Improvement of the low-field-induced magnetocaloric effect in EuTiO3 compounds* *Project supported by the National Key Research and Development Program of China (Grant No. 2017YFB0702704), the National Natural Science Foundation of China (Grant Nos. 11504266 and 51676198), the Tianjin Natural Science Foundation, China (Grant No. 17JCQNJC02300), and the Science & Technology Development Fund of Tianjin Education Commission for Higher Education, China

Abstract

The magnetocaloric effect of Mn, Ni, and Mn–Ni-doped EuTiO3 compounds are studied in the near-liquid-helium-temperature range. The Eu(Ti0.9375Mn0.0625)O3, Eu(Ti0.975Ni0.025)O3, and Eu(Ti0.9125Mn0.0625Ni0.025)O3 are prepared by the sol–gel method. The Eu(Ti0.9375Mn0.0625)O3 and Eu(Ti0.9125Mn0.0625Ni0.025)O3 exhibit ferromagnetism with second-order phase transition, and the Eu(Ti0.975Ni0.025)O3 displays antiferromagnetic behavior. Under the magnetic field change of 10 kOe (1 Oe = 79.5775 A⋅m−1), the values of magnetic entropy change are 8.8 J⋅kg−1⋅K−1, 12 J⋅kg−1⋅K−1, and 10.9 J⋅kg−1⋅K−1 for Eu(Ti0.9375Mn0.0625)O3, Eu(Ti0.975Ni0.025)O3, and Eu(Ti0.9125Mn0.0625Ni0.025)O3, respectively. The co-substitution of Mn and Ni can not only improve the magnetic entropy change, but also widen the refrigeration temperature window, which greatly enhances the magnetic refrigeration capacity. Under the magnetic field change of 10 kOe, the refrigerant capacity value of Eu(Ti0.9125Mn0.0625Ni0.025)O3 is 62.6 J⋅kg−1 more than twice that of EuTiO3 (27 J⋅kg−1), indicating that multi-component substitution can lead to better magnetocaloric performance.