含铋层状结构铁电体PbBi_4Ti_4O_(15)和SrBi_4Ti_4O_(15)的X射线衍射数据的测定

用衍射仪和Guinier聚焦相机收集了含秘层状结构铁电体PbBi_4Ti_4O_(15)SrBi_4Ti_4O_(15)的X射线粉末衍射图谱(Cu Ka),给出了d值大1.13A的88和76条衍射线的衍射数据和指标。它们都属正交晶系,空间群Bb2_1m(C_2v~(12)),点阵常数和X射线理论密度为 PbBi_4Ti_4O_(15)α=5.431A,b=5.459A,c=41.36A;z=4;D_x=7.986g/cm~3. SrBi_4Ti_4O_(15):α=5.428A,b=5.438A,c=40.94A;Z=4;D_x=7.447g/cm~3.     

SrBi4Ti4O15的化学键性质和铁电性研究

通过原子环境计算方法分析了正交相SrBi₄Ti₄O₁₅晶体内的键络结构、各原子的空间配位数及局域团簇结构. 在此基础上, 结合晶体分解理论将SrBi₄Ti₄O₁₅晶体分解为多个二元赝晶体, 根据化学键介电理论计算得到各赝晶体所对应化学键的有效价电子密度、离子性等化学键性质. 通过键偶极矩建立了铁电体自发极化强度与化学键性质之间的关系, 求得正交相SrBi₄Ti₄O₁₅沿a轴方向的自发极化强度为28.03 μC/cm², 与实验结果和其他理论计算值符合较好.     

Mo掺杂SrBi4Ti4O15陶瓷的铁电介电性能

用传统的固相烧结工艺，制备了钼掺杂铁电陶瓷样品SrBi₄Ti₄O₁₅(SBTi)铁电陶瓷SrBi_4-2x/3Ti_4-xMo_xO₁₅(x=0.00，0.003，0.012，0.03，0.06，0.09).X射线衍射的结果表明，样品均为单一的层状钙钛矿结构相，Mo掺杂未改变SBTi的晶体结构.通过扫描电子显微镜观测发现，样品晶粒为片状，随掺杂量的增加，晶粒逐 关键词： 4Ti₄O₁₅')" href="#">SrBi₄Ti₄O₁₅ Mo掺杂 剩余极化 居里温度     

La掺杂SrBi4Ti4O15铁电材料性能研究

按x=0.00，0.10，0.25，0.50，0.75和1.00，采用固相烧结工艺，制备了不同La掺杂量的SrBi_4-xLa_xTi₄O₁₅的陶瓷样品. 用x射线衍射对其微结构进行了分析，并测量了铁电、介电性能.结果发现，La掺杂未改变SrBi₄Ti ₄O₁₅的晶体结构.随掺杂量的增加，样品的矫顽场(E_c)下降，剩余极化(2P_{关键词： 4-x}La_xTi₄O₁₅')" href="#">SrBi_4-xLa_xTi₄O₁₅ La掺杂 铁电性能 相变温度 弛豫铁电     

SrBi4Ti4O15铁电薄膜的制备工艺及薄膜生长机理 研究

以氯化锶，硝酸铋和钛酸丁酯为原料，柠檬酸为络合剂，乙二醇为交联剂，无水乙醇为钛酸 丁酯的溶剂，盐酸为硝酸铋的溶剂，去离子水为氯化锶的溶剂，配制了稳定的SrBi_{4Ti4O15(SBTi)前驱液.采用溶胶凝胶工艺，在Pt/Ti/SiO2 /Si基片上制备了a轴取向增强的SBTi铁电薄膜.研究了一次性晶化快速退火工艺、两 层晶化快速退火工艺、逐层晶化快速退火工艺以及成膜次数对薄膜结晶性、微观结构和生长 行为的影响.实验结果表明，逐层快速退火工艺可有效抑制焦绿石相的形成；随着涂覆次数 的增加，薄膜的结晶性变好；由于SBTi晶体生长的各向异性及单层膜厚对晶体沿(119)方向 生长的限制，随着涂覆次数的增加，SBTi薄膜(119)峰和(200)峰的强度逐渐增大，而(00l) 峰的强度反而略有减小，从而使I(200)/I(119)，I(200)/I(0010)，I(119)/I(0010)逐渐增 大. 关键词： 铁电薄膜 钛酸锶铋 逐层快速退火工艺 生长行为}     

B位等价掺杂SrBi4Ti4O15铁电材料的性能研究

采用了传统的固相烧结工艺,制备了不同Zr和Hf掺杂量的SrBi₄Ti_4-xZr_xO₁₅（x=000,003, 006,010,020）和SrBi₄Ti_4－xHf_xO₁₅（x=000,0005, 0015,0030,0060）的陶瓷 关键词： 4Ti_4-xZr_xO₁₅')" href="#">SrBi₄Ti_4-xZr_xO₁₅ 4Ti_4－xHf_xO₁₅')" href="#">SrBi₄Ti_4－xHf_xO₁₅ 铁电性能 介电性能     

铁电体SrBi2Nb2O2电子能带结构的第一性原理研究

采用第一性原理的方法计算了SrBi₂Nb_2O.9（SBN）的顺电相、铁电相的电子结构.顺电相是间接带隙, 铁电相是直接带隙，它们的大小分别为1.57和2.23 eV.顺电相和铁电相的价带顶均主要来自于O₂p态的贡献.而顺电相和铁电相的导带底则分别来自Nb₄d态和Bi₆p态的贡献.计算表明SBN铁电相的低的漏电流与Bi 6p轨道有关.由顺电相到铁电相时，Nb₄d和O_{2 关键词： 顺电相 铁电相 态密度 电子能带结构}     

非晶和纳米ZrO2·Y2O3(15%)的X射线衍射与扩展X射线吸收精细结构研究

利用粉末X射线衍射和扩展X射线吸收精细结构(EXAFS)技术对用化学共沉淀法制备的非晶和纳米ZrO₂·15%Y₂O₃体系进行了研究.粉末X射线衍射结果表明,300℃温度处理的样品呈非晶态,500℃时样品已经晶化,形成单一立方相的纳米结构.EXAFS分析显示,在从非晶态向纳米结构晶化的过程中,最近邻的ZrO配位层的配位数和键长没有发生明显的改变,说明300℃时已经形成和900℃相同的最近邻局域结构.而对于ZrZr(Y)配位层,随着晶粒尺寸的减 关键词： EXAFS 晶化 配位数 键长     

SrBi2Ta2O9/Bi4Ti3O12复合铁电薄膜的制备与特性研究

采用溶胶凝胶工艺在p-Si衬底上制备了SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂复合铁电薄膜. 研究了SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂复合薄膜的微观结构与生长行为、铁电性能和疲劳特性. 研究表明: Si衬底Bi₄Ti< 关键词： 2Ta₂O₉')" href="#">SrBi₂Ta₂O₉ 4Ti₃O₁₂')" href="#">Bi₄Ti₃O₁₂ 复合铁电薄膜 溶胶凝胶工艺     

CaCu3Ti4O12陶瓷的微观结构和电学性能

利用传统的固相反应工艺，在不同的烧结温度下制备了一系列的CaCu₃Ti₄O₁₂陶瓷样品，考察了其微观结构以及介电和复阻抗方面的电学性质.研究发现这些样品在微观结构方面可分为三种类型，高介电性与微观结构有着密切的关联性.室温下，样品的低频介电常数随陶瓷晶粒尺寸的增大而提高.随着测试温度的升高，不同微观结构类型的样品呈现出不同的电学性质的变化，但其中也存在着一些相同的特征.高温下，介电频谱呈现出一个低频介电响应和两个类Debye型弛豫色散，复阻抗谱呈现出三个Cole-Cole半圆弧.将实验上观测到的电学性质的起因归于陶瓷多晶微结构中的晶畴、晶界和晶粒内的缺陷. 关键词： 3Ti₄O₁₂')" href="#">CaCu₃Ti₄O₁₂ 微观结构 电学性质     

Properties of vanadium-doped SrBi4Ti4O15 ferroelectric ceramics

Using the standard solid-state reaction method, several vanadium-doped ferroelectric ceramics of type SrBi_4−x/3Ti_4−xV_xO₁₅ (SBTV−x) were synthesized. The vanadium doping content, x, rangs from 0.00 to 0.06. The crystal structure of SrBi₄Ti₄O₁₅ is not affected by V-doping. The electric breakdown voltage of the samples increases with V content. Meanwhile, V-doping results in a notable enlargement of remnant polarization (2P_r). The 2P_r of STBV−0.03 reaches a very large value, which is over 50 μC/cm² and is nearly twice greater than that at zero doping. The Curie temperatures of V-doped samples decrease slightly in comparison with that of SrBi₄Ti₄O₁₅. V-doping can improve the electric properties of SrBi₄Ti₄O₁₅ without sacrificing its thermal stableness.     

Properties of vanadium-doped SrBi4Ti4O15 ferroelectric ceramics

Using the standard solid-state reaction method, several vanadium-doped ferroelectric ceramics of type SrBi_4−x/3Ti_4−xV_xO₁₅ (SBTV-x) were synthesized. The vanadium doping content, x, ranges from 0.000 to 0.06. The crystal structure of SrBi₄Ti₄O₁₅ is not affected by V-doping. The electric breakdown voltage of the samples increases with V content. Meanwhile, V-doping results in a notable enlargement of remnant polarization (2P_r). The 2P_r of STBV-0.03 reaches a very large value, which is over 50 μC/cm² and is nearly twice greater than that at zero doping. The Curie temperatures of V-doped samples decrease slightly in comparison with that of SrBi₄Ti₄O₁₅. V-doping can improve the electric properties of SrBi₄Ti₄O₁₅ without sacrificing its thermal stableness.     

La substitution in four-layers Aurivillius phase SrBi4Ti4O15

Ceramics with the nominal composition of SrBi_4−xLa_xTi₄O₁₅ have been prepared within the range of 0≤x≤1.8, and the dielectric properties are investigated. Single phase SrBi_4−xLa_xTi₄O₁₅ solid solution exists until the secondary phase of La_2/3TiO₃ appears at x=1.6. The Curie temperature is 520 °C for pure SrBi₄Ti₄O₁₅, and it shifts to low temperature with increasing x, which is due to the smaller structural distortion caused by La³⁺ substitution. In addition, the dielectric constant anomaly is suppressed with the substitution. No dielectric relaxation behavior is observed. When x≥1.2, the paraelectric state is attained in the present ceramics. La³⁺ substitution effects on the SrBi₄Ti₄O₁₅ ceramics are also compared with the previous work on Bi_4−xLa_xTi₃O₁₂.     

磷酸铝(AlPO4)晶体中缺陷的X射线形貌研究

用X射线衍射形貌法研究了AlPO₄晶体中的微观缺陷。在所研究的晶体中,主要晶体缺陷是生长层,沉淀物和位错。位错密度在晶体表面附近最大,晶体中部较低。位错主要起源于热应力和由沉淀物或生长层所造成的晶格畸变。多数位错的柏氏矢量是b=(a+c)<1123>型,部分的是b=a[2110]。分析了晶体缺陷与生长条件之间的关系。控制生长过程中的温度波动,特别是晶体出炉时的冷却速度,对提高晶体完美性是重要的。 关键词：     

Effects of vanadium doping on structure and electrical properties of SrBi4Ti4O15 thin films

The effects of vanadium(V) doping into SrBi₄Ti₄O₁₅ (SBTi) thin films on the structure, ferroelectric, leakage current, dielectric, and fatigue properties have been studied. X-ray diffraction result showed that the crystal structure of the SBTi thin films with and without vanadium is the same. Enhanced ferroelectricity was observed in the V-doped SrBi₄Ti₄O₁₅ (SrBi_4−x/3Ti_4−xV_xO₁₅, SBTiV-x (x = 0.03, 0.06, and 0.09)) thin films compared to the pure SrBi₄Ti₄O₁₅ thin film. The values of remnant polarization (2P_r) and coercive field (2E_c) of the SBTiV-0.09 thin film capacitor were 40.9 μC/cm² and 105.6 kV/cm at an applied electric field of 187.5 kV/cm, respectively. The 2P_r value is over five times larger than that of the pure SBTi thin film capacitor. At 100 kHz, the values of dielectric constant and dielectric loss were 449 and 0.04, and 214 and 0.06 for the SBTiV-0.09 and the pure SBTi thin film capacitors, respectively. The leakage current density of the SBTiV-0.09 thin film capacitor measured at 100 kV/cm was 6.8 × 10⁻⁹ A/cm², which is more than two and a half orders of magnitude lower than that of the pure SBTi thin film capacitor. Furthermore, the SBTiV-0.09 thin film exhibited good fatigue endurance up to 10¹⁰ switching cycles. The improved electrical properties may be related to the reduction of internal defects such as bismuth and oxygen vacancies with changes in the grain size by doping of vanadium into SBTi.     

PbBi2Nb2O9的晶体结构

PbBi₂Nb₂O₉晶体属正交晶系,空间群为D_2h²³-Fmmm。晶胞参数为a=5.4806(7)?,b=5.4791(7)?,c=25.416(3)?,α=β=γ=90.0(0)°,V=763.2(2)?³。单位晶胞内化学式数z=4,D_obs=7.91g/cm³,D_x=8.26g/cm³ 关键词：