复合层状Bi7Ti4NbO21铁电陶瓷的结构与介电和压电性能研究

制备了Bi₇Ti₄NbO_{21，Bi4Ti3O12及Nb掺杂Bi4Ti3O12(Nb-Bi4Ti3O12)层状结构铁电陶瓷材料.结合Nb-Bi 4Ti3O12的介电温谱和 退极化实验结果，研究了Bi7Ti4NbO21的晶体结构 对其介电、压电性能的影响 .高分辨透射电镜结果表明，在Bi7Ti4NbO21中， 沿着c轴方向，(Bi2Ti3O10)^2-和(BiTiNbO7)^2-两个类钙钛矿层分别 与(Bi2O2)²⁺层叠加堆积而成.这种晶体结构决定了Bi7Ti4NbO21的 介电温谱在668℃和845℃出现介 电双峰.结合极化样品的退化实验分析，说明材料在这两个温度附近发生了铁电—铁电相变 、铁电—顺电相变，分别是(Bi2Ti3O10)^{2-< /sup>和(BiTiNbO7)2-层状 结构发生微观结构相变的结果.在退极化过程中，由于受热时钙钛矿层内空位引起的缺陷偶 极子的定向排列受到破坏，引起材料部分退极化，表现为300℃热处理后Bi7Ti 4NbO 21的压电活性降低了10%，显示了室温下材料的压电性能来源于自发极化的固有电 偶极子和缺陷偶极子的共同贡献.}}     

Nd掺杂对Bi4Ti3O12铁电薄膜的微结构和铁电性能的影响

利用溶胶-凝胶法在Pt/Ti/SiO₂/Si(100)衬底上制备了Nd掺杂Bi₄Ti₃O₁₂(Bi_4-xNd_xTi₃O₁₂, x=0.00,0.30,0.45,0.75,0.85,1.00,1.50)铁电薄膜样品.研究了Nd掺杂对Bi₄Ti₃O₁₂薄膜的微结构和铁电性能的影响.研究结果表明:Nd掺杂未改变Bi₄Ti₃O₁₂薄膜的基本晶体结构.在掺杂量x<0.45时,Nd³⁺只取代类钙钛矿层中的A位Bi³⁺.当x=0.45时,样品剩余极化强度达最大值,在270kV·cm^-1的电场下为32.7μC·cm^-2.掺杂量进一步增加时,结构无序度开始明显增大,Nd³⁺开始进入(Bi₂O₂)²⁺层,削弱其绝缘层和空间电荷库的作用,导致材料剩余极化逐渐下降.当掺杂量x达到1.50时,掺杂离子最终破坏(Bi₂O₂)²⁺层的结构,材料发生铁电-顺电相变.     

Gd2O3:Eu3+纳米晶的燃烧合成及光致发光性质

采用柠檬酸作燃烧剂用燃烧合成法制备了Gd₂O₃:Eu³⁺纳米晶.用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)和荧光分光光度计等对Gd₂O₃:Eu³⁺纳米晶的结构、形貌和发光性能进行了分析.结果表明：不同柠檬酸与稀土离子配比(C/M)制备的样品经800℃ 退火1 h后，均得到了纯立方相的Gd₂O₃:Eu³⁺纳米晶，晶粒尺寸约为30 nm，尺寸分布较窄，其中以C/M=1.0时制备的纳米晶结晶性最好，发光强度最大.Gd₂O₃:Eu³⁺纳米晶主发射峰位置均在612 nm处 (⁵D₀→⁷F₂跃迁)，激发光谱中电荷迁移态发生红移，观察到Gd³⁺向Eu³⁺的有效能量传递.对柠檬酸与稀土离子配比(C/M)对结晶度、发光性质等的影响也进行了分析和讨论.     

NaREO2 (RE= Lu，Y) 的制备及其结构的研究

用高温固相法制备了NaLuO₂和NaYO₂晶体粉体.制备纯相的NaLuO₂粉体晶体困难，而制备纯相NaYO₂粉体晶体相对容易.为了测定NaLuO₂产物中含少量Lu₂O₃不纯相的量，用X射线衍射绝标法确定了样品中这两者的重量比和谱峰比的关系，得到了绝标法常数k^Lu₂O₃相似文献   

Al2O3:V3+晶体局域结构及其自旋哈密顿参量研究

提出了解释掺杂离子局域结构畸变的配体平面移动模型，建立了此模型下晶体微观结构与自旋哈密顿参量之间的定量关系.在考虑自旋与自旋、自旋与另一电子轨道和轨道与轨道作用等微小磁相互作用的基础上，采用全组态完全对角化方法，对Al₂O₃晶体中V³⁺的局域结构和自旋哈密顿参量进行了系统的研究.结果表明，V³⁺掺入Al₂O₃晶体后，上下配体氧平面间距离增大了0.0060 nm.从而成功地解释了Al₂O₃:V³⁺晶体的自旋哈密顿参量.在此基础上，研究了三角晶场下3d²离子自旋哈密顿参量的微观起源.研究发现，自旋三重态对自旋哈密顿参量的贡献是主要的，微小磁相互作用对自旋哈密顿参量的贡献只与自旋三重态有关.     

Ag-Cu纳米颗粒修饰的N掺杂TiO2纳米棒阵列及其高效光催化CO2还原应用

本文采用微纳加工方法制备了负载高密度Ag-Cu纳米颗粒的N掺杂TiO₂纳米棒阵列样品. 通过TiO₂的N掺杂,可将其吸光范围调控至与Ag纳米颗粒的等离激元吸收频率相匹配的波段,从而实现复合材料中肖特基结与共振能量转移过程的协同作用. 与此同时,Cu纳米颗粒可以为CO₂还原提供活性位点. 在全谱光照射下,复合样品光催化CO₂还原的活性显著提高,CH₄生成速率可达720 μmol·g^-1·h^-1.     

纤维状TiO2/Bi2O3光催化剂的制备及其光催化性能

以C₁₆H₃₆O₄Ti和Bi(NO₃)·5H₂O为原料,以棉花纤维为生物模板,合成了系列纤维状TiO₂/Bi₂O₃光催化剂．采用XRD、SEM、UV-Vis等测试技术对样品的相结构、形貌和吸光性能等进行了表征分析．结果表明,样品中的Bi₂O₃为单斜相和四方相共存的混晶,纤维长度达到毫米级,     

脉冲激光沉积温度及氧压对Bi2Sr2Co2Oy热电薄膜晶体结构与电输运性能的影响

利用脉冲激光沉积技术在c-Al₂O₃单晶基片上制备了Bi₂Sr₂Co₂O_y热电薄膜并研究了沉积温度和氧压对薄膜晶体结构及电输运性能的影响.在最佳沉积条件下制备的单相、c轴取向的Bi₂Sr₂Co₂O_y薄膜的室温电阻率ρ和塞贝克系数S分别为2.9mΩ/cm和110μupV/K,其功率因子S²/ρ好于在单晶样品上得到的值.此外,该薄膜在低温下表现出较强的负磁阻效应,在2K,9T时达到了40%.     

Er3+及Er3+/Yb3+掺杂ZrO2-Al2O3的制备及发光性质

采用共沉淀法制备了纳米晶ZrO₂-Al₂O₃∶Er³⁺发光粉体.所制备的粉体室温下具有Er3+离子特征荧光发射,主发射在绿光,其中位于547 nm、560 nm的绿光最强,并得出稀土离子与基质之间有能量传递.对不同煅烧温度下的样品研究表明:因不同温度下所制得的样品晶相不同.研究了纳米晶ZrO2-Al2O3∶Er3+及ZrO₂-Al₂O₃∶Er³⁺/Yb³⁺的上转换发光,并分析了上转换的跃迁机制.发现ZrO₂-Al₂O₃∶Er³⁺的绿光为双光子过程,而ZrO₂-Al₂O₃∶Er³⁺、Yb³⁺的上转换光谱中,红光和绿光也为双光子过程,而极弱的蓝光为三光子过程.讨论了Er³⁺的浓度猝灭现象.最适宜掺杂浓度的原子分数为2%（Er³⁺/Zr⁴⁺）.     

In2O3 透明薄膜晶体管的制备及其电学性能的研究

采用磁控溅射方法在玻璃衬底上生长了In₂O₃晶体薄膜.该薄膜具有(111)晶面择优取向,晶粒尺寸达到33 nm.利用光刻工艺制作了以In₂O₃晶体薄膜为沟道层的底栅式薄膜晶体管.In₂O₃薄膜晶体管具有良好的栅压调制特性,场效应迁移率达到6.3 cm²/(V·s),开关电流比为3×10³,阈值电压为-0.9 V.结果表明,In相似文献   

La掺杂对Bi4Ti3O12薄膜铁电性能的影响

利用Sol-Gel法在Pt/Ti/SiO₂/Si衬底上制备出Bi₄Ti₃O₁₂和Bi_3.25La_0.75Ti₃O₁₂薄膜，研究了La掺杂对Bi₄Ti₃O₁₂薄膜的晶体结构、铁电性能和疲劳特性的影响，发现La掺杂没有改变Bi₄Ti₃O₁₂薄膜的基本晶体结构，并且提高了Bi₄Ti₃O₁₂铁电薄膜的剩余极化值和抗疲劳性能，对La掺杂改善Bi₄Ti₃O₁₂铁电薄膜性能的机理进行了讨论. 关键词： 铁电性能 4Ti₃O₁₂薄膜')" href="#">Bi₄Ti₃O₁₂薄膜 3.25La_0.75Ti₃O₁₂薄膜')" href="#">Bi_3.25La_0.75Ti₃O₁₂薄膜 sol-gel法 La掺杂     

Si基Bi3.25La0.75Ti3O12铁电薄膜的制备与特性研究

采用Sol-Gel工艺低温制备了Si基Bi_3.25La_0.75Ti₃O₁₂铁电薄膜.研究了退火温度对薄膜微观结构、介电特性与铁电性能的影响.500℃退火处理的Bi_3.25La_0.75Ti₃O₁₂薄膜未能充分晶化，晶粒细小且有非晶团聚，介电与铁电性能均较差.高于550℃退火处理的Bi_3.25La_{0.75 关键词： 铁电薄膜 3.25}La_0.75Ti₃O₁₂')" href="#">Bi_3.25La_0.75Ti₃O₁₂ Sol-Gel工艺     

Structure, ferroelectric and dielectric properties of Bi2WO6 with different bismuth content

This paper reports that the Bi 2 WO 6 ferroelectric ceramics with excess Bi 2 O 3 of 0.0, 2.0, 3.5 and 5.0 wt.% of the stoichiometric composition are prepared by the conventional solid-state reaction method. Their microstructure, ferroelectric properties, the concentration and mobility of the defects have been analysed systematically. With increasing Bi content, the remnant polarization decreases, and the broken-down voltage increases. The optimum Bi excess, 3.5, lowers the oxygen vacancy concentration, while further Bi-addition brings about more defects. The activation energies fitted from cole-cole plots are 0.97 eV, 1.07 eV, 1.18 eV, and 1.33 eV, respectively. This suggests that the mobility of the defects is weakened by Bi-addition, which may be due to the increase of the ratio of the number of Bi 2 O 2 layers to that of the perovskite blocks.     

圆盘状Bi2WO6-BiPO4异质结的水热合成及光催化性能 (cited: 1)

采用水热法制备Bi₂WO₆-BiPO₄异质结光催化剂．利用模拟太阳光照射下的罗丹明B降解实验评价了Bi₂WO₆-BiPO₄复合物的光催化性能．结果表明,Bi₂WO₆-BiPO₄光催化活性比Bi₂WO₆和BiPO₄高得多．当Bi₂WO₆与BiPO₄的摩尔比为1:1时复合光催化剂对罗丹明B的降解率最高．Bi₂WO₆-BiPO₄催化活性增强主要归结为两者之间形成了有效的异质结结构,其内建电场能够促进光生载流子的分离．同时,Bi₂WO₆的加入增强了其对可见光的吸收．研究表明O₂· ^-和h⁺在光催化降解过程中是主要的活性物种     

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     

Si基Bi4Ti3O12铁电薄膜的制备与特性研究

采用sol-gel工艺, 在分层快速退火的工艺条件下成功地制备了高质量Si基Bi_{4Ti3O12铁电薄膜. 研究了Si基Bi4Ti3O12薄膜的生长行为、铁电性能、C-V特性和疲劳特性. 研究表明: Si基Bi4Ti3O12薄膜具有随退火温度升高沿c轴择优生长的趋势; 退火温度通过影响薄膜的晶粒尺寸、生长取向和薄膜中载流子的浓度来改变Si基Bi关键词： sol-gel法 铁电薄膜 4Ti3O12')" href="#">Bi4Ti3O12 C-V特性}     

Photoelectrocatalytic degradation of organic contaminants at Bi2O3/TiO2 nanotube array electrode

In the current work, TiO₂ nanotube array was prepared via electrochemical anode method. Then the Bi₂O₃ nanoparticles were deposited onto the TiO₂ nanotube array via dip-coating method from an amorphous complex precursor. The crystal structures were characterized via X-ray diffraction analysis. Their surface textures were observed via electron-scanning microscope. The prepared composite array electrode exhibited high photoelectrocatalytic activities towards degrading organic contaminants under visible light irradiation. High photoelectrocatalytic activities were also exhibited under UV light irradiation. The catalytic mechanism was discussed based on the analysis of electrochemical and degradation kinetics results. It is suggested a P (Bi₂O₃)-N (TiO₂) junction was formed to increase the catalytic activates. The stability of the electrode materials was confirmed finally.     

Enhanced photoluminescence of Sm/Bi co-doped Gd2O3 phosphors by combustion synthesis

Gd₂O₃:Sm³⁺ and Gd₂O₃:Sm³⁺,Bi³⁺ powders were prepared by a combustion method. Their structures were determined using X-ray diffraction. UV-visible absorption and photoluminescence spectra were investigated for Gd₂O₃:Sm³⁺ and Gd₂O₃:Sm³⁺,Bi³⁺ at different annealing temperatures and different doping concentrations. The emission spectra of all samples presented the characteristic emission narrow lines arising from the ⁴G_5/2→⁶H_J transitions (J=5/2, 7/2, and 9/2) of Sm³⁺ ions upon excitation with UV irradiation. The emission intensity of Sm³⁺ ions was largely enhanced with introducing Bi³⁺ ions into Gd₂O₃:Sm³⁺ and the maximum occurred at a Bi³⁺ concentration of 0.5 mol%. The relevant mechanisms were discussed with the sensitization theory by Dexter and the aggregation behavior of Bi³⁺ ions.     

Chemical bath deposition of Bi2S3 films by a novel deposition system

Bismuth sulfide (Bi₂S₃) films were chemically deposited by a novel deposition system in which ammonium citrate was used as the chelating reagent. Two sulfur source thioacetamide (TA) and sodium thiosulfate (Na₂S₂O₃) were used to prepare Bi₂S₃ films. Both the as-prepared films have amorphous structure. However, annealing can improve the crystallization of the films. The composition of the films prepared by TA and Na₂S₂O₃ are all deviate from the stoichiometric ratio of Bi₂S₃. The Bi₂S₃ films are all homogeneous and well adhered to the substrate. The optical properties of the Bi₂S₃ films are studied. The electrical resistivity of the as-prepared films are all around 7 × 10³ Ω cm in dark, which decreases to around 1 × 10³ Ω cm under 100 mW/cm² tungsten-halogen illumination. After the annealing, the dark resistivity of the Bi₂S₃ film prepared by TA decreases by four magnitudes. In contrast, the dark resistivity of the Bi₂S₃ film prepared by Na₂S₂O₃ only decreases slightly.     

Y2O3:Eu纳米晶中能量传递相互作用的研究

通过浓度猝灭曲线确定了引起Y₂O₃纳米晶中Eu³⁺发光浓度猝灭的是交换相互作用.测量了两种颗粒尺寸下Eu³⁺的⁵D₀—⁷F₂跃迁发光衰减曲线随掺杂浓度的变化,利用交换相互作用的理论衰减曲线对实验衰减曲线进行拟合.计算Eu³⁺离子的交换相互作用能量传递的效率,分析了Y₂O_{3关键词： 能量传递 2}O₃Eu纳米晶')" href="#">Y₂O₃Eu纳米晶 发光衰减