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Phase composition, morphology, and microwave dielectric properties of (1−x) LiAl0.98(Zn0.5Si0.5)0.02O2 + x CaTiO3 (0.05 ≤ x ≤ 0.20) materials synthesized via the solid state reaction method were investigated. All these densified materials were obtained at a sintering temperature of 1150°C. All compositions showed a major LiAlO2 phase that was accompanied by a minor CaTiO3 phase. The εr value increased gradually from 10.88 to 11.60, whereas the Q × f value remarkably decreased from 33 251 GHz to 13 511 GHz. The τf value changes from −85 ppm/°C to 212 ppm/°C, thereby indicating that CaTiO3 could effectively adjust this value. HBO3‐doping was used to further decrease the sintering temperature to 900°C. The optimum value was obtained at 7 wt.% HBO3 doped with microwave dielectric properties of εr = 9.39, Q × f = 10 224 GHz, and τf = −7.8 ppm/°C. This material also exhibited chemical compatibility with silver, making it a candidate for low temperature co‐fired ceramics applications. [ABSTRACT FROM AUTHOR]

Novel LiAl5−xZnxO8−0.5x microwave dielectric ceramics were synthesized through a solid‐state reaction route. Phase evolution of LiAl5−xZnxO8−0.5x was determined by XRD analysis. The XRD results indicated that the phase compositions had a P4332 space group when 0 ≤ x ≤ 0.2 and a spinel structure when 0.3 ≤ x ≤ 0.5. The dielectric constant (εr) of this series' solid solutions decreased with the increase in Zn doping content, which was in good agreement with the Clausius‐Mossotti relation. Oxygen vacancy and the decreased degree of order degraded the quality factor (Q × f) of the two structures. The deterioration in quality factor was further verified by impedance spectroscopy. The temperature coefficient of the resonant frequency (τf) decreased with the increase in x and was correlated with the unit cell volume. Finally, CaTiO3 was used as a compensation material to obtain a near‐zero τf of the LiAl5O8 ceramic. [ABSTRACT FROM AUTHOR]

Ba 2 ZnSi 2 O 7 ceramic was prepared by conventional solid-state method and sintering under four different atmospheres (air, O 2 , N 2 , and N 2 –1 vol% H 2). The Ba 2 ZnSi 2 O 7 ceramic exhibited a single phase under air, O 2 , and, N 2 , whereas two phases (including BaSiO 3 impurity) were observed under the N 2 –1 vol% H 2 atmosphere due to Zn2+ evaporation. Dielectric loss was proportional to oxygen partial pressure due to the conduction mechanism of dominant holes. The Ba 2 ZnSi 2 O 7 ceramic exhibited good microwave dielectric properties (ε r = 8.3, Q × f = 27200 GHz, τ f = −41.5 ppm/°C) under the N 2 –1 vol% H 2 atmosphere, making it a novel candidate with good anti-reductive characteristics for base metal electrode–multilayer ceramic capacitor applications. [ABSTRACT FROM AUTHOR]

Ba1+1/ M[Si2O5+1/ M] low-permittivity microwave dielectric ceramics are prepared using the conventional solid-state method. Pure phases are obtained in barium silicates with M = 1, 3, 4, 5, and ∞, except for M = 7, in which two phases, Ba5Si8O21 and BaSi2O5, are observed. As the complexity of the crystal structure described by the Shannon information per reduced unit cell increases, the τf value tends to change from a negative to a positive value, except for M = 5, which has the highest complexity. A single Ba5Si8O21 phase with εr anomaly peak at −180°C exhibits a rare positive τf value (+25 ppm/°C), which is a novel temperature compensator. [ABSTRACT FROM AUTHOR]