Molten salt synthesis of δ-CaCr2O4 and its annealing to prepare β-CaCr2O4

Abstract Molten salt synthesis (MSS), due to the high reactivity of salts, small diffusion distance and high mobility of species in molten salt, can not only reduce the synthesis temperature but also shorten the reaction time. Herein, MSS method was employed to synthesize δ-CaCr 2 O 4 powder by using CaO, Cr 2 O 3 as raw materials and CaCl 2 which has a high solubility of CaO as molten salt. The influence of reaction time was investigated and δ-CaCr 2 O 4 with platelet morphology was obtained after reaction for 2 h at 900 °C. Pure rod-like β-CaCr 2 O 4 was further prepared by simply annealing the as-synthesized δ-CaCr 2 O 4 in argon atmosphere for 3 h at 1100 °C. The magnetization and its corresponding reciprocal susceptibility of δ-CaCr 2 O 4 and β-CaCr 2 O 4 samples was also measured and calculated, which indicated a paramagnetic arrangement and an antiferromagnetic arrangement during the test temperature range 2–250 K, respectively.