钛酸铅纳米颗粒的形成机理(英文)

本文报导了采用以下三种不同反应物形成钛酸铅纳米颗粒的机理。 1 ,铅 -钛共沉淀物 ;2 ,高能球磨后的铅 -钛共沉淀物 ;3 ,氧化铅和氧化钛的混合物。实验结果表明 ,在众多因素中 ,存在于氧化钛中的钛 -氧八面体对钛酸铅的形成起到了主要的影响。主要表现在 :已存在钛 -氧八面体的反应物可以直接形成钛酸铅 ,而没有钛 -氧八面体的反应物在形成钛酸铅之前会形成一种亚稳态的中间相。该亚稳相在有关钛酸铅的研究中首次被发现和报导。此外 ,本文还报导了球磨过程中 ,不同的球磨时间对钛酸铅的形成过程以及形成后钛酸铅颗粒的均匀性和尺寸的影响

Formation Mechanisms of PbTlO3 Nano-Rarticles

We report on the formation mechanisms of PbTiO3 nano - particles from three different types of starting materials: amorphous Pb - Ti - O precursor synthesized by a modified co - precipitation method, the precursor after high - energy ball milling, and the mixed oxides. We show that, among the factors affecting the formation of the PbTiO3 phase, the existence of the TiO6 octahedra in the starting TiO2 in the mixed oxides has a major influence. The TiO6 octahedra, which also exist in the final PbTiO3 perovskite ferroelectric, make the formation of the PbTiO3 phase more favorable energetically and direct, as compared to starting materials without the TiO6 octohedra where the PbTiO3 formation is indirect through a metastable phase despite the much smaller particle size of the starting materials.The ball milling process has two effects on the PbTiO3 formation. For shorter milling time, the main effect is a better mixing of the starting material, resulting in more uniform PbTiO3 grains. For longer milling time, ball milling alone can form PbTiO3 crystallites, which act as the nuclei in the subsequent calcinations process. In this case, the density of such nuclei is the main determinant factor for the PbTiO3 grain size. Raman spectroscopy, X - ray diffraction, scanning electron microscopy, atomic force microscopy, electron transmission microscopy and energy dispersive X - ray spectrometry are used in our study to characterize the samples.