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采用燃烧法合成了纳米La2O3/La2O2CO3复合材料,以六水合硝酸镧和一水合柠檬酸分别为镧源和络合剂,以氨水调节p H值,p H=2~4、柠檬酸与硝酸镧的摩尔比在1.0~1.2∶1.0之间,将得到的凝胶加热到一定温度发生自蔓延燃烧反应,燃烧反应产物在600~700℃煅烧1~2 h,得到膨松粉末状纳米La2O3/La2O2CO3复合产物。煅烧温度和恒温煅烧时间不同,得到不同粒径和组分比例的纳米La2O3/La2O2CO3复合材料。利用X射线衍射(XRD)、差热-热重分析(TG-DTA)和透射扫描电镜(TEM)等测试方法对凝胶热分解过程产物及最终形成的纳米La2O3/La2O2CO3复合产物粉体进行了分析和表征,产物的平均粒径在30~100 nm之间可控。纳米La2O3/La2O2CO3复合产物中的纳米La2O3在空气中具有不稳定性,极易与空气中的H2O发生反应生成La(OH)3,生成了La(OH)3/La2O2CO3复合产物,而产物在650℃煅烧2 h后即可完全转化为La2O3/La2O2CO3复合产物,说明这个过程是可逆的。
Nanometer La2O3 / La2O2CO3 composite was synthesized by combustion method. Lanthanum nitrate hexahydrate and citric acid monohydrate were used respectively as lanthanum source and complexing agent, p H value was adjusted with ammonia solution, p H = 2 ~ 4, citric acid and lanthanum nitrate The molar ratio of 1.0 to 1.2: 1.0, the resulting gel is heated to a certain temperature self-propagating combustion reaction, the combustion reaction product calcined at 600 ~ 700 ℃ 1 ~ 2 h, to obtain a loose powder nano La2O3 / La2O2CO3 Composite product. Calcination temperature and constant temperature calcination time are different to obtain a different particle size and composition of nano La2O3 / La2O2CO3 composite material. The products of pyrolysis of gel and the powders of La2O3 / La2O2CO3 nanocomposites were finally analyzed by XRD, TG-DTA and TEM. Analysis and characterization, the average particle size of the product is controlled between 30 ~ 100 nm. Nanocrystalline La2O3 / La2O2CO3 nanocomposite lanthanum oxide (La2O3) has instability in the air and easily reacts with H2O in the air to form La (OH) 3, resulting in La (OH) 3 / La2O2CO3 composite product. ℃ calcined 2 h can be completely converted into La2O3 / La2O2CO3 composite product, indicating that the process is reversible.