Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite

Publication date: March 2019Source: Results in Physics, Volume 12Author(s): Sanam Garehbaghi, Abbas KianvashAbstractSr-hexaferrite powders with Fe/Sr molar ratio of 11 was synthesized via conventional ceramic route. Powders were milled for 5–25 h, then pressed to make green compacts by applying a pressure of 100–400 MPa. In other series, K2CO3 was used in starting materials. K2CO3/SrCO3 mixing molar ratio was 0.05 and 0.5. First series were calcined at 1250 °C, and the second series were calcined at 1000 °C for 2 h. The XRD characterization results revealed Sr-hexaferrite structure has been produced in both series; Crystallite size is constant then increases while lattice strain rises by variation of milling time from 5 h to 25 h. (BH)max and Br increase by increasing milling time to 25 h and (BH)max reaches to optimized value of 24.75 kJ/m3. SEM was used for microstructure investigation; particle morphologies are hexagonal shape. Addition of slight amount of K2CO3 makes SrFe12O19 crystallites get less platelet shape and more regular shape. By increasing pressure morphology of the grain enhances in regularity. Magnetic properties were measured via permagraph; By increasing sintering temperature from 1150 °C to 1200 °C, density increases from 3.38 g/cm3 to 4.85 g/cm3. Maximum energy product varies from 9.54 kJ/m3 to 25.27 kJ/m3. Between the sintering temperatures of 1200–1250 °C maximum energy product stays at the highest values, But ...

Source: Results in Physics - February 6, 2019 Category: Physics Source Type: research