We report the world-leading performance of a 1.3 GHz cryomodule equipped with eight 9-cell superconducting radio-frequency cavities that underwent a medium-temperature furnace baking process.During continuous wave hor...We report the world-leading performance of a 1.3 GHz cryomodule equipped with eight 9-cell superconducting radio-frequency cavities that underwent a medium-temperature furnace baking process.During continuous wave horizontal testing,these cavities achieved unprecedented average intrinsic quality factors of 4.0×10^(10)at 20 MV/m and 3.2×10^(10)at 29 MV/m,with no instances of field emission.The cryomodule demonstrates near-complete preservation of ultra-high quality factors and ultra-high accelerating gradients from vertical to horizontal testing,marking a significant milestone in continuous-wave superconducting radio-frequency accelerator technology.This letter presents the cryomodule development experience,includ-ing cavity preparation,cryomodule assembly,degaussing,fast cooldown,and performance testing.展开更多
To address the challenge of achieving both high sensitivity and a high quality factor in quartz crystal microbalance(QCM)humidity sensors,a nanodiamond(ND)/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was fab...To address the challenge of achieving both high sensitivity and a high quality factor in quartz crystal microbalance(QCM)humidity sensors,a nanodiamond(ND)/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was fabricated.The material characteristics of ND,Ti_(3)C_(2)MXene,and ND/Ti_(3)C_(2)MXene composite were analyzed by transmission electron microscopy(TEM)and Fourier transform infrared(FTIR)spectroscopy.The experimental results demonstrated that the hydrophilic ND nanoparticles coated on Ti_(3)C_(2) MXene nanosheet prevented the self-stacking of Ti_(3)C_(2)MXene and enhanced the sensitivity of Ti_(3)C_(2) MXene-based QCM humidity sensor.Moreover,the high mechanical modulus of Ti_(3)C_(2) MXene material helped ND/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor to achieve a high quality factor(>20,000).ND/Ti_(3)C_(2)MXene compositecoated QCM humidity sensor exhibited a sensitivity of 82.45 Hz/%RH,a humidity hysteresis of 1.1%RH,fast response/recovery times,acceptable repeatability,and good stability from 11.3%RH to 97.3%RH.The response mechanism of ND/Ti_(3)C_(2) MXene composite-coated QCM humidity sensor was analyzed in combination with a bi-exponential kinetic adsorption model.Finally,the potential application of ND/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was demonstrated through its frequency response to wooden blocks with different moisture contents.展开更多
In order to significantly improve the absorption efficiency of monolayer molybdenum disulfide(M-MoS_(2)), an ultranarrowband M-MoS_(2)metamaterial absorber was obtained through theoretical analysis and numerical calcu...In order to significantly improve the absorption efficiency of monolayer molybdenum disulfide(M-MoS_(2)), an ultranarrowband M-MoS_(2)metamaterial absorber was obtained through theoretical analysis and numerical calculation using the finite difference time domain method. The physical mechanism can be better analyzed through critical coupling and guided mode resonance. Its absorption rate at λ = 806.41 nm is as high as 99.8%, which is more than 12 times that of bare MMoS_(2). From the simulation results, adjusting the geometric parameters of the structure can control the resonant wavelength range of the M-MoS_(2). In addition, we also found that the maximum quality factor is 1256.8. The numerical result shows that the design provides new possibilities for ultra-narrowband M-MoS_(2) perfect absorbers in the near-infrared spectrum.The results of this work indicate that the designed structure has excellent prospects for application in wavelength-selective photoluminescence and photodetection.展开更多
Combining bright-feld and edge-enhanced imaging affords an effective avenue for extracting complex morphological information from objects,which is particularly beneficial for biological imaging.Multiplexing metalenses...Combining bright-feld and edge-enhanced imaging affords an effective avenue for extracting complex morphological information from objects,which is particularly beneficial for biological imaging.Multiplexing metalenses present promising candidates for achieving this functionality.However,current multiplexing meta-lenses lack spectral modulation,and crosstalk between different wavelengths hampers the imaging quality,especilly for biological samples requiring precise wavelength specificity.Here,we experimentally demonstrate the nonlocal Huygens'meta-lens for high-quality-factor spin-multiplexing imaging.Quasi-bound states in the continuum(q-BlCs)are excited to provide a high quality factor of 90 and incident-angle dependence.The generalized Kerker condition,driven by Fano-like interactions between q-BIC and in-plane Mie resonances,breaks the radiation symmetry,resulting in a transmission peak with a geometric phase for polarization-converted light,while unconverted light exhibits a transmission dip without a geometric phase.Enhanced polarization conversion efficiency of 65%is achieved,accompanied by a minimal unconverted value,surpassing the theoretical limit of traditional thin nonlocal metasurfaces.Leveraging these effects,the output polarization-converted state exhibits an efficient wavelengthselective focusing phase profle.The unconverted counterpart serves as an effective spatial frequency filter based on incident-angular dispersion,passing high-frequency edge details.Bright-field imaging and edge detection are thus presented under two output spin states.This work provides a versatile framework for nonlocal metasurfaces,boosting biomedical imaging and sensing applications.展开更多
In superconducting circuit,microwave resonators and capacitors are crucial components,and their quality has a strong impact on circuit performance.Here we develop a novel wet etching process to define these two compon...In superconducting circuit,microwave resonators and capacitors are crucial components,and their quality has a strong impact on circuit performance.Here we develop a novel wet etching process to define these two components using common photoresist developer as etchant.This method reduces subsequent steps and can be completed immediately after development.By measuring the internal quality factor of resonators,we show that it is possible to achieve similar or better performance when compared with samples made by standard etching processes.This easy-to-implement method may boost the yield hence providing an alternative fabrication process for microwave resonators and capacitors.展开更多
Refractive index(RI)sensors play an important role in various applications including biomedical analysis and food processing industries.However,developing RI sensors with both high resolution and wide linear range rem...Refractive index(RI)sensors play an important role in various applications including biomedical analysis and food processing industries.However,developing RI sensors with both high resolution and wide linear range remains a great challenge due to the tradeoff between quality(Q)factor and free spectral range(FSR)of resonance mode.Herein,the optical steelyard principle is presented to address this challenge by synergizing resonances from the FabryPerot(FP)cavity and metasurface,integrated in a hybrid configuration form on the end facet of optical fibers.Specifically,the FP resonance acting like the scale beam,offers high resolution while the plasmonic resonance acting like the weight,provides a wide linear range.Featuring asymmetric Fano spectrum due to modal coupling between these two resonances,a high Q value(~3829 in liquid)and a sensing resolution(figure of merit)of 2664 RIU^(-1)are experimentally demonstrated.Meanwhile,a wide RI sensing range(1.3301.430 in the simulation and 1.34031.3757 in the experiment)is realized,corresponding to a spectral shift across several FSRs(four and two FSRs in the simulation and experiment,respectively).The proposed steelyard RI sensing strategy is promising in versatile monitoring applications,e.g.,water salinity/turbidity and biomedical reaction process,and could be extended to other types of sensors calling for both high resolution and wide linear range.展开更多
Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties sim...Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties simultaneously remains a difficult challenge due to their mutually restrictive relationship.Here 0.5Pb(Ni_(1/3)Nb_(2/3))O_(3)-0.5Pb(Zr_(0.3)Ti_(0.7))O_(3) piezoceramic with tetragonal(T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions.The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of P_(s),restrict domain wall motion and improve Q_(m).At the same time,the substituted Mn ions will introduce local random field,destroying the long-range or-dering of ferroelectric domain and reducing domain size.The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d_(33).Guided by this strategy,Q_(m) has increased by more than 10 times and d_(33) has only decreased by about 25%.The optimized electromechanical performance with Q_(m)=822,d_(33)=502 pC/N,k_(p)=0.55 and tanδ=0.0069 can be obtained in the present study.展开更多
We demonstrate that a moirésuperlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics,which is beneficial from the high-quality factor and high coupling efficiency ...We demonstrate that a moirésuperlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics,which is beneficial from the high-quality factor and high coupling efficiency of the flat-band mode with zero group velocity.From a silicon moirésuperlattice nanocavity integrated with few-layer gallium selenide(GaSe),the second-harmonic generation(SHG)of GaSe is enhanced by over 10,000 times,and the third-harmonic generation(THG)is enhanced by 8500 times.Our results suggest the moirésuperlattice nanocavity could be considered as a promising platform for developing high-efficiency nonlinear photonic devices.展开更多
A terahertz asymmetrically coupled resonator （ACR） consisting of two different split ring resonators （SRRs） was designed. Using finite difference time domain （FDTD）, the transmission of ACR and its refractive-in...A terahertz asymmetrically coupled resonator （ACR） consisting of two different split ring resonators （SRRs） was designed. Using finite difference time domain （FDTD）, the transmission of ACR and its refractive-index- based sensing performaance were simulated and analyzed. Results show that the ACR possesses a sharp coupled transparent peak or high quality factor （Q）, its intensity and bandwidth can be easily adjusted by spacing the two SRRs. Furthermore, the resonator exhibits high sensitivity of 75 GHz/RIU and figure of merit （FOM） of 4.4, much higher than the individual SRR sensors. The ACR were fabricated by using laser-induced and chemical non-electrolytic plating with copper on polyimide substrate, the transmission of which measured by terahertz time-domain spectroscopy system is in good agreement with simulations.展开更多
The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size limitations.In this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-spar...The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size limitations.In this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-sparse configuration is proposed to achieve a high quality factor(Q-factor)and uniform magnetic field,which ensures high efficiency and improves the misalignment tolerance for several-megahertz WPT systems.Furthermore,a closed-form expression for the Q-factor is provided and analyzed for coil optimization.By using this method,a TX-coil with an outer diameter of 100 mm and a wire diameter of 1.5 mm is designed and tested at 1 MHz.Finite element method simulations and experimental results demonstrate that the Q-factor is increased by about 8%in comparison with evenly spaced planar spiral coils,which is achieved while ensuring a relatively uniform magnetic field.展开更多
With high carrier mobility and intrinsic low lattice thermal conductivity,Ag_(2)Se compounds have attracted increasing attention for thermoelectric application near room temperature.Due to its phase transition at~406 ...With high carrier mobility and intrinsic low lattice thermal conductivity,Ag_(2)Se compounds have attracted increasing attention for thermoelectric application near room temperature.Due to its phase transition at~406 K and resulting thermal volume expansion,the growth and thermoelectric properties of large-sized Ag_(2)Se single crystals have seldom been reported so far.In this work,the vertical Bridgeman method was used for growing bulk Ag_(2)Se single crystal,with an orientation preference along lowsymmetric(201)plane.The Hall mobility as high as 2000 cm^(2)/(V·s)and weak electron-phonon coupling contributes to a high electronic quality BE of~7.0 in near-room-temperature b-Ag_(2)Se single crystals,which is superior to the high-temperature phase a-Ag_(2)Se.The observed low lattice thermal conductivity of 0.8 W/(m·K)at 300 K is due to the low group speeds and strong anharmonicity.A promising peak zT of 0.66 at 375 K and an average zT of 0.65 at 300-375 K were realized in b-Ag_(2)Se crystals.The low Vickers hardness and good ductile properties were confirmed by experiment and theoretical analysis.This work not only synthesized large-sized and highly-orientated Ag_(2)Se crystals,but also revealed its great potential of thermoelectric performance and mechanical properties for various applications near room temperature.展开更多
基金supported by Zhangjiang Laboratory,the SHINE R&D project(No.2017SHZDZX02)the SHINE projectthe National Natural Science Foundation of China(No.12125508).
文摘We report the world-leading performance of a 1.3 GHz cryomodule equipped with eight 9-cell superconducting radio-frequency cavities that underwent a medium-temperature furnace baking process.During continuous wave horizontal testing,these cavities achieved unprecedented average intrinsic quality factors of 4.0×10^(10)at 20 MV/m and 3.2×10^(10)at 29 MV/m,with no instances of field emission.The cryomodule demonstrates near-complete preservation of ultra-high quality factors and ultra-high accelerating gradients from vertical to horizontal testing,marking a significant milestone in continuous-wave superconducting radio-frequency accelerator technology.This letter presents the cryomodule development experience,includ-ing cavity preparation,cryomodule assembly,degaussing,fast cooldown,and performance testing.
基金financially supported by the Project funded by the National Natural Science Foundation of China(No.61401047)the China Postdoctoral Science Foundation(No.2018M633349)+1 种基金the Oversea Students Funding Project of the Department of Human Resources and Social Security of Sichuanthe Scientific Research Foundation of CUIT(No.KYQN202210)。
文摘To address the challenge of achieving both high sensitivity and a high quality factor in quartz crystal microbalance(QCM)humidity sensors,a nanodiamond(ND)/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was fabricated.The material characteristics of ND,Ti_(3)C_(2)MXene,and ND/Ti_(3)C_(2)MXene composite were analyzed by transmission electron microscopy(TEM)and Fourier transform infrared(FTIR)spectroscopy.The experimental results demonstrated that the hydrophilic ND nanoparticles coated on Ti_(3)C_(2) MXene nanosheet prevented the self-stacking of Ti_(3)C_(2)MXene and enhanced the sensitivity of Ti_(3)C_(2) MXene-based QCM humidity sensor.Moreover,the high mechanical modulus of Ti_(3)C_(2) MXene material helped ND/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor to achieve a high quality factor(>20,000).ND/Ti_(3)C_(2)MXene compositecoated QCM humidity sensor exhibited a sensitivity of 82.45 Hz/%RH,a humidity hysteresis of 1.1%RH,fast response/recovery times,acceptable repeatability,and good stability from 11.3%RH to 97.3%RH.The response mechanism of ND/Ti_(3)C_(2) MXene composite-coated QCM humidity sensor was analyzed in combination with a bi-exponential kinetic adsorption model.Finally,the potential application of ND/Ti_(3)C_(2)MXene composite-coated QCM humidity sensor was demonstrated through its frequency response to wooden blocks with different moisture contents.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11604311, 61705204, and 21506257)the Scientific Research Fund of Si Chuan Provincial Science and Technology Department, China (Grant Nos. 2020YJ0137 and 2020YFG0467)+1 种基金the National Defense Science and Technology Innovation Special Zone Project of China (Grant No. 19-163-21-TS-001-067-01)the College Students’s Innovation and Entrepreneurship Training Program (Grant No. S202110619065)。
文摘In order to significantly improve the absorption efficiency of monolayer molybdenum disulfide(M-MoS_(2)), an ultranarrowband M-MoS_(2)metamaterial absorber was obtained through theoretical analysis and numerical calculation using the finite difference time domain method. The physical mechanism can be better analyzed through critical coupling and guided mode resonance. Its absorption rate at λ = 806.41 nm is as high as 99.8%, which is more than 12 times that of bare MMoS_(2). From the simulation results, adjusting the geometric parameters of the structure can control the resonant wavelength range of the M-MoS_(2). In addition, we also found that the maximum quality factor is 1256.8. The numerical result shows that the design provides new possibilities for ultra-narrowband M-MoS_(2) perfect absorbers in the near-infrared spectrum.The results of this work indicate that the designed structure has excellent prospects for application in wavelength-selective photoluminescence and photodetection.
基金supported by the University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region,China[Project No.AoE/P-502/20,CRF Project:C5031-22G,GRF Project:CityU15303521,CityU11305223,CityU11300224]City University of Hong Kong[Project No.9380131 and 7005867]+3 种基金National Natural Science Foundation of China[Grant No.62375232]S.X.acknowledges financial support from National Natural Science Foundation of China(Grant Nos.62125501,and 6233000076)Fundamental Research Funds for the Central Universities(Grant No.2022FRRK030004)Shenzhen Fundamental Research Projects(Grant Nos.JCYJ20220818102218040).
文摘Combining bright-feld and edge-enhanced imaging affords an effective avenue for extracting complex morphological information from objects,which is particularly beneficial for biological imaging.Multiplexing metalenses present promising candidates for achieving this functionality.However,current multiplexing meta-lenses lack spectral modulation,and crosstalk between different wavelengths hampers the imaging quality,especilly for biological samples requiring precise wavelength specificity.Here,we experimentally demonstrate the nonlocal Huygens'meta-lens for high-quality-factor spin-multiplexing imaging.Quasi-bound states in the continuum(q-BlCs)are excited to provide a high quality factor of 90 and incident-angle dependence.The generalized Kerker condition,driven by Fano-like interactions between q-BIC and in-plane Mie resonances,breaks the radiation symmetry,resulting in a transmission peak with a geometric phase for polarization-converted light,while unconverted light exhibits a transmission dip without a geometric phase.Enhanced polarization conversion efficiency of 65%is achieved,accompanied by a minimal unconverted value,surpassing the theoretical limit of traditional thin nonlocal metasurfaces.Leveraging these effects,the output polarization-converted state exhibits an efficient wavelengthselective focusing phase profle.The unconverted counterpart serves as an effective spatial frequency filter based on incident-angular dispersion,passing high-frequency edge details.Bright-field imaging and edge detection are thus presented under two output spin states.This work provides a versatile framework for nonlocal metasurfaces,boosting biomedical imaging and sensing applications.
基金Project supported by the National Key R&D Program of China(Grant No.2016YFA0301802)the National Natural Science Foundation of China(Grant Nos.61521001 and 11890704)the Key R&D Program of Guangdong Province,China(Grant No.2018B030326001).
文摘In superconducting circuit,microwave resonators and capacitors are crucial components,and their quality has a strong impact on circuit performance.Here we develop a novel wet etching process to define these two components using common photoresist developer as etchant.This method reduces subsequent steps and can be completed immediately after development.By measuring the internal quality factor of resonators,we show that it is possible to achieve similar or better performance when compared with samples made by standard etching processes.This easy-to-implement method may boost the yield hence providing an alternative fabrication process for microwave resonators and capacitors.
基金support from the National Natural Science Foundation of China(62275221).
文摘Refractive index(RI)sensors play an important role in various applications including biomedical analysis and food processing industries.However,developing RI sensors with both high resolution and wide linear range remains a great challenge due to the tradeoff between quality(Q)factor and free spectral range(FSR)of resonance mode.Herein,the optical steelyard principle is presented to address this challenge by synergizing resonances from the FabryPerot(FP)cavity and metasurface,integrated in a hybrid configuration form on the end facet of optical fibers.Specifically,the FP resonance acting like the scale beam,offers high resolution while the plasmonic resonance acting like the weight,provides a wide linear range.Featuring asymmetric Fano spectrum due to modal coupling between these two resonances,a high Q value(~3829 in liquid)and a sensing resolution(figure of merit)of 2664 RIU^(-1)are experimentally demonstrated.Meanwhile,a wide RI sensing range(1.3301.430 in the simulation and 1.34031.3757 in the experiment)is realized,corresponding to a spectral shift across several FSRs(four and two FSRs in the simulation and experiment,respectively).The proposed steelyard RI sensing strategy is promising in versatile monitoring applications,e.g.,water salinity/turbidity and biomedical reaction process,and could be extended to other types of sensors calling for both high resolution and wide linear range.
基金financially supported by the National Natural Science Foundation of China(Nos.52172181 and22105017).
文摘Piezoelectric ceramics with high mechanical quality factor Q_(m) and large piezoelectric coefficient d_(33) are urgently required for advanced piezoelectric applications.However,obtaining both of these prop-erties simultaneously remains a difficult challenge due to their mutually restrictive relationship.Here 0.5Pb(Ni_(1/3)Nb_(2/3))O_(3)-0.5Pb(Zr_(0.3)Ti_(0.7))O_(3) piezoceramic with tetragonal(T)-rich MPB is designed as a matrix to construct the defect engineering by doping low-valent Mn ions.The strong coupling of defect dipole and T-rich phase can effectively hinder the rotation of P_(s),restrict domain wall motion and improve Q_(m).At the same time,the substituted Mn ions will introduce local random field,destroying the long-range or-dering of ferroelectric domain and reducing domain size.The miniaturized domain structure can increase poling efficiency and inhibit the reduction of d_(33).Guided by this strategy,Q_(m) has increased by more than 10 times and d_(33) has only decreased by about 25%.The optimized electromechanical performance with Q_(m)=822,d_(33)=502 pC/N,k_(p)=0.55 and tanδ=0.0069 can be obtained in the present study.
基金National Key Research and Development Program of China(2022YFA1404800)National Natural Science Foundation of China(12374359,62375225,62305270,62205273,62104198)+2 种基金Xi'an Science and Technology Plan Project(2023JH-ZCGJ-0023)Shaanxi Fundamental Science Research Project for Mathematics and Physics(22JSY004,22JSQ039)Key R&D Program of Shaanxi Province(2023-JC-YB-502)。
文摘We demonstrate that a moirésuperlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics,which is beneficial from the high-quality factor and high coupling efficiency of the flat-band mode with zero group velocity.From a silicon moirésuperlattice nanocavity integrated with few-layer gallium selenide(GaSe),the second-harmonic generation(SHG)of GaSe is enhanced by over 10,000 times,and the third-harmonic generation(THG)is enhanced by 8500 times.Our results suggest the moirésuperlattice nanocavity could be considered as a promising platform for developing high-efficiency nonlinear photonic devices.
文摘A terahertz asymmetrically coupled resonator （ACR） consisting of two different split ring resonators （SRRs） was designed. Using finite difference time domain （FDTD）, the transmission of ACR and its refractive-index- based sensing performaance were simulated and analyzed. Results show that the ACR possesses a sharp coupled transparent peak or high quality factor （Q）, its intensity and bandwidth can be easily adjusted by spacing the two SRRs. Furthermore, the resonator exhibits high sensitivity of 75 GHz/RIU and figure of merit （FOM） of 4.4, much higher than the individual SRR sensors. The ACR were fabricated by using laser-induced and chemical non-electrolytic plating with copper on polyimide substrate, the transmission of which measured by terahertz time-domain spectroscopy system is in good agreement with simulations.
基金Supported by the Key Program of National Natural Science Foundation of China(51437005).
文摘The structural optimization of coils is a key issue in wireless power transfer(WPT)applications owing to size limitations.In this study,a novel planar-spiral transmitter coil(TX-coil)with an outer-tight and inner-sparse configuration is proposed to achieve a high quality factor(Q-factor)and uniform magnetic field,which ensures high efficiency and improves the misalignment tolerance for several-megahertz WPT systems.Furthermore,a closed-form expression for the Q-factor is provided and analyzed for coil optimization.By using this method,a TX-coil with an outer diameter of 100 mm and a wire diameter of 1.5 mm is designed and tested at 1 MHz.Finite element method simulations and experimental results demonstrate that the Q-factor is increased by about 8%in comparison with evenly spaced planar spiral coils,which is achieved while ensuring a relatively uniform magnetic field.
基金National Natural Science Foundation of China(Grant No.52001231,52272006,U22A2073)the Shanghai Shuguang Program,the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions,the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission,Natural Science Foundation of Zhejiang Province(LY22A040001)+1 种基金S&T Innovation 2025 Major Special Program of Ningbo(2020Z054)Wenzhou Municipal Natural Science Foundation(G20210016).
文摘With high carrier mobility and intrinsic low lattice thermal conductivity,Ag_(2)Se compounds have attracted increasing attention for thermoelectric application near room temperature.Due to its phase transition at~406 K and resulting thermal volume expansion,the growth and thermoelectric properties of large-sized Ag_(2)Se single crystals have seldom been reported so far.In this work,the vertical Bridgeman method was used for growing bulk Ag_(2)Se single crystal,with an orientation preference along lowsymmetric(201)plane.The Hall mobility as high as 2000 cm^(2)/(V·s)and weak electron-phonon coupling contributes to a high electronic quality BE of~7.0 in near-room-temperature b-Ag_(2)Se single crystals,which is superior to the high-temperature phase a-Ag_(2)Se.The observed low lattice thermal conductivity of 0.8 W/(m·K)at 300 K is due to the low group speeds and strong anharmonicity.A promising peak zT of 0.66 at 375 K and an average zT of 0.65 at 300-375 K were realized in b-Ag_(2)Se crystals.The low Vickers hardness and good ductile properties were confirmed by experiment and theoretical analysis.This work not only synthesized large-sized and highly-orientated Ag_(2)Se crystals,but also revealed its great potential of thermoelectric performance and mechanical properties for various applications near room temperature.
