Ji Qing, Xue Piaojie, Wu Heng, Pei Zhipeng, Zhu Xinhua
National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing, 210093, China.
Nanoscale Res Lett. 2019 Feb 21;14(1):62. doi: 10.1186/s11671-019-2899-9.
By reaction of PbCO and TiO in the eutectic NaCl-KCl salts, both sphere- and rod-like PbTiO (PTO) powders were synthesized via molten salt synthesis (MSS) and template MSS methods, respectively. X-ray diffraction patterns reveal that all the PTO powders crystallize in a tetragonal phase structure. Increasing the molar ratio of PbCO:TiO:NaCl:KCl from 1:1:10:10 to 1:1:60:60 in the MSS process has little effect on the sphere-like morphology of the PTO powders synthesized at 950 °C for 5 h. Large-scale polycrystalline rod-like PTO powders with diameters of 480 nm-1.50 μm and lengths up to 10 μm were synthesized at 800 °C for 5 h by template MSS method, where the rod-like anatase TiO precursors were used as templates and the molar ratio of PbCO:TiO:NaCl:KCl was equal to 1:1:60:60. X-ray energy dispersive spectroscopy spectra reveal that all the PTO powders are composed of Pb, Ti, and O elements, and the measured Pb:Ti atomic ratios are close to 1:1. In the template MSS process, the molten salt content plays an important role in forming the rod-like PTO powders. Under low molten salt content, the rod-like PTO powders cannot be synthesized even if the rod-like TiO templates are used. In addition, prolonging the reaction time suppressed the formation of rod-like PTO powders but promoted the formation of sphere-like PTO nanoparticles. The dielectric properties the sphere- and rod-like PTO powders were comparatively investigated. At room temperature, the dielectric constant and dielectric loss of the spherical PTO powders synthesized by MSS method with the molar ratio of PbCO:TiO:NaCl:KCl equal to 1:1:30:30 were ~ 340 and 0.06 (measured at 10 Hz), respectively. The corresponding values for the rod-like PTO powders synthesized by template MSS method with the molar ratio of PbCO:TiO:NaCl:KCl equal to 1:1:60:60 were 140 and 0.08, respectively. The present results demonstrate the sphere-like PTO powders have better dielectric properties, which have promising applications in the fields of multilayer capacitors and resonators.
通过在共晶NaCl-KCl盐中使碳酸铅（PbCO）与二氧化钛（TiO）反应，分别采用熔盐合成法（MSS）和模板MSS法合成了球状和棒状的钛酸铅（PTO）粉末。X射线衍射图谱表明，所有PTO粉末均结晶为四方相结构。在MSS过程中，将PbCO:TiO:NaCl:KCl的摩尔比从1:1:10:10增加到1:1:60:60，对在950℃下反应5小时合成的球状PTO粉末的形貌影响不大。通过模板MSS法，以棒状锐钛矿TiO前驱体为模板，在800℃下反应5小时，合成了直径为480nm-1.50μm、长度可达10μm的大规模多晶棒状PTO粉末，此时PbCO:TiO:NaCl:KCl的摩尔比为1:1:60:60。X射线能量色散光谱表明，所有PTO粉末均由Pb、Ti和O元素组成，测得的Pb:Ti原子比接近1:1。在模板MSS过程中，熔盐含量对棒状PTO粉末的形成起着重要作用。在低熔盐含量下，即使使用棒状TiO模板也无法合成棒状PTO粉末。此外，延长反应时间会抑制棒状PTO粉末的形成，但会促进球状PTO纳米颗粒的形成。对球状和棒状PTO粉末的介电性能进行了比较研究。在室温下，通过MSS法合成的PbCO:TiO:NaCl:KCl摩尔比为1:1:30:30的球状PTO粉末的介电常数和介电损耗（在10Hz下测量）分别约为340和0.06。通过模板MSS法合成的PbCO:TiO:NaCl:KCl摩尔比为1:1:60:60的棒状PTO粉末的相应值分别为140和0.08。目前的结果表明，球状PTO粉末具有更好的介电性能，在多层电容器和谐振器领域具有广阔的应用前景。
