derived and can reasonably explain the question in the current finite element analysis for ferroelectrics. 相似文献