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本文用均相沉淀法对 La_2Ti_2O_7的合成进行了研究。以 TiCl_4、La_2O_3为原料,用尿素作均相沉淀剂,首先于水溶液中合成出中间体 A。再于1100℃灼烧1h,粉碎得产品。经 X 射线物相分析,产品为 La_2Ti_2O_7,属单斜晶系。实验表明,当 pH 值>7,反应温度90℃,灼烧温度超过1000℃的,才能生成 La_2Ti_2O_7。振动光谱分析表明,在 La_2Ti_2O_7晶体中,Ti 将以四面体形式同氧配位,晶体属类钙钛矿型。热分析结合 X 射线分析表明,合成过程中,产品首先以非晶态的 La_2TI_2O_7∶3H_2O 形式出现,然后在280℃脱去结晶水,在850℃附近结晶。
In this paper, the homogeneous precipitation method La_2Ti_2O_7 synthesis were studied. Using TiCl_4 and La_2O_3 as raw materials and urea as a homogeneous precipitating agent, the intermediate A was firstly synthesized in aqueous solution. Then fired at 1100 ℃ 1h, smash the product. After X-ray phase analysis, the product is La_2Ti_2O_7, which belongs to monoclinic system. Experiments show that when pH> 7, the reaction temperature is 90 ℃ and the burning temperature is over 1000 ℃, La_2Ti_2O_7 can be formed. Vibrational spectroscopic analysis shows that in the La 2 Ti 2 O 7 crystal, Ti will coordinate with oxygen in tetrahedron form, and the crystal belongs to perovskite type. Thermal analysis combined with X-ray analysis showed that during the synthesis process, the product first appeared in the form of amorphous La_2Ti_2O_7: 3H_2O, then de-crystallized at 280 ℃ and crystallized at 850 ℃.