SiO2 Glass Ceramics Research Articles

Synthesis of highly dispersed metallic bismuth nanoparticles in CuO–Bi2O3–SiO2 glass-ceramics for sodium ion battery anode

The formation of bismuth and copper nanoparticles from CuO–Bi2O3–SiO2 glass by heat treatment in the presence of hydrogen and their functionality as anode active material in sodium ion batteries was examined. Oxides consisting of xCuO-(85-x)Bi2O3–15SiO2 (mol%) vitrify in the composition range of x from 5 to 30. In compositions with large amounts of copper oxide (x > 35), Cu2O crystallizes, suggesting the presence of Cu+ and Cu2+ with different valence states in the glass. Heat treatment in a mixed atmosphere of hydrogen and nitrogen resulted in the crystallization of bismuth oxide and their reduction to form glass ceramics with dispersed bismuth and copper particles. As bismuth and copper are consumed from the glass matrix by phase separation, a cross-linked structure of silica develops in residual glass matrix. The resulting bismuth particles was small in size than borate-based glass ceramics, indicating that the cross-linked silicates have an inhibiting effect on bismuth grain growth. Charge-discharge tests in a sodium ion battery showed a reversible charge-discharge profile without the initial irreversible reaction of bismuthate reduction.

Sintering behaviors, microstructure and properties of CaO–B2O3–SiO2 glass-ceramics for LTCC applications

The aim of this work was to investigate the impacts of MgO on the crystalline behaviors, microstructure, and properties of CaO–B2O3–SiO2 (CBS) glass-ceramics. In the study, the CBS samples with various MgO contents were developed via the melting and quenching route. Subsequently, a CBS casting tape and a multi-layered LTCC microcircuit module were created by using the tape casting method. Results indicated that MgO could break the glass network and promote the formation of liquid phase during the sintering process. A suitable amount of MgO additive promoted densification during firing process and improved the properties of the CBS materials. The CBS sample with 1.5 wt% MgO fired at 875 °C exhibited outstanding properties, including a dielectric constant (εr) of 6.5 (at 10 GHz), a dielectric loss (tan δ) of 8 × 10−4, a flexural strength of 167 MPa, a coefficient of thermal expansion (CTE) of 6.8 ppm/°C, and a thermal conductivity (λ) of 2.2 W/mK. In addition, this LTCC material demonstrated good co-firing compatibility with silver electrodes and superior temperature stability, showing its great potential for microelectronic applications.

The effect of degree of sintering on the structural and mechanical properties of Si3N4–SiO2 glass ceramics

Silica-based glass ceramics have been extensively used in biomedical applications due to their superior biocompatibility and controllable properties. However, their low mechanical strength limits their application. This could be addressed by optimizing the crystalline phase which determines their final properties. Silicon nitride has attracted attention due to its combination of good mechanical and biological properties. Therefore, to combine the advantage of silica-based glass and silicon nitride ceramic, this study developed a silicon nitride-silicon dioxide (Si3N4–SiO2) glass ceramics. The effects of spark plasma sintering parameters on the structural and mechanical properties of Si3N4–SiO2 glass ceramics were investigated. Full densification was reached at a sintering temperature of 1300 °C, a holding time of 10 min and an applied pressure of 80 MPa (relative density = 99.19 %). No silicon oxynitride (Si2N2O) crystalline phase was formed in the sintered glass ceramics, as confirmed by XRD. The interface between the β-Si3N4 crystalline and amorphous SiO2 was investigated by HRTEM, and the results indicated that an amorphous interfacial oxide was formed at the interface. The mechanical properties increased with increasing sintering temperature, as a result of the increased density. The Si3N4–SiO2 glass ceramics sintered at 1500 °C exhibited the highest value of toughness and flexural strength, at 4.6 ± 0.28 MPa m1/2 and 360 ± 27 MPa. The indentation cracks observed by SEM showed that the large β-Si3N4 grains promoted crack deflection, while the equiaxed Si3N4 grains with a lower aspect ratio led to transgranular fracture. The mechanical properties of these Si3N4–SiO2 glass ceramics are comparable to commercial glass ceramics, indicating their promising aspects in biomedical applications.

A novel Gd2O3–Al2O3–SiO2 glass-ceramics substrate material with comprehensive performance

A novel Gd2O3–Al2O3–SiO2 glass-ceramics (GAS GCS) for substrate application was prepared using the melt-quenching method. The present study pay attention to investigate the crystallization and sintering behaviors, phase compositions, micromorphology, dielectric and mechanical properties of GAS glass-ceramics. An appropriate amount of Gd2O3 diminished the glass viscosity while enhancing structural stability, thereby reducing the activation energy for crystallization and sintering. This contributed to the GAS GCS achieve dense microstructure and high crystallinity. X-ray diffraction (XRD) and Raman spectroscopy analyses confirmed the presence of high-density crystal phases, namely Gd2SiO5 and Gd2Si2O7, which significantly contribute to the enhanced density of the samples. Moreover, a positive correlation was observed between the dielectric constant and crystallinity. Notably, the GAS GCS composition of 41 wt% Gd2O3-21.3 wt% Al2O3-37.7 wt% SiO2 exhibited optimal properties, including a flexural strength of 243.4 MPa, Vickers hardness of 7.77 GPa, elastic modulus of 154.02 GPa, coefficient of thermal expansion of 5.9 × 10−6/°C, dielectric constant of 7.43, and dielectric loss of 4.05 × 10−3. These outstanding characteristics position it as a promising candidate for substrate materials.

Effects of Cr2O3 doping on crystallization behavior and electrochemical properties of Li2O–Al2O3–TiO2–P2O5–SiO2 glass-ceramics

Bulk glass-ceramic solid electrolytes of the Li2O–Al2O3–TiO2–P2O5–SiO2 system were prepared by melt-quenching and one-step heat treatment method in this work. The effects of the gradual substitution of Al3+ by Cr3+ and the elevation of the heat treatment temperature on the phase composition, microstructure, and ionic conductivity of the solid electrolytes were systematically investigated. The results show that the major crystalline phase is LiTi2(PO4)3, and the conductivity of the glass-ceramics initially enhances and then decreases as the Cr2O3 content increases from 0 mol% to 3 mol%. The highest conductivity is obtained when the Cr2O3 content is 2 mol%, measuring 4.45 × 10−4 S/cm at 25 °C. Additionally, the mechanism of the surface exfoliation of the glass-ceramics and the enhancement achieved by doping with Cr3+ are explained according to microstructure analysis. This work provides a simple method to enhance the electrical conductivity and physical properties of LATP glass-ceramic solid electrolytes, which is of great significance for the design of lithium-ion solid electrolytes.

Crystallization behavior and properties of ZnO–MgO–Al2O3–SiO2 transparent glass-ceramics with SnO2 and ZrO2 as nucleating agents

Transparent ZnO–MgO–Al2O3–SiO2 (ZMAS) glass-ceramics comprising ZrO2 and SnO2 as nucleating agents were prepared via melting and two-step heat treatment. The effects of varying the SnO2 concentration (1–3 mol%) on the crystallization behavior, microstructures, and mechanical properties of the glass-ceramics were investigated. Increasing the SnO2 content promoted the precipitation of spinel and gahnite because SnO2 improved the formation of ZrO2 nanocrystals, which provided nucleation sites for subsequent crystallization. When the SnO2 content was varied between 2 and 3 mol%, the crystallization behavior of the ZMAS glass-ceramics showed little difference, and SnO2 crystals precipitated from the glass at a relatively low crystallization temperature. In addition, glass-ceramics containing 2 and 3 mol% SnO2 exhibited average grain sizes of ∼26 and ∼29 nm, respectively, but their transmittance decreased to ∼52% and ∼50%, respectively, owing to grain aggregation. The best overall performance was achieved when the SnO2 content of the glass-ceramic was 3 mol% and heat treatment was conducted at 780 °C for 3 h and 960 °C for 2 h, with the resulting glass-ceramic exhibiting a bending strength of ∼187 MPa and a Vickers hardness of ∼845 kgf/mm2.

Insight into the structure and crystallization of SiO2-Al2O3-P2O5-Na2O-MgO-CaO glass system with Mg-Ca substitution: A molecular dynamics study

Transparent glass ceramics (TGCs) have shown great prospects in many application fields. Understanding the effect of oxides on glass network structure and crystallization is essential for designing TGCs. A series of 18Na2O-(16-x)CaO-xMgO-3P2O5-2.5Al2O3-60.5SiO2 (mol%, x = 0, 4, 8, 12, 16) glass-ceramics were studied with Molecular dynamics (MD) simulations, and the effect of CaO substituted by MgO on the glass structure and crystallization was analyzed in details. The results show that MgO statistically behaves as a network former, and the overall network connectivity increases with the substitution of MgO for CaO. Further structure analysis shows that the complex glass system consists of Si-rich and P-rich phases, which respectively contain Si-Mg-rich regions with 2Mg1Si-related tricluster oxygens (TBOs) and P-Mg-rich regions. The energetically unfavorable TBOs and Mg4-O-Mg4 linkages provide favorable nucleation sites for homogeneous nucleation, and the so-called ‘Coordination matching’ principles are proposed to explain the type of crystals. These results help us understand the crystallization of Mg-containing glass ceramics and benefit the future design of novel spontaneous TGCs.

Radio-photoluminescence Properties of Sm-doped HfO2–Al2O3–SiO2 Glass Ceramics

Radio-photoluminescence Properties of Sm-doped HfO2–Al2O3–SiO2 Glass Ceramics

Effect of heating rate on crystallisation and properties of R2O–CaO–MgO–CuO–Al2O3–SiO2 glass-ceramics

R2O–CaO–MgO–CuO–Al2O3–SiO2 (RNa, K) glass-ceramics were fabricated using the melt-quenching method and the effect of heating rate on the microstructure and properties of the glass-ceramics was investigated. The results demonstrated that the main crystal phase of the samples was clinoenstatite, and the secondary crystal phases were forsterite and diopside. With an increase in heating rate, the diffraction peak intensity of clinoenstatite gradually increased, and the morphology of the particles changed from short columns to long needles. When the heating rate was 1 °C/min, the sample exhibited flexural strength and Vickers hardness of 7.38 GPa and 84.33 MPa, respectively. When the heating rate was 10 °C/min, the Cu+ content in the sample reached the maximum of 2.1 wt%, which is 1.4 times of Cu+ in the brown sample obtained by heat-treatment at 1 °C/min. The colour of the sample intensified as the heating rate was increased from 1 °C/min to 20 °C/min, and the sample heated at 10 °C/min was brownish-red. The heating rate has a significant effect on the colour of glass-ceramics with the same CuO content, providing a new approach for regulating the colour of glass-ceramics. Further, this study has significant prospects in enriching the colour of glass-ceramics for architectural decoration and reducing production costs.

Unveiling the effect of phase separation on crystallization of calcium borosilicate glass-ceramics

The CaO–B2O3–SiO2(CBS) glass-ceramics with low sintering temperature and good microwave dielectric properties have been applied on the famous commercial low temperature co-fired ceramics (LTCC) Tape for passivation substrate materials for 5G/6G technology. However, the phase separation and its relationship with the crystallization is rarely studied but extremely important for understanding and designing the high-performance CBS glass-ceramics. Herein, we find that the phase separation type of CBS glass-ceramics changes from metastable immiscibility to stable immiscibility with the increase of B2O3 content. In the metastable immiscible glass-ceramics, three phases are observed, including continuous borate-rich and silicate-rich phases as well as spherical silicate-rich phases. In the stable immiscible glass-ceramics, the silicate-rich phases transform into petal-liked shapes. β-CaSiO3 nuclei are formed in fractions with BO3/SiO4 equaling to 0.56. Notably the β-CaSiO3 nucleus do not grow after heat treatment at 850 °C, but grow at higher temperatures. Phase separation hinders the precipitation of β-CaSiO3 and promoted the formation of CaB2O4 and SiO2. In addition, interfacial defects caused by phase separation alter the crystal barrier and promote the formation of α-CaSiO3. However, α-CaSiO3 dissolves at 1000 °C and may provide Ca2+ cations together with the borate-rich phase for the regrowth of β-CaSiO3. Our work provides another perspective for understanding the effects of phase separation on crystallization in CBS glass-ceramics, contributing to improving the microwave dielectric performance by structural design.

Effect of partial substitution of Ta2O5 by ZrO2 on the structure and ionic conductivity of Li2O-Ta2O5-2 SiO2 glass and glass-ceramics

LiTaSiO5 system is considered as type of solid electrolyte with great potential for application as ionic conductor. It is well-known that it is difficult to obtain pure dense LiTaSiO5 phase by traditional synthesis methods, because dielectric LiTaO3 phase easily precipitates during synthesis, which affects ionic conductivity. In this work, a glass-ceramic electrolyte with main LiTaSiO5 phase was obtained by controlled crystallization of Li2OTa 2O5-2 SiO2 glass without porosity. The precipitation of LiTaO3 phase at the grain boundary was effectively inhibited by adding an appropriate amount of ZrO2. Among all the glass-ceramic samples, the glass containing 4.76mol% ZrO2 had the maximum ionic conductivity of 8.40 ? 10?6 S/cm at 25?C, which is two order of magnitude greater than the ionic conductivity of the matrix glass. These glass-ceramic samples have the potential to be used as solid electrolytes in electrochemical applications.

Influence of sintering atmosphere on the formation of ZrSiO4 by solid‐state sintering method

AbstractExploring the influence of sintering atmosphere on the formation of ZrSiO4 is of great significance. Herein, ZrSiO4 ceramics were prepared by the solid‐state reactive sintering method under different atmospheres (air, N2, vacuum, and Ar + 5%H2). The influence of sintering atmosphere on the phase and microstructure evolutions of the obtained ceramics was investigated. It was found that ZrSiO4 ceramics could be prepared under air atmosphere, whereas ZrO2–SiO2 glass ceramics were obtained under N2, vacuum, and Ar + 5%H2 atmosphere, which may be due to the fact that the oxygen‐deficient environment inhibits the transformation of ZrO2 to tetragonal phase (t‐ZrO2) and the crystallization of amorphous SiO2. The results demonstrated that t‐ZrO2 and c‐SiO2 were beneficial for the formation of ZrSiO4. The ZrSiO4 conversion fraction was up to 96.16% under air atmosphere at 1450°C for 6 h. Furthermore, the predominant formation mechanism of ZrSiO4 was the reaction between t‐ZrO2 and c‐SiO2.

Effects of CaO additive on sintering behaviour and properties of CaO–B2O3–SiO2 glass-ceramics for LTCC applications

The effects of CaO additive on the phase composition, sintering behaviour, microstructure, and properties of CaO–B2O3–SiO2 (CBS) glass-ceramics were investigated. The results revealed that a small amount of added CaO (0.5 wt%, 1 wt%) facilitated the transformation of α-CaSiO3 to β-CaSiO3 and improved the crystallinity. When the amount was greater than 1 wt%, it weakened this transformation and also decreased the crystallinity. The pure CBS sample needed a sintering temperature of 850 °C for maximum densification, whereas the CaO-added samples achieved densification at a sintering temperature of 750–770 °C. The addition of an appropriate amount of CaO significantly enhanced the densification, dielectric properties, and flexural strength of CBS glass-ceramics. However, the addition of CaO had minimal impact on the coefficient of thermal expansion (CTE), which varied from 7.69 to 8.51 ppm/°C. The sample doped with 1 wt% CaO was sintered at 770 °C for 15 min, and it exhibited fairly ideal performance with a bulk density of 2.64 g/cm3, εr of 6.43, tanδ of 0.9 × 10−3 (15 GHz), and a CTE value of 7.69 ppm/°C.

Optical and scintillation properties of the Eu2O3-doped HfO2-Al2O3–SiO2 glass ceramics

In this study, Eu-doped 10HfO2–10Al2O3–80SiO2 glass ceramics with different Eu concentrations were prepared by the melt-quenching method using an optical floating zone furnace, and optical and scintillation properties were investigated to apply them for radiation detectors. All the glass ceramic samples were transparent, although they included not only an amorphous phase but also a crystal phase of cubic-HfO2. Photoluminescence and scintillation peaks due to Eu2+ were detected at 400–550 nm. In the glass ceramic samples with higher Eu concentration, the luminescence of Eu3+ was also observed. Quantum yields and afterglow levels decreased with increasing Eu concentration. The 1.0% Eu-doped sample had the highest light yield among all our glass samples, and the light yield was 630 photons/MeV under γ-ray irradiation from 137Cs.

Densification and microstructure of a ZrO2–SiO2 glass-ceramic prepared by using mesoporous particles as raw powder

Ceramic sintering is an energy-consuming process. Reducing sintering temperature and shortening dwelling time are significant to the reduction of carbon footprint. It has been reported that utilizing mesoporous particles as raw powder for sintering is a promising strategy to achieve the above goal. The goal of this study is to verify if this strategy also works for the sintering of ZrO2–SiO2 glass-ceramics. We synthesized mesoporous particles through a micelle-assisted co-precipitation process, followed by sintering by fast hot pressing (FHP) and pressureless sintering (PS) to obtain ZrO2–SiO2 glass-ceramics. For comparison, solid particles without mesopores were synthesized by a sol-gel method and consolidated by the two sintering techniques. The densification behaviors of the two types of particles were comparatively investigated. Results showed that the mesopores collapsed at ∼850 °C during FHP due to the applied pressure, which resulted in a peak densification rate during the whole sintering process. The mesoporous particles (∼820 °C) had a lower densification starting temperature than that of the solid particles (∼910 °C). However, the mesoporous particles showed a longer densification process and a lower average densification rate than those of the solid particles. The samples sintered from mesoporous particles showed a heterogeneous microstructure, predominately consisting of ZrO2 nanocrystallites embedded in a SiO2 matrix, but in some regions ZrO2 sub-microcrystallites were connected with each other by grain boundaries, without the presence of SiO2 matrix. During PS, there was not significant differences in the densification between the mesoporous particles and the solid ones. These results demonstrated that the mesoporous particles did not show significant advantages over solid ones, in terms of the densification of ZrO2–SiO2 glass-ceramics.

Effect of Ti/P ratio on structure, crystallization behaviour and photocatalytic activity of MgO–TiO2–P2O5–Al2O3–SiO2 glass-ceramics

In the present work, MgO–TiO2–P2O5–Al2O3–SiO2 glasses with different Ti/P ratios were prepared by the melt-quenching method, and Mg0.5Ti2(PO4)3 glass-ceramics were obtained by controllable crystallization. The effects of the Ti/P ratio on the structure, crystallization behaviour, and properties of the glasses and glass-ceramics were studied by FTIR, DSC, XRD, EDS, UV–Vis DRS, and so on. The results show that with the increase of the Ti/P ratio, the content of the [TiO6] group and Ti–O–P bond in the glass network increases, which strengthens the cross-linking of the glass network. However, the decrease of glass former P2O5 reduces the thermal stability of the glass. The appropriate Ti/P ratio is beneficial to the formation of single-phase glass-ceramics, and the band gap width of glass-ceramics containing single Mg0.5Ti2(PO4)3 crystal phase is 3.0 eV. With the irradiation of a high-pressure mercury lamp for 120 min, the glass-ceramics after crystallization at 850 °C for 4 h can effectively degrade MB dye solution (41%∼75%). The potential application prospect of the prepared glass-ceramics in the field of water purification of organic dyes was confirmed.

Particle size modulation for effectively optimizing the dielectric and mechanical properties of La2O3–B2O3 based glass-ceramic/ceramic LTCC substrates

Lanthanum borate-based glass-ceramic has recently received considerable attention in the field of high-frequency communications as a sintering aid, due to the low sintering temperature and the precipitation of crystalline phases with excellent dielectric and mechanical properties. Importantly, the densification and crystallization behaviors of glass-ceramic are not only determined by its composition, but also affected by various processing parameters, such as the initial particle size, which is rarely explored for optimizing the dielectric and mechanical properties of lanthanum borate-based glass-ceramic/ceramic composites. Herein, La2O3–B2O3–CaO–P2O5–SiO2 (LBCPS) glass-ceramics with a series of initial particle sizes are achieved by ball milling method through controlling the milling time. Employing LBCPS glass-ceramics with different particle sizes as the sintering aid, various LBCPS/Al2O3 composites are fabricated, and the dielectric and mechanical properties of which are further investigated. Notably, the LBCPS/Al2O3 composite with a moderate glass-ceramic particle size of 2.7 μm exhibits the excellent comprehensive performance with a low dielectric loss of 8.6 × 10−4 at 9.8 GHz and a high flexural strength of 199 MPa. Moreover, the influencing mechanisms of the glass-ceramic particle size on the crystallization, microstructure, and densification of the LBCPS/Al2O3 composite have also been systematically explored and proposed. This research work provides an intriguing strategy for optimizing the dielectric and mechanical properties of the glass-ceramic/ceramic as the high-performance low-temperature co-fired ceramic (LTCC) substrate.

Relationship between the structural and dielectric properties of sol-gel derived CaO–MgO–B2O3–SiO2 glass-ceramics for 5G applications in the millimeter-wave bands

In this study, CaO–MgO–B2O3–SiO2 glass-ceramics were fabricated using a sol–gel method, and their dielectric properties in the millimeter-wave (mm-wave) bands were evaluated. The glass transition temperature of the as-prepared CaO–MgO–B2O3–SiO2 glass-ceramics decreased slightly with increasing MgO/CaO ratio because the field strength of Mg2+ ions was higher than that of Ca2+ ions. After sintering at 900–950 °C, only orthorhombic CaB2O4 or monoclinic Mg2B2O5 crystallites were observed in the X-ray diffraction (XRD) patterns of the glass-ceramics, depending on the MgO/CaO ratio. The Fourier-transform infrared and Raman spectra of the glass-ceramics confirmed the XRD results. The quantity and grain size of crystallites and the content and size of pores of the glass-ceramics decreased with increasing MgO/CaO ratio. The CaO–MgO–B2O3–SiO2 glass-ceramics exhibited excellent mm-wave dielectric properties. For example, the 7.3CaO‒7.2MgO‒22.2B2O3‒63.3SiO2 glass-ceramic exhibited a dielectric constant of 4.21 and a dielectric loss of 0.0025 at 60 GHz, a breakdown strength of 14.9 kV/mm, an electric resistivity of 7.64 × 1013 Ω cm, a coefficient of thermal expansion of 4.0 ppm/°C, and a thermal conductivity of 1.29 W/mK. The low-dielectric-constant and low-loss characteristics of the MgO–CaO–B2O3–SiO2 glass-ceramics prepared in this study enables to provide very low propagation delay of signals and to offer low signal attenuation in 5 G applications.

Tuning energy storage and light transmittance properties in ZrO2-modified Na2O–K2O–Nb2O5–SiO2 glass-ceramics

Crystallization kinetics in ZrO2-modified glass-ceramics, (35-x)Na2O–5K2O–40Nb2O5–20SiO2-xZrO2 (x = 0, 1, 3, 5, 10 mol%), is analyzed by crystallization activation energy Ec and kinetic parameter k. A large kinetic parameter k of 1.657 × 1025 is found for the sample with x = 1, which indicates a high tendency toward crystallization. NaNbO3 is formed as the major phase, and its crystallinity changes significantly by the addition of ZrO2. It is found that the dielectric permittivity and maximum polarization are affected by crystallinity. Large domains are formed, and a relaxation process appears at high frequencies. In addition, the breakdown strength (BDS) is affected by the strong electric field distortion rather than the resistance in this system. Complex impedance analysis shows that resistance decreases with the addition of ZrO2. The electric field distortion of the glass-ceramics is simulated by COMSOL. A low interfacial polarization activation energy Ea of 0.821 eV is achieved by the addition of ZrO2. The maximum pulse power density reaches 90 MW/cc at 350 kV/cm for the sample with x = 10, and the pulse energy density attains 0.91 J/cm3 at 300 kV/cm for the sample with x = 1. Light transmittance is achieved because of the low crystallinity and the disappearance of cristobalite SiO2 in the Na2O–K2O–Nb2O5–SiO2 glass-ceramics.

Tailoring microwave-millimeter-wave dielectric and mechanical properties in CaO–SiO2 glass-ceramics by P2O5 nucleating agent

Glass-ceramics have demonstrated excellent dielectric properties in low-temperature co-fired ceramic (LTCC) technology used in 5G/6G wireless devices. This work studies the mechanical strengths and dielectric properties from microwave to millimeter-wave frequencies in the CaO–SiO2 glass-ceramics modified via the P2O5 as a nucleating agent. The β-wollastonite phase was identified as the primary structure with the preferred (202‾) orientation and parallel plate-like structure in the matrix as P2O5 content increases up to 3.5∼5.5 wt%. The P2O5 nucleating agent increases degree of long-range crystallization. Elevated mechanical flexural strength of approximately 170 MPa, hardness of ∼720 MPa, and outstanding high-frequency dielectric properties were obtained in the 3.5–5.5 wt% P2O5-added CaO–SiO2 glass-ceramics, due to the enhanced interatomic Si–O bonding in the network. The improved mechanical and dielectric characteristics of the P2O5–added CaO–SiO2 glass-ceramics make the crystallized wollastonite materials for the 5G/6G devices possible.