Buscaglia Maria Teresa, Buscaglia Vincenzo, Viviani Massimo, Dondero Giovanni, Röhrig Serge, Rüdiger Andreas, Nanni Paolo
Institute of Energetics and Interphases, National Research Council, Via De Marini 6, I-16149 Genoa, Italy.
Nanotechnology. 2008 Jun 4;19(22):225602. doi: 10.1088/0957-4484/19/22/225602. Epub 2008 Apr 25.
Hollow particles of barium titanate were obtained by a two-step process combining colloidal chemistry and solid-state reaction. BaCO(3) crystals (size ≈1 µm) suspended in a peroxy-Ti(IV) aqueous solution were coated with an amorphous TiO(2) shell using a precipitation process. Calcination of the BaCO(3)@TiO(2) core-shell particles at 700 °C resulted in the formation of BaTiO(3) hollow particles (shell thickness of ≈70 nm) which retain the morphology of the BaCO(3) crystals. Formation of the cavity occurs because out-diffusion of the core phase is much faster than in-diffusion of the shell material. X-ray diffraction (XRD) and Raman spectroscopy indicate that the hollow particles possess a tetragonal ferroelectric structure with axial ratio c/a = 1.005. Piezoresponse force microscopy has shown strong piezoactivity and 180° ferroelectric domains. The process described provides a general route to fabricate hollow ferroelectric structures of several compounds.
通过结合胶体化学和固态反应的两步法制备了钛酸钡空心颗粒。将悬浮在过氧钛（IV）水溶液中的碳酸钡晶体（尺寸约为1微米）通过沉淀工艺包覆一层非晶态二氧化钛壳层。将碳酸钡@二氧化钛核壳颗粒在700°C下煅烧，形成了钛酸钡空心颗粒（壳层厚度约为70纳米），其保留了碳酸钡晶体的形态。空洞的形成是因为核相的向外扩散比壳层材料的向内扩散快得多。X射线衍射（XRD）和拉曼光谱表明，空心颗粒具有四方铁电结构，轴比c/a = 1.005。压电响应力显微镜显示出强压电活性和180°铁电畴。所描述的工艺为制备几种化合物的空心铁电结构提供了一条通用途径。
