Microwave Dielectric Properties Of Ceramics Research Articles

Ni-Co Complex Ionic Synergistically Modifying Octahedron Lattice of Cordierite Ceramics for the Application of 5G Microwave-Millimeter-wave Antennas.

In this work, phase-pure Mg1.8(Ni1-xCox)0.2Al4Si5O18 (0 ≤ x ≤ 1) ceramics were synthesized by a high-temperature solid-state method. On the basis of Rietveld refinement data of X-ray powder diffraction and Phillips-Vechten-Levine theory, the atomic ionicity, lattice energy, and bond energy of the compound were calculated to explore their influence on the microwave dielectric properties of ceramics. The Mg1.8Ni0.1Co0.1Al4Si5O18 (x = 0.5) ceramic exhibited the best microwave dielectric properties: εr = 4.44, Qf = 73 539 GHz@13 GHz, and τf = -23.9 ppm/°C. (Ni1-xCox)2+ complex ionic doping, compared with only Ni2+ or Co2+, is beneficial for improving the symmetry of [Si4Al2O18] hexagonal rings and reducing distortion. Subsequently, 8 wt % TiO2 was added to Mg1.8Ni0.1Co0.1Al4Si5O18, resulting in a near-zero τf and high Qf values for the composite ceramic, with εr = 5.22, Qf = 58 449 GHz@13 GHz, and τf = -2.06 ppm/°C. Finally, a 5G millimeter-wave antenna with a central operating frequency of 25.52 GHz was designed and fabricated using the Mg1.8Ni0.1Co0.1Al4Si5O18-8 wt % TiO2 ceramics. Operating in the 24.7-26.0 GHz range, it demonstrated favorable radiation characteristics with a simulated efficiency of 85.2% and a gain of 4.58 dBi. The antenna's performance confirms the high potential of the cordierite composite for application in 5G communication systems.

Zero-Temperature Coefficient of Resonant Frequency in [(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-Ca0.6(La0.9Y0.1)0.2667TiO3 Ultra-Low-Loss Composite Dielectrics

Investigating the microwave dielectric properties of ceramics prepared through the conventional solid-state route, such as x[(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-(1−x)Ca0.6(La0.9Y0.1)0.2667TiO3, reveals notable characteristics. [(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02 shows a permittivity (εr) of approximately 20, a high quality factor (Q × f) ranging between 250,000 and 560,000 GHz, and a temperature coefficient of resonant frequency (τf) of approximately −65 ppm/°C. To enhance the temperature stability, Ca0.6(La0.9Y0.1)0.2667TiO3 featuring a τf value of +374 ppm/°C was incorporated into the [(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02 composition. τf demonstrated an increase with rising Ca0.6(La0.9Y0.1)0.2667TiO3 content, reaching zero at x = 0.95. A ceramic composition of 0.95[(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-0.05Ca0.6(La0.9Y0.1)0.2667TiO3, incorporating 3wt.% BaCu(B2O5) as sintering aids, exhibited outstanding microwave dielectric properties: εr~22.5, Q × f~195,000 (at 9 GHz), and τf~0.1ppm/°C, with a sintering temperature at 950 °C. This material is proposed as a prospective candidate for 6G band components and GPS antennas.

Crystal structure and microwave dielectric properties of Li2(Mg1–xCux)2Mo3O12 ceramics sintered at ultra‐low temperature

AbstractLi2(Mg1–xCux)2Mo3O12 (0 ≤x ≤0.1) ceramics were prepared using the conventional solid‐phase method to study the effect of the Cu2+ substitution for Mg2+ on the sintering behavior, crystal structure, and microwave dielectric properties of ceramics. The experimental results show that the substitution of Cu2+ for Mg2+ reduces the sintering temperature of the ceramics to 550°C. X‐ray diffraction patterns show that the introduction of Cu2+ does not produce a new phase, but rather promotes the formation of Li2(Mg1–xCux)2Mo3O12 solid solution. The microwave dielectric properties of the ceramics are influenced by the cell parameters, bond lengths, and structural stability. However, Cu2+ creates oxygen vacancies during sintering, thereby deteriorating the dielectric properties (Q × f decreases). The microwave dielectric properties of Li2(Mg1–xCux)2Mo3O12 ceramics are optimal at a sintering temperature of 550°C and x = 0.02, with εr = 9.17, Q × f = 7960 GHz, and τf = –58.77 ppm/°C. Additionally, these ceramics are compatible with Al electrodes.

Effects of Ga2O3 doping on the microstructure and dielectric properties of SrTiO3–SmAlO3 ceramics for microwave applications

xSrTiO3-(1-x)SmAlO3 (ST-SA) (x = 0.4, 0.5, 0.6) microwave dielectric ceramics were prepared by solid-state reaction method and the microwave dielectric properties (εr, Q × f, τf) were studied. The 0.4ST-0.6SA component with better Q × f and τf was selected and the effects of different ywt % Ga2O3 (y = 0.5, 1.0, 1.5, 2.0, 2.5) doping on the phase structure, microstructure, and microwave dielectric properties of ceramics were investigated. X-ray diffraction analysis showed that Ga3+ mainly replaced Ti4+ site when y ≤ 0.5, and when y > 0.5, Ga3+ start to replace Al3+ site. The best grain uniformity of the ceramics was observed at y = 2.0 by scanning electron microscopy testing. Raman spectroscopy shows that the stability of the oxygen octahedron is improved after Ga2O3 doping with increased Q × f value. The change of Ga2O3 doping amount also affects the dielectric properties of ST-SA ceramics. The optimum Q × f value of the ceramic is improved by about 50% from 10,278 GHz (7.465 GHz, 0.4ST-0.6SA) to 15,712 GHz (6.950 GHz, 0.4ST-0.6SA-2.0 wt% Ga2O3) with improved dielectric properties (εr = 36.14，τf = 4.17 ppm/°C).

Effect of sol-gel and solid-state synthesis techniques on structural, morphological, dielectric properties and sintering mechanism of Li2ZnTi3O8 microwave ceramics

Li2ZnTi3O8 (LZTO) microwave ceramics have been prepared by sol-gel synthesis and solid state reaction techniques. The powder obtained by sol-gel synthesis method and solid state reaction method were calcined at 700 °C for 4 h and 900 °C for 4 h, respectively, and pressed into disc shaped pellets, which were then sintered at 800–950 °C (sol-gel synthesis method) and 1050–1200 °C (solid state reaction method). The microwave dielectric properties of ceramics were investigated. Compared to Li2ZnTi3O8 ceramics prepared by solid-state process (εr = 24.1, Q × f = 56874 GHz, τf = -17.6 × 10−6/°C, at 1150 °C), the ceramics synthesized through sol-gel techniques exhibited a more compact structure at a lower sintering temperature of 900 °C and demonstrated improved microwave dielectric properties: εr = 27.7,Q × f = 60579 GHz,τf = −15.68 × 10−6/°C. A comprehensive explanation of the sintering mechanism was provided to better understand and control the sintering behavior.

Correlations between the crystal structure and microwave dielectric properties in Ce2[Zr1-xMx]3(MoO4)9 (M = Mn1/3Nb2/3, Mn1/3Ta2/3) solid-solution ceramics

Ce2[Zr1-xMx]3(MoO4)9 (M = Mn1/3Nb2/3, Mn1/3Ta2/3;x = 0.02, 0.04, 0.06, 0.08 and 0.10) (abbreviated as CZ1-xNx and CZ1-xTx) ceramics were prepared through the solid-state reaction method. Effects of (Mn1/3Nb2/3)4+ and (Mn1/3Ta2/3)4+ ions on the sintering characteristics, crystal structures, microwave dielectric properties and infrared vibrational modes were studied in detail. X-ray diffraction (XRD) results reveal the formation of solid solutions for all components. Based on the chemical bond theory and Rietveld refinement, intrinsic structure parameters including the polarizability (P), the packing fraction (P.F.) and the octahedral distortion (Δocta.), and bond parameters including the lattice energy (U), bond energy (E) and thermal expansion coefficient (α) were calculated. Interestingly, the Ce–O bond plays a major role in the bond ionicity (fi), while Mo–O bond dominates the contributions in the lattice energy (U), bond energy (E) and thermal expansion coefficient (α). In addition, these parameters are used to explain the variations of the microwave dielectric properties of ceramics either changing the doping contents or replacing different ions at x = 0.06. Furthermore, far infrared (FIR) spectra uncover that the phonon modes provide the major polarization contribution of 68.59% in the CZ0.9T0.1 ceramic, implying that the main contribution to εr stems from the ionic polarization instead of the electronic polarization. Typically, the optimum microwave dielectric properties are achieved for the CZ0.9N0.1 and CZ0.9T0.1 ceramics with εr = 10.76, Q × f = 85,893 GHz (at 9.52 GHz), τf = −14.83 ppm °C−1 and εr = 10.72, Q × f = 87,355 GHz (at 9.81 GHz) and τf = −8.68 ppm °C−1, respectively. Notably, the CZ0.9T0.1 ceramic has a markedly increased Q × f while maintaining a good τf = −8.68 ppm °C−1 and a low sintering temperature of 700 °C.

Low‐temperature‐sintered MgO‐based microwave dielectric ceramics with ultralow loss and high thermal conductivity

AbstractWith the development of 5G/6G communication, the requirements of portable devices for miniaturization and multifunction make low‐temperature co‐fired ceramic (LTCC) more and more important. In the area of high‐frequency high‐density passive integration, microwave dielectric ceramics with a low dielectric loss and high thermal conductivity are urgently needed to ensure the effective signals transmission and system reliability. However, most microwave dielectric ceramics with a low dielectric loss were not applicable for the LTCC technology due to the high sintering temperature. In this work, a series of MgO‐based ceramics [(100 − x) wt.% MgO–x wt.% (0.2SrF2–0.8LiF) (x = 5,7,10)] were prepared by solid‐state reaction method. The addition of sintering aid 0.2SrF2–0.8LiF (S2L8) decreased the sintering temperature below 880°C without degrading the microwave dielectric properties of ceramics. Microwave dielectric properties of ceramics, including quality factor Q × f, relative permittivity εr, and temperature coefficient of resonant frequency τf, were investigated to find the optimum composition and sintering temperature. In general, MgO–7 wt.% S2L8 ceramic sintered at 860°C exhibits outstanding properties of Q × f = 180 233 GHz, εr = 9.11, τf = −40.33 ppm/°C, and a high thermal conductivity of 24.02 W/(m K). This series of ceramics are suitable to be co‐fired with Ag electrodes. With all those great properties, this series of MgO‐based ceramics are expected to be the candidates for LTCC applications in 5G/6G technology.

Effects of Strontium on the Structural, Optical, and Microwave Dielectric Properties of Ba2Ti9O20 Ceramics Synthesized by a Mixed Oxide Route.

Solid solutions of Sr-doped barium nonatitanate (Ba2Ti9O20) ceramics were synthesized by a mixed oxide route, studied their structural, microstructural, optical, and microwave dielectric properties were studied. X-ray diffraction (XRD) has been used to reveal the structure and crystallite size of doped Ba2Ti9O20 ceramics. Rietveld refinements of XRD patterns revealed that all of the ceramics have a tetragonal structure with space group I4/m. The surface morphologies of all the samples were characterized by using scanning electron microscopy (SEM). Fourier transform infrared (FT-IR) studies gave the O–H and Ti–O modes of vibrations. The stretching modes of Ti–O and O–H were noted at 1400, 2960, 3700, and near to 440 cm–1, respectively. The band gap energy decreases with increasing Sr2+ contents, and a high value (2.12 eV) was observed in the base sample. The microwave dielectric properties of the ceramic samples were studied at different frequencies ranging from 1 to 2 GHz by using impedance spectroscopy. The obtained results showed the suitability of these samples for microwave dielectric resonator (antenna) applications.

Ultra-low temperature sintering and microwave dielectric properties of mg-substituted SrCoV2O7 ceramics

ABSTRACT SrCo1-xMgxV2O7 (x = 0–0.09) dielectrics were prepared via the solid state route and the effect of Mg substitution on the microwave dielectric properties of the ceramics was systematically investigated. In addition to the relative density and microstructure, the dielectric polarizability, packing fraction, lattice energy and bond valence also play a crucial role in controlling the dielectric properties of the ceramics at microwave frequencies. A high lattice energy representing a high structural stability leads to a low dielectric loss in the specimen. Fluctuated variation of the τf was highly related to the bond valence of the samples. Specimens with x = 0.07 at 660°C revealed the highest Q × f of 23,000 GHz along with an εr of 13.2 and a τf of – 95 ppm/°C and it is chemically compatible with the Al electrode, suggesting that the dielectric is highly promising for ULTCC applications.

Sintering behavior, phase structure and microwave dielectric properties of CeO2 added CaTiO3-SmAlO3 ceramics prepared by reaction sintering method

Novel 0.695CaTiO3-0.305SmAlO3+xwt% CeO2 (x = 0, 0.5, 1.0, 1.5) ceramics were fabricated using a reaction-sintering (RS) approach. The crystal structure, morphology, and microwave dielectric properties of ceramics were systematically studied. The addition of CeO2 could effectively improve the sintering behavior of 0.695CaTiO3-0.305SmAlO3 (CTSA) ceramics. When x = 0.5 wt%, the ceramics exhibited optimal microwave dielectric properties, with εr = 43.9, Q×f = 48 779 GHz, and τƒ = −0.24 ppm/°C, thereby indicating that the samples prepared via the RS route possess superior dielectric properties compared to those prepared by the conventional solid phase reaction. The results demonstrate that CaTiO3-SmAlO3 ceramics can be prepared simply and efficiently through a reaction-sintering process.

TiO2-(Zn1/3Nb2/3)O2-ZrO2 microwave dielectric ceramics with near-zero temperature coefficient of resonant frequency

(56.33-x)TiO2-x(Zn1/3Nb2/3)O2-43.67ZrO2 (x = 2.60-37.66) ceramics with 0.5%wt CuO addition were prepared by the mixed metal oxide route. Effects of sintering temperature were investigated on the sintering behavior and microwave dielectric properties of ceramics. For all ceramics with x = 2.60-37.66, the optimal sintering temperature range was determined to be around 1280 °C. XRD analysis showed that the main crystalline phase of ceramics sintered at 1280 °C changed from ZrTiO4 type at x = 2.60-30.20 to ZrTi2O6 type at x = 30.20-37.66. In addition to the main crystalline phase, trace amounts of secondary phases ZrO2 and ZnCuTiO4 were also observed from SEM and EDS analysis for all ceramics. The permittivity decreased with the increasing x in the range of x = 2.60-30.20 and then remained stable at x = 30.20-37.66, corresponding to the density and covalency bond due to the substitution of (Zn1/3Nb2/3)4+ for Ti4+ and phase transition at x = 30.20. Furthermore, it was surprisingly found that the temperature coefficient of resonant frequency was near-zero (τf = -9.2 to +9.9 ppm/°C) in a very wide range of x = 10.80-30.20.

Structural evolution, Raman spectra, and microwave dielectric properties of Zr-substituted ZnTiTa2O8 ceramics

A series of Zn(Ti1−xZrx)Ta2O8 (x = 0, 0.2, 0.4, 0.6, 0.8, 1) ceramics samples were synthesized by conventional solid-state reaction route. The sintering behavior, crystal structure, Raman spectroscopy, microstructure, and microwave dielectric properties were studied. The crystal structure, lattice parameters, and bonding of the ceramics were analyzed using X-ray powder diffraction and Raman spectroscopy. As Zr4+ content increasing, the structural transition followed the sequence: tri-rutile → coexistence of tri-rutile and columbite → columbite → wolframite. The microwave dielectric properties of ceramics were considerably affected by the structural transition. Compared with pure phase ZnTiTa2O8 ceramics, a small amount of Zr-substitution (x = 0.2) could significantly improve the Q × f values (from 19,852 to 44,048 GHz) and τf values (from 77.1 to − 11.9 ppm/°C) of ceramics. Typically, ZnTi0.8Zr0.2Ta2O8 (x = 0.2) ceramics exhibited an excellent microwave dielectric property of er ~ 29.9, Q × f ~ 44,048 GHz, and τf ~ − 11.9 ppm/°C as the sintering temperature was 1300 °C.

Effects of Sm2O3/SrO/LiF doping and cooling rate on sintering characteristics and microwave dielectric properties of (Zr0.8Sn0.2)TiO4 ceramics

The present study aims to synthesize (Zr0.8Sn0.2)TiO4 (ZST) ceramics and determine the optimum content of Sm2O3/SrO/LiF doping and cooling rate to improve processing and microwave dielectric properties of the ceramics. The initial content of three additives was preliminarily determined by analyzing the phase composition, microstructure, sintering characteristics and microwave dielectric performance of ZST ceramics samples. As a typical fluxing agent, the optimum LiF content was further explored, and the effects of different LiF contents on 0.8 wt% Sm2O3 + 0.4 wt% SrO doped ceramics were investigated. A suitable amount of liquid phase could be formed at a lower temperature when adding suitable LiF content into ceramics. The results showed the 0.3 wt% LiF not only promoted densification process but also reduced the sintering temperature to 1285 °C, which made the dielectric properties better. Moreover, the cooling rate also affected the performance of ZST ceramics, and the optimum cooling rate was determined through analyzing the lattice parameters and microstructure. Comparing the comprehensive properties of various ZST ceramics doped with 0.8 wt% Sm2O3 + 0.4 wt% SrO + 0.3 wt% LiF, the ceramic exhibited the densest microstructure and the best dielectric performance where er = 39.66, Q × f = 45,150 GHz (f = 5.6 GHz), and τf = − 4.88 ppm/°C when the cooling rate was 1 °C/min and the sintering temperature was 1285 °C.

Phase Evolution, Microstructure, Conductivity Behavior and Microwave Dielectric Properties of Li2O-2MgO-Al2O3-6MoO3 Ceramics

Li2O-2MgO-Al2O3-6MoO3 system ceramics were synthesized by a solid-state reaction method. The phase composition, microstructure, dielectric temperature spectrum, impedance and microwave dielectric properties of ceramics were studied. X-ray diffraction patterns showed that the ceramics were multiphase composite and the main phase transformed from Li2Al2MoO15 to LiMgAl(MoO4)3. The temperature spectrum shown that there existed phase transition with increasing the measured temperature. The impedance analysis identified that conductivity behavior came from the effect of grain boundaries. The ceramics could be densified at 650∼725°C. After sintering at 700°C, the ceramics exhibited the best microwave dielectric properties with Q × f = 21,731 GHz, er = 6.76 and τf = − 50 ppm/°C, indicating that it is a candidate for low-temperature cofired ceramic devices.

Magnesium fluoride doped MgTiO3 ceramics with ultra-high Q value at microwave frequencies

Microwave ceramic with ultra-high Q value is one of the most significant classes of material to realize the miniaturization and integration of microwave devices. In this paper, to improve the microwave dielectric properties of ceramics, MgTiO3-x wt.% MgF2 (x = 0, 3, 4, 5, and 6) microwave ceramics with high-quality factor were synthesized by solid-state reaction method. The effects of MgF2 addition on the phase composition, sintering behavior, and microwave dielectric properties of MgTiO3 were investigated. In comparison to pure MgTiO3, our study demonstrates that the Q × f values can be dramatically enhanced with the doping of MgF2. After being sintered at 1300 °C for 4 h, the MgTiO3-3 wt.% MgF2 showed the best microwave dielectric properties of εr ∼18.09, Q × f ∼262,900 GHz (at 8.98 GHz) and τf ∼ −41.5 ppm/°C. The outstanding performance of MgF2 doped MgTiO3 ceramics provides a solid foundation for widespread applications of microwave dielectric substrates, resonators, filters and patch antennas in modern wireless communication equipment.

Sintering Characteristics and Microwave Dielectric Properties of (1 − x)Li0.5Sm0.5TiO3–xNa0.5Sm0.5TiO3 (x = 0.35 to 0.45) Ceramics

(1 − x)Li0.5Sm0.5TiO3–xNa0.5Sm0.5TiO3 (LST-NST, x = 0.35 to 0.45) microwave dielectric ceramics with orthorhombic perovskite structure have been fabricated by a conventional solid-state reaction method. The densification behavior of the LST-NST ceramic samples was investigated by dilatometry analyses. The effects of the sintering temperature and composition on the microstructure and microwave dielectric properties of the ceramic samples were investigated in detail. Generally, 1180°C was found to be the optimal sintering temperature for the LST-NST ceramics. The optimal microwave dielectric properties of the LST-NST ceramics were achieved for the 0.63LST-0.37NST (x = 0.37) composition with er = 96.8, Q × f = 5102 GHz, and near-zero τf of − 4.35 ppm/°C.

Influence of Co substitution on the phase, microstructure, and microwave dielectric properties of MgSiO3 ceramics

Solid-state sintering method was used for the synthesis of Mg1−xCoxSiO3 (x = 0–0.25) ceramics. Phase, microstructure and microwave dielectric properties of the ceramics were investigated. With increase in Co2+ content, the increase was observed in the lattice parameters. The Qufo value of MgSiO3 was enhanced from 103,453 to 145,846 GHz with increasing the value of x content from 0 to 0.15. The Co2+ substitution also led to an obvious decrease in the sintering temperature by ~ 100 °C. Clino-enstatite phase formed for the composition with x = 0 while Proto-enstatite formed as the major along with minor clino-enstatite phase for the compositions with x > 0. Good dielectric properties at microwave frequencies i.e. er ~ 8.11, Qufo ~ 145,846 GHz and τf ~ − 12 ppm/°C were obtained for the composition with x = 0.15 sintered at 1350 °C for 9 h. This is suggested to be a very favorable dielectric material for millimeterwave applications.

Low permittivity MgO–xB2O3–yBaCu(B2O5) microwave dielectric ceramics for low temperature co-fired ceramics technology

MgO–xB2O3–yBaCu(B2O5) ceramics were prepared by a solid-state reaction method. The phase composition and microwave dielectric properties of ceramics were studied. The MgO-rich ceramics (x = 1/4, 1/3 and 1/2) contain MgO and Mg3B2O6. But the B2O3-rich ceramics (x = 1, 2 and 3) contain B2O3, MgB2O4 and Mg2B2O5. The MgO–xB2O3 (x = 1/4, 1/3, 1/2, 1, 2 and 3) ceramics show high Q × f of 41,754–105,852 GHz, low er of 4.24 ~ 7.68 and negative τf values of − 56 to − 30 ppm °C−1 with tuning the x values. The BaCu(B2O5) (BCB) was used to reduce the sintering temperature of MgO–2B2O3 ceramic. The MgO–2B2O3-4 wt% BCB ceramic sintered at 925 °C exhibits good microwave dielectric properties with high Q × f of 30,589 GHz, low er of 4.8 and negative τf value of − 40 ppm °C−1. Importantly, MgO–2B2O3-4 wt% BCB ceramic has a good chemical compatibility with Ag, which illustrates that it is a candidate material for low temperature co-fired ceramic devices.

Effects of Li-ion substitution on the microwave dielectric properties of low-temperature sintered ceramics with nominal composition Li2xMg2−xSiO4

The effects of the partial substitution of Li+ for Mg2+ on the microstructure and microwave dielectric properties of ceramics with nominal composition Li2xMg2−xSiO4 (0.25 ≤ x ≤ 1.25) were investigated. Li2xMg2−xSiO4 powders were synthesised by the traditional solid-state reaction. A fixed amount of Li2O-B2O3-Bi2O3-SiO2 (LBBS) glass was used as a sintering aid to help decrease the sintering temperature to around 900°C. X-ray diffraction (XRD) patterns of the sintered specimens revealed that the phase of Li2MgSiO4 gradually replaced that of Mg2SiO4 as the major phase with increased x content in the ceramics with said nominal composition. Scanning electron microscopy (SEM) images showed that moderate Li substitution contributed to densification and uniform grains in the Li2xMg2−xSiO4 (0.25 ≤ x ≤ 1.25) ceramics. Additionally, microwave dielectric properties were strongly related to the substitution content and sintering temperature. The sintered sample of ceramics with nominal composition Li2xMg2−xSiO4 exhibited good microwave dielectric properties when x = 1 and sintered at 900°C: εr = 6.1, Q×f = 44,500GHz and τf=−13ppm/℃. These findings indicated high potential for LTCC applications.

Effects of lithium fluoride addition on sintering characteristics and microwave dielectric properties of rock–salt structure Li2Mg4TiO7 ceramics

Li2Mg4TiO7 ceramics doped with 1–5 wt% LiF were successfully prepared by the conventional solid-state method. The sintered samples could be well indexed as the rock salt structure with space group Fm-3m (JCPDS #70-2711). The sintering behaviors, phase compositions, microstructures and microwave dielectric properties of ceramics were associated with the sintering temperature and the amount of LiF addition. The e r and Q·f values of the Li2Mg4TiO7 ceramics increased firstly and then decreased with increasing the amount of LiF addition. A near zero temperature coefficient of resonant of frequency (τ f ) value could be obtained by adjusting the amount of LiF additions. The Li2Mg4TiO7 ceramics doped with 2 wt% LiF sintered at 950 °C for 4 h possessed promising microwave dielectric properties with e r value of 14.43, Q·f value of 48,700 GHz and τ f value of −3.83 ppm/°C, making them suitable for low-temperature co-fired ceramic applications.