Lattice structure analysis and optimised microwave dielectric properties of LiAl1-x(Zn0.5Si0.5)xO2 solid solutions

Low-permittivity LiAl_1-x(Zn_0.5Si_0.5)_xO₂ microwave dielectric ceramics were prepared by the solid-state reaction method. Single-phase LiAlO₂ solid solutions with a tetragonal structure were achieved at x ≤ 0.12. Partial substitution of [Zn_0.5Si_0.5]³⁺ for Al³⁺ could improve the microstructure and prevent from absorbing moisture of pure LiAlO₂ ceramics, which slightly increases their relative permittivity (ε_r). The quality factor (Q × f) and temperature coefficient of resonant frequency (τ_f) were closely related to the crystallinity and cation disorder of the B-site characterized by the full width at half-maximum of B₁⁽¹⁾ –mode assigned to Li–O–Al stretching. The optimum microwave dielectric properties (ε_r = 6.12, Q × f = 56986 GHz and τ_f = -122 ppm/°C) were obtained in the sample with x = 0.02 sintered at 1300 °C.     

Crystal structure,microwave dielectric properties and low temperature sintering of (Al0.5Nb0.5)4+ co-substitution for Ti4+ of LiNb0.6Ti0.5O3 ceramics

The phase composition, microstructure, microwave dielectric properties of (Al_0.5Nb_0.5)⁴⁺ co-substitution for Ti site in LiNb_0.6Ti_0.5O₃ ceramics and the low temperature sintering behaviors of Li₂O-B₂O₃-SiO₂ (LBS) glass were systematically discussed. XRD patterns and EDS analysis result confirmed that single phase of Li_1.075Nb_0.625Ti_0.45O₃ solid solution was formed in all component. The increase of dielectric constant (ε_r) is ascribed to the improvement of bulk density. The restricted growth of grain has a negative influence on quality factor (Q×f) value. The τ_f value could be continuously shifted to near zero as the doping content increases. Great microwave dielectric properties were obtained in LiNb_0.6Ti_(0.5-x)(Al_0.5Nb_0.5)_xO₃ ceramics (x?=?0.10) when sintered at 1100?℃ for 2?h: ε_r =?70.34, Q×f =?5144?GHz, τ_f =?4.8?ppm/℃. The sintering aid, LBS glass, can effectively reduce the temperature and remain satisfied microwave performance. Excellent microwave dielectric properties for x?=?0.10 were obtained with 1.0?wt% glass: ε_r =?70.16, Q×f =?4153?GHz (at 4?GHz), τ_f =?-0.65?ppm/℃ when sintered at 925?℃ for 2?h.     

Structure,Infrared Reflectivity and Microwave Dielectric Properties of (Na0.5La0.5)MoO4–(Na0.5Bi0.5)MoO4 Ceramics

A series of temperature‐stable microwave dielectric ceramics, (1?x)(Na_0.5La_0.5)MoO₄–x(Na_0.5Bi_0.5)MoO₄ (0.0 ≤ x ≤ 1.0) were prepared by using solid‐state reaction. All specimens can be well sintered at temperature of 580°C–680°C. Sintering behavior, phase composition, microstructures, and microwave dielectric properties of the ceramics were investigated. X‐ray diffraction results indicated that tetragonal scheelite solid solution was formed. Microwave dielectric properties showed that permittivity (ε_r) and temperature coefficient of resonant frequency (τ_f) were increased gradually, while quality factor (Q × f) values were decreased, at the x value was increased. The 0.45(Na_0.5La_0.5)MoO₄–0.55(Na_0.5Bi_0.5)MoO₄ ceramic sintered at 640°C with a relative permittivity of 23.1, a Q × f values of 17 500 GHz (at 9 GHz) and a near zero τ_f value of 0.28 ppm/°C. Far‐infrared spectra (50–1000 cm^?1) study showed that complex dielectric spectra were in good agreement with the measured microwave permittivity and dielectric losses.     

Effect of Bi2O3 additives on sintering and microwave dielectric behavior of La(Mg0.5Ti0.5)O3 ceramics

Bi₂O₃ was selected as liquid phase sintering aid to lower the sintering temperature of La(Mg_0.5Ti_0.5)O₃ ceramics. The sintering temperature of La(Mg_0.5Ti_0.5)O₃ ceramics is generally high, about 1600 °C. However, the sintering temperature was significantly lowered about 275 °C from 1600 °C to 1325 °C by incorporating in 15 mol% Bi₂O₃ and revealed the optimum microwave dielectric properties of dielectric constant (?_r) value of 40.1, a quality factor (Q × f) value of 60,231 GHz, and the temperature coefficient (τ_f) value of 70.1 ppm/°C. During all addition ranges, the relative dielectric constants (?_r) were different and ranged from 32.0 to 41.9, the quality factors (Q × f) were distributed in the range of 928–60,231 GHz, and the temperature coefficient (τ_f) varies from 0.3 ppm/°C to 70.3 ppm/°C. Noticeably, a nearly zero τ_f can be found for doping 5 mol% Bi₂O₃ sintering at 1325 °C. It implies that nearly zero τ_f can be achieved by appropriately adjusting the amount of Bi₂O₃ additions and sintering temperature for La(Mg_0.5Ti_0.5)O₃ ceramics.     

Correlation between crystal structure,bond characteristics,Raman vibrations,and improved microwave dielectric properties of high-performance Zn0.5Zr0.5NbO4 ceramics: First principle calculation and experiment

The structure–performance mechanism provides new insights into performance modification and materials discovery. Herein, the electronic structure, Raman vibration, chemical bond factors and enhanced microwave dielectric properties of Zn_0.5Zr_0.5NbO₄ ceramics through oxygen-assisted reaction sintering were investigated by Raman spectroscopy, first-principle calculations, and complex P–V-L theory. Pure-phase Zn_0.5Zr_0.5NbO₄ ceramics were synthesized under oxygen-assisted reaction sintering, confirmed by XRD refinement and Raman analysis. Systematic vibration analysis was first introduced to provide complete mode assignments and Raman shift. Optimized microstructure with full density was obtained through morphology and EDS analysis. First-principle calculations indicated that the d orbit exerts the main contribution to Fermi energy with energy gap of 3.51 eV and Nb–O bonds may possess strong vibration, exhibiting a remarkable effect on dielectric loss. P–V-L results showed that Nb–O bonds have a significant influence on the dielectric constant and Q×f value while the Zn–O bonds dominate the τ_f value. In addition, high-performance Zn_0.5Zr_0.5NbO₄ ceramics were fabricated through oxygen-assisted reaction sintering at 1250 °C, with ε_r = 28.4, Q×f = 79,800 GHz, and τ_f = −47.7 ppm/^°C, exhibiting tremendous superiorities for commercial production.     

Influence of Zn0.5Ti0.5NbO4 on the structure and microwave dielectric properties of ZrTiO4 ceramics

In this work, xZn_0.5Ti_0.5NbO₄-(1-x) ZrTiO₄ (0.1 ≤ x ≤ 0.5) ceramics were prepared through the traditional solid-state route. The microstructure, phase evolution and crystallographic variations were investigated in detail. An orthorhombic structure solid solution was formed with the composition of Zr_1-xZn_0.5xTi_1-0.5xNb_xO₄ (0.1 ≤ x ≤ 0.5). Variations of lattice parameters were responsible for the opposite movement of different XRD peaks as increasing x value. Chemical bond theories include that bond ionicity, bond susceptibility, lattice energy, bond energy and linear thermal expansion coefficient are correlated with dielectric properties. Temperature stable ceramics were obtained when x = 0.2 with excellent dielectric performances: Q × f = 26741 GHz, ε_r = 41.93 and τ_f = −2.3 ppm/^oC.     

High-Qf value and temperature stable Zn2+-Mn4+ cooperated modified cordierite-based microwave and millimeter-wave dielectric ceramics

Cordierite-based dielectric ceramics with a lower dielectric constant would have significant application potential as dielectric resonator and filter materials for future ultra-low-latency 5G/6G millimeter-wave and terahertz communication. In this article, the phase structure, microstructure and microwave dielectric properties of Mg₂Al_4–2x(Mn_0.5Zn_0.5)_2xSi₅O₁₈ (0 ≤ x ≤ 0.3) ceramics are studied by crystal structure refinement, scanning electron microscope (SEM), the theory of complex chemical bonds and infrared reflectance spectrum. Meanwhile, complex double-ions coordinated substitution and two-phase complex methods were used to improve its Q×f value and adjust its temperature coefficient. The Q×f values of Mg₂Al_4–2x(Mn_0.5Zn_0.5)_2xSi₅O₁₈ single-phase ceramics are increased from 45,000 GHz@14.7 GHz (x = 0) to 150,500 GHz@14.5 GHz (x = 0.15) by replacing Al³⁺ with Zn²⁺-Mn⁴⁺. The positive frequency temperature coefficient additive TiO₂ is used to prepare the temperature stable Mg₂Al_3.7(Mn_0.5Zn_0.5)_0.3Si₅O₁₈-ywt%TiO₂ composite ceramic. The composite ceramic of Mg₂Al_3.7(Mn_0.5Zn_0.5)_0.3Si₅O₁₈-ywt%TiO₂ (8.7 wt% ≤ y ≤ 10.6 wt%) presents the near-zero frequency temperature coefficient at 1225 °C sintering temperature: ε_r = 5.68, Q×f = 58,040 GHz, τ_f = ?3.1 ppm/°C (y = 8.7 wt%) and ε_r = 5.82, Q×f = 47,020 GHz, τ_f = +2.4 ppm/°C (y = 10.6 wt%). These findings demonstrate promising application prospects for 5 G and future microwave and millimeter-wave wireless communication technologies.     

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.     

Phase composition,Raman spectra,infrared spectra and dielectric properties of Li2MgTi1-x(Mg1/3Nb2/3)xO4 ceramics at microwave frequency

The Li₂MgTi_1-x(Mg_1/3Nb_2/3)_xO₄ (0?≤x?≤?0.5) ceramics were prepared by the conventional solid-state method. The relationship among phase composition, substitution amount and microwave dielectric properties of the ceramics was symmetrically investigated. All the samples possess the rock salt structure with the space group of Fm-3m. As the x value increases from 0 to 0.5, the dielectric constant linearly decreases from 16.75 to 15.56, which can be explained by the variation of Raman spectra and infrared spectra. The Q·f value shows an upward tendency in the range of 0?≤x?≤?0.3, but it then decreases when x?>?0.3. In addition, the temperature coefficient of resonant frequency (τ_f) is shifted toward zero with the increasing (Mg_1/3Nb_2/3)⁴⁺ addition. By comparison, the Li₂MgTi_0.7(Mg_1/3Nb_2/3)_0.3O₄ ceramics sintered at 1400?°C can achieve an excellent combination of microwave dielectric properties: ε_r=?16.19, Q·f =?160,000?GHz and τ_f =??3.14?ppm/°C.     

Improved sinterability and microwave dielectric properties of [Zn0.5Ti0.5]3+-doped ZnAl2O4 spinel solid solution

Low-permittivity ZnAl_2-x(Zn_0.5Ti_0.5)_xO₄ ceramics were synthesized via conventional solid-state reaction method. A pure ZnAl₂O₄ solid-state solution with an Fd-3m space group was achieved at x ≤ 0.1. Results showed that partial substitution of [Zn_0.5Ti_0.5]³⁺ for Al³⁺ effectively lowered the sintering temperature of the ZnAl₂O₄ ceramics and remarkably increased the quality factor (Q × f) values. Optimum microwave dielectric properties (ε_r = 9.1, Q × f = 115,800 GHz and τ_f = −78 ppm/°C) were obtained in the sample with x = 0.1 sintered at 1400°C in oxygen atmosphere for 10 h. The temperature used for the sample was approximately 250°C lower than the sintering temperature of conventional ZnAl₂O₄ ceramics.     

Effects of Ni2+ substitution on the crystal structure,bond valence,and microwave dielectric properties of BaAl2–2xNi2xSi2O8–x ceramics

BaAl_2?2xNi_2xSi₂O_8?x (x = 0, 0.005, 0.01, 0.02, 0.03) ceramics were prepared using traditional solid phase reaction method. The microwave dielectric properties, including permittivity (ε_r), quality factor (Q × f), and temperature coefficient of resonant frequency (τ_f), were discussed based on the bond valence theory. The first-principle calculation was adopted to determine the site (Ba, Al, and Si) where doping element (Ni²⁺) would be inclined to occupy. The substitution of Ni²⁺ for Al³⁺ contributed to the breaking of Al-O and Si-O bonds and then facilitated the BaAl₂Si₂O₈ (BAS) hexacelsian-celsian transformation. Moreover, this substitution could change the bond strength between cation and oxygen anion due to the variation of the bond valence, which reasonably explained the variation of ε_r, Q × f, and τ_f values. Well-sintered and completely transformed celsian ceramics can be obtained after doping with Ni²⁺. When x = 0.01, compact BaAl_1.98Ni_0.02Si₂O_7.99 ceramic exhibited highly promising microwave dielectric properties: ε_r = 6.89, Q × f = 53, 287 GHz and τ_f = -25.31 × 10^?6 /°C.     

Sintering behaviour and microwave dielectric properties of BaAl2−2x(ZnSi)xSi2O8 ceramics

BaAl_2?2x(ZnSi)_xSi₂O₈ (x = 0.2–1.0) ceramics were prepared using the conventional solid-state reaction method. The sintering behaviour, phase composition and microwave dielectric properties of the prepared compositions were then investigated. All compositions showed a single phase except for x = 0.8. By substituting (Zn_0.5Si_0.5)³⁺ for Al³⁺ ions, the optimal sintering temperatures of the compositions decreased from 1475 °C (x = 0) to 1000 °C (x = 0.8), which then slightly increased to 1100 °C (x = 1.0). Moreover, the phase stability of BaAl₂Si₂O₈ was improved. A novel BaZnSi₃O₈ microwave dielectric ceramic was obtained at the sintering temperature of 1100 °C. This ceramic possesses good microwave dielectric properties with ε_r = 6.60, Q × f = 52401 GHz (at 15.4 GHz) and τ_f = ?24.5 ppm/°C.     

Effects of (Mg1/3Ta2/3)-substitution for Ti-site on the microwave dielectric properties of Li2MgTiO4 ceramics

Novel high quality factor microwave dielectric ceramics Li₂MgTi_1?x(Mg_1/3Ta_2/3)_xO₄ (0 ≤ x ≤ 0.5) were successfully prepared via a conventional solid-state ceramic route. The effects of isovalent substitutions (Mg_1/3Ta_2/3)⁴⁺ at the Ti-site on the sintering behaviors, microstructures, and microwave dielectric properties of Li₂MgTiO₄ ceramics were investigated in this paper. The sintered samples exhibited the single phase with cubic rock-salt structure belonging to Fm-3m space group in the whole composition range. Rietveld refinement which could be performed by the Fullprof program was taken to explain the effects of (Mg_1/3Ta_2/3)⁴⁺ ion substitution on the crystal structures of Li₂MgTiO₄ ceramics. With the (Mg_1/3Ta_2/3)⁴⁺ content increasing from 0 to 0.5, the quality factor Q·f firstly increased and decreased thereafter, while the dielectric constant ε_r almost linearly decreased. In addition, the τ_f values shifted to positive value with the amount of (Mg_1/3Ta_2/3)⁴⁺ increasing. The best composition appeared to be Li₂MgTi_0.6(Mg_1/3Ta_2/3)_0.4O₄, which showed excellent microwave dielectric properties of ε_r = 15.73, Q·f = 184,000 GHz and τ_f = ? 12.54 ppm/°C. This made the Li₂MgTi_0.6(Mg_1/3Ta_2/3)_0.4O₄ ceramic a very promising candidate for use as a low-loss microwave material.     

Effects of Ti-substitution on the crystal structures,micro-structures and microwave dielectric properties of Li2Mg3Zr1-xTixO6 (0 ≤ x ≤ 1) ceramics

Li₂Mg₃Zr_1?xTi_xO₆ (x = 0, 0.2, 0.4, 0.6, 0.8, 1) ceramics were prepared via a solid-state reaction method. Crystal structures, sintering behaviors, micro-structures and microwave dielectric properties of Li₂Mg₃Zr_1?xTi_xO₆ (0 ≤ x ≤ 1) ceramics were investigated by XRD, SEM and chemical bond theory. XRD results showed that a single phase with the rock-salt structure was formed in all ranges. On the basis of the Rietveld refinement and chemical bond theory, several intrinsic parameters were calculated and connections between intrinsic parameters and microwave dielectric properties were investigated. The substitutions of Ti⁴⁺ for Zr⁴⁺ obviously increased the relative density and improved the quality factors. Variations of ε_r could be explained by changes of the polarizability. Q·f values showed the similar trend with the packing fractions, average bond valences and lattice energy of Zr–O bonds. τ_? values significantly correlated with the bond energy of Zr–O bonds.     

Improvement of microwave dielectric properties of the LiNb0.6Ti0.5O3 M-phase by doping with (Co1/3Nb2/3)4+

Structural evolution and microwave dielectric properties of LiNb_0.6(Ti_1-x[Co_1/3Nb_2/3]_x)_0.5O₃ (.05≤x≤.2) ceramics have been studied in this paper. Although the doped compositions maintain the M-phase solid solutions, compositional fluctuation due to nonuniform dispersion of minor dopants could be observed as x < .05, and trace amount of Li₂TiO₃-based solid solution (Li₂TiO₃ss) secondary phase presents in the x > .05 compositions. The microwave dielectric properties could be remarkably improved by the doping of (Co_1/2Nb_1/2)⁴⁺ in comparison to the undoped counterpart. Optimized microwave dielectric properties with Q × f = ∼6500 GHz, ε_r = ∼74 and τ_f = +8.2 ppm/°C could be obtained at x = .10 after sintering at 1050°C/2 h. The sintering temperature could be further reduced to 900°C/2 h by adding .2 wt% B₂O₃ without affecting significantly its microwave dielectric properties: ε_r = 73, Q × f = 6000 GHz, τ_f = +8.5 ppm/°C. The LiNb_0.6(Ti_1-x[Co_1/3Nb_2/3]_x)_0.5O₃ ceramics obtained in this case exhibit large dielectric permittivity coupled with much improved Q × f values, near zero τ_f, and low sintering temperature simultaneously, which makes it a promising high-k microwave dielectric material for low temperature cofired ceramic applications.     

Low-temperature sintering and microwave dielectric properties of B2O3-added ZnO-deficient Zn2GeO4 ceramics for advanced substrate application

ZnO-deficient Zn_2-xGeO_4-x ceramics with 0.05?≤?x?≤?0.15 were synthesized because a ZnO secondary phase is formed in the stoichiometric Zn₂GeO₄ ceramics synthesized using micrometer-sized ZnO and GeO₂ powders. The Zn_1.9GeO_3.9 ceramic sintered at 1000?°C showed a homogeneous Zn₂GeO₄ phase with good microwave dielectric properties: ε_r of 6.8, Q?×?f of 49,000?GHz, and τ_f of ?16.7?ppm/°C. However, its sintering temperature was still too high for it to be used as an advanced substrate for low-temperature co-fired ceramic devices. Therefore, various amounts of B₂O₃ were added to the Zn_1.9GeO_3.9 ceramics to reduce their sintering temperature. Owing to the formation of a B₂O₃-GeO₂ liquid phase, these ceramics were well sintered at low temperatures between 925?°C and 950?°C. In particular, 15?mol% B₂O₃-added Zn_1.9GeO_3.9 ceramic sintered at 950?°C showed promising microwave dielectric properties for advanced substrates without the reaction with an Ag electrode: ε_r?=?6.9, Q?×?f?=?79,000?GHz, and τ_f?=??15?ppm/°C.     

Sintering behavior and dielectric properties of SiO2–BPO4 glass-fluxed ceramics

(1–x)SiO₂–xBPO₄ (x?=?23–70?wt%) glass-fluxed ceramics have been prepared by a traditional ceramic process. The phase assemblage, sintering, crystallization behavior, microwave dielectric properties and chemical compatibility with Ag/Cu have been studied. The SiO₂-rich compositions (x?=?23–50?wt%) could be well densified at ～975?°C/2?h, while the BPO₄-rich compositions demonstrated poor sinterability and porous microstructure. The SiO₂-rich compositions sintered at 975?°C/2?h contained BPO₄, low temperature cristobalite and glassy phases. Crystallization of BPO₄ occurred at lower temperature than that of SiO₂. Good combined microwave dielectric properties with ?_r?=?～5, Q?×?f?=?25,000?GHz and τ_f value of –7.3?ppm/°C could be obtained when 10?wt% TiO₂ was added after sintering at 975?°C/2?h. The x?=?23?wt% composition chemically reacted with Ag, but exhibited good chemical compatibility with Cu after sintering at 975?°C/2?h.     

Weak ferroelectricity and low-permittivity microwave dielectric properties of Ba2Zn(1+x)Si2O(7+x) ceramics

Ba₂Zn_(1+x)Si₂O_(7+x) ceramics were prepared using the conventional solid-state method at 1200 °C for 3 h in air. Apart from the previously reported Ba₂Zn_(1+x)Si₂O_(7+x) (x = 0) with a monoclinic structure (C 2/c), the end-member compositions at x = −1 and 1 exhibit single-phase β-BaSiO₃ with an orthorhombic structure (P2₁2₁2₁) and BaZnSiO₄ with a hexagonal structure (P6₃), and possess a coexistence of weak ferroelectricity and low-permittivity microwave dielectric properties. A reduction in Zn²⁺ content mainly decreases the intensity of the ε_r anomaly peak at lower temperature and increases the ε_r (or frequency) stability against temperature. The Zn²⁺-rich BaZnSiO₄ phase has a τ_f value of −181 ppm/°C, whereas the τ_f value of Zn²⁺-free BaSiO₃ phase decreases to −35.4 ppm/°C. The Zn²⁺ deficiency in Ba₂ZnSi₂O₇ composition could inhibit the presence of BaZnSiO₄ phase and improve the τ_f value, whereas excessive Zn²⁺ cations prompt the formation of the BaZnSiO₄ phase to deteriorate significantly the τ_f value.     

Effects of structural characteristics on microwave dielectric properties of low-loss (Zn1-xNix)ZrNbTaO8 ceramics

Low-loss (Zn_1-xNi_x)ZrNbTaO₈ (0.02?≤?x?≤?0.10) ceramics possessing single wolframite structure are initiatively synthesized by solid-state route. Based on the results of Rietveld refinement, complex chemical bond theory is used to establish the correlation between structural characteristics and microwave performance in this ceramic system. A small amount of Ni²⁺ (x?=?0.06) in A-site with the fixed substitution of Ta⁵⁺ in B-site can effectually raise the Q?×?f value of ZnZrNb₂O₈ ceramic, embodying a dense microstructure and high lattice energy. The dielectric constant and τ_f are mainly affected by bond ionicity and the average octahedral distortion. The (Zn_0.94Ni_0.06)ZrNbTaO₈ ceramic sample sintered at 1150?°C for 3?h exhibits an outstanding combination of microwave dielectric properties: ε_r =?27.88, Q?×?f?=?128,951?GHz, τ_f =?–39.9?ppm/°C. Thus, it is considered to be a candidate material for the communication device applications at high frequency.     

Microwave dielectric properties of SnO2-doped CaSiO3 ceramics

SnO₂-doped CaSiO₃ ceramics were successfully synthesized by a solid-state method. Effects of different SnO₂ additions on the sintering behavior, microstructure and dielectric properties of Ca(Sn_1−xSi_x)O₃ (x=0.5–1.0) ceramics have been investigated. SnO₂ improved the densification process and expanded the sintering temperature range effectively. Moreover, Sn⁴⁺ substituting for Si⁴⁺ sites leads to the emergence of Ca₃SnSi₂O₉ phase, which has a positive effect on the dielectric properties of CaO–SiO₂–SnO₂ materials, especially the Qf value. The Ca(Sn_0.1Si_0.9)O₃ ceramics sintered at 1375 °C possessed good microwave dielectric properties: ε_r =7.92, Qf =58,000 GHz and τ_f=−42 ppm/°C. The Ca(Sn_0.4Si_0.6)O₃ ceramics sintered at 1450 °C also exhibited good microwave dielectric properties of ε_r=9.27, Qf=63,000 GHz, and τ_f=−52 ppm/°C. Thus, they are promising candidate materials for millimeter-wave devices.