Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples ...Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples at a relatively low temperature(170℃)using the cold sintering process(CSP)with AgNO_(3)solution as a transient liquid agent.The effect of AgNO_(3)addition during CSP on the micro-structure and TE properties was investigated.The results from phase,composition and microstructure analyses showed that the introduc-tion of AgNO_(3)solution induced the formation of Ag nano-precipitates within the Ag_(2)Se matrix.Although the nano-precipitates do not af-fect the phase and crystal structure of orthorhombicβ-Ag_(2)Se,they suppressed crystal growth,leading to reduced crystallite sizes.The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density.Consequently,these effects contributed to sig-nificantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorpor-ated.This resulted in an improved average power factor from~1540μW·m^(−1)·K^(−2)for pure Ag_(2)Se to~1670μW·m^(−1)·K^(−2)for Ag_(2)Se with additional Ag precipitates.However,excessive Ag addition had a detrimental effect on the power factor.Furthermore,thermal conductiv-ity was effectively suppressed in Ag_(2)Se fabricated using AgNO_(3)-assisted CSP,attributed to enhanced phonon scattering at crystal inter-faces,pores,and Ag nano-precipitates.The highest figure-of-merit(zT)of 0.92 at 300 K was achieved for the Ag_(2)Se with 0.5wt%Ag dur-ing CSP fabrication,equivalent to>20%improvement compared to the controlled Ag_(2)Se without extra Ag solution.Thus,the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag_(2)Se and enhance its TE performance at room temperature.展开更多
A high voltage gradient(V_(g))of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices.However,improving V_(g) of ZnObased varistor ceramics through conventi...A high voltage gradient(V_(g))of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices.However,improving V_(g) of ZnObased varistor ceramics through conventional high-temperature sintering process remains a significant challenge.Here,we present a strategy to fabricate ultrahigh voltage-gradient ZnO-based varistor ceramics by combining cold sintering process/spark plasma sintering(CSP–SPS)with post-annealing process.Employing CSP–SPS,the ZnO-based varistor ceramics were initially densified at 300℃ and subsequently annealed at a low temperature of 700–900℃.CSP–SPS technique combined with a low annealing temperature enables the production of ZnO-based varistor ceramics with fine and homogeneous microstructures,while suppressing the volatilization of Bi-rich phases at grain boundaries.This approach achieves the ultrahigh V_(g) of~1832.71 V/mm,high nonlinear coefficient(α)of~106.69,and low leakage current density(J_(L))of less than 0.2μA/cm^(2).This work shows that the integration of CSP–SPS and post-annealing provides a promising way to design ZnO-based varistor ceramics with ultrahigh V_(g).展开更多
Cold sintering is a newly developed low-temperature sintering technique that has attracted extensive attention in the fabrication of functional materials and devices.Low sintering temperatures allow for a substantial ...Cold sintering is a newly developed low-temperature sintering technique that has attracted extensive attention in the fabrication of functional materials and devices.Low sintering temperatures allow for a substantial reduction in energy consumption,and simple experimental equipment offers the possibility of large-scale fabrication.The cold sintering process(CSP)has been demonstrated to be a green and cost-effective route to fabricate thermoelectric(TE)materials where significant grain growth,secondary phase formation,and element volatilization,which are prone to occur during high-temperature sintering,can be well controlled.In this review,the historical development,understanding,and application of thermoelectric materials produced via cold sintering are highlighted.The latest attempts related to the cold sintering process for thermoelectric materials and devices are discussed and evaluated.Despite some current technical challenges,cold sintering provides a promising and sustainable route for the design of advanced high-performance thermoelectrics.展开更多
Dielectric materials,such as barium titanate(BT)-based materials,have excellent dielectric properties but require high temperatures(above 1300℃)for ceramic fabrication,leading to high costs and energy loss.The cold s...Dielectric materials,such as barium titanate(BT)-based materials,have excellent dielectric properties but require high temperatures(above 1300℃)for ceramic fabrication,leading to high costs and energy loss.The cold sintering process(CSP)offers a solution to these issues and is gaining worldwide attention as an innovative fabrication route.In this work,we proposed an alternative organic ferroelectric phase,gamma-glycine(γ-GC),which acts as a transient liquid phase to fabricate high-density composites with barium titanate(BT)at low temperatures through CSP.Our findings show that the density of 15γ-GC/85BT reached 96.7%±1.6%when it was sintered at 120℃for 6 h under 10 MPa uniaxial pressure.Scanning electron microscopy‒energy dispersive X-ray spectroscopy(SEM‒EDS)mappings of the composite suggested thatγ-GC completely underwent the precipitation-dissolution process and,therefore,filled between BT particles.Moreover,X-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR)confirmed the preservation ofγ-GC without undesired phase transformation.In addition,the ferroelectric and dielectric properties ofγ-GC/BT composites have been reported.The high dielectric constant(ε_(r))was 3600,and the low dielectric loss(tanδ)was 1.20 at 200℃and 100 kHz for the 15γ-GC/85BT composite.The hysteresis loop showed a remanent polarization(P_(r))of 0.55µC·cm^(−2)and a coercive field(E_(c))of 7.25 kV·cm^(−1).Our findings reaffirmed that an organic ferroelectric material(γ-GC)can act as a transient liquid phase in a CSP that can successfully and sustainably fabricateγ-GC/BT composites at low temperatures while delivering outstandingly high performance.展开更多
A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperatur...A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperature 300℃ under uniaxial pressure in the presence of small amount o f transient liquid.The fabricated composite achieved as high as 98.65% of the theoretical density.The NaCl-Al2O3 composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750℃-850℃ together with a holding period o f 24h at 850℃.X-ray diffraction measurements indicated congruent solubility o f the alumina in chloride salt,excellent compatibility o f NaCl with Al2O3,and chemical stability at high temperature.Structural analysis by scanning electron microscope also showed limited grain growth,high density,uniform NaCl distribution and clear faceted composite structure without inter-diffusion.The latent heat storage density o f 252.5J/g was obtained from simultaneous thermal analysis.Fracture strength test showed high sintered strength around 5 GPa after 50 min.The composite was found to have fair mass losses due to volatilization.Overall,cold sintering process has the potential to be an efficient,safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.展开更多
In traditional ceramic processing techniques,high sintering temperature is necessary to achieve fully dense microstructures.But it can cause various problems including warpage,overfiring,element evaporation,and polymo...In traditional ceramic processing techniques,high sintering temperature is necessary to achieve fully dense microstructures.But it can cause various problems including warpage,overfiring,element evaporation,and polymorphic transformation.To overcome these drawbacks,a novel processing technique called“tcold sintering process(CSP)”has been explored by Randall et al.CSP enables densification of ceramics at ultra-low temperature(<300℃)with the assistance o f transient aqueous solution and applied pressure.In CSP,the processing conditions including aqueous solution,pressure,temperature,and sintering duration play critical roles in the densification and properties of ceramics,which will be reviewed.The review will also include the applications of CSP in solid-state rechargeable batteries.Finally,the perspectives about CSP is proposed.展开更多
Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fab...Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods.Herein,we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method,cold sintering process(CSP),at 300℃.(1–x)ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol%are densified with relative density of over 97%.Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases,which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites.For the 60 vol%ZnO–40 vol%PTFE ceramic composite,superhydrophobic properties are optimized with static water contact angles(WCAs)and sliding angles(SAs)of 162°and 7°,respectively.After abrading into various thicknesses(2.52,2.26,and 1.99 mm)and contaminating with graphite powders on the surface,WCA and SA are still maintained with a high level of 157°–160°and 7°–9.3°,respectively.This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.展开更多
Glass with high visible-light transparency is widely considered as the most important optical material,which typically requires a processing temperature higher than 1000℃.Here,we report a translucent aluminosilicate ...Glass with high visible-light transparency is widely considered as the most important optical material,which typically requires a processing temperature higher than 1000℃.Here,we report a translucent aluminosilicate glass that can be prepared by cold sintering process(CSP)at merely 300℃.After eliminating structural pores in hexagonal faujasite(EMT)-type zeolite by heat treatment,the obtained highly active nanoparticles are consolidated to have nearly full density by adding NaOH solution as liquid aids.However,direct densification of EMT powder cannot remove the structural pores of zeolite completely,leading to an opaque compact after the CSP.It is proved that the chemical reaction between the NaOH-and zeolite-derived powders is highly beneficial to dissolution–precipitation process during sintering,leading to the ultra-low activation energy of 27.13 kJ/mol.Although the addition of 5 M NaOH solution greatly promotes the densification via the reaction with aluminosilicate powder,lower or higher concentration of solvent can deteriorate the transmittance of glass.Additionally,the CSP-prepared glass exhibits a Vickers hardness of 4.3 GPa,reaching 60%of the reported value for spark plasma sintering(SPS)-prepared sample.展开更多
This study demonstrates the successful fabrication of solid-state bilayers using LiFePO_(4)(LFP)cathodes and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)-based Composite Solid Electrolytes(CSEs)via Cold Sintering Proces...This study demonstrates the successful fabrication of solid-state bilayers using LiFePO_(4)(LFP)cathodes and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)-based Composite Solid Electrolytes(CSEs)via Cold Sintering Process(CSP).By optimizing the sintering pressure,it is achieved an intimate contact between the cathode and the solid electrolyte,leading to an enhanced electrochemical performance.Bilayers cold sintered at 300 MPa and a low-sintering temperature of 150℃exhibit high ionic conductivities(0.5 mS cm^(-1))and stable specific capacities at room temperature(160.1 mAh g^(-1)LFP at C/10 and 75.8 mAh g^(-1)_(LFP)at 1 C).Moreover,an operando electrochemical impedance spectroscopy(EIS)technique is employed to identify limiting factors of the bilayer kinetics and to anticipate the overall electrochemical behavior.Results suggest that capacity fading can occur in samples prepared with high sintering pressures due to a volume reduction in the LFP crystalline cell.This work demonstrates the potential of CSP to produce straightforward high-performance bilayers and introduces a valuable non-destructive instrument for understanding and avoiding degradation in solid-state lithium-based batteries.展开更多
The cold sintering process(CSP)is an advanced low-temperature sintering technology whose effectiveness is closely related to the selection of transient liquid phases(TLPs).While water serves as an ideal TLP for water-...The cold sintering process(CSP)is an advanced low-temperature sintering technology whose effectiveness is closely related to the selection of transient liquid phases(TLPs).While water serves as an ideal TLP for water-soluble ceramics,most water-insoluble materials necessitate acids,bases,or specialized solvents instead.This limitation has severely restricted the application of CSP,as many water-insoluble ceramics cannot be densified due to the lack of suitable TLPs.This study demonstrates a breakthrough approach that exploits nanoscale effects to enable water to act as an effective TLP for the densification of water-insoluble Li_(2)TiO_(3)ceramics.A comparison of nano(19.71 nm)and microscale Li_(2)TiO_(3)powders under identical sintering conditions revealed that despite the exceptionally low aqueous solubility of Li_(2)TiO_(3),the nanopowders achieved 94.33%relative density at only 300°C and 700 MPa,whereas the micropowders attained only 78%density.Further analysis revealed a distinctive densification mechanism that integrates dislocation-mediated plastic deformation with localized dissolution phenomena at nanoparticle interfaces.Compared with conventional sintering(1000°C),the resulting nanoceramics exhibited superior Vickers hardness(905 HV)and enhanced electrical conductivity while maintaining a refined nanoscale grain structure(26.42 nm).This study established an effective strategy for the cold sintering of water-insoluble ceramics with layered structures using water as a TLP,significantly expanding the applicability of CSP technology and offering new pathways for the energy-efficient fabrication of advanced functional ceramics.展开更多
Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susc...Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susceptibility to degradation and failure when exposed to ambient environment significantly hampers their widespread applications.Herein,we reported an effective strategy to encapsulate CsPbBr_(3)nanocrystals into robust KBr matrix via cold sintering process at 120℃.The well prepared translucent CsPbBr_(3)@KBr ceramic displays a narrow green photoluminescence(with a fullwidth at half-maximum of~22 nm)and an quantum yield of 73.6%with remarkable thermal stability.By incorporating red emitting K_(2)SiF_(4):Mn^(4+)phosphor into the KBr matrix,the color gamut of the constructed white LED improves to 118%of the National Television System Committee(NTSC)standard,suggesting that the thermally robust and narrow-band green emitter holds significant promise for widecolor-gamut liquid crystal displays.展开更多
Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to...Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat.However,achieving adequate thermal conductivity(k)in ceramics sintered at low temperatures is challenging.In this study,we employed the cold sintering process(CSP)to fabricate Li_(2)MoO_(4)-x%Al_(2)O_(3)(0≤x≤80,in volume)ceramics under 200 MPa pressure at 150℃.The Li_(2)MoO_(4)-40%Al_(2)O_(3)composite exhibited significantly enhanced k of 5.4 W·m^(-1)·K^(-1),an 80%increase compared to pure Li_(2)MoO_(4)ceramic with k of 3 W·m^(-1)·K^(-1).At 40%Al_(2)O_(3)content,the Li_(2)MoO_(4)eAl_(2)O_(3)ceramic demonstrated notable microwave properties(ε~6.67,Q×f~17,846 GHz,tf~^(-1)05×10^(-6)℃^(-1)).Additionally,simulation of a microstrip patch antenna for 5 GHz applications using Li_(2)MoO_(4)-20%Al_(2)O_(3)ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance,with radiation efficiency exceeding 99%and low return loss(S_(11)<-30 dB)at both 4.9 GHz and 28.0 GHz center frequencies.These findings underscore the suitability of Li_(2)MoO_(4)eAl_(2)O_(3)ceramics for microwave dielectric substrate.展开更多
The cold sintering process(CSP)and Bi_(2)O_(3)-activated liquid-phase sintering(LPS)are combined to densify Mg-doped NASICON(Na_(3.256)Mg_(0.128)Zr_(1.872)Si_(2)PO_(12))to achieve high densities and conductivities at ...The cold sintering process(CSP)and Bi_(2)O_(3)-activated liquid-phase sintering(LPS)are combined to densify Mg-doped NASICON(Na_(3.256)Mg_(0.128)Zr_(1.872)Si_(2)PO_(12))to achieve high densities and conductivities at reduced temperatures.As an example,a cold-sintered specimen with the addition of 1.1wt%Bi_(2)O_(3)sintering additive achieved a high conductivity of 0.91 mS/cm(with~96%relative density)after annealing at 1000℃;this conductivity is>70%higher than that of a cold-sintered specimen without adding the Bi_(2)O_(3)sintering additive,and it is>700%of the conductivity of a dry-pressed counterpart with the same amount of Bi_(2)O_(3)added,all of which are subjected to the same heating profile.The highest conductivity achieved in this study via combining CSP and Bi_(2)O_(3)-activated LSP is>1.5 mS/cm.This study suggests an opportunity to combine the new CSP with the traditional LPS to sinter solid electrolytes to achieve high densities and conductivities at reduced temperatures.This combined CSP-LPS approach can be extended to a broad range of other materials to fabricate the“thermally fragile”solid electrolytes or solid-state battery systems,where reducing the processing temperature is often desirable.展开更多
With the rapid development of the electronics industry,the demand for dielectric materials with high permittivities,low losses,and excellent electrical breakdown strengths prepared via low-temperature fabrication tech...With the rapid development of the electronics industry,the demand for dielectric materials with high permittivities,low losses,and excellent electrical breakdown strengths prepared via low-temperature fabrication techniques is increasing.Herein,we propose a one-step cold sintering process route to improve the comprehensive performance of BaTiO_(3)−based ceramics by integrating polyetherimide(PEI).Dense BaTiO_(3)–PEI nanocomposites can be prepared via a cold sintering process at 250℃ using Ba(OH)_(2)∙8H_(2)O and H_(2)TiO_(3) as the transient liquid phase.The grain growth of BaTiO_(3) is inhibited,and thin PEI layers less than 10 nm in size are located at the grain boundaries.The dissolution‒precipitation process triggered by the transient liquid phase and viscous flow assisted by PEI dominates the cold sintering mechanism of the(1−x)BaTiO_(3)–xPEI nanocomposites.The dielectric properties are stable over a broad temperature range up to 200℃.Compared with BaTiO_(3),80%BaTiO_(3)–20%PEI has superior performance,with a relative permittivity of 163 and a low dielectric loss of 0.014,and the electrical breakdown strength is increased by 80.65%compared with BaTiO_(3).Overall,the cold sintering process provides a potential way to develop dielectric nanocomposites with excellent comprehensive performance.展开更多
Internal stress engineering has demonstrated remarkable potential in enhancing the mechanical and functional properties of ceramics.However,conventional regulation strategies relying on mismatch of thermal expansion c...Internal stress engineering has demonstrated remarkable potential in enhancing the mechanical and functional properties of ceramics.However,conventional regulation strategies relying on mismatch of thermal expansion coefficient encounter great challenges in terms of precise stress modulation and material selection.Recently,a novel internal stress regulation approach exploiting the mismatch of elastic modulus has been proposed to effectively break these limitations.Through precisely controlled external pressure during cold sintering process,the incorporated secondary phase with ultra-high modulus enables the creation of tunable internal stress reaching gigapascal in the matrix.This stress engineering strategy gives rise to significantly enhanced mechanical properties and unique functional characteristics of the ceramic matrix,which might greatly influence the future design of high-performance ceramic composites.展开更多
基金supported by the National Research Council of Thailand(NRCT)(Nos.N42A650237 and N41A661163)the National Science,Research and Innovation Fund(NSRF)via the Fundamental Fund of Khon Kaen Universitythe NSRF via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(No.B37G660011).
文摘Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples at a relatively low temperature(170℃)using the cold sintering process(CSP)with AgNO_(3)solution as a transient liquid agent.The effect of AgNO_(3)addition during CSP on the micro-structure and TE properties was investigated.The results from phase,composition and microstructure analyses showed that the introduc-tion of AgNO_(3)solution induced the formation of Ag nano-precipitates within the Ag_(2)Se matrix.Although the nano-precipitates do not af-fect the phase and crystal structure of orthorhombicβ-Ag_(2)Se,they suppressed crystal growth,leading to reduced crystallite sizes.The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density.Consequently,these effects contributed to sig-nificantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorpor-ated.This resulted in an improved average power factor from~1540μW·m^(−1)·K^(−2)for pure Ag_(2)Se to~1670μW·m^(−1)·K^(−2)for Ag_(2)Se with additional Ag precipitates.However,excessive Ag addition had a detrimental effect on the power factor.Furthermore,thermal conductiv-ity was effectively suppressed in Ag_(2)Se fabricated using AgNO_(3)-assisted CSP,attributed to enhanced phonon scattering at crystal inter-faces,pores,and Ag nano-precipitates.The highest figure-of-merit(zT)of 0.92 at 300 K was achieved for the Ag_(2)Se with 0.5wt%Ag dur-ing CSP fabrication,equivalent to>20%improvement compared to the controlled Ag_(2)Se without extra Ag solution.Thus,the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag_(2)Se and enhance its TE performance at room temperature.
基金supported by the Joint Funds of the National Natural Science Foundation of China(No.U23B20115)the Fok Ying-Tong Education Foundation,China(No.171050)。
文摘A high voltage gradient(V_(g))of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices.However,improving V_(g) of ZnObased varistor ceramics through conventional high-temperature sintering process remains a significant challenge.Here,we present a strategy to fabricate ultrahigh voltage-gradient ZnO-based varistor ceramics by combining cold sintering process/spark plasma sintering(CSP–SPS)with post-annealing process.Employing CSP–SPS,the ZnO-based varistor ceramics were initially densified at 300℃ and subsequently annealed at a low temperature of 700–900℃.CSP–SPS technique combined with a low annealing temperature enables the production of ZnO-based varistor ceramics with fine and homogeneous microstructures,while suppressing the volatilization of Bi-rich phases at grain boundaries.This approach achieves the ultrahigh V_(g) of~1832.71 V/mm,high nonlinear coefficient(α)of~106.69,and low leakage current density(J_(L))of less than 0.2μA/cm^(2).This work shows that the integration of CSP–SPS and post-annealing provides a promising way to design ZnO-based varistor ceramics with ultrahigh V_(g).
基金Jinxue Ding acknowledges financial support from the China Scholarship Council(No.202106290061)Jing Guo is thankful for the financial support provided by the Natural Science Foundation of Shaanxi Province,China(No.2024JC-YBMS-349)+1 种基金Wei Li and Yanqin Fu appreciate the financial support provided by the TU Darmstadt Career Bridging Grant.Wenjie Xie and Anke Weidenkaff are grateful for the financial support from the Seed-funding of TUDa(Project-ID:40101580)the DAAD Förderprogramme(Project-ID:57610929).
文摘Cold sintering is a newly developed low-temperature sintering technique that has attracted extensive attention in the fabrication of functional materials and devices.Low sintering temperatures allow for a substantial reduction in energy consumption,and simple experimental equipment offers the possibility of large-scale fabrication.The cold sintering process(CSP)has been demonstrated to be a green and cost-effective route to fabricate thermoelectric(TE)materials where significant grain growth,secondary phase formation,and element volatilization,which are prone to occur during high-temperature sintering,can be well controlled.In this review,the historical development,understanding,and application of thermoelectric materials produced via cold sintering are highlighted.The latest attempts related to the cold sintering process for thermoelectric materials and devices are discussed and evaluated.Despite some current technical challenges,cold sintering provides a promising and sustainable route for the design of advanced high-performance thermoelectrics.
基金supported by King Mongkut’s Institute of Technology Ladkrabang(KMITL)under Grant Nos.KREF116501 and 2567-02-05-020funded by Grant No.KREF016412+2 种基金supported by the National Research Council of Thailand(NRCT)through Grant No.N42A650220support from the School of Science at KMITL.T.Bongkarn acknowledges financial assistance from Naresuan University,the National Science,Research,and Innovation Fund(NSRF)under Grant No.R2567B001the Global and Frontier Research University Fund at Naresuan University(NU)under Grant No.R2567C001.
文摘Dielectric materials,such as barium titanate(BT)-based materials,have excellent dielectric properties but require high temperatures(above 1300℃)for ceramic fabrication,leading to high costs and energy loss.The cold sintering process(CSP)offers a solution to these issues and is gaining worldwide attention as an innovative fabrication route.In this work,we proposed an alternative organic ferroelectric phase,gamma-glycine(γ-GC),which acts as a transient liquid phase to fabricate high-density composites with barium titanate(BT)at low temperatures through CSP.Our findings show that the density of 15γ-GC/85BT reached 96.7%±1.6%when it was sintered at 120℃for 6 h under 10 MPa uniaxial pressure.Scanning electron microscopy‒energy dispersive X-ray spectroscopy(SEM‒EDS)mappings of the composite suggested thatγ-GC completely underwent the precipitation-dissolution process and,therefore,filled between BT particles.Moreover,X-ray diffraction(XRD)and Fourier-transform infrared spectroscopy(FTIR)confirmed the preservation ofγ-GC without undesired phase transformation.In addition,the ferroelectric and dielectric properties ofγ-GC/BT composites have been reported.The high dielectric constant(ε_(r))was 3600,and the low dielectric loss(tanδ)was 1.20 at 200℃and 100 kHz for the 15γ-GC/85BT composite.The hysteresis loop showed a remanent polarization(P_(r))of 0.55µC·cm^(−2)and a coercive field(E_(c))of 7.25 kV·cm^(−1).Our findings reaffirmed that an organic ferroelectric material(γ-GC)can act as a transient liquid phase in a CSP that can successfully and sustainably fabricateγ-GC/BT composites at low temperatures while delivering outstandingly high performance.
文摘A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperature 300℃ under uniaxial pressure in the presence of small amount o f transient liquid.The fabricated composite achieved as high as 98.65% of the theoretical density.The NaCl-Al2O3 composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750℃-850℃ together with a holding period o f 24h at 850℃.X-ray diffraction measurements indicated congruent solubility o f the alumina in chloride salt,excellent compatibility o f NaCl with Al2O3,and chemical stability at high temperature.Structural analysis by scanning electron microscope also showed limited grain growth,high density,uniform NaCl distribution and clear faceted composite structure without inter-diffusion.The latent heat storage density o f 252.5J/g was obtained from simultaneous thermal analysis.Fracture strength test showed high sintered strength around 5 GPa after 50 min.The composite was found to have fair mass losses due to volatilization.Overall,cold sintering process has the potential to be an efficient,safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.
文摘In traditional ceramic processing techniques,high sintering temperature is necessary to achieve fully dense microstructures.But it can cause various problems including warpage,overfiring,element evaporation,and polymorphic transformation.To overcome these drawbacks,a novel processing technique called“tcold sintering process(CSP)”has been explored by Randall et al.CSP enables densification of ceramics at ultra-low temperature(<300℃)with the assistance o f transient aqueous solution and applied pressure.In CSP,the processing conditions including aqueous solution,pressure,temperature,and sintering duration play critical roles in the densification and properties of ceramics,which will be reviewed.The review will also include the applications of CSP in solid-state rechargeable batteries.Finally,the perspectives about CSP is proposed.
基金The authors acknowledge the support from the funding of the National Natural Science Foundation of China(Grant No.51877016)the Fok Ying-Tong Education Foundation,China(Grant No.171050)Science and Technology Project of State Grid Co.,Ltd.,China(Grant No.5500-202399372A-2-2-ZB).
文摘Composite coatings or films with polytetrafluoroethylene(PTFE)are typically utilized to offer superhydrophobic surfaces.However,the superhydrophobic surfaces usually have limited durability and require complicated fabrication methods.Herein,we report the successful integration of PTFE with ZnO ceramics to achieve superhydrophobicity via a one-step sintering method,cold sintering process(CSP),at 300℃.(1–x)ZnO–x PTFE ceramic composites with x ranging from 0 to 70 vol%are densified with relative density of over 97%.Micro/nano-scale PTFE polymer is dispersed among ZnO grains forming polymer grain boundary phases,which modulate surface morphology and surface energy of the ZnO–PTFE ceramic composites.For the 60 vol%ZnO–40 vol%PTFE ceramic composite,superhydrophobic properties are optimized with static water contact angles(WCAs)and sliding angles(SAs)of 162°and 7°,respectively.After abrading into various thicknesses(2.52,2.26,and 1.99 mm)and contaminating with graphite powders on the surface,WCA and SA are still maintained with a high level of 157°–160°and 7°–9.3°,respectively.This work indicates that CSP provides a promising pathway to integrate polymers with ceramics to realize stable superhydrophobicity.
基金financially supported by the National Natural Science Foundation of China(No.52122203).
文摘Glass with high visible-light transparency is widely considered as the most important optical material,which typically requires a processing temperature higher than 1000℃.Here,we report a translucent aluminosilicate glass that can be prepared by cold sintering process(CSP)at merely 300℃.After eliminating structural pores in hexagonal faujasite(EMT)-type zeolite by heat treatment,the obtained highly active nanoparticles are consolidated to have nearly full density by adding NaOH solution as liquid aids.However,direct densification of EMT powder cannot remove the structural pores of zeolite completely,leading to an opaque compact after the CSP.It is proved that the chemical reaction between the NaOH-and zeolite-derived powders is highly beneficial to dissolution–precipitation process during sintering,leading to the ultra-low activation energy of 27.13 kJ/mol.Although the addition of 5 M NaOH solution greatly promotes the densification via the reaction with aluminosilicate powder,lower or higher concentration of solvent can deteriorate the transmittance of glass.Additionally,the CSP-prepared glass exhibits a Vickers hardness of 4.3 GPa,reaching 60%of the reported value for spark plasma sintering(SPS)-prepared sample.
基金support from Generalitat Valenciana under Pla Complementari“Programa de Materials Avanc¸ats”,2022(grant number MFA/2022/030)Ministerio de Ciencia,Innovaci´on y Universidades(Spain)(grant number MCIN/AEI/10.13039/501100011033)+1 种基金support from UJI(UJI-2023-16 and GACUJIMC/2023/08)Generalitat Valenciana through FPI Fellowship Program(grant numbers ACIF/2020/294 and CIACIF/2021/050).
文摘This study demonstrates the successful fabrication of solid-state bilayers using LiFePO_(4)(LFP)cathodes and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)-based Composite Solid Electrolytes(CSEs)via Cold Sintering Process(CSP).By optimizing the sintering pressure,it is achieved an intimate contact between the cathode and the solid electrolyte,leading to an enhanced electrochemical performance.Bilayers cold sintered at 300 MPa and a low-sintering temperature of 150℃exhibit high ionic conductivities(0.5 mS cm^(-1))and stable specific capacities at room temperature(160.1 mAh g^(-1)LFP at C/10 and 75.8 mAh g^(-1)_(LFP)at 1 C).Moreover,an operando electrochemical impedance spectroscopy(EIS)technique is employed to identify limiting factors of the bilayer kinetics and to anticipate the overall electrochemical behavior.Results suggest that capacity fading can occur in samples prepared with high sintering pressures due to a volume reduction in the LFP crystalline cell.This work demonstrates the potential of CSP to produce straightforward high-performance bilayers and introduces a valuable non-destructive instrument for understanding and avoiding degradation in solid-state lithium-based batteries.
基金supported by the Natural Science Foundation of Sichuan Province of China(No.2023NSFSC5889).
文摘The cold sintering process(CSP)is an advanced low-temperature sintering technology whose effectiveness is closely related to the selection of transient liquid phases(TLPs).While water serves as an ideal TLP for water-soluble ceramics,most water-insoluble materials necessitate acids,bases,or specialized solvents instead.This limitation has severely restricted the application of CSP,as many water-insoluble ceramics cannot be densified due to the lack of suitable TLPs.This study demonstrates a breakthrough approach that exploits nanoscale effects to enable water to act as an effective TLP for the densification of water-insoluble Li_(2)TiO_(3)ceramics.A comparison of nano(19.71 nm)and microscale Li_(2)TiO_(3)powders under identical sintering conditions revealed that despite the exceptionally low aqueous solubility of Li_(2)TiO_(3),the nanopowders achieved 94.33%relative density at only 300°C and 700 MPa,whereas the micropowders attained only 78%density.Further analysis revealed a distinctive densification mechanism that integrates dislocation-mediated plastic deformation with localized dissolution phenomena at nanoparticle interfaces.Compared with conventional sintering(1000°C),the resulting nanoceramics exhibited superior Vickers hardness(905 HV)and enhanced electrical conductivity while maintaining a refined nanoscale grain structure(26.42 nm).This study established an effective strategy for the cold sintering of water-insoluble ceramics with layered structures using water as a TLP,significantly expanding the applicability of CSP technology and offering new pathways for the energy-efficient fabrication of advanced functional ceramics.
基金supported by the National Natural Science Foundation of China(No.52350443 and No.52122203)the Natural Science Foundation of Shanghai(No.21ZR1400300).
文摘Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susceptibility to degradation and failure when exposed to ambient environment significantly hampers their widespread applications.Herein,we reported an effective strategy to encapsulate CsPbBr_(3)nanocrystals into robust KBr matrix via cold sintering process at 120℃.The well prepared translucent CsPbBr_(3)@KBr ceramic displays a narrow green photoluminescence(with a fullwidth at half-maximum of~22 nm)and an quantum yield of 73.6%with remarkable thermal stability.By incorporating red emitting K_(2)SiF_(4):Mn^(4+)phosphor into the KBr matrix,the color gamut of the constructed white LED improves to 118%of the National Television System Committee(NTSC)standard,suggesting that the thermally robust and narrow-band green emitter holds significant promise for widecolor-gamut liquid crystal displays.
基金supported by National Natural Science Foundation of China(No.52361165625)Shenzhen Science and Technology Program,Guangdong Province,China(Nos.KQTD20180411143514543,JCYJ20220818100613029,and JSGGZD20220822095603006)We acknowledge the support of Project 2019CX01C079 of Guangdong Province。
文摘Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat.However,achieving adequate thermal conductivity(k)in ceramics sintered at low temperatures is challenging.In this study,we employed the cold sintering process(CSP)to fabricate Li_(2)MoO_(4)-x%Al_(2)O_(3)(0≤x≤80,in volume)ceramics under 200 MPa pressure at 150℃.The Li_(2)MoO_(4)-40%Al_(2)O_(3)composite exhibited significantly enhanced k of 5.4 W·m^(-1)·K^(-1),an 80%increase compared to pure Li_(2)MoO_(4)ceramic with k of 3 W·m^(-1)·K^(-1).At 40%Al_(2)O_(3)content,the Li_(2)MoO_(4)eAl_(2)O_(3)ceramic demonstrated notable microwave properties(ε~6.67,Q×f~17,846 GHz,tf~^(-1)05×10^(-6)℃^(-1)).Additionally,simulation of a microstrip patch antenna for 5 GHz applications using Li_(2)MoO_(4)-20%Al_(2)O_(3)ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance,with radiation efficiency exceeding 99%and low return loss(S_(11)<-30 dB)at both 4.9 GHz and 28.0 GHz center frequencies.These findings underscore the suitability of Li_(2)MoO_(4)eAl_(2)O_(3)ceramics for microwave dielectric substrate.
基金acknowledge partial support by a Vannevar Bush Faculty Fellowship sponsored by the Basic Research Office of the Assistant Secretary of Defense for Research and Engineering and funded by the Office of Naval Research through grant N00014-16-1-2569.
文摘The cold sintering process(CSP)and Bi_(2)O_(3)-activated liquid-phase sintering(LPS)are combined to densify Mg-doped NASICON(Na_(3.256)Mg_(0.128)Zr_(1.872)Si_(2)PO_(12))to achieve high densities and conductivities at reduced temperatures.As an example,a cold-sintered specimen with the addition of 1.1wt%Bi_(2)O_(3)sintering additive achieved a high conductivity of 0.91 mS/cm(with~96%relative density)after annealing at 1000℃;this conductivity is>70%higher than that of a cold-sintered specimen without adding the Bi_(2)O_(3)sintering additive,and it is>700%of the conductivity of a dry-pressed counterpart with the same amount of Bi_(2)O_(3)added,all of which are subjected to the same heating profile.The highest conductivity achieved in this study via combining CSP and Bi_(2)O_(3)-activated LSP is>1.5 mS/cm.This study suggests an opportunity to combine the new CSP with the traditional LPS to sinter solid electrolytes to achieve high densities and conductivities at reduced temperatures.This combined CSP-LPS approach can be extended to a broad range of other materials to fabricate the“thermally fragile”solid electrolytes or solid-state battery systems,where reducing the processing temperature is often desirable.
基金supported by the Natural Science Foundation of Shaanxi Province,China(No.2024JC-YBMS-349)the Guangdong Provincial Key Laboratory Program(No.2021B1212040001)the staff at the Instrument Analysis Centre of Xi’an Jiaotong University for the XRD,FT-IR,and TEM measurements.We also thank Xiaohua Cheng from the School of Materials Science and Engineering,Xi’an Jiaotong University for SEM measurements.
文摘With the rapid development of the electronics industry,the demand for dielectric materials with high permittivities,low losses,and excellent electrical breakdown strengths prepared via low-temperature fabrication techniques is increasing.Herein,we propose a one-step cold sintering process route to improve the comprehensive performance of BaTiO_(3)−based ceramics by integrating polyetherimide(PEI).Dense BaTiO_(3)–PEI nanocomposites can be prepared via a cold sintering process at 250℃ using Ba(OH)_(2)∙8H_(2)O and H_(2)TiO_(3) as the transient liquid phase.The grain growth of BaTiO_(3) is inhibited,and thin PEI layers less than 10 nm in size are located at the grain boundaries.The dissolution‒precipitation process triggered by the transient liquid phase and viscous flow assisted by PEI dominates the cold sintering mechanism of the(1−x)BaTiO_(3)–xPEI nanocomposites.The dielectric properties are stable over a broad temperature range up to 200℃.Compared with BaTiO_(3),80%BaTiO_(3)–20%PEI has superior performance,with a relative permittivity of 163 and a low dielectric loss of 0.014,and the electrical breakdown strength is increased by 80.65%compared with BaTiO_(3).Overall,the cold sintering process provides a potential way to develop dielectric nanocomposites with excellent comprehensive performance.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030001)the National Natural Science Foundation of China(Nos.52002075 and 62204179).
文摘Internal stress engineering has demonstrated remarkable potential in enhancing the mechanical and functional properties of ceramics.However,conventional regulation strategies relying on mismatch of thermal expansion coefficient encounter great challenges in terms of precise stress modulation and material selection.Recently,a novel internal stress regulation approach exploiting the mismatch of elastic modulus has been proposed to effectively break these limitations.Through precisely controlled external pressure during cold sintering process,the incorporated secondary phase with ultra-high modulus enables the creation of tunable internal stress reaching gigapascal in the matrix.This stress engineering strategy gives rise to significantly enhanced mechanical properties and unique functional characteristics of the ceramic matrix,which might greatly influence the future design of high-performance ceramic composites.
