Structural, electrical and thermal properties of borosilicate glass–alumina composites
2012; Elsevier BV; Volume: 538; Linguagem: Inglês
10.1016/j.jallcom.2012.05.024
ISSN1873-4669
AutoresMaria Margarida Rolim Augusto Lima, Regina da Conceição Corredeira Monteiro, M.P.F. Graça, M.G. Ferreira da Silva,
Tópico(s)Ferroelectric and Piezoelectric Materials
ResumoBorosilicate glass–alumina composites with (1 − x) Glass + x Al2O3 (x = 0, 5, 10, 25 vol.%) were prepared and the effect of Al2O3 addition on the structural, electrical and thermal characteristics was investigated. XRD patterns revealed the presence of cristobalite (SiO2) in sintered borosilicate glass and that the addition of Al2O3 hinders cristobalite formation. This behavior is due to the diffusion of some Al3+ ions from alumina to glass, which leads to changes in glass structure and composition as identified by SEM/EDS. Cristobalite was undetected in composites containing 10% Al2O3 that attained the lowest thermal expansion coefficient value (∼4.6 × 10−6 °C−1). Conductivity (dc and ac) increased with the amount of Al3+ ions present in the glass structure as modifiers and formers. Dielectric constant values, in the range 5.0–7.2, increased with Al2O3 addition and the values of loss tan δ (1.5–2.1 × 10−2) indicate that these materials are good insulators.
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