Magnetic properties and heat capacity of CoTiO_3 nanopowders prepared by stearic acid gel method

摘要

Pure cobalt titanate nanopowders were successfully prepared in wet-chemistry synthesis method, using cobalt acetate and tetra-n-butyl titanate as Co and Ti sources and stearic acid as complexing reagent. The gel was calcined at different temperatures in air ranging from 500℃ to 650℃. Results of thermal analysis are given; including both differential thermal gravimetry (DTG) and thermogravimetric. X-ray diffraction was used to characterise the crystallisation process, the particle size and morphology of the calcined powders. The results indicated that cobalt nanopowders with a particle size of about 35nm could be obtained after calcinations of the dried gel at 600℃for 2 h. In the temperature range between 80℃ and 500℃, the empirical equation (C_P (JK~(-1) mol~(-1))=-136.311t0.141 T-3.551×10~7/T~2) for the CP of CoTiO_3 was determined from differential scanning calorimetry. The synthesised CoTiO_3 indicate a superparamagnetic behaviour, as evidenced by using vibrating sample magnetometer at room temperature.