Among the lead-free piezoceramics, (1−x)BiFeO3−xBaTiO₃ (BF-BT) is considered a promising candidate for high-temperature piezoelectric materials owing to its high Curie temperature (TC>400∘C) and good electromechanical properties. In this work, the hydrothermal synthesis method was used to prepare the precursor powders of BiFeO₃ and BaTiO₃, and then the mixed powder compacts with the chemical composition of 0.7BF–0.3BT were sintered under pressureless conditions. The influence of the hydrothermal reaction times (12–24h) of BiFeO₃ on the structures and electric properties of the sintered ceramics was instigated. First, all the samples synthesized with the tetragonal BaTiO₃ and BiFeO₃ powders were identified with relatively stable dielectric properties. As the hydrothermal reaction time to synthesize BiFeO₃ increased, the dielectric properties as well as the temperature stability of the 0.7BiFeO₃–0.3BaTiO₃ ceramics also improved. At the condition of a hydrothermal reaction time of 24h, the sample obtained possesses both the lowest temperature coefficient of dielectric constant (Tkε=1.53×10−2/∘C between RT and 300∘C) and the highest Curie temperature (TC=471∘C at 100kHz). Moreover, at high temperatures, it exhibits a higher AC impedance than others. The calculating result based on the resistive constant-phase-element model (R-CPE) circuit model showed that the grain boundary of the 0.7BF–0.3BT ceramics contributes more resistance to the conductivity at high temperatures. In summary, the hydrothermal reaction proved to be a useful way that achieves the preparation of single-phase 0.7BF–0.3BT ceramics with improved electrical properties.

本文针对煤气化渣(CGFS)资源化利用困难的问题, 以CGFS为原料, 采用碱熔活化-水浸-水热法合成4A分子筛。在水钠比(n(H2O)/n(Na2O), 摩尔比)为80、硅铝比(n(SiO2)/n(Al2O3), 摩尔比)为2的条件下, 探讨了反应时间、水热温度和前驱液老化对合成的4A分子筛物相结构和微观形貌的影响, 提出了活化CGFS-P1分子筛-4A分子筛快速高效的转晶合成机理, 并利用硫酸铜溶液模拟含重金属离子工业废水, 测试了制备的4A分子筛对Cu2+的吸附性。结果表明, 在100 ℃反应12 h条件下能够制备出尺寸均一且结晶良好的4A分子筛, 其对Cu2+的吸附主要发生在前10 min, 吸附率达69.7%, 90 min时的最大吸附率高达97.3%, 饱和吸附容量为196.4 mg/g, 制备的4A分子筛表现出良好的吸附性能, 为CGFS高值化利用提供了理论依据和试验基础。

硒化物常被应用于钠离子电池负极材料，具有更高可逆容量和合适的工作电位，然而，循环过程中的体积变化较大，电导率较低，限制了其实际应用。通过简单的水热反应制备了FeSe2/Ti3C2Tx复合材料作为钠离子电池负极材料。Fe2+首先与乙二胺四乙酸配位并形成螯合物，经过水热反应，Ti3C2Tx和Fe2+螯合物之间产生静电作用，合成了FeSe2/Ti3C2Tx复合材料。FeSe2/Ti3C2Tx呈开放式的“花瓣”结构，Ti3C2Tx为材料提供了强导电网络并且缓解了一定的体积膨胀。电化学测试表明：FeSe2/Ti3C2Tx电极在0.5 A/g下经过150次循环后容量达到455 mA?偸h/g，相同电流密度下，FeSe2电极循环100圈后的容量仅为335 mA?偸h/g，并且在随后的循环中容量迅速衰减，以上结果表明合理的结构设计使得FeSe2/Ti3C2Tx电极具有优异的电化学储钠性能和循环稳定性。

一维TiO2纳米材料良好的电子传输特性为有效提高钙钛矿太阳电池等新型太阳电池的光电性能提供了理论基础。采用水热法在FTO上制备了垂直定向生长的一维单晶金红石相TiO2纳米棒薄膜; 利用XRD、SEM、UV-Vis、TEM和SAED对样品进行了表征; 研究了钛酸丁酯的用量和水热反应次数对纳米棒薄膜的形态和光学性能的影响。结果表明, 在水∶浓盐酸∶钛酸丁酯=30∶30∶1(体积比)和循环水热反应2次时, 得到均匀致密且沿［001］晶向定向生长的一维单晶TiO2纳米棒薄膜, 它在紫外光、可见光区的光吸收增强, 且带边红移, 禁带宽度为3.0eV。

采用微波水热方法合成了Er3+/Yb3+及Tm3+/Yb3+两个共掺杂的绣球花状NaY(WO4)2微米球样品。XRD结果表明所获得的产物为纯相体心结构的NaY(WO4)2, 利用SEM观察发现产物粒子结构为纳米片组装成的绣球花状。考虑到红外激光辐照对样品产生加热效应, 采用380 nm激发下不同温度的发射光谱获得了Er3+/Yb3+共掺杂NaY(WO4)2微米球的温度传感特性曲线和灵敏度曲线。把Er3+/Yb3+共掺杂NaY(WO4)2与Tm3+/Yb3+共掺杂的NaY(WO4)2按质量比1∶10进行混合, 采用980 nm激发测量了混合物的上转换发光光谱, 研究了激光持续辐照对Tm3+/Yb3+掺杂NaY(WO4)2样品的加热效应和Tm3+的1G4→3H6跃迁发光强度随激光辐照时间的变化。实验发现980 nm激光辐照使Tm3+/Yb3+掺杂NaY(WO4)2样品的温度持续升高并达到某一平衡温度, Tm3+的蓝色上转换发光也随着激光辐照时间的延长而增强, 最后达到饱和。此外, 在相同条件下, Tm3+/Yb3+共掺杂样品的激光辐照热效应比Er3+/Yb3+共掺杂样品的热效应更为显著。