Structure, Microwave Dielectric Properties, and Novel Low-Temperature Sintering of xSrTiO₃–(1−x)LaAlO₃ Ceramics with LTCC Application

xSrTiO₃–(1−x)LaAlO₃ ceramics with ZnO–B₂O₃ sintering aid were prepared by solid-state reaction method leading to a significant decrease in sintering temperature from 1550°C to 1050°C. The structure, microwave dielectric properties, and low-temperature sintering behavior were systematically investigated. The results revealed the relationships among ionic size, ionic polarizability and cell volume. With increasing additive, chemical ordering of B-site cations was indicated with selected area electron diffraction (SAED) patterns, HRTEM images and Raman spectrum, which contributed to the greatly enhanced microwave dielectric properties. Particularly, the 0.7Sr_0.85 Mg_0.15TiO₃–0.3LaAlO₃ ceramics modified with 10 wt % ZnO-B₂O₃ can further decrease the sintering temperature down to 950°C without deteriorating its performance. Thermal tests implied ceramics featured good chemical compatibility with Cu/Ag electrode. Thus, they can be cofired with internal Cu/Ag electrodes in special patterns to fulfill different electrical functions for LTCC (low-temperature cofired ceramic) application.