Effects of lanthanum doping on the preferred orientation, phase structure and electrical properties of sol-gel derived Pb1-3x/2Lax (Zr0.6Ti0.4)O3 thin films

Research highlights: → Lanthanum doping is favorable to enhance crystalline and obtain (1 0 0)-preferred orientation of the films. → The films undergo a structure change from 'rhombohedral' phase to monoclinic phase as the lanthanum-doped content is increased to x ∼ 0.05. → Lanthanum doping contributes to improve film dielectric constant and dielectric loss while it brings about a strikingly decreasing remnant polarization value. - Abstract: Pb1-3x/2Lax (Zr0.6Ti0.4)O3 thin films (0 ≤ x ≤ 0.08) were prepared on the Pt (1 1 1)/Ti/SiO2/Si (1 0 0) substrates by a sol-gel method. The morphology, preferred orientation, phase structure, dielectric and ferroelectric properties of the films have been investigated. Our results show that lanthanum doping is favorable to enhance crystalline and obtain (1 0 0)-preferred orientation of the films. Meanwhile, it is suggested that the films undergo a structure change from 'rhombohedral' phase to monoclinic phase as the lanthanum-doped content is increased to x ∼ 0.05. Results of dielectric properties and ferroelectric properties indicate that lanthanum doping contributes to improve film dielectric constant and dielectric loss while it brings about a striking decrease in remnant polarization value. Possible explanations for the variations of electrical properties have been discussed in terms of preferred orientation, phase structure and large lattice distortion.