Ni and Zn doped MgTiO_3 thin films: Structure, microstructure, and dielectric characteristics

摘要

The addition of low loss ilmenite impurities, can effectively tailor the dielectric properties of MgTiO_3 without modifying the crystal structure. In the present study, the modification of the structural and dielectric properties of sol gel derived MgTiO_3 films by doping with Ni and Zn is exploited. The change of the dielectric response and unit cell parameters of doped MgTiO_3 is correlated with Ni and Zn occupancy. The temperature stability of MgTiO_3 thin films is improved with doping, while the dielectric losses are aggravated with both Zn and Ni doping, which is correlated with the localized d electrons of the dopant cations. The dielectric permittivity decreased with Ni doping while it increased with Zn, which is attributed to the lower ionic polarizability of Ni~(2+) (1.23 A~3) as in comparison with Mg~(2+) (1.32 A~3) while Zn~(2+) has a higher ionic polarizability (2.04 A~3).