Journal of the American Ceramic Society, Vol.103, No.3, 1563-1574, 2020
Role of various alcohol washing media in obtaining a remarkable texture for La2Ce2O7 powders and ceramics
La2Ce2O7 has not been explored much for application purposes due to several material and/or process issues; the concerns involve phase, compositional purity, modest thermal conductivity, poor sintered density etc. Through this work, we demonstrate a panacea for all such issues via a simple process modification, viz., treatments with alcohol washing and ultrasonication for the synthesis of La2Ce2O7 nanopowders. Dense ceramics (>97%) along with absolute phase and compositional purity were obtained via pressureless conventional sintering at 1400 degrees C; the sintered ceramic also depicted a high (111) texture (Lotgering factor similar to 0.9). The root cause of this texture was traced to an "oriented attachment"-type growth mechanism of the La2Ce2O7 nanocrystals that gets extended in micron scale leading to the formation of an organized and uniform rice flake-type microstructure. The ionic conductivity data of the La2Ce2O7 ceramics showed significant improvement (in orders of magnitude) for the ethanol-washed sample. This work has been presented as a case study to acknowledge the additional benefit (of obtaining a homogeneous microstructure via "oriented aggregation") of ethanol and ultrasonication treatment for a ceramic system leading to multiple advantages, viz., full densification at low temperature, high texture etc.