Dielectric response of PZN-based MPB composition doped with lanthanum

• Published in: Materials chemistry and physics 2002-01, Vol.73 (1), p.62-69
• Main Authors: Zhu, W.Z., Kholkin, A., Mantas, P.Q., Baptista, J.L.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Curie–Weiss behavior; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; La-doping; Niobates, titanates, tantalates, pzt ceramics, etc; Physics; Relaxors; X-ray diffraction analysis
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/S0254-0584(01)00356-X

Dielectric and piezoelectric properties of the lanthanum-doped morphotropic phase boundary (MPB) composition in the Pb(Zn 1/3Nb 2/3)O 3–BaTiO 3–PbTiO 3 system have been studied. Compositions of the samples were intentionally modified so that the compensation for the charge difference between La 3+ and Pb 2+ ions was realized by the increased Zn/Nb ratio. The solid solubility limit of La 2O 3 is shown to be less than 5 mol% by X-ray diffraction analysis. Rhombohedral phase is increasingly stabilized against tetragonal phase with progressive incorporation of the dopant into the A-site of perovskite structure, alternatively, the location of the MPB composition range is shifted towards PT-rich end. Moreover, it was revealed that the lattice distortion of either tetragonal or rhombohedral phase can be reduced by La-doping. The dielectric permittivity maximum ε max′ and the temperature of ε max′ are remarkably decreased by increasing La 2O 3 content, whilst the degree of the frequency-dispersion is slightly weakened. Both the degree of diffuse phase transition (DPT) and the non-Curie–Weiss behavior can be significantly promoted by La-doping.