片状Sr_3Ti_2O_7中间体的熔盐法合成

Tabular Sr_3Ti_2O_7 Intermediates Synthesized by Molten Salt Method

以SrCO3和TiO2为原料，采用熔盐法合成出片状Sr3Ti2O7中间体。探讨了熔盐种类（NaCl和KCl）、反应温度及反应时间对片状Sr3Ti2O7中间体合成的影响。采用X-射线衍射（XRD）和扫描电镜（SEM）分析粉体的相组成和显微结构。结果表明：以KCl为熔盐所得中间粉体的相组成为Sr3Ti2O7和Sr3Ti2O4相，SrCO3过量及提高合成温度，对相的组成和相的含量影响不大；而以NaCl为熔盐合成中间粉体的相组成为Sr3Ti2O7、Sr2TiO4和Sr4Ti3O10相，SrCO3过量及提高合成温度，使Sr3Ti2O7的含量增加，而Sr2TiO4的含量明显减少。以NaCl为熔盐，1300℃保温4h的工艺条件所得中间体为长方片状，边长为30-60μm，厚为2～5μm，是外延生长〈001〉SrTiO3片状晶体的理想模板；而以KCl为熔盐，所得中间体也为长方片状，边长为10～20μm，厚为5～10μm。

Using SrCO3 and TiO2 as raw materials, the tabular intermediates St3 Ti2 O7 was synthesized by molten salt method. The phase composition and mierostructure of these powders were analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The effects of molten salt （NaCl and KCl）, reactive temperature and reactive time on the synthesis of tabular intermediates Sr3Ti2O7 were discussed in this paper. The results showed that the intermediates obtained by using KCl as molten salt were composed of anisotropic Sr3Ti2O7 and Sr2 TiO4. The intermediates obtained by using NaCl molten salt were composed of auisotropic St3 Ti2 O7, Sr2 TiO4 and Sr4 Ti3 O10. There have little effect on phase composition and phase contents by using excessive SrCO3 or improving synthesis temperature. Moreover, by using excessive SrCO3 or improving synthesis temperature, the contents of Sr3Ti2O7 increase, but that of Sr2TiO4 decreases. The intermediates obtained at t 300 ℃ for 4 h by using NaCl as molten salt were rectangle and tabular, its edge length and thickness is 30-60 μm and 2-5 μm respectively, which is the idea template for epitaxial growth of 〈001〉SrTiO3 tabular crystals. However, the intermediates obtained by using KC; as molten salt were also rectangle and tabular, its edge length and thickness is 10-20μm and 5-10 μm.