Influence of Lithium Substitution for Zinc on Crystal Structure and Microwave Dielectric Properties of Willemite Li2xZn2-xGeO4

Willemite ceramics have recently received considerable attention for microwave or millimeter-wave telecommunication because of their extremely high quality factor. Unfortunately, it suffers from difficulty in the formation of pure phase Zn2GeO4. Reducing ZnO content is favorable for its phase purification. In this work, an alternative method, introducing 2 Li to substitute Zn, was proposed to reduce the Zn content. Some Li(2x)Zn(2-x)GeO(4)ceramics were designed and fabricated. Limited solid solutions were revealed and single phase willemite-based ceramics were obtained whenx <= 0.04, beyond which a Li-rich phase Li(2)ZnGeO(4)appeared. Li substitution was also found not only reducing the densification temperature but also improving the relative permittivity and quality factor of Zn(2)GeO(4)ceramics. The densification temperature of Zn(2)GeO(4)ceramics was further reduced to 950 degrees C after 5wt.% B(2)O(3)additives, rendering their potential applications in low-temperature devices.