Effects of CaO Additions on the Structure and Dielectric Properties of Aluminoborosilicate Glasses

Glasses with compositions xCaO-(60-x)SiO2-5MgO-15Al2O3-20B2O3 (x=0, 3, 6 and 9 mol %) were prepared by conventional melting method. Fourier-transform infrared spectroscopy (FTIR) indicated that the addition of CaO converted trigonal boron ([B) to tetrahedral boron ([B). The glass transition temperatures (Tg) were determined using a differential scanning calorimetry (DSC). Tg increased with increasing CaO content. Thus, the addition of CaO instead of SiO2 strengthened the glass network. The dielectric εr and loss tanδ were measured for the MgO-B2O3-Al2O3-SiO2 glass system in the frequency range 103-105 Hz. The decrease in εr and tanδ could be attributed to the increase in the rigidity of the glass network.

Effects of CeO2 Additions on the Structure and Dielectric Properties of Aluminoborosilicate Glasses

Glasses with compositions 15Al2O3-20B2O3-50SiO2-5CaO-(10-x)MgO-xCeO2 (x=0, 1, 2 and 3 mol %) were prepared by conventional melting method. Fourier-transform infrared spectroscopy (FTIR) indicated that the addition of CeO2 converted trigonal boron ([B) to tetrahedral boron ([B). The glass transition temperatures (Tg) were determined using a differential scanning calorimetry (DSC). Tg increased with increasing CeO2 content. Thus, the addition of CeO2 instead of MgO strengthened the glass network. The dielectric constant εr and loss tanδ were measured for these glasses at 105 Hz. The decrease in εr and tanδ could be attributed to the increase in the rigidity of the glass network as the CeO2 content increased.