摘要
采用熔盐法分两步合成了片状SrTiO3晶体.研究了合成温度、熔盐种类对Sr3Ti2O7前驱体以及片状SrTiO3晶体形貌和尺寸的影响.在第1步过程中,低温下,首先生成亚微米级立方SrTiO3颗粒,随着温度的升高,SrTiO3颗粒逐渐生长成片状Sr3Ti2O7晶体.在第2步过程中,随着温度的提高,片状Sr3Ti2O7前驱体逐渐转变为片状SrTiO3晶体.熔盐的选择对片状SrTiO3晶体的最终形貌、尺寸有着显著的影响.以KC l作为熔盐,在1 200℃下合成的片状SrTiO3晶体边长为10-15μm,而使用NaCl所得SrTiO3晶体边长为30-50μm,宽厚比最高达到25∶1.片状SrTiO3晶体的形成机理是在高温条件下,由于熔盐中TiO2的作用,Sr3Ti2O7晶体中岩盐结构的SrO层被破坏,并以Sr^2＋、O^2-形式溶出,剩余的SrTiO3结构重新叠合联结,产物基本保持原来Sr3Ti2O7片状晶体的外形,溶出的Sr^2＋、O^2-与熔体中的TiO2反应生成SrTiO3.
A two-step molten salt method was utilized to synthesize platelet SrTiO3 crystals. The effects of synthesis temperature and salts on the morphology and size of Sr3Ti2O7 precursor as well as platelet SrTiO3 crystals were studied. In the first step, submicron cubic SrTiO3 was initially synthesized at low temperature. With the increase of temperature, submicron cubic SrTiO3 gradually transformed to platelet Sr3 TiE 07 crystals. In the second step, platelet Sr3Ti2O7 precursor transformed to platelet SrTiO3 crystals with the increase of temperature. The salt was crucial to the morphology and size of SrTiO3 crystals. The final platelet SrTiO3crystals were 10 - 15 μm in length in KCl flux under 1 200 ℃. However, the size of platelet SrTiO3 were 30 -50 μm in length with width to thick ratio of25：1 using NaCl as molten salt. The formation mechanism of the platelet SrTiO3 is that under the high temperature, rock salt structured SrO layers in Sr3Ti2O7crystals are destroyed because of the effects of TiO2, and extracted in the form of Sr^2＋ O^2- , and then the residual SrTiO3 blocks are reconstructed to form SrTiO3 layer. The products maintain platelet morphology of original Sr3Ti2O7 crystals, Sr^2＋ and O^2- react with TiOEin the molten salt to produce SrTiO3.
出处
《南京工业大学学报（自然科学版）》
CAS
2007年第3期13-19,共7页
Journal of Nanjing Tech University(Natural Science Edition)
