In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate （LAST） glass ceramics was investigated. Nanocrystallineβ-quartz solid solution （s.s.） was obse...In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate （LAST） glass ceramics was investigated. Nanocrystallineβ-quartz solid solution （s.s.） was observed to be the main phase crystallized in this system. Com-parable refractive indices of the glassy matrix andβ-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. Optical investi-gations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lat-tice, and the enhancement of structural arrangement degree, respectively.展开更多
Novel transparent ceramics of Zr^4+doped Ba(Mg,Ta)O3(BMT)with a high refractive index of 2.037 at 587.56 nm were successfully fabricated via high temperature solid-state-reaction sintering method.To make it transparen...Novel transparent ceramics of Zr^4+doped Ba(Mg,Ta)O3(BMT)with a high refractive index of 2.037 at 587.56 nm were successfully fabricated via high temperature solid-state-reaction sintering method.To make it transparent,the pure cubic Ba(Zr,Mg,Ta)O3phases(BZMT)were realized in advance by skillfully modulating the lattice structure of BMT from trigonal symmetric to cubic symmetric through doping Zr4 into the lattice of BMT crystal.Highly optical transmittance of 74%at 650 nm,which hit the upper limit of the theory,was achieved for BZMT.Both abbe number of 23.4 and the bandgap Eg of 3.22 eV have been calculated.展开更多
A neodymium doped yttrium aluminum gamet （Nd：YAG） transparent ceramic was fabricated by a solid state reaction method using commercial α-Al2O3, Y2O3, and Nd2O3 powders as starting materials and tetraethyl orthosil...A neodymium doped yttrium aluminum gamet （Nd：YAG） transparent ceramic was fabricated by a solid state reaction method using commercial α-Al2O3, Y2O3, and Nd2O3 powders as starting materials and tetraethyl orthosilicate （TEOS） as sintefing aid. The morphology and microstructure of the nanopowders and the Nd：YAG transparent ceramic were investigated. The fully dense Nd：YAG ceramic with an average grain size of-20 μm was obtained by vacuum sintering at 1720℃ for 12 h. Few pores and grain-boundary phases were observed. The in-line transmittance of the ceramic was 81.5% at 1064 nm.展开更多
Samarium doped Yttrium aluminum garnet (YAG) nanopowders with different concentration (0.5%, 1%, 2%, 3%, 5% and 8% mol) were prepared by simple and low cost co-precipitation method. We found that the precursor begins ...Samarium doped Yttrium aluminum garnet (YAG) nanopowders with different concentration (0.5%, 1%, 2%, 3%, 5% and 8% mol) were prepared by simple and low cost co-precipitation method. We found that the precursor begins converting to pure YAG at relatively low temperature around 900°C, and no intermediate phases were detected. The powders annealed at 900°C and 1000°C in air with average particle size around ≈30 nm were characterized by means of X-ray diffraction (XRD) analysis and infrared (IR) spectroscopy. The photoluminescent measurements showed that the reddish-orange (RO) emission transition 4G5/2:6H7/2 is more prominent. In addition, the optimum concentration of doped Sm ions that lead to maximum intensity was reported. Also, fluorescence efficiencies as pumping power dependence for different Sm3+ ions concentrations were explored.展开更多
The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated. The relative sintered densities, transmittances, color and the microstructure of the composit...The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated. The relative sintered densities, transmittances, color and the microstructure of the composite ceramics were studied. The experimental results showed that the relative sintered densities and transmittances decreased with alumina addition. The lightness increased obviously but the chroma change was small. Pure zirconia nanopowders sintered densely could obtain the relatively high transmittance, while the transmittance and the lightness of slight addition changed significantly. The zirconia/alumina composite ceramics with alumina addition less than 7.5wt% could achieve the relatively stable and reliable optical properties.展开更多
The polycrystalline ceramic Pb0.5Ba1.5BiVO6 manifesting the complex double perovskite structure was tailored by the conventional solid state route at a moderate temperature.Qualitative phase analysis and formation of ...The polycrystalline ceramic Pb0.5Ba1.5BiVO6 manifesting the complex double perovskite structure was tailored by the conventional solid state route at a moderate temperature.Qualitative phase analysis and formation of the ceramic were affirmed by XRD analysis.The X-ray powder diffraction pattern of the compound explored at room temperature affirms the single phase formation with double perovskite structure exhibiting rhombohedral phase.Microstructural analysis of the studied compound procured from the Scanning Electron Microscope(SEM)validates the formation of dense microstructures and nonuniformly distributed grains with minimal voids.Compositional analysis was shaped through the Electron Diffraction Spectroscopy(EDS)confirming the absence of con-tamination of any other metals apart from the mentioned ones.Dielectric(Cr and tanδ)parameters of the compound were studied using the LCR analyzer at different temperatures and wide range of frequencies.The polarization and dielectric study affirms the presence of ferroelectricity in the material with transition temperature much above the room temperature.The tangent dielectric loss of this sample being almost minimal at room temperature attributes it to find applications in different grounds of electronics.Optical equities of the ceramic were further analyzed by the RAMAN,FTIR,UV–Vis and Photoluminescence spectroscopy.展开更多
Faraday isolators can prevent the front-end system from disturbance and damage caused by a back-reflected beam,so they are important elements in laser systems.As magneto-optical materials are the most important compon...Faraday isolators can prevent the front-end system from disturbance and damage caused by a back-reflected beam,so they are important elements in laser systems.As magneto-optical materials are the most important component in Faraday isolators,the studies on magneto-optical materials have attracted much attention these years.Tb_(3)Al_(5)O_(12)(TAG)ceramics are considered to be one of the most promising magneto-optical materials for visible to near-infrared wavelength band application because of their outstanding comprehensive magneto-optical performance.However,the optical quality of TAG ceramics needs further optimization to meet the application requirements.In this work,high optical quality(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)(x=0,0.05,0.1,0.2,and 0.3)magneto-optical ceramics were fabricated successfully by solid-state reaction sintering combined with hot isostatic pressing(HIP)post-treatment.All the ceramics obtained showed a single garnet phase for different values of x in the range studied.The addition of Y_(2)O_(3) was found to suppress the secondary phase and improve optical quality significantly.The ceramic samples obtained had clear grain boundaries and possessed the in-line transmittance values of 82.9%at 1064 nm and 82.2%at 633 nm,respectively.The Verdet constants of(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)ceramics with x=0,0.05,0.1,0.2,and 0.3 were−188.1,−175.4,−168.5,−143.0,and−119.9 rad/(T·m),respectively.The thermal conductivity of TAG ceramics was found to be 5.23 W/(m·K)at 25℃,and when 20%Y was substituted in place of Tb,the thermal conductivity decreased by only 9.4%.展开更多
A chemical co-precipitation strategy was employed to synthesize a series of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12)(x=0.1−0.95)powder phosphors,followed by vacuum sintering to achieve transparent garnet ceramic ph...A chemical co-precipitation strategy was employed to synthesize a series of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12)(x=0.1−0.95)powder phosphors,followed by vacuum sintering to achieve transparent garnet ceramic phosphors.The density functional theory indicated Lu_(3)Al_(5)O_(12) was formed in priority compared with Gd_(3)Al_(5)O_(12) during solid-phase reaction.Upon high-temperature sintering,the Lu^(3+)substitution for Gd^(3+)suppressed point mass diffusion leading to a smaller grain size.The in-line transmittances of bulk specimens with x=0.1,0.3,0.5,0.7,and 0.95 nm were~83.5%,80.1%,68.8%,73.7%,and 82.2%at 710 nm(Eu^(3+)emission center),respectively,among which the sample of x=0.1 exhibited the optical grade with near-zero optical loss in agreement with the defect-free single crystal(~100%of the theoretical transmittance).The resulting particle and ceramic materials both presented characteristic Eu^(3+)emission arising from 5D0→7FJ(J=1−4)transition,where the dominant far-red emission at~710 nm arising from ^(5)D_(0)→^(7)F_(4) transition overlapped with the absorption of phytochrome(PFR).The photoluminescence excitation and photoluminescence intensities of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12) powders and ceramics generally increased at a higher Gd^(3+)/Lu^(3+)ratio.Lu^(3+)dopants delayed the fluorescence lifetime while the bulk samples had shorter lifetime compared to the particle counterparts.The transparent(Gd_(0.85)Lu_(0.1)Eu_(0.05))3Al_(5)O_(12) ceramic phosphor exhibited good thermal stability with a high thermal quenching temperature above 533 K.The designed ceramic phosphor-converted light-emitting diode had a saturation injection current of 435 mA and a current-dependent color rendering index.More importantly,our report marked the developmental stage of transparent ceramic materials towards zero optical loss.展开更多
Transparent YAG (yttrium aluminum garnet) ceramics were fabricated by solid-state reaction method. Effect of additive (tetraethyl orthosilicate, TEOS) on microstructure of YAG ceramics was investigated. If the additio...Transparent YAG (yttrium aluminum garnet) ceramics were fabricated by solid-state reaction method. Effect of additive (tetraethyl orthosilicate, TEOS) on microstructure of YAG ceramics was investigated. If the addition of TEOS is more than 3% (mass fraction), large amount of liquid phase can be yielded at grain boundaries, resulting in the formation of second phase particles at grain boundaries. If the addition is less than 0.05% (mass fraction), pores are entrapped in the grains. The suitable amount is 0.5% (mass fraction). A fully transparent YAG ceramic was fabricated by vacuum sintering at 1700 ℃ for 5 h. Optical transmittance of the YAG ceramic is 63% in the visible light wavelengths and 70% in the infrared wavelengths.展开更多
Ultraviolet(UV)radiation poses risks to both human health and organics.In response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding m...Ultraviolet(UV)radiation poses risks to both human health and organics.In response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite films.However,existing UV shielding materials,though suitable for daily use,cannot meet the demands of extreme conditions.In this work,we incorporated CeO_(2)as a UV absorber into Y_(2)O_(3)transparent ceramics for UV-shielding.The effect of CeO_(2)concentration on the optical,mechanical,and thermal properties of Y_(2)O_(3)ceramics was systematically investigated.These findings indicate that CeO_(2)serves not only as a UV absorber but also as an effective sintering aid for Y_(2)O_(3)transparent ceramics.The 5 at%Ce-doped Y_(2)O_(3)transparent ceramics exhibit the optimal optical quality,with in-line transmittance of~77%at 800 nm.The introduction of Ce shifted the UV cutoff edge of Y_(2)O_(3)transparent ceramics from 250 to 375 nm,which was attributed to the visible band absorption of Ce^(4+).This shift grants UV shielding capabilities to Y_(2)O_(3)transparent ceramics,resulting in 100%shielding for ultraviolet C(UVC,100-280 nm)and ultraviolet B(UVB,280-320 nm)and~95%shielding for ultraviolet A(UVA,320-400 nm).The service stability(optical properties)under various corrosive conditions(acid,alkali,UV irradiation,and high temperature)was investigated,confirming the excellent stability of this transparent ceramic UV-shielding material.A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses,films,and coatings was conducted.Our work provides innovative design concepts and an effective solution for UVshielding materials for extreme conditions.展开更多
Generally the preparation of lithium aluminosilicate（LAS） glasses is difficult on account of their high melting temperature. This research managed to prepare LAS glasses doped with Nd^3＋ ions by the conventional me...Generally the preparation of lithium aluminosilicate（LAS） glasses is difficult on account of their high melting temperature. This research managed to prepare LAS glasses doped with Nd^3＋ ions by the conventional melting and quenching technique, at a relatively low melting temperature and by the use of some additives. Lithium aluminosilicate glasses were transformed to glass-ceramics by controlled nucleation and the crystallization process. The characterizations were performed by differential thermal analysis, X-ray diffraction, UV-Vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The research focused on the photoluminescence spectra of the initial glass and the glass-ceramics under different heat-treatment schedules. Three main fluorescence bands centering at about 890, 1065, and 1330 nm were ob- served, which corresponded to the transitions of ^4F3/2→^4I9/2, ^4F3/2→^4I11/2, and ^4F3/2→^4I13/2, respectively. Phase compositions of glass-ceramics were found to affect their fluorescent characteristics considerably. The fluorescent intensity increased markedly when Nd^3 ＋ ions entered the LixAlxSi1-xO2 β-eucryptite solid solution （SS）. Quenching occurred when Nd^3 ＋ ions located at LixAlxSi3-xO6β-eucryptite SS. Quenching disappeared after LixAlxSi3-xO6 β-eucryptite SS recrystallized into β-spodumene SS. The effectively induced cross section σin of Nd^3＋ ions located at the LixAlxSi1-xO2 β-eucryptite SS was 1.931 ×10^-21 cm^2 at 1065 nm.展开更多
Based on material design idea,we employ a co-precipitation strategy to obtain sinterable Ho_(2)Zr_(2)O_(7) flu-orite particles,successfully leading to novel transparent Ho_(2)Zr_(2)O_(7) ceramics with good optical/mag...Based on material design idea,we employ a co-precipitation strategy to obtain sinterable Ho_(2)Zr_(2)O_(7) flu-orite particles,successfully leading to novel transparent Ho_(2)Zr_(2)O_(7) ceramics with good optical/magneto-optical properties.The resulting precipitation precursor is identified to be hydrated basic carbonate upon calcination at the optimum temperature of 1250℃into near-spherical Ho_(2)Zr_(2)O_(7) nanopowder with an average size of~64 nm and unimodal narrow size distribution.The crystal intrinsic oxygen defect in fluorite ceramic generally exists in the form of F+center.The best bulk specimen achieved in this work exhibits a high refractive index of~2.1 and a high transparency of~74.4%at 1000 nm comparable with the corresponding defect-free single crystal(~76.4%in theory).In the Ho_(2)Zr_(2)O_(7) structure system,the elec-tronic polarizability of O_(2)-anion generally remains constant around 2.2?3 in the visible region and the corresponding optical basicity is approximately 0.9.The developed magneto-optical transparent Ho_(2)Zr_(2)O_(7) ceramic has Verdet constants of-180±3,-157±5,-87±2,-54±2,and-43±2 rad T^(-1) m^(-1) at 515,635,780,980,and 1064 nm,respectively,which are roughly 1.2-fold higher than the commercial TGG crystal.展开更多
Polycrystalline PZT,PLT and PbTiO ferroelectric thin films,highly oriented PbTiOferroelectric thin films and epitaxial growth PZT,PLT ferroelectric thin films with per-ovskite-type structure were prepared by the sol-g...Polycrystalline PZT,PLT and PbTiO ferroelectric thin films,highly oriented PbTiOferroelectric thin films and epitaxial growth PZT,PLT ferroelectric thin films with per-ovskite-type structure were prepared by the sol-gel method.Ferroelectric properties of theceramic thin films were confirmed by P-E hysteresis loops.The pyroelectric and opticalproperties were also measured.展开更多
文摘In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate （LAST） glass ceramics was investigated. Nanocrystallineβ-quartz solid solution （s.s.） was observed to be the main phase crystallized in this system. Com-parable refractive indices of the glassy matrix andβ-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. Optical investi-gations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lat-tice, and the enhancement of structural arrangement degree, respectively.
基金Supported by the National Key Research and Development Program of China(2017YFB0403200)
文摘Novel transparent ceramics of Zr^4+doped Ba(Mg,Ta)O3(BMT)with a high refractive index of 2.037 at 587.56 nm were successfully fabricated via high temperature solid-state-reaction sintering method.To make it transparent,the pure cubic Ba(Zr,Mg,Ta)O3phases(BZMT)were realized in advance by skillfully modulating the lattice structure of BMT from trigonal symmetric to cubic symmetric through doping Zr4 into the lattice of BMT crystal.Highly optical transmittance of 74%at 650 nm,which hit the upper limit of the theory,was achieved for BZMT.Both abbe number of 23.4 and the bandgap Eg of 3.22 eV have been calculated.
基金supported by the Natural Science fund of Jiangsu Province,China(No.BK2007724)
文摘A neodymium doped yttrium aluminum gamet （Nd：YAG） transparent ceramic was fabricated by a solid state reaction method using commercial α-Al2O3, Y2O3, and Nd2O3 powders as starting materials and tetraethyl orthosilicate （TEOS） as sintefing aid. The morphology and microstructure of the nanopowders and the Nd：YAG transparent ceramic were investigated. The fully dense Nd：YAG ceramic with an average grain size of-20 μm was obtained by vacuum sintering at 1720℃ for 12 h. Few pores and grain-boundary phases were observed. The in-line transmittance of the ceramic was 81.5% at 1064 nm.
文摘Samarium doped Yttrium aluminum garnet (YAG) nanopowders with different concentration (0.5%, 1%, 2%, 3%, 5% and 8% mol) were prepared by simple and low cost co-precipitation method. We found that the precursor begins converting to pure YAG at relatively low temperature around 900°C, and no intermediate phases were detected. The powders annealed at 900°C and 1000°C in air with average particle size around ≈30 nm were characterized by means of X-ray diffraction (XRD) analysis and infrared (IR) spectroscopy. The photoluminescent measurements showed that the reddish-orange (RO) emission transition 4G5/2:6H7/2 is more prominent. In addition, the optimum concentration of doped Sm ions that lead to maximum intensity was reported. Also, fluorescence efficiencies as pumping power dependence for different Sm3+ ions concentrations were explored.
基金Funded by the National High-Tech Research and Development Program of China (863 Program) (No. 2006AA03Z440)
文摘The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated. The relative sintered densities, transmittances, color and the microstructure of the composite ceramics were studied. The experimental results showed that the relative sintered densities and transmittances decreased with alumina addition. The lightness increased obviously but the chroma change was small. Pure zirconia nanopowders sintered densely could obtain the relatively high transmittance, while the transmittance and the lightness of slight addition changed significantly. The zirconia/alumina composite ceramics with alumina addition less than 7.5wt% could achieve the relatively stable and reliable optical properties.
文摘The polycrystalline ceramic Pb0.5Ba1.5BiVO6 manifesting the complex double perovskite structure was tailored by the conventional solid state route at a moderate temperature.Qualitative phase analysis and formation of the ceramic were affirmed by XRD analysis.The X-ray powder diffraction pattern of the compound explored at room temperature affirms the single phase formation with double perovskite structure exhibiting rhombohedral phase.Microstructural analysis of the studied compound procured from the Scanning Electron Microscope(SEM)validates the formation of dense microstructures and nonuniformly distributed grains with minimal voids.Compositional analysis was shaped through the Electron Diffraction Spectroscopy(EDS)confirming the absence of con-tamination of any other metals apart from the mentioned ones.Dielectric(Cr and tanδ)parameters of the compound were studied using the LCR analyzer at different temperatures and wide range of frequencies.The polarization and dielectric study affirms the presence of ferroelectricity in the material with transition temperature much above the room temperature.The tangent dielectric loss of this sample being almost minimal at room temperature attributes it to find applications in different grounds of electronics.Optical equities of the ceramic were further analyzed by the RAMAN,FTIR,UV–Vis and Photoluminescence spectroscopy.
基金the National Key R&D Program of China(Nos.2021YFE0104800 and 2023YFB3812000)the General Project of Shanghai Natural Science Foundation(No.22ZR1471500)+2 种基金the International Partnership Program of Chinese Academy of Sciences(No.121631KYSB20200039)the International Cooperation Project of Shanghai Science and Technology Commission(No.20520750200)and National Center for Research and Development(Contract No.WPC2/1/SCAPOL/2021).Partial work was also financially supported by the Hengdian Group.
文摘Faraday isolators can prevent the front-end system from disturbance and damage caused by a back-reflected beam,so they are important elements in laser systems.As magneto-optical materials are the most important component in Faraday isolators,the studies on magneto-optical materials have attracted much attention these years.Tb_(3)Al_(5)O_(12)(TAG)ceramics are considered to be one of the most promising magneto-optical materials for visible to near-infrared wavelength band application because of their outstanding comprehensive magneto-optical performance.However,the optical quality of TAG ceramics needs further optimization to meet the application requirements.In this work,high optical quality(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)(x=0,0.05,0.1,0.2,and 0.3)magneto-optical ceramics were fabricated successfully by solid-state reaction sintering combined with hot isostatic pressing(HIP)post-treatment.All the ceramics obtained showed a single garnet phase for different values of x in the range studied.The addition of Y_(2)O_(3) was found to suppress the secondary phase and improve optical quality significantly.The ceramic samples obtained had clear grain boundaries and possessed the in-line transmittance values of 82.9%at 1064 nm and 82.2%at 633 nm,respectively.The Verdet constants of(Tb_(1−x)Y_(x))_(3)Al_(5)O_(12)ceramics with x=0,0.05,0.1,0.2,and 0.3 were−188.1,−175.4,−168.5,−143.0,and−119.9 rad/(T·m),respectively.The thermal conductivity of TAG ceramics was found to be 5.23 W/(m·K)at 25℃,and when 20%Y was substituted in place of Tb,the thermal conductivity decreased by only 9.4%.
基金supported by Zhejiang Provincial Natural Science Foundation of China(Grant No.LY23F050007).
文摘A chemical co-precipitation strategy was employed to synthesize a series of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12)(x=0.1−0.95)powder phosphors,followed by vacuum sintering to achieve transparent garnet ceramic phosphors.The density functional theory indicated Lu_(3)Al_(5)O_(12) was formed in priority compared with Gd_(3)Al_(5)O_(12) during solid-phase reaction.Upon high-temperature sintering,the Lu^(3+)substitution for Gd^(3+)suppressed point mass diffusion leading to a smaller grain size.The in-line transmittances of bulk specimens with x=0.1,0.3,0.5,0.7,and 0.95 nm were~83.5%,80.1%,68.8%,73.7%,and 82.2%at 710 nm(Eu^(3+)emission center),respectively,among which the sample of x=0.1 exhibited the optical grade with near-zero optical loss in agreement with the defect-free single crystal(~100%of the theoretical transmittance).The resulting particle and ceramic materials both presented characteristic Eu^(3+)emission arising from 5D0→7FJ(J=1−4)transition,where the dominant far-red emission at~710 nm arising from ^(5)D_(0)→^(7)F_(4) transition overlapped with the absorption of phytochrome(PFR).The photoluminescence excitation and photoluminescence intensities of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12) powders and ceramics generally increased at a higher Gd^(3+)/Lu^(3+)ratio.Lu^(3+)dopants delayed the fluorescence lifetime while the bulk samples had shorter lifetime compared to the particle counterparts.The transparent(Gd_(0.85)Lu_(0.1)Eu_(0.05))3Al_(5)O_(12) ceramic phosphor exhibited good thermal stability with a high thermal quenching temperature above 533 K.The designed ceramic phosphor-converted light-emitting diode had a saturation injection current of 435 mA and a current-dependent color rendering index.More importantly,our report marked the developmental stage of transparent ceramic materials towards zero optical loss.
文摘Transparent YAG (yttrium aluminum garnet) ceramics were fabricated by solid-state reaction method. Effect of additive (tetraethyl orthosilicate, TEOS) on microstructure of YAG ceramics was investigated. If the addition of TEOS is more than 3% (mass fraction), large amount of liquid phase can be yielded at grain boundaries, resulting in the formation of second phase particles at grain boundaries. If the addition is less than 0.05% (mass fraction), pores are entrapped in the grains. The suitable amount is 0.5% (mass fraction). A fully transparent YAG ceramic was fabricated by vacuum sintering at 1700 ℃ for 5 h. Optical transmittance of the YAG ceramic is 63% in the visible light wavelengths and 70% in the infrared wavelengths.
基金funded by the National Natural Science Foundation of China(Nos.U21A20441 and U22B2070).
文摘Ultraviolet(UV)radiation poses risks to both human health and organics.In response to the urgent demand for UV-shielding across various applications,extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite films.However,existing UV shielding materials,though suitable for daily use,cannot meet the demands of extreme conditions.In this work,we incorporated CeO_(2)as a UV absorber into Y_(2)O_(3)transparent ceramics for UV-shielding.The effect of CeO_(2)concentration on the optical,mechanical,and thermal properties of Y_(2)O_(3)ceramics was systematically investigated.These findings indicate that CeO_(2)serves not only as a UV absorber but also as an effective sintering aid for Y_(2)O_(3)transparent ceramics.The 5 at%Ce-doped Y_(2)O_(3)transparent ceramics exhibit the optimal optical quality,with in-line transmittance of~77%at 800 nm.The introduction of Ce shifted the UV cutoff edge of Y_(2)O_(3)transparent ceramics from 250 to 375 nm,which was attributed to the visible band absorption of Ce^(4+).This shift grants UV shielding capabilities to Y_(2)O_(3)transparent ceramics,resulting in 100%shielding for ultraviolet C(UVC,100-280 nm)and ultraviolet B(UVB,280-320 nm)and~95%shielding for ultraviolet A(UVA,320-400 nm).The service stability(optical properties)under various corrosive conditions(acid,alkali,UV irradiation,and high temperature)was investigated,confirming the excellent stability of this transparent ceramic UV-shielding material.A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses,films,and coatings was conducted.Our work provides innovative design concepts and an effective solution for UVshielding materials for extreme conditions.
基金Project supported bythe Chinese Ministry of Educationfor Financial Support (KB20026) and the Chinese Ministry of Educa-tion for Financial Support (205037)
文摘Generally the preparation of lithium aluminosilicate（LAS） glasses is difficult on account of their high melting temperature. This research managed to prepare LAS glasses doped with Nd^3＋ ions by the conventional melting and quenching technique, at a relatively low melting temperature and by the use of some additives. Lithium aluminosilicate glasses were transformed to glass-ceramics by controlled nucleation and the crystallization process. The characterizations were performed by differential thermal analysis, X-ray diffraction, UV-Vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The research focused on the photoluminescence spectra of the initial glass and the glass-ceramics under different heat-treatment schedules. Three main fluorescence bands centering at about 890, 1065, and 1330 nm were ob- served, which corresponded to the transitions of ^4F3/2→^4I9/2, ^4F3/2→^4I11/2, and ^4F3/2→^4I13/2, respectively. Phase compositions of glass-ceramics were found to affect their fluorescent characteristics considerably. The fluorescent intensity increased markedly when Nd^3 ＋ ions entered the LixAlxSi1-xO2 β-eucryptite solid solution （SS）. Quenching occurred when Nd^3 ＋ ions located at LixAlxSi3-xO6β-eucryptite SS. Quenching disappeared after LixAlxSi3-xO6 β-eucryptite SS recrystallized into β-spodumene SS. The effectively induced cross section σin of Nd^3＋ ions located at the LixAlxSi1-xO2 β-eucryptite SS was 1.931 ×10^-21 cm^2 at 1065 nm.
基金supported by the Zhejiang Provincial Natural Science Foundation of China (Grant No.LY23F050007)the Department of Education of Zhejiang Province (No.Y202146207).
文摘Based on material design idea,we employ a co-precipitation strategy to obtain sinterable Ho_(2)Zr_(2)O_(7) flu-orite particles,successfully leading to novel transparent Ho_(2)Zr_(2)O_(7) ceramics with good optical/magneto-optical properties.The resulting precipitation precursor is identified to be hydrated basic carbonate upon calcination at the optimum temperature of 1250℃into near-spherical Ho_(2)Zr_(2)O_(7) nanopowder with an average size of~64 nm and unimodal narrow size distribution.The crystal intrinsic oxygen defect in fluorite ceramic generally exists in the form of F+center.The best bulk specimen achieved in this work exhibits a high refractive index of~2.1 and a high transparency of~74.4%at 1000 nm comparable with the corresponding defect-free single crystal(~76.4%in theory).In the Ho_(2)Zr_(2)O_(7) structure system,the elec-tronic polarizability of O_(2)-anion generally remains constant around 2.2?3 in the visible region and the corresponding optical basicity is approximately 0.9.The developed magneto-optical transparent Ho_(2)Zr_(2)O_(7) ceramic has Verdet constants of-180±3,-157±5,-87±2,-54±2,and-43±2 rad T^(-1) m^(-1) at 515,635,780,980,and 1064 nm,respectively,which are roughly 1.2-fold higher than the commercial TGG crystal.
基金the High Technology Research and Development Programme of China.
文摘Polycrystalline PZT,PLT and PbTiO ferroelectric thin films,highly oriented PbTiOferroelectric thin films and epitaxial growth PZT,PLT ferroelectric thin films with per-ovskite-type structure were prepared by the sol-gel method.Ferroelectric properties of theceramic thin films were confirmed by P-E hysteresis loops.The pyroelectric and opticalproperties were also measured.
