Sintering Characteristic, Structure, Microwave Dielectric Properties and Compatibility with Ag of Novel 3MgO-B2O3-xwt% Ba(CuB2)O5-ywt% H3BO3 Ceramics

In this study, 3MgO-B2O3-xwt%BCB-ywt%H3BO3 (2 ≤ x ≤ 8, 0 ≤ y ≤ 20) ceramics were sintered at the optimum temperature to form Mg3B2O6 and MgO phases. The effects of H3BO3 and BCB on product characteristics, phase transition, microstructure, and microwave properties of 3Mg-B2O3 ceramics were investigated. The intensities of diffraction peaks of two phases varied with changing the x and y values. After sintering at 950 °C, the ceramics with x = 6 and y = 15 achieved excellent microwave properties with a εr of 6.72, Q × f of 83205 GHz, and τf of −65.05 ppm/℃. Besides, the ceramic with x = 8 and y = 5 sintered at 925 ℃ also achieved good microwave dielectric properties with a εr of 6.64, Q × f of 78173 GHz, and τf of −57.27 ppm/℃. The sintering temperatures of above both ceramics are well lower than the melting point of Ag, showing promising applications in low temperature cofired ceramic devices. In particular, these two ceramics can be used as potential candidate materials for microwave ceramics for 5G technology, provided that τf can be further optimized.

Structural, Optical and Microwave Dielectric Properties of Ba(Ti1-xSnx)4O9, 0 ≤ x ≤ 0.7 Ceramics

Sn-doped BaTi4O9 (BT4) microwave ceramics were prepared by a mixed oxide route. Preliminary X-ray diffraction (XRD) structural study shows that the samples have orthorhombic symmetry with space group (Pnmm). Scanning electron microscopy (SEM ) shows that the grain size of the samples decreases with increasing Sn4+ contents. The presence of the metal oxide efficient group was revealed by Fourier transform infrared (FTIR) spectroscopy. The Photoluminescence spectra of the samples reported red color ~ 603, 604, 606.5 and 605 nm with excitation energy ~ 2.06, 2.05, 2.04 and 2.05 eV for Sn content at x = 0.0, 0.3, 0.5, and 0.7, respectively. The microwave dielectric properties of all the samples were investigated by an impedance analyzer. The excellent microwave dielectric properties i.e. high relative permittivity (εr = 57.29), high-quality factor (Qf = 11,852), and low-dielectric loss (3.007) has been observed.

Effect of B2O3 On the Microstructure and Microwave Dielectric Properties of Ba(Mg1/3Nb2/3)O3 Ceramics

The influences of different doping contents of additive B2O3 on the sintering behavior, microstructure and microwave properties of Ba(Mg1/3Nb2/3)O3 (BMN) microwave ceramics were studied. The main phase in the sintered ceramics was crystallized as Ba(Mg1/3Nb2/3)O3 (BMN). Ba2B2O5 as secondary phase was observed with x ≥ 10. Scanning electron microscopy (SEM) analysis revealed that the photograph of optimally nonstoichiometric ceramics sintered at 900 ℃ for 5 h displayed a dense microstructure. The dielectric properties and microstructures of BMN ceramics were very sensitive to the nonstoichiometry. The addition of B2O3 had a positive influence on the Q×f value, for example the sample with x = 7 showed the highest Q×f value of 89800 GHz. Finally, excellent microwave dielectric properties (εr = 31.6, Q×f = 89,800 GHz and τf = 3.6 ppm/℃) were achieved for the sample with x = 7 sintered at 900 ℃ for 5 h.