Principal element design of garnets to access structure stability and excellent microwave dielectric properties
Hongrong Mei, Liangbin Zhang, Feilong Chen, Zhiguo Wang, Zhenggang Rao, Chunchun Li
Abstract
Abstract Guided by the tolerance factor and average electronegativity difference, two stable garnets with compositions Ca 3 BTiGe 3 O 12 (B = Mg, Zn) were designed, synthesized followed by structural, and dielectric characterization. The phase purity and structural characteristics were analyzed using X‐ray, Rietveld refinement, and microstructural analysis through scanning electron microscopy. A cubic structure with an Ia‐ 3 d space group was confirmed for synthesized compositions. A combination of microwave dielectric properties for both garnets suggested that Ca 3 MgTiGe 3 O 12 ceramic possessed a much higher quality factor ( Q × f ) ∼ 84 000 ± 3000 GHz coupled by a higher dielectric constant ( ε r ) ∼ 12.97 ± 0.03, and a smaller temperature coefficient of resonance frequency ( τ f ) ∼ −29.4 ± 1.5 ppm/°C compared to its Zn counterpart ( Q × f ∼ 45 000 ± 2000 GHz, ε r ∼ 12.84 ± 0.03, and τ f ∼ −33.19 ± 1.6 ppm/°C). Such differences in dielectric performances were further explored utilizing packing fraction, ion polarizability, bond valence, Raman, and infrared spectrum to understand structure–property relationship.