TiO2 .nH2O凝胶预处理对水热合成SrTiO3粉的影响

以TiCl4为钛源,首先制备TiO2*nH2O凝胶,然后在80℃的水热条件下制备了SrTiO3粉.利用X射线衍射(XRD)、透射电子显微镜(TEM)和红外光谱(FTIR)研究了TiO2*nH2O凝胶水洗方式、阴离子(Cl-和NO3-)以及TiO2*nH2O热处理对SrTiO3粉性能的影响.结果表明,水洗和热处理都能使TiO2*nH2O凝胶产生晶化;TiO2*nH2O的晶化程度对产物SrTiO3颗粒的粒度和粒度分布有很大影响,以非晶质TiO2*nH2O为钛源制备的SrTiO3颗粒粒度大且粒度分布宽.以结晶TiO2*nH2O为钛源制备的SrTiO3颗粒粒度小且粒度分布窄,而且可以得到纳米颗粒.水热反应液相中存在Cl-或NO3-能使产物SrTiO3颗粒粒度稍有增大.综合以上结果,TiO2*nH2O凝胶水洗对产物颗粒的影响主要是由于使凝胶产生了晶化,而由阴离子脱除产生的影响很小.因此,在不考虑阴离子对其它工程化影响(如设备腐蚀等)的前提下,可采用热处理代替水洗.

The Influence of Pre-processing of TiO2. nH2O Gel on SrTiO3 Powders from Hydrothermal Synthesis

The SrTiO3powders were synthesized from TiO2·nH2O gel under moderate hydrothermal condition. TiO2·nH2O gel was prepared by diluting TiCl4with cold distilled water. The influence of pre-processing of TiO2·nH2O gel and anions (Cl-and NO3-) on the properties of SrTiO3 powders was studied in details by X-ray diffraction (XRD), transition electron microscopy (TEM) and Fourier transform infrared spectrometry (FTIR). The results showed that TiO2·nH2O could be crystallized during the washing and thermal processing. The crystallization of TiO2·nH2O had an important influence on the product particle size and particle size distribution. The SrTiO3powders prepared from amorphous TiO2·nH2O are with big particle size and wide particle size distribution, and those from crystallized TiO2·nH2O are with small particle size and narrow particle size distribution. To get nanometer SrTiO3powders, the suitable crystallization of TiO2·nH2O gel is essential. The chloride and nitrate ions can accelerate the formation of large-grained particles of SrTiO3, but such effect is very small. In a word, the main reason for the effect of washing of TiO2·nH2O on properties of SrTiO3powders is the crystallization of TiO2·nH2O gel during the washing, and the washing process can be substituted by thermal processing neglecting the effect of anions.