Reducing-atmosphere resistant mechanism on microwave dielectric enhancement of CaMgSi2O6 glass-ceramics

Highlights: • This work highlights a reducing-atmosphere resistance using amphoteric ion doping. • Al₂O₃ plays both donor and acceptor roles in CaMgSi₂O₆ glass ceramics. • Al₂O₃ doping could reduce defects and enhance microwave dielectric properties. • This work can provide an approach for the base-metal-electrode in LTCC or MLCC. This work highlights a reducing-atmosphere resistance using amphoteric ion doping to reduce defects and to enhance microwave dielectric properties in CaMgSi₂O₆ glass-ceramics. Amphoteric Al³⁺ ion (Al₂O₃ doping) was selected with both donor and acceptor roles to restrict free electrons and oxygen vacancies in specimens sintered in reducing atmosphere. The X-ray absorption and X-ray photoelectron spectra indicate decreased oxygen vacancies and a valence shift from a mixture of Si²⁺ and Si³⁺ to Si⁴⁺ in the Al³⁺–doped CaMgSi₂O₆ glass-ceramics sintered in reducing-atmosphere. The amphoteric Al³⁺ ion plays an acceptor role as entering Si⁴⁺ site to form oxygen vacancies, meanwhile Al³⁺ plays a donor role as entering Mg²⁺ site to compensate free electrons. The amphoteric Al–doped diopside glass-ceramic can increase the electric resistivity and quality factors. This work can provide an efficient approach for the base-metal-electrode (BME) in low-temperature co-fired ceramics (LTCC) and multilayer ceramic capacitors (MLCC).