Tunable critical temperature and magnetocaloric effect in ternary Prussian blue analogue

A comprehensive study of structural, magnetic and magnetocaloric properties in the ternary Prussian blue analogue (PBA) Ni1.5[Fe(CN)6]x[Cr(CN)6]1-x·nH2O (x = 0, 0.25, 0.5, 0.75 and 1) is presented. For all compounds the second-order magnetic phase transition from high temperature paramagnetic to the low temperature ferromagnetic state at the Curie temperature (Tc) is observed. We show the possibility of tuning the magnetic and magneto-caloric properties of PBA materials by changing the compositional factor of the metal centres involved in the cyano-bridging. An increase in Fe content leads to increase in the coercive field, whereas the critical temperature decreases from 60 to 22 K. The magnetic entropy change ΔS, as well as the related Relative Cooling Power (RCP), vary with x parameter in the regular way. The highest value of ΔS was observed for sample with x = 1 and was equal to 3.49 J mol−1K−1 under a magnetic field of 50 kOe, whereas the RCP varied from 62 J mol−1 (145.35 J kg−1) to 118 J mol−1 (273.33 J kg−1), when x decreased from 1 to 0.