纳米K_2Ti_6O__(13)w合成中的形态演化和生长机理

Morphologic Evolution and Growth Mechanism Involved in the Synthesis of Nanometer K_2Ti_6O_(13)w

以纳米TiO_2为原料,通过煅烧反应制备了纳米K_2Ti_6O_(13)晶须,对晶须合成中温度和时间诱导的相变、形态演化和生长机理等进行了原位研究．结果表明：纳米TiO_2作原料可显著降低晶须合成温度,适宜的煅烧温度为900～1100℃．形态演化观察和高温XRD分析表明：K_2Ti_6O_(13)晶须的相变及生长对温度极为敏感,形态演化是基于初期爆发式的相变和随后串并联式的长大．K_2Ti_6O_(13)晶须的生长遵守本研究提出的串并联机制,晶须轴向的生长台阶是串并联生长的直接结果．

The present work was aimed at in situ studies of temperature and time induced phase transition, morphologic evolution, growth mechanism, and microstructure of K2Ti6O13 nanowhiskers synthesized by calcination reaction using nanometer TiO2 as the starting material. The experimental results indicate that the use of nanometer TiO2 greatly reduces calcination temperature with a suitable calcination temperature range of 900-1100℃. Observation of morphologic evolution and dynamic HTXRD analysis show that the phase transition and growth of K2Ti6O13 whiskers are quite sensitive to calcination temperature, and the morphologic evolution of K2Ti6O13 whiskers is mainly based on the fulminous phase transition at the initial stage and subsequent concatenation-parallel growth in length and diameter. The growth of K2Ti6O13 whiskers follows the concatenation-parallel growth mechansim developed in this study, which directly results in the formation of growth steps along the axis of the whiskers.