Characterization of structural, chemical, and dielectric properties of (K, Na, Li)(Ta, Sb, Nb)O₃ single crystals grown by Bridgman-Stockbarger method

Autor(es)

Fernandes, Thissiana da C. ; Eiras, Jose A. ; Lente, Manuel H.

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS; v. 36, n. 10, p. 11-pg., 2025-04-01.

Resumo

Environmental concerns about the effects of the continued use of Pb-based ferroelectric single crystals are encouraging research on alternative lead-free compositions. Among the lead-free materials, (K, Na)NbO3-based ferroelectric single crystals are one of the most promising candidates for the substitution of Pb-based ones. In this work, it was investigated the structural, chemical, and dielectric properties of lead-free Li, Ta, and Sb-modified (K, Na)NbO3 (KNN-LTS) single crystals grown by vertical Bridgman-Stockbarger method. The polycrystalline X-ray diffraction characterization of the crushed KNN-LTS crystals showed a single perovskite phase of the as-grown KNN-LTS boule, thus revealing the success of the growing process. The compositional segregation observed in the crystals was similar to that reported in the literature. The temperature and frequency dependence of the dielectric permittivity were characterized for the [100]c, [001]c, and [111]c crystallographic directions. The results revealed that the domain configuration related to the different measured crystallographic directions played an important role in the dielectric permittivity from room temperature to near the TO-T transition. Higher dielectric permittivity was observed for the [001]c and [100]c directions, due to the contribution of 60 degrees and 90 degrees domain walls. On the other hand, at higher temperatures, it was seen that the compositional variations of Ta5+ content presented a more important influence on the dielectric properties. Similarly, observed in bulk ceramics, it was verified that the higher the Ta5+ amount in the ferroelectric crystals, the lower the dielectric constant near the Curie temperature. (AU)

• Processo FAPESP: 17/13769-1 - Materiais multiferróicos e ferroelétricos para conversores de energia: síntese, propriedades, fenomenologia e aplicações
• Beneficiário: José Antonio Eiras
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 19/26807-4 - Crescimento e caracterização de monocristais piezoelétricos livres de chumbo
• Beneficiário: Thissiana da Cunha Fernandes
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto