Dielectric and microwave properties of common sintering aids for the manufacture of thermally stable ceramics. Issue 16 (November 2019)

• Record Type: Journal Article
• Authors: Silva, M.A.S.; Oliveira, R.G.M.; Sombra, A.S.B.
• Is Part Of: Ceramics international. Volume 45:Issue 16(2019)
• Page Start: 20446
• Page End: 20450
• Publication Date: 2019-11
• Subjects: sintering aid -- Oxide -- Impedance spectroscopy -- Microwave range; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2019.07.021
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: This work presents the dielectric properties of several oxides used as sintering aids for the manufacture of thermally stable ceramics in the radio frequency (RF) and microwave ranges. The oxides were prepared in pallets and cylinder geometries, with sintering close to their melting point for 4 h. The dielectric properties in the RF range were analysed by impedance spectroscopy, while the Hakki-Coleman and Silva-Fernandes-Sombra techniques were used for dielectric analysis in the microwave range. The temperature effect on the dielectric properties was also analysed in both frequency ranges. In the RF range, V2 O5, Al2 O3, ZnO and Nb2 O5 presented lower insulating properties than the other oxides studied due to their lower activation energies. In the microwave range, only CaTiO3, ZnO and TiO2 presented positive temperature coefficients of resonant frequency ( τ f ) with CaTiO3, while TiO2 presented the highest dielectric permittivity and Al2 O3 and B2 O3 presented the lowest dielectric permittivities. These dielectric properties are a feature that is relevant for future technological applications.