Enhancement of magnetic and ferroelectric behaviour in (Ca, Co) co-doped HoMnO3 multiferroics

The effect of sintering temperature on structural, electrical and magnetic behaviours of polycrystalline samples of Ho0.9Ca0.1Mn0.9Co0.1O3 prepared by the solid state reaction route sintered at three different temperature 1250 °C, 1350 °C, 1450 °C for 10 h are investigated. XRD, SEM, magnetization, dielectric and ferroelectric measurements were carried out. Experimental results showed the nucleation of orthorhombic phase as the sintering temperature increases from 1250 °C to 1450 °C. Ferroelectric (Tc) and antiferromagnetic transition temperature (TN) increases with increase in sintering temperature. Strong bifurcation of FC and ZFC curve in sample sintered at 1450 °C showed a clear onset of ferromagnetic state around 165 °K, which is confirmed from M to H graph at 165 °K. All the sample showed ferroelectric behaviour at room temperature which are leaky in nature. Sintering temperature along with Ca and Co doping in HoMnO3 ceramics plays an important role in phase transformation along with enhancement in multiferroic properties. - Highlights: • Doping of Ca and Co ions causes structural transformation from hexagonal to orthorhombic. • Ferromagnetic Tc shifts to higher temp. with increase in sintering temp. for Ho0.9Ca0.1Mn0.9Co0.1O3. • The origin of ferromagnetism at 165 K is attributed to Mn3+–Mn4+exchange interaction. • Ho0.9Ca0.1Mn0.9Co0.1O3 sample sintered at 1450 °C exhibits a sharp dielectric anomaly around 560 K. • Ca and Co doping causes structural distortion which leads to the origin of ferroelectricity at room temperature