Effect of calcination on structural and supercapacitance properties of hydrothermally synthesized plate-like SrFe12O19 hexaferrite nanoparticles

Abstract Nanocrystalline Sr 1 Fe 12 O 19 hexaferrite particles were successfully synthesized via hydrothermal route from Sr and Fe nitrates at molar ratio of 1:9 (Fe/Sr). As-synthesized powders were subsequently subjected to calcination at 900, 1000, 1100 and 1200 °C for 4 h to evaluate their structural, morphological and supercapacitance behavioral changes with temperature. The XRD results revealed Sr 1 Fe 12 O 19 phase formation in the presence of Fe 2 O 3 , SrCo 3 phases in the calcined samples. The percentage of Sr 1 Fe 12 O 19 phase showed an increase by increasing the calcination temperature. Furthermore, the average crystallite size was increased from 28 nm to 361 nm by increasing the calcination temperature from 900° to 1200°C. The formation of metal oxide (Fe-O) bonds was also confirmed from strong absorption peak between 448 and 568 cm − 1 in FT-IR analysis. The FESEM images exhibited plate-like particles, which are distributed in the range of 1–8 µm in the as-synthesized samples calcined up to 1000 °C, but their shaped became almost irregular by increasing temperature to 1200 °C and the particles size distribution were broadened to 2–15 µm. Electrochemical performance of the pseudocapacitor ( Sr 1 Fe 12 O 19 ) was studied by cyclic voltammetry. It was found that by increasing the calcination temperature from 900° to 1100°C, the specific capacitance increased from 44.0 to 133.9 F. g − 1 , respectively. Thereafter, its value decreased to 15.5 F. g − 1 by calcination at 1200 °C. It should be noted that the cycle stability of Sr 1 Fe 12 O 19 calcined powder at 1100 °C was at an acceptable level, which maintains 84% of the initial capacitance after 5000 cycles.