Effect of scandium substitution on magnetic and transport properties of the M-type barium hexaferrites

Polycrystalline M-type barium hexaferrite compounds with scandium doping BaFe12-xScxO19 (0 <= x <= 2.5) were prepared by the solid state route. Room temperature neutron diffraction measurements show that the prepared samples are in single phase and exhibit a ferrimagnetic structure at room temperature. Temperature and field dependent magnetization study shows that due to doping of scandium, T-c is lowered from 696 K in the undoped compound to 428 K for x = 2.5. The transport properties were investigated by ac conductivity measurements. Our results indicate that the temperature dependence of dc conductivity for x = 2.5 does not follow Arrhenius behaviour but rather closely follows the Mott variable range hopping mechanism (VRH) of polarons. For the parent compound and with for Sc doping x = 1.5, the conductivity is found to be due to overlapping large polaron tunnelling (OLPT). (C) 2019 Elsevier B.V. All rights reserved.