掺Sr铬酸镧粉体的合成及低温烧结行为研究

通过溶胶-凝胶法制备了La_1-xSr_xCrO₃纳米粉体并实现了低温致密烧结, 用X射线衍射仪、透射电镜、差示扫描量热分析仪和扫描电镜对粉体和烧结体进行分析. 结果表明: 粉体的平均直径<50nm, 当x=0, 0.1时, 粉体为单一的La_1-xSr_xCrO₃, x=0.3时存在第二相SrCrO₄. Sr掺杂使铬酸镧晶格产生畸变, 随Sr含量的增加, 晶格常数逐渐变小. 铬酸镧纳米粉体的烧结分为两个阶段, 1200℃以前的缓慢放热和1350℃左右的较快放热, 分别对应烧结的初期和中期. 依据DSC分析结果制订了烧结工艺, 并在1380℃烧结得到相对密度91％的铬酸镧烧结体.

Synthesis and Low-temperature Sintering Behavior of Sr-doped Lanthanum Chromite Powders

La_1-x Sr_xCrO₃ powders were synthesized by a sol-gel method and sintered at a low temperature. The powders and sintered pellets were characterized by XRD, TEM, DSC and SEM. It is found that the mean particle size is below 50nm. The powder with x=0 and 0.1 of single phase of La_1-x Sr_xCrO₃, and another phase SrCrO₄ appears with x=0.3. Lattice distorts and lattice parameters of lanthanum chromite decrease with increasing Sr content. The sintering process of lanthanum chromite can be divided into two stages: a slow exothermic effect below 1200℃ and a quick exothermic effect near 1350℃, corresponding to the primary and intermediate sintering stage, respectively. The relative density of the sintered body (x=0.3) after sintering at 1380℃ is 91％, according to the procedure derived from the DSC analysis.