Principal element design of garnets to access structure stability and excellent microwave dielectric properties

Guided by the tolerance factor and average electronegativity difference, two stable garnets with compositions Ca3BTiGe3O12 (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‐3d space group was confirmed for synthesized compositions. A combination of microwave dielectric properties for both garnets suggested that Ca3MgTiGe3O12 ceramic possessed a much higher quality factor (Q × f) ∼ 84 000 ± 3000 GHz coupled by a higher dielectric constant (εr) ∼ 12.97 ± 0.03, and a smaller temperature coefficient of resonance frequency (τf) ∼ −29.4 ± 1.5 ppm/°C compared to its Zn counterpart (Q × f ∼ 45 000 ± 2000 GHz, εr ∼ 12.84 ± 0.03, and τf ∼ −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.