Effects of non-magnetic Ti⁴⁺ ion doping on the structural, magnetic and magnetocaloric properties of La_0.65Dy_0.05Sr_0.3Mn_1−xTi_xO₃ compounds

Perovskite manganites have many prospective applications as magnetic solids, however, their synthesis remains challenging of a high purity and a high crystallinity. Herein, a solid state method has been successfully employed for the synthesis of the La_0.65Dy_0.05Sr_0.3Mn_1−xTi_xO₃ (x = 0.05 and x = 0.10) materials. Moreover, the impact of the Mn by Ti ion substitution on the structural, magnetic and magnetocaloric properties has fully been looked into. The Rietveld refinement technique showed that all the compounds crystallize in the orthorhombic structure with Pbnm space group and that the Mn⁴⁺ by Ti⁴⁺ substitution causes the increase of the unit cell volume. Magnetization versus temperature measurements shows a large ferromagnetic–paramagnetic transition with decreasing temperature. The Curie temperature T_C fall with the rise of titanium content from 175 K for x = 0.05 to 114 K for x = 0.10. An analysis of both Banerjee criteria and Landau theory revealed a second-order magnetic phase transition at T_C for the current manganites. The magnetocaloric impact is calculated through the measurement of initial isothermal magnetization versus magnetic applied field at various temperatures. The maximum magnetic entropy change \(\left| {\Delta {\text{S}}_{\text{M}}^{ \hbox{max} }} \right|\), which is calculated on the basis of isothermal magnetization curves under magnetic field change of 5 T is found to be 1.79 J kg⁻¹ K⁻¹ and 1.49 J kg⁻¹ K⁻¹ for x = 0.05 and 0.10, respectively. The relative cooling power (RCP) rose to 239 J kg⁻¹ and 211 J kg⁻¹ at 5 T for x = 0.05, 0.10, respectively. In fact, our results match those about some other doped manganites, which imply that these materials may be appropriate candidates as working substances in magnetic cooling applications. Furthermore, by normalizing the \(\Delta {\text{S}}_{{\text{M}}} ({\text{T}},\mu_{0}{\text{H}})\) curves to their respective \(\Delta S^{\prime}\left( {{{ = \Delta {\text{S}}_{{\text{M}}} \left( {\text{T}} \right)} \mathord{\left/ {\vphantom {{ = \Delta {\text{S}}_{{\text{M}}} \left( {\text{T}} \right)} {\Delta {\text{S}}_{{\text{M}}}^{{{\text{Max}}}} }}} \right. \kern-\nulldelimiterspace} {\Delta {\text{S}}_{{\text{M}}}^{{{\text{Max}}}} }}} \right)\) values, we noticed that all the obtained curves drop to a universal master curve. The combination of experiment data and theory analysis is favorable for a better understanding of manganite properties.