Solid-state reaction in nanoparticulate alumina/LZSA glass-ceramic composites

Abstract

In this work, some properties, such as sinterability, modulus of elasticity (E), coefficient of thermal expansion (CTE) and dielectric constant (ε r ), of composites constituted by nanoparticulate alumina (27-43 nm, 35 m 2 .g -1 ) in different contents (0 to 77 vol%) and a LZSA glass-ceramic composition (17.7Li 2 O-5.2ZrO 2 -68.1SiO 2 -9.0Al 2 O 3 , molar basis) were evaluated. Dry powders of the raw materials (alumina and LZSA parent glass, frit) were uniaxially pressed (40 MPa) and the obtained compacts were sintered at 600-950 °C (1 h holding time). X-ray diffraction (XRD) study was performed in order to investigate the solid-state reactions occurred in LZSA-based compositions during sintering. XRD results were correlated to the CTE, E and ε r of sintered samples. The CTE of the obtained composites decreased as alumina content increased mainly due to the β-spodumene ss (solid solution Li 2 O.Al 2 O 3 .4-10SiO 2 ) formation. The results concerning the E (22.3±1.5 GPa) and ε r (3.1±1.3) for the composite with 5.6 vol% addition sintered at 850 °C for 1 h indicated, in a preliminary way, the possibility of development of materials with suitable properties for applications concerning to the low temperature co-fired ceramic (LTCC) technology.