Effects of alumina on the crystallization behavior, densification and dielectric properties of BaO–ZnO–SrO–CaO–Nd2O3–TiO2–B2O3–SiO2 glass–ceramics

Abstract The alumina addition effects on the crystallization, sintering behaviors and dielectric properties of BaO–ZnO–SrO–CaO–Nd 2 O 3 –TiO 2 –B 2 O 3 –SiO 2 (Ba–Zn–Sr–Ca–Nd–Ti–B–Si) glass powder were investigated using the differential thermal analyzer (DTA), thermo-mechanical analyzer (TMA), X-ray diffractometer (XRD). The results showed that the addition of alumina powder into Ba–Zn–Sr–Ca–Nd–Ti–B–Si glass changed the crystallization sequence from Nd 2 Ti 4 O 11 –Nd 0.66 TiO 3 to Nd 2 Ti 3 O 8.7 –Nd 2 Ti 2 O 7 –Nd 2 Ti 4 O 11 and increased the densification activation energy due to the dissolution of Al 3+ ions into the glass structure. Fully densified 30 vol.% alumina-added Ba–Zn–Sr–Ca–Nd–Ti–B–Si glass can be obtained via glass viscous flow before the second and third crystalline phases, Nd 2 Ti 2 O 7 and Nd 2 Ti 4 O 11 crystallization. The 30 vol.% alumina-added Ba–Zn–Sr–Ca–Nd–Ti–B–Si glass–ceramics sintered at 900 °C exhibited a high dielectric constant of 17 and a quality factor of about 820, which provided a promising candidate for LTCC applications.