Effect of La2O3 addition on the synthesis of tungsten nanopowder via combustion-based method.

In this study, the influences of La 2 O 3 added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis (SCS) were investigated for the first time. And tungsten nanopowders with different La 2 O 3 doping amount (0.5∼5.0 wt%) were successfully prepared by SCS and followed hydrogen reduction. The results showed that with the increase of La 2 O 3 addition, the product synthesized by SCS changed from needle-like W 18 O 49 to irregularly granulated H 0.53 WO 3 and the complete reduction temperature also increased form 700 ℃ to 850 ℃. The densification behavior of as-prepared W nanopowders revealed that the densification inhibitory effect of La 2 O 3 was enhanced as the La 2 O 3 addition increased. Nevertheless, due to the optimal size and distribution of La 2 O 3 particles, the sample with 2.0 wt% La 2 O 3 addition has a smallest grain size of 0.47 μm and a highest microhardness value of 739.3 Hv 0.2 , which are the best compared with the literature. [ABSTRACT FROM AUTHOR]