Effects of 5d Ir-substitution on structures, transport and magnetic properties of Sr2FeMoO6

Sr2Fe1−0.5xMo1−0.5xIrxO6 ceramics (x=0, 0.02, 0.04, 0.06, and 0.08) have been synthesized and the structures, magnetic and transport properties have been investigated. X-ray diffraction reveals a very low solution limit of x=0.06, which however, results in significantly decreased Fe/Mo ordering degree and thus decreased magnetization value. On the other hand, the Curie temperature (Tc) rises from 390 K (x=0) to 400 K (x=0.02) firstly, and then decreases to 360 K and 340 K for the compositions with x=0.04 and 0.06, respectively. In addition, the resistivity and magnetoresistance drop drastically with increasing x. The composition with x=0 shows semiconductor transport behavior in the temperature range of 10–400 K, whereas the other compositions show a minimum resistivity around 120 K. These results are discussed in detail by considering the effects of Ir substitution.