Crystallization and microwave dielectric properties of novel CaO-Al2O3-B2O3 glass-ceramics with different Al2O3 content

CaO-Al2O3-B2O3 (CAB) glass-ceramics with varying Al2O3 content were fabricated using the melting method including melting and quenching of mixture of raw materials. The obtained glass powder was pressed into the desired shape and sintered for measurement. At 900 degrees C, the crystallinity initially increased and then decreased with increasing Al2O3 content. The highest crystallinity of 62.29 % was obtained when the Al2O3 content was 0.5 mol%, and exhibited excellent dielectric properties: epsilon r = 4.35, Q x f = 53,085 GHz, and tau f = -33.95 ppm/degrees C. The variation of dielectric properties with increasing Al2O3 content is attributed to the crystallinity process. The crystallization process of CAB system was determined by crystallization activation energy, the lowest value of 302.085 kJ/mol corresponds to the highest crystallinity. The crystallization, dielectric properties and sintering behavior of CAB system indicate that CAB system prepared by melting method have promising prospect as new LTCC glass-ceramics.