Low-temperature synthesis of ZrB2 powder from oxides using Na

ZrB2 was synthesized by heating a mixture of ZrO2, B2O3, and Na in a molar ratio of 1:1:5 at 873–1273 K. While unreacted ZrO2 remained in the sample synthesized at 873 K, single phase ZrB2 powders were obtained at temperatures ≥1073 K. The diameters of the ZrB2 particles obtained at 1073 and 1273 K were 0.1–20 and 10–100 μm, respectively. Single phase ZrB2 was also obtained at 873 K when the starting material was rich in B2O3 and Na (ZrO2:B2O3:Na = 1:5:15). This route yielded fine particle aggregates of ZrB2, which were found to be <0.1 μm in size.