Spontaneous nucleation of SiC particles and giant macroscopic steps result in the surface roughness of the grown crystal for the top-seeded solution growth of SiC crystal.To suppress the surface roughness,the temperat...Spontaneous nucleation of SiC particles and giant macroscopic steps result in the surface roughness of the grown crystal for the top-seeded solution growth of SiC crystal.To suppress the surface roughness,the temperature gradient was carefully adjusted by changing the relative position of the crucible and induction coils.The numerical simulation and experimental results show that the surface morphology of the grown crystal becomes smoother and there are fewer spontaneous nucleation particles attached to the growth surface with the decrease in the relative crucible position,due to the increase of temperature at the entire solution surface and the reducing of temperature gradient near the growth surface.Accordingly,a lower temperature gradient,a larger solution velocity,a higher carbon concentration,and a smaller carbon supersaturation near the growth surface can be obtained when the relative position between the crucible and the induction coil is 70 mm,which is demonstrated to be the most favorable for the elimination of spontaneous nucleation of small SiC particles and suppressing surface roughening with the full width at half maximum(FWHM)of 37.5 arcsec of 4Hsingle bondSiC crystals.展开更多
The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media...The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media is becoming increasingly urgent.This study reports a novel Yb^(3+),Er^(3+)co-doped KBa_(0.94)Ca_(0.06)Y(MoO_(4))_(3) (KBCYM)crystal.In this crystal,Yb^(3+)serves as a sensitizer,significantly enhancing the emission intensity of Er^(3+)in both visible and near-infrared bands.Notably,when the concentration of Yb^(3+)reaches 6 mol%,the emission intensity peaks at 1.55μm.Optical cross-section calculations reveal that the crystal exhibits a low laser pumping threshold at this concentration,demonstrating its potential as a laser gain medium.However,the crystal inevitably generates thermal effects during operation,which may adversely affect its performance.Therefore,real-time monitoring of the operating temperature is crucial.The thermal stability of the crystal was evaluated by measuring the temperature dependence of its luminescence intensity in the near-infrared band.Remarkably,even when the temperature rises to 553 K,the emission intensity at 1.55μm only decreases by 10.9%.Additionally,the temperature sensing performance was evaluated using fluorescence intensity ratio techniques,yielding absolute and relative sensitivities of 0.00981 K^(-1)at 453 K and 1.32%/K at 303 K,respectively,highlighting its potential for optical temperature sensing.Finally,through leveraging the unique properties of Yb^(3+),Er^(3+):KBCYM crystals,we successfully developed 1.55μm luminescent optical devices with practical applications.These devices not only exhibit efficient luminescent performance,but also possess a self-temperature measu rement functio n,opening up new avenues for the further development of laser technology.展开更多
KTb（WO4）2（KTW） single crystal with dimensions up to 30 mm×30 mm 10 mm was grown by the top-seeded solution growth （TSSG） method for the first time. The crystal structure was refined at room temperature by u...KTb（WO4）2（KTW） single crystal with dimensions up to 30 mm×30 mm 10 mm was grown by the top-seeded solution growth （TSSG） method for the first time. The crystal structure was refined at room temperature by using single crystal X-ray diffiaction data. Ab- sorption and fluorescence spectra were measured at room temperature. The fluorescence lifetime of KTb（WO4）2 was 114 μs. The specific heat of the KTh（WO4）2 crystal was also measured at room temperature.展开更多
The laser host crystals of KLu(WO4)2(KLuW) with large sizes up to 43 × 35 × 16 mm3 have been grown along, [110], b, and c crystallographic directions, respectively, by the top-seeded solution growth (TSSG) s...The laser host crystals of KLu(WO4)2(KLuW) with large sizes up to 43 × 35 × 16 mm3 have been grown along, [110], b, and c crystallographic directions, respectively, by the top-seeded solution growth (TSSG) slow-cooling method. The macro defects are observed using optical microscopy. The main defects found were cracks, inclusions, growth striations, sector boundaries and twin boundaries. The formation mechanism and approaches to reduce or eliminate the defects have been analyzed.展开更多
The 0.96Na_(0.5)Bi_(0.5)TiO_(3)-0.04K_(0.5)Bi_(0.5)TiO_(3)(NKBT96/4)lead-free single crystal was successfullygrown by top-seeded solution growth method.The effective segregation coefficient for K was calculated to be ...The 0.96Na_(0.5)Bi_(0.5)TiO_(3)-0.04K_(0.5)Bi_(0.5)TiO_(3)(NKBT96/4)lead-free single crystal was successfullygrown by top-seeded solution growth method.The effective segregation coefficient for K was calculated to be 0.20.X-ray powder difraction measurement showed that the as-grown crystalpossesses rhombohedral perovskite structure at room temperature.X-ray rock curve measureindicated that the as-grown single crystal owned relatively higher quality.The NKBT96/4 singlecrystal exhibits apparent diffused dielectric behavior,where the diffusiveness index aαis 1.79 forthe[001]-oriented crystal planes.A notable thermal hysteresis,△T_(h),of 25℃was disclosed for thetetragonal antiferroelectric-tetragonal paraelectric phase transition in the dielectric propertystudies between heating and cooling.The highest remnant polarization,P_(r),16.8μC/cm^(2),wasobtained at 100℃.The electromechanical coupling coefficient k_(t)of the[001]-oriented crystalplanes at room temperat ure was determined to be 38%using resonance-antiresonance technique.The room temperature piezoelectric constant d_(33)reaches 120 pC/N.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52302007,52327801,51906086)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20210762).
文摘Spontaneous nucleation of SiC particles and giant macroscopic steps result in the surface roughness of the grown crystal for the top-seeded solution growth of SiC crystal.To suppress the surface roughness,the temperature gradient was carefully adjusted by changing the relative position of the crucible and induction coils.The numerical simulation and experimental results show that the surface morphology of the grown crystal becomes smoother and there are fewer spontaneous nucleation particles attached to the growth surface with the decrease in the relative crucible position,due to the increase of temperature at the entire solution surface and the reducing of temperature gradient near the growth surface.Accordingly,a lower temperature gradient,a larger solution velocity,a higher carbon concentration,and a smaller carbon supersaturation near the growth surface can be obtained when the relative position between the crucible and the induction coil is 70 mm,which is demonstrated to be the most favorable for the elimination of spontaneous nucleation of small SiC particles and suppressing surface roughening with the full width at half maximum(FWHM)of 37.5 arcsec of 4Hsingle bondSiC crystals.
基金Project supported by Jilin Provincial Department of Education(JJKH20230821KJ,JJKH20230822KJ,JJKH20230823KJ,JJKH20240930KJ,20240101107JC)。
文摘The 1.55μm laser technology is widely applied in military,information communication,biomedicine and other fields.With the deepening development of these application areas,the demand for novel 1.55μm laser gain media is becoming increasingly urgent.This study reports a novel Yb^(3+),Er^(3+)co-doped KBa_(0.94)Ca_(0.06)Y(MoO_(4))_(3) (KBCYM)crystal.In this crystal,Yb^(3+)serves as a sensitizer,significantly enhancing the emission intensity of Er^(3+)in both visible and near-infrared bands.Notably,when the concentration of Yb^(3+)reaches 6 mol%,the emission intensity peaks at 1.55μm.Optical cross-section calculations reveal that the crystal exhibits a low laser pumping threshold at this concentration,demonstrating its potential as a laser gain medium.However,the crystal inevitably generates thermal effects during operation,which may adversely affect its performance.Therefore,real-time monitoring of the operating temperature is crucial.The thermal stability of the crystal was evaluated by measuring the temperature dependence of its luminescence intensity in the near-infrared band.Remarkably,even when the temperature rises to 553 K,the emission intensity at 1.55μm only decreases by 10.9%.Additionally,the temperature sensing performance was evaluated using fluorescence intensity ratio techniques,yielding absolute and relative sensitivities of 0.00981 K^(-1)at 453 K and 1.32%/K at 303 K,respectively,highlighting its potential for optical temperature sensing.Finally,through leveraging the unique properties of Yb^(3+),Er^(3+):KBCYM crystals,we successfully developed 1.55μm luminescent optical devices with practical applications.These devices not only exhibit efficient luminescent performance,but also possess a self-temperature measu rement functio n,opening up new avenues for the further development of laser technology.
基金Project supported by Natural Science Foundation of Shandong Province (ZR2011EMM010)the Innovation Foundation of Shandong University
文摘KTb（WO4）2（KTW） single crystal with dimensions up to 30 mm×30 mm 10 mm was grown by the top-seeded solution growth （TSSG） method for the first time. The crystal structure was refined at room temperature by using single crystal X-ray diffiaction data. Ab- sorption and fluorescence spectra were measured at room temperature. The fluorescence lifetime of KTb（WO4）2 was 114 μs. The specific heat of the KTh（WO4）2 crystal was also measured at room temperature.
文摘The laser host crystals of KLu(WO4)2(KLuW) with large sizes up to 43 × 35 × 16 mm3 have been grown along, [110], b, and c crystallographic directions, respectively, by the top-seeded solution growth (TSSG) slow-cooling method. The macro defects are observed using optical microscopy. The main defects found were cracks, inclusions, growth striations, sector boundaries and twin boundaries. The formation mechanism and approaches to reduce or eliminate the defects have been analyzed.
基金the Ministry of Science and Technology of China through 973 Program(No.2009CB623305)National Key Technology R&D Program(No.2010BAK69B26)+3 种基金the Natural Science Foundation of China(Nos.60837003,50777065,61001041 and 11090332)Science and Technology Commission of Shanghai Municipality(Nos.10520712700,10JC1415900 and 10dz0583400)the Innovation Fund of Shanghai Institute of Ceramics(Nos.O99ZC4140G andO99ZC1110G)Shanghai Rising-Star Program(No.11QA1407500).
文摘The 0.96Na_(0.5)Bi_(0.5)TiO_(3)-0.04K_(0.5)Bi_(0.5)TiO_(3)(NKBT96/4)lead-free single crystal was successfullygrown by top-seeded solution growth method.The effective segregation coefficient for K was calculated to be 0.20.X-ray powder difraction measurement showed that the as-grown crystalpossesses rhombohedral perovskite structure at room temperature.X-ray rock curve measureindicated that the as-grown single crystal owned relatively higher quality.The NKBT96/4 singlecrystal exhibits apparent diffused dielectric behavior,where the diffusiveness index aαis 1.79 forthe[001]-oriented crystal planes.A notable thermal hysteresis,△T_(h),of 25℃was disclosed for thetetragonal antiferroelectric-tetragonal paraelectric phase transition in the dielectric propertystudies between heating and cooling.The highest remnant polarization,P_(r),16.8μC/cm^(2),wasobtained at 100℃.The electromechanical coupling coefficient k_(t)of the[001]-oriented crystalplanes at room temperat ure was determined to be 38%using resonance-antiresonance technique.The room temperature piezoelectric constant d_(33)reaches 120 pC/N.
