含镧的Bi_2Te_3基化合物的溶剂热合成及微观结构

Solvothermal Synthesis and Microstructures of Bi_2Te_3 Based Compounds Containing Lanthanum

以BiCl3,LaCl3和Te粉为原料,用溶剂热合成法制备了含稀土元素的单相LaxBi4Te6(x≤1)热电材料纳米粉末。研究发现,三元化合物LaxBi4Te6具有与二元Bi2Te3化合物相同的晶体结构和相似的晶格常数。LaxBi4Te6中的La含量随合成温度升高而增加,但与反应时间没有显著关系。LaxBi4Te6合成粉末的颗粒尺寸在30nm左右,并且几乎与反应温度和反应时间没有关系。在120℃合成的粉末基本上为不规则多面体形状,在150℃及以上温度合成的粉末则趋向于薄片状,并存在一些直径在50～80nm之间的纳米管。

Rare-earth element-contained thermoelectric La_xBi_4Te_6 (x≤1) nano-sized powders have been prepared by solvothermal synthesis from BiCl_3, LaCl_3 and pure telluride powder. It is found that the ternary compounds La_xBi_4Te_6 have the same crystal structure and similar lattice parameters as binary Bi_2Te_3. The lanthanum contents in La_xBi_4Te_6 increase with the synthesis temperature and are independent on the reaction time. The average size of synthesized La_xBi_4Te_6 powders is about 30 nm, which is not influenced by the reaction temperature and time. The powders synthesized at 120 ℃ have an irregular polyhedral morphology, while those synthesized at 150 ℃ or above tend to be formed in thin sheets. Nano-tubes with a diameter between 50 and 80 nm have been found in the powders synthesized at 150 ℃ or above.