Dielectric characterization at high temperature of iron doped potassium strontium niobate ceramic by impedance spectroscopy

• Autor(a) principal: de Lima, Caio Vinicius [UNESP]
• Data de Publicação: 2015
• Outros Autores: Lima Nobre, Marcos Augusto [UNESP], Lanfredi, Silvania [UNESP]
• Tipo de documento: Artigo de conferência
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.4028/www.scientific.net/MSF.820.187; http://hdl.handle.net/11449/168318
• topic: Dielectric properties; Impedance spectroscopy; Niobate; Tetragonal tungsten bronze structure

Tetragonal Tungsten Bronze structure TTB-type structure has attracted interest by the high anisotropy of the crystal structure. The dielectric characterization of iron-doped niobate of TTB-type structure, with stoichiometry KSr2(Fe0. 25Nb4. 75)O15- δ, prepared by Modified Polyol Method was investigated. Nanocrystalline single phase powders were obtained after calcination of the precursor powder at 1150 °C for 10 hours in an oxygen atmosphere. The dielectric characterization was performed by impedance spectroscopy, from room temperature to 600 °C, in the frequency range of 5 Hz to 13 MHz. The permittivity values obtained for KSr2(Fe0. 25Nb4. 75)O15- δ showed superior to the permittivity values of the KSr2Nb5O15 host structure in all temperature range investigated. At room temperature, the permittivity values (2100) of KSr2(Fe0. 25Nb4. 75)O15- δ is two times the permittivity values of KSr2Nb5O15. The substitution of niobium cation by iron cation in the KSr2Nb5O15 host structure showed a suppression of the ferroelectric (P4bm) → paraelectric (P4/mbm) phase transition.