Principal element design of garnets to access structure stability and excellent microwave dielectric properties. Issue 7 (6th April 2022)

• Record Type: Journal Article
• Authors: Mei, Hongrong; Zhang, Liangbin; Chen, Feilong; Wang, Zhiguo; Rao, Zhenggang; Li, Chunchun
• Is Part Of: Journal of the American Ceramic Society. Volume 105:Issue 7(2022)
• Page Start: 4805
• Page End: 4814
• Publication Date: 2022-04-06
• Subjects: average electronegativity difference -- ceramic -- garnet -- microwave dielectric properties -- tolerance factor; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.18459
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Guided by the tolerance factor and average electronegativity difference, two stable garnets with compositions Ca3 BTiGe3 O12 (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 Ca3 MgTiGe3 O12 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.