Microstructure and microwave dielectric properties of lead borosilicate glass ceramics with Al2O3

• Published in: Journal of Central South University of Technology. Science & technology of mining and metallurgy Vol. 18; no. 6; pp. 1838 - 1843
• Main Authors: Wei, Peng-fei, Zhou, Hong-qing, Wang, Jie, Zhang, Yi-yuan, Zeng, Feng
• Format: Journal Article
• Language: English
• Published: Heidelberg Central South University 01.12.2011
• Subjects: Engineering; Metallic Materials; microstructure; PbO-B; glass ceramics; dielectric properties; SiO; Al; Fourier transform infrared spectroscope; O
• ISSN: 1005-9784; 1993-0666
• DOI: 10.1007/s11771-011-0911-3

The effects of Al 2 O 3 addition on both the sintering behavior and microwave dielectric properties of PbO-B 2 O 3 -SiO 2 glass ceramics were investigated by Fourier transform infrared spectroscope (FTIR), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that with the increase of Al 2 O 3 content the bands assigned to [SiO 4 ] nearly disappear. Aluminum replaces silicon in the glass network, which is helpful for the formation of boron-oxygen rings. The increase of the transition temperature T g and softening temperature T f of PbO-B 2 O 3 -SiO 2 glass ceramics leads to the increase of liquid phase precipitation temperature and promotes the structure stability in the glasses, and consequently contributes to the decreasing trend of crystallization. Densification and dielectric constants increase with the increase of Al 2 O 3 content, but the dielectric loss is worsened. By contrast, the 3% (mass fraction) Al 2 O 3 -doped glass ceramics sintered at 725 °C have better properties of density ρ =2.72 g/cm 3 , dielectric constant ɛ r =6.78, dielectric loss tan δ =2.6×10 −3 (measured at 9.8 GHz), which suggest that the glass ceramics can be applied in multilayer microwave devices requiring low sintering temperatures.