Structural, magnetic and transport properties of La0.70Sr0.21K0.09MnO3

• La0.70Sr0.21K0.09MnO3 compound was produced using standard sol–gel route.
• The produced compound possesses an orthorhombic perovskite structure belonging to Pnma space group.
• Replacing 9% Sr by K in the compound La0.70Sr0.30MnO3 decreased TC and TIM to room temperature.
• The resistivity obeys ρ(T) = ρ0 + ρ0.5T0.5 + ρ2T2 + ρ4.5T4.5 equation up to 285 K.

In this work we investigated structural, magnetic and transport properties of La0.70Sr0.21K0.09MnO3 compound produced by the standard sol–gel route. The crystal structure was determined by analyzing XRD data and found to be an orthorhombic perovskite belonging to Pnma space group. The Curie temperature, TC, of the compound was determined to be 295 K, which is near room temperature. The calculated magnetic entropy change was 0.77 J/kg K which is not high enough for magnetic cooling application. Insulator–Metal transition temperature, TIM, was determined to be 294 K, which coincides with TC. The low temperature peak near TIM reveals the coexistence of ferromagnetic and paramagnetic phases in the ferromagnetic region. The temperature dependence of resistivity was well fitted (with R2 = 0.9999) to ρ(T) = ρ0 + ρ0.5T0.5 + ρ2T2 + ρ4.5T4.5 in a wide temperature interval including low temperature resistivity upturn.