Effect of TiO2 doping on dielectric properties and temperature stability of Ca3(BO3)2 microwave ceramics with feasibility simulation for 5G antennas

Low-perittivity (1– x )Ca 3 (BO 3 ) 2 – x TiO 2 (CBTO, x = 0–0.25) ceramics were fabricated via cold sintering. Phase composition was confirmed by XRD. The effects of TiO 2 doping on the dielectric properties and temperature stability ( τ f ) were systematically investigated. Guided by lattice dynamics, phonon characteristics were probed using Raman and FTIR spectroscopy. Eight Raman-active and ten infrared-active modes were identified. A four-parameter semi-quantum model successfully extracted the intrinsic dielectric parameters, revealing that vibrations related to Ca 2+ (Mode 4) contributed most significantly (21.89% to ε ᵣ, 32% to loss). TiO 2 addition effectively tuned τ f from –39.89×10 −6 °C −1 towards zero. This comprehensive phonon analysis established a clear structure–property relationship. The optimal composition ( x = 0.20) exhibited a balanced performance: ε ᵣ = 10.56, Q × f = 10,896 GHz, and τ f = –6.58×10 −6 °C −1 . To demonstrate practical utility, a 5G microstrip patch antenna was designed using this ceramic. The antenna resonated at 9.97 GHz with excellent impedance matching ( S 11 = –49.56 dB) and a peak gain of 6.39 dBi. These results confirm CBTO ceramics as a promising candidate for temperature-stable, high-frequency applications. • Based on lattice dynamics theory, the phonon characteristics of the (1- x )Ca 3 (BO 3 ) 2 - x TiO 2 ceramics were analyzed in detail. • Four-parameter semiquantum model fitted intrinsic dielectric properties and revealed response mechanisms via infrared spectroscopy. • Raman modes established relationships between crystal structures and dielectric properties of (1– x )Ca 3 (BO 3 ) 2 - x TiO 2 ceramics. • TiO 2 regulate the τ f value close to zero, at x = 0.20, ε r = 10.56, Q × f = 10,896 GHz , and τ f = –6.58×10 −6 °C −1 , promising for 5G/6G technology. • HFSS antenna simulation: center frequency 9.97 GHz, S 11 =-49.56 dB, gain 6.39 dBi, suitable for high-performance antenna equipment.