Solid Solutions of Lead Metaniobate-Stabilization of the Ferroelectric Polymorph and the Effect on the Lattice Parameters, Dielectric, Ferroelectric, and Piezoelectric Properties

Autor(es)

Sahini, Mtabazi G. ^[1] ; Grande, Tor ^{[1, 2]} ; Fraygola, Barbara ^{[1, 3]} ; Biancoli, Alberto ^[1] ; Damjanovic, Dragan ^[1] ; Setter, Nava ^[1]

Afiliação do(s) autor(es)

^[1] EPFL Swiss Fed Inst Technol, Ceram Lab, CH-1015 Lausanne - Switzerland

^[2] Norwegian Univ Sci & Technol, Dept Mat Sci & Engn, N-7491 Trondheim - Norway

^[3] Univ Fed Sao Carlos, Grp Ceram Ferroeletr GCFerr, Dept Fis, BR-13565670 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of the American Ceramic Society; v. 97, n. 1, p. 220-227, JAN 2014.
• Citações Web of Science: 11

Resumo

Ferroelectric orthorhombic lead metaniobate (PbNb2O6) is known to be metastable with respect to the thermodynamically stable nonferroelectric rhombohedral polymorph. The high-temperature tetragonal to low temperature rhombohedral phase transition is reconstructive and thereby sluggish; ferroelectric PbNb2O6 is obtained by quenching from the stable phase field of the tetragonal polymorph. We report on the stabilization of the ferroelectric tungsten bronze polymorphs of PbNb2O6 by minor chemical substitution in the series {[}(1 - x) PbNb2O6-xBiTiNbO(6)], {[}(1 - x)PbNb2O6-xNa(0.5)Bi(0.5)Nb(2)O(6)], {[}(1 - x)PbNb2O6-xK(0.5)Bi(0.5)Nb(2)O(6)], and {[}(1 - x)PbNb2O6-xCaTiO(3)]. The high- temperature tungsten bronze polymorph is entropy stabilized with respect to the stable rhombohedral polymorph, and we propose that the tungsten bronze is further entropy stabilized by chemical substitution, reducing the transition temperature of the rhombohedral polymorph and further disfavoring the kinetics of the undesired phase transition. Optimized solid-state synthesis and processing to obtain dense ceramics were developed for the solid solutions, and the dielectric, ferroelectric, and piezoelectric properties of the PbNb2O6 solid solutions are reported. Curie temperature is suppressed with chemical substitution in all the systems. Lattice cell parameters display systematic variation with composition, reducing the molar volume, and the lattice parameter ratio 2b/a with increasing degree of substitution, reflecting a suppression of the polarization along the (010) direction due to chemical substitution. The piezoelectric properties improved with increasing substitution level probably due to the ease of poling of the materials with lower T-c. However, some improvements seen with 2% CaTiO3 were not accompanied by T-c decrease. (AU)

• Processo FAPESP: 12/07936-9 - Contribuições intrínsecas ao coeficiente de acoplamento magnetoelétrico em materiais multiferróicos monofásicos
• Beneficiário: Barbara Maraston Fraygola
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado