Bond characteristics and microwave dielectric properties on Zn3-xCux(BO3)2 ceramics with ultralow dielectric loss

The crystal structure and microwave dielectric properties of Zn_3-xCu_x(BO₃)₂ (x = 0–0.12) ceramics prepared via a traditional solid-state reaction method were investigated by means of X-ray diffraction (XRD) utilizing the Rietveld refinement, complex chemical bond theory, and Raman spectroscopy. XRD showed that all samples were single phase. The samples maintained a low permittivity, even at higher Cu²⁺ contents, which is conducive to the shortening of signal delay time, and intimately related to the average bond ionicity and Raman shift. Moreover, proper Cu²⁺ substitution greatly reduced the dielectric loss associated with the lattice energy. Cu²⁺ entering the lattice optimized the temperature coefficient of resonance frequency (τ_f) values and improved the temperature stability of samples by affecting the bond energy. Optimal microwave dielectric properties were: ε_r = 6.64, Q × f = 160,887 GHz, τ_f = ?42.76 ppm/°C for Zn_2.96Cu_0.04(BO₃)₂ ceramics sintered at 850 °C for 3 h, which exhibited good chemical compatibility with silver and are therefore good candidate materials for Low temperature co-fired ceramic applications.     

Effects of W6+ substitution on crystal structure and microwave dielectric properties of Li3Mg2NbO6 ceramics

Li₃Mg₂(Nb_1-xW_x)O_6+x/2 (0 ≤ x ≤ 0.08) ceramics were synthesized by the solid-state reaction route. The effects of W⁶⁺ substitution on the phase composition, microstructure and microwave dielectric properties of Li₃Mg₂NbO₆ ceramics were investigated systematically. The XRD results showed that all the samples formed a pure solid solution in the whole doping range. The SEM iamges and relative density revealed the dense structure of Li₃Mg₂(Nb_1-xW_x)O_6+x/2 ceramics. The relationship between the crystal structure and dielectric properties of Li₃Mg₂(Nb_1-xW_x)O_6+x/2 ceramics was researched through polarizability, average bond valence, and bond energy. The substitution of W⁶⁺ for Nb⁵⁺ in Li₃Mg₂(Nb_1-xW_x)O_6+x/2 ceramics significantly promoted the Q × f values. In addition, the increase of W⁶⁺ content improved the thermal stability of the Li₃Mg₂(Nb_1-xW_x)O_6+x/2 ceramics. The Li₃Mg₂(Nb_0.94W_0.06)O_6.03 ceramics sintered at 1175 °C for 6h possessed excellent properties: ε_r ~ 15.82, Q × f ~ 124,187 GHz, τ_f ~ −18.28 ppm/°C.     

Structure and microwave dielectric properties of Li(Al1-xLix)SiO4-x ceramics

Li(Al_1-xLi_x)SiO_4-x (x = 0.005, 0.01, 0.015, and 0.02) ceramics were synthesized via a traditional solid phase reaction method with different sintering temperatures. To determine the positions occupied by Li⁺ in the lattice, the defect formation energies and total energies of various sites of LiAlSiO₄ (LAS) occupied by Li⁺ were examined, and the energy of LAS systems were calculated using density functional theory of first-principle with the CASTEP module. The results demonstrated that the Al-sites occupied by Li⁺ had the lowest formation energies and total energy, so Li ⁺ should substitute Al³⁺. The impacts of replacing Al³⁺ with Li⁺ on the bulk density, sintering properties, phase composition, microstructure, and microwave dielectric properties of Li(Al_1-xLi_x)SiO_4-x (0 = x ≤ 0.02) ceramics were thoroughly studied. With Li⁺-doping, the sintering temperature decreased from 1300 °C (x = 0) to 1175 °C (x = 0.02), while the Q × f and τ_f values of LAS ceramics significantly increased. The Li(Al_0.99Li_0.01)SiO_3.99 ceramic was fully sintered at 1250 °C for 10 h to obtain excellent microwave dielectric properties: ε_r = 3.49, Q × f = 51,358 GHz, and τ_f = ?51.48 × 10^?6 °C^?1.     

Effect of ZnO doping on the microstructure and microwave dielectric properties of 0.2CaTiO3-0.8(Li0.5Sm0.5)TiO3 ceramics

0.2CaTiO₃-0.8(Li_0.5Sm_0.5)TiO₃-xZnO(x = 0, 0.3, 0.6, 0.9, 1.2 wt%, 0.2CT-0.8LST-xZnO) with orthogonal perovskite structure were fabricated by the solid state method. The effects of ZnO additives on the microwave dielectric properties of 0.2CT-0.8LST ceramics were systematically investigated. With increasing the dopant (x) concentration, the dielectric constant (ε_r) and the temperature co-efficient of resonance frequency (τ_f) decreased, however, the Q × f values increased. The relationship between vibration mode and microwave dielectric properties was studied using Raman spectroscopy. The Q × f value of ceramics was related to the half-height width of Raman scattering. Narrower Raman scattering peaks corresponded to longer microwave energy propagation decay times and higher Q × f value. Based on X-ray photoelectron spectroscopy (XPS), the addition of Zn²⁺ ions limited the reduction of Ti⁴⁺ cations. The excellent dielectric properties were obtained when x = 1.2 wt% with ε_r = 100.25, Q × f = 6525 GHz, and τ_f = ?12.12 ppm/°C.     

Enhancement of structural and microwave properties of Zn2+ ion-substituted Li2MgSiO4 ceramics for LTCC applications

In this study, Zn²⁺-substituted Li₂MgSiO₄ ceramics (Li₂(Mg_1-xZn_x)SiO₄, x = 0.00, 0.05, 0.10, 0.15, and 0.20) were synthesized using a traditional solid-state method. A fixed amount of LiF sintering aid (1.5 wt%) was added to the ceramics for decreasing the sintering temperature and adjusting their microwave dielectric properties. X-ray diffraction (XRD) results revealed no secondary phases, and scanning electron microscopy (SEM) data suggest that the Zn²⁺ ion substitution increased the size and uniformity of the grains, thereby affecting the densification of the prepared ceramics. The maximum bulk density (2.94 g/cm³) was found in a Zn²⁺ ion-substituted ceramic with x = 0.10 at a relative density of 94.2% (compared with the XRD theoretical density). Excellent microwave dielectric properties (ε_r = 6.28, Q × f = 50400 GHz, and τ_f = ?145 ppm/°C) can also be obtained at this zirconium content. We believe that the developed ceramics are promising for use as antenna substrates or transmit/receive modules in low-temperature co-firing ceramic applications.     

Novel Temperature Stable Li2MnO3 Dielectric Ceramics with High Q for LTCC Applications

Novel microwave dielectric ceramics in the Li₂MnO₃ system with high Q prepared through a conventional solid‐state route had been investigated. All the specimens exhibited single phase ceramics sintered in the temperature range 1140°C–1230°C. The microwave dielectric properties of Li₂MnO₃ ceramics were strongly correlated with sintering temperature and density. The best microwave dielectric properties of ε_r = 13.6, Q × f = 97 000 (GHz), and τ_f = ?5.2 ppm/°C could be obtained as sintered at 1200°C for 4 h. BaCu(B₂O₅) (BCB) could effectively lower the sintering temperature from 1200°C to 930°C and slightly induced degradation of the microwave dielectric properties. The Li₂MnO₃ ceramics doped with 2 wt% BaCu(B₂O₅) had excellent dielectric properties of ε_r = 11.9, Q × f = 80 600 (GHz), and τ_f = 0 ppm/°C. With low sintering temperature and good dielectric properties, the BCB added Li₂MnO₃ ceramics are suitable candidates for LTCC applications in wireless communication system.     

Investigation of the microwave dielectric properties of the Li4x/3Zn2−2xTi1+2x/3O4 system by P–V–L theory and vibration spectroscopy

Li_4x/3Zn_2–2xTi_1+2x/3O₄ microwave dielectric ceramics with a spinel phase were prepared via a high-temperature solid-phase method. P–V–L theory, vibration spectra, and XPS were utilized to establish the links between the intrinsic and extrinsic factors and the microwave dielectric properties. According to the characterization, the change in permittivity (ε_r) was ascribed to the increase in the average bond ionicity of Ti–O(Af_iTi-O) and the polar mode of the lattice vibration; the change in quality factor(Q × f) resulted from the change in the Ti–O lattice energy (AU_Ti-O) and existence of oxygen vacancy; the increase in temperature coefficient of the resonance frequency (τ_f) was triggered by the increase in the Ti–O bond energy. The Li_0.6Zn_1.1Ti_1.3O₄ ceramics (x = 0.45) sintered at 1125 °C finally obtained optimal microwave dielectric constants of ε_r = 17.3, Q × f = 76,318 GHz and τ_f = -58 ppm/°C.     

Low-temperature firing and microwave dielectric properties of MgNb2-xVx/2O6-1.25x ceramics

MgNb_2-xV_x/2O_6-1.25x (0.1≤x≤0.6) ceramics with orthorhombic columbite structures were prepared at low-temperature by a solid-phase process. The phase component, microscopic morphology, low-temperature sintering mechanism and microwave dielectric performance of MgNb_2-xV_x/2O_6-1.25x ceramics were comprehensively investigated. Low-temperature sintering densification of dielectric ceramics was achieved via the nonstoichiometric substitution of vanadium (V) at the Nb-site. In contrast to pure MgNb₂O₆ ceramics, the sintering temperature of MgNb_2-xV_x/2O_6-1.25x (x = 0.2) ceramics was reduced by nearly 300 °C owing to the liquid-phase assisted sintering mechanism. The liquid phase arises from the autogenous low-melting-point phase. Meanwhile, MgNb_2-xV_x/2O_6-1.25x (x = 0.2) samples with nonstoichiometric substitution could achieve a more than 900% improvement in the Q × f value, compared with stoichiometrically MgNb_2-xV_xO₆ (x = 0.1, 0.2) ceramics. Finally, MgNb_2-xV_x/2O_6-1.25x dielectric ceramics possess outstanding microwave dielectric properties: ε_r = 20.5, Q × f = 91000, and τ_f = -65 ppm/°C when sintered at 1030 °C for x = 0.2, which provides an alternative material for LTCC technology and an effective approach for low-temperature sintering of Nb-based microwave dielectric ceramics.     

Effect of substituting Al3+ for Ti4+on the microwave dielectric performance of Mg2Ti1-xAl4/3xO4 (0.01 ≤ x ≤ 0.09) ceramics

In this paper, Mg₂Ti_1-xAl_4/3xO₄ ceramics (0.01 ≤ x ≤ 0.09) were synthesized through conventional solid-state ceramic route. The cubic spinel structure, microstructure and microwave properties of Mg₂Ti_1-xAl_4/3xO₄ (x = 0.01, 0.03, 0.05, 0.07, 0.09) ceramics were investigated by X-ray diffraction, Raman spectra, infrared spectra. Rietveld refinements confirm that a spinel structure phase with space group Fd-3m is formed. The variation of the permittivity was concerned with the ionic polarizability, and the value of τ_f was influenced by the bond valence. Both Q × f values and relative density showed an identical trend. Intrinsic properties of Mg₂Ti_1-xAl_4/3xO₄ ceramics were analyzed by infrared spectra and Raman spectra. In addition, the Mg₂Ti_1-xAl_4/3xO₄ ceramic sintered at 1420 °C for 4 h possessed optimal dielectric properties (ε_r = 14.65, Q × f = 182347 GHz, τ_f = −57.7 ppm/°C) when x = 0.09.     

Improved microstructure and high quality factor of Li2Ti0.9(Zn1/3Ta2/3)0.1O3 microwave ceramics with LiF additive for LTCC applications

In this study, LiF was utilized to decrease sintering temperature, improve microstructure, enhance Q×f, and regulate τ_f of Li₂Ti_0.9(Zn_1/3Ta_2/3)_0.1O₃ (abbreviated as LTZT) ceramics. A complete solid solution together with a phase transition from monoclinic to cubic rock salt structure occurred. The cell volume of LTZT ceramics decreased as the LiF content increased. Relatively dense and uniform microstructures were observed for the ceramics as the LiF content was not less than 2 wt%. The dielectric constant of LTZT ceramics initially increased and then decreased with the increasing LiF content. The FWHM of the Raman band at about 808 cm^?1 was closely related to the Q×f value. Notably, the samples with 3 wt% LiF exhibited the highest relative density of 97.4 % and satisfactory microwave dielectric properties of ε_r = 23.14 ± 0.16, Q×f = 110,090 ± 1100 GHz, and τ_f = +3.25 ± 1.45 ppm/°C when sintered at 950 °C. Good chemical compatibility with silver indicated the ceramic is a promising candidate in LTCC applications.     

Low‐Temperature Sinterable (1−x)Ba3(VO4)2–xLiMg0.9Zn0.1PO4 Microwave Dielectric Ceramics

The novel low‐temperature sinterable (1 ? x)Ba₃(VO₄)₂–xLiMg_0.9Zn_0.1PO₄ microwave dielectric ceramics were prepared by cofiring the mixtures of pure‐phase Ba₃(VO₄)₂ and LiMg_0.9Zn_0.1PO₄. The phase structure and grain morphology of the ceramics were evaluated using X‐ray diffraction, Raman spectra, and scanning electron microscopy. The results indicated that Ba₃(VO₄)₂ and LiMg_0.9Zn_0.1PO₄ phases can well coexist in the sintered body. Nevertheless, a small amount of LiZnPO₄ and some vanadate phases with low melting points were observed, which not only can influence the microwave dielectric properties of the ceramic but also can obviously improve the densification behavior at a relatively low sintering temperature. The near‐zero temperature coefficients of the resonant frequency (τ_f) could be achieved by adjusting the relative content of the two phases owing to their opposite τ_f values and simultaneously a desirable quality factor Q × f value can be maintained. No chemical reaction between the matrix ceramic phase and Ag took place after sintering at 800°C for 4 h. The ceramics with 45 vol% LiMg_0.9Zn_0.1PO₄ can be well sintered at only 800°C and exhibit excellent microwave dielectric properties of ε_r ~ 10, Q × f ~ 64 500 GHz, and τ_f ~ ?2.1 ppm/°C, thus showing a great potential as a low‐permittivity low‐temperature cofired microwave dielectric material.     

Effects of Magnesium–Tungsten co-substitution on crystal structure and microwave dielectric properties of CaTi1-x(Mg1/2W1/2)xO3 ceramics

CaTi_1-x (Mg_1/2W_1/2)_xO₃ (x = 0, 0.02, 0.04, 0.06, 0.08) dielectric ceramics were synthesized via the traditional solid-state reaction method. Crystal structure and microwave dielectric properties of CaTi_1-x (Mg_1/2W_1/2)_xO₃ system were systematically investigated based on chemistry bond theory (P–V-L theory) for the first time. The pure perovskite phase was obtained for all doped samples, as confirmed through the XRD and Rietveld refinement results. The lattice characteristics were closely related to the microwave dielectric properties. The bond ionicity, lattice energy, and bond energy affected the dielectric constant, quality factor, and temperature stability of the ceramic material. Through the use of (Mg_1/2W_1/2)⁴⁺ doped on B-site, the CaTi_1-x (Mg_1/2W_1/2)_xO₃ system can maintain a high dielectric constant (ε_r > 100) while effectively reducing the τ_f value from 800 ppm/^°C to less than 300 ppm/^°C and improving the Q × f value to 9650 GHz (at 3.76 GHz).     

Structural dependence of microwave dielectric properties in ilmenite-type Mg(Ti1-xNbx)O3 solid solutions by Rietveld refinement and Raman spectra

Mg(Ti_1-xNb_x)O₃ (x = 0–0.09) ceramics were prepared by the conventional solid-state reaction method. The phase composition, sintering characteristics, microstructure and dielectric properties of Ti⁴⁺ replacement by Nb⁵⁺ in the formed solid solution Mg(Ti_1-xNb_x)O₃ (x = 0–0.09) ceramics were systematically studied. The structural variations and influence of Nb⁵⁺ doping in Mg(Ti_1-xNb_x)O₃ were also systematically investigated by X-ray diffraction and Raman spectroscopy, respectively. X-ray diffraction and its Rietveld refinement results confirmed that Mg(Ti_1-xNb_x)O₃ (x = 0–0.09) ceramics crystallised into an ilmenite-type with R-3 (148) space group. The replacement of the low valence Ti⁴⁺ by the high valence Nb⁵⁺ can improve the dielectric properties of Mg(Ti_1-xNb_x)O₃ (x = 0–0.09). This paper also studied the different sintering temperatures for Mg(Ti_1-xNb_x)O₃ (x = 0–0.09) ceramics. The obtained results proved that 1350 °C is the best sintering temperature. The permittivity and Q × f initially increased and then decreased mainly due to the effects of porosity caused by the sintering temperature and the doping amount of Nb₂O₅, respectively. Furthermore, the increased Q × f is correlated to the increase in Ti–O bond strength as confirmed by Raman spectroscopy, and the electrons generated by the oxygen vacancies will be compensated by Nb⁵⁺ to a certain extent to suppress Ti⁴⁺ to Ti³⁺, which was confirmed by XPS. The increase in τ_f from ?47 ppm/°C to ?40.1 ppm/°C is due to the increment in cell polarisability. Another reason for the increased τ_f is the reduction in the distortion degree of the [TiO₆] octahedral, which was also confirmed by Raman spectroscopy. Mg(Ti_0.95Nb_0.05)O₃ ceramics sintered at 1350 °C for 2 h possessed excellent microwave dielectric properties of ε_r = 18.12, Q × f = 163618 GHz and τ_f = ?40.1 ppm/°C.     

Ilmenite-type MgTiO3 ceramics by complex (Mn1/2W1/2)4+ cation co-substitution producing improved microwave characteristics

In this article, the (Mn_1/2W_1/2)⁴⁺ complex cation co-doped ilmenite MgTiO₃ ceramics with improved microwave characteristics were synthesized. The correlations between the crystal structural evolution induced by ionic substitution and the microwave characteristics were investigated using the structural analysis and the P–V–L bond theory. Theoretically, the Mg–O bond should have a larger value of covalency than Ti–O bond, attributing to the distribution of densities of states, where the s and p states of the Mg atom overlap with those of the O atom. This conclusion fits well the bond theory estimation. The dielectric constant is dominated predominantly by the average bond covalency, which is intrinsically caused by the increase of doping contents. Moreover, the structural stability declines slightly with the increase of (Mn_1/2W_1/2) contents. From the perspective of structural evolution, this dielectric performance is also reflected by the variations of the Raman shift and the FWHM value of A_g⁵ mode. The actual Q × f value, however, experiences a great enhancement at x = 0.010, which benefits generally from the uniformity of the grain size and the inhibition of reduction of Ti⁴⁺ valence. The excellent microwave characteristics of MgTi_0.99(Mn_1/2W_1/2)_0.01O₃ ceramics were achieved: a ε_r of 18.74, a Q × f value of 160992 GHz and a τ_f of ?58.2 ppm/°C, when sintered at 1325 °C.     

Structure and microwave dielectric properties of Li2Mg3Ti1-x(Al1/2Nb1/2)xO6 ceramics

Aiming to establish relationships between intrinsic structure factors and dielectric characteristics, a series of Li₂Mg₃Ti_1-x(Al_1/2Nb_1/2)_xO₆ (x = 0.0, 0.04, 0.08, 0.12, 0.16, 0.20) ceramics were synthesized to investigate the influences of (Al_1/2Nb_1/2)⁴⁺ substitution on the dielectric properties of Li₂Mg₃TiO₆ ceramics. The XRD and SEM results revealed that the pure rock salt phase (space group: Fm-3m) with a dense microstructure could be obtained with increasing the (Al_1/2Nb_1/2)⁴⁺ concentration, which is accompanied by an increase in the grain size from 11.69 to 22.81 μm. Meanwhile, some intrinsic factors, such as the average ionic polarizability, bond energy, packing fraction and lattice energy were calculated according to the complex chemical bond theory and refinement results. The unusual change in the dielectric constant (ε_r) was explained by the combined effects of the average ionic polarizability and relative density. The variation in the quality factor (Q × f) was ascribed to the packing fraction and lattice energy. The temperature coefficient of the resonant frequency (|τ_f|) reduced gradually with the increase in the octahedral bond energy, which enhanced the system thermal stability. Particularly, the Li₂Mg₃Ti_0.92(Al_1/2Nb_1/2)_0.08O₆ sample exhibited outstanding dielectric characteristics:ε_r = 15.256, Q × f = 174,300 GHz and τ_f = −19.97 ppm/°C.     

The structure evolution and microwave dielectric properties of MgAl2-x(Mg0·5Ti0.5)xO4 solid solutions

In the present work, MgAl_2-x(Mg_0·5Ti_0.5)_xO₄ (x = 0.02, 0.04, 0.06, 0.08, 0.10) solid solutions were synthesized via the traditional solid-state reaction route. The valence state of Ti ions, crystal structural characteristics, and microwave dielectric properties were discussed. A solid solution with spinel structure was revealed by the Rietveld refinement results. The partial substitution of (Mg_0·5Ti_0.5)³⁺ for Al³⁺ lowered the sintering temperature and improved the Q × f value of MgAl₂O₄ ceramic. The MgAl_2-x(Mg_0·5Ti_0.5)_xO₄ solid solutions with x = 0.06 can be well sintered at 1425 °C in an oxygen atmosphere for 8 h and exhibits excellent microwave dielectric properties with ε_r = 9.1, Q × f = 98,000 GHz, τ_f = −61.36 ppm/°C. The sintering temperature of MgAl_1·94(Mg_0·5Ti_0.5)_0.06O₄ microwave dielectric ceramics was approximately 200 °C lower than that of conventional MgAl₂O₄ ceramics.     

A Novel Low‐Firing and Low Loss Microwave Dielectric Ceramic Li2Mg2W2O9 with Corundum Structure

The crystal structure and microwave dielectric properties of a novel low‐firing compound Li₂Mg₂W₂O₉ were investigated in this study. The phase purity and crystal structure were investigated using X‐ray diffraction analyses and Rietveld refinement. The best microwave dielectric properties of the ceramic with a low permittivity (ε_r) ~11.5, a quality factor (Q × f) ~31 900 GHz (at 10.76 GHz) and a temperature coefficient of the resonant frequency (τ_f) ~ ?66.0 ppm/°C were obtained at the optimum sintering temperature (920°C). CaTiO₃ was added into the Li₂Mg₂W₂O₉ ceramic to obtain a near zero τ_f, and 0.93Li₂Mg₂W₂O₉–0.07CaTiO₃ ceramic exhibited improved microwave dielectric properties with a near‐zero τ_f ~ ?1.3 ppm/°C, a ε_r ~21.6, a high Q_u × f value ~20 657 GHz. The low sintering temperature and favorable microwave dielectric properties make it a promising candidate for LTCC applications.     

Microwave Dielectric Properties of Novel Glass‐Free Low‐Firing Li2CeO3 Ceramics

Novel glass–free low temperature firing microwave dielectric ceramics Li₂CeO₃ with high Q prepared through a conventional solid‐state reaction method had been investigated. All the specimens in this paper have sintering temperature lower than 750°C. XRD studies revealed single cubic phase. The microwave dielectric properties were correlated with the sintering conditions. At 720°C/4 h, Li₂CeO₃ ceramics possessed the excellent microwave dielectric properties of ε_r = 15.8, Q × f = 143 700 (GHz), and τ_f  = ?123 ppm/°C. Li₂CeO₃ ceramics could be excellent candidates for glass‐free low‐temperature co‐fired ceramics substrates.     

Synthesis,Microstructure, and Microwave Dielectric Properties of Spinel ZnGa2O4 Ceramics

Spinel ZnGa₂O₄ ceramics were synthesized by conventional solid‐state method and their microwave dielectric properties were investigated. The phase evolution and microstructures of specimens were studied by XRD and SEM. The textured surface microstructures of ZnGa₂O₄ ceramics formed at high sintering temperatures. The spinel‐structured ZnGa₂O₄ ceramics sintered at 1385°C exhibited excellent microwave dielectric properties: a dielectric constant (ε_r) of 10.4, a quality factor (Q × f) of 94.600 GHz, and a temperature coefficient of resonant frequency (τ_f) of ?27 ppm/°C. ZnGa₂O₄ ceramics have a low sintering temperature, a wide temperature region, and a small negative τ_f value. They are promising candidate materials for millimeter‐wave devices.     

Low‐Temperature Sintering and Microwave Dielectric Properties of (Mg0.95Zn0.05)2(Ti0.8Sn0.2)O4–(Ca0.8Sr0.2)TiO3 Composite Ceramics

0.9(Mg_0.95Zn_0.05)₂(Ti_0.8Sn_0.2)O₄–0.1(Ca_0.8Sr_0.2)TiO₃ (MZTS–CST) ceramics were prepared by a conventional solid‐state route. The MZTS–CST ceramics sintered at 1325°C exhibited ε_r = 18.2, Q × f = 49 120 GHz (at 8.1 GHz), and τ_f = 15 ppm/°C. The effects of LiF–Fe₂O₃–V₂O₅ (LFV) addition on the sinterability, phase composition, microstructure, and microwave dielectric properties of MZTS–CST were investigated. Eutectic liquid phases 0.12CaF₂/0.28MgF₂/0.6LiF and MgV₂O₆ were developed, which lowered the sintering temperature of MZTS–CST ceramics from 1325°C to 950°C. X‐ray powder diffraction (XRPD) and energy dispersive spectroscopy (EDS) analysis revealed that MZTS and CST coexisted in the sintered ceramics. Secondary phase Ca₅Mg₄(VO₄)₆ as well as residual liquid phase affected the microwave dielectric properties of MZTS–CST composite ceramics. Typically, the MZTS–CST–5.3LFV composite ceramics sintered at 950°C showed excellent microwave dielectric properties: ε_r = 16.3, Q × f = 30 790 GHz (at 8.3 GHz), and τ_f = ?10 ppm/°C.