A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials.Postulated conditio...A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials.Postulated condition of the model was that subsurface damage depth and peak-to-valley surface roughness are equal to depth of radial and lateral cracks in brittle surface induced by small-radius(radius≤200 μm)spherical indenter,respectively.And contribution of elastic stress field to the radial cracks propagation was also considered in the loading cycle.Subsurface damage depth of ground BK7 glasses was measured by magnetorheological finishing spot technique to validate theoretical ratio of subsurface damage to surface roughness.The results show that the ratio is directly proportional to load of abrasive grains and hardness of optical materials,while inversely proportional to granularity of abrasive grains and fracture toughness of optical materials.Moreover,the influence of the load and fracture toughness on the ratio is more significant than the granularity and hardness,respectively.The measured ratios of 80 grit and 120 grit fixed abrasive grinding of BK7 glasses are 5.8 and 5.4,respectively.展开更多
Ca 4YO(BO 3) 3(YCOB) which possesses good NLO properties and chemical stability,is an excellent candidate for frequency conversion crystals to produce green and blue light (SHG and THG of Nd∶YAG laser).In this paper,...Ca 4YO(BO 3) 3(YCOB) which possesses good NLO properties and chemical stability,is an excellent candidate for frequency conversion crystals to produce green and blue light (SHG and THG of Nd∶YAG laser).In this paper,preparation of the feed material and the vertical Bridgman growth condition for YCOB crystal is reported for the first time to our knowledge. YCOB crystals have been grown from the feed materials composed of Y 2O 3(4N),CaCO 3/CaO (A.R.) and H 3BO 3/B 2O 3(4N)by vertical Bridgman method.Since Ca 4YO(BO 3) 3 melts congruently,the feed material should be prepared in the stoichiometric composition.The evaporation of B 2O 3 at high temperature and the hygroscopicity of CaO,B 2O 3 and Y 2O 3 were carefully considered.It was showed by experiments that the feed material prepared by directly and thoroughly mixing together stoichiometric amount of Y 2O 3,CaO and B 2O 3 is suitable for the Bridgman growth of YCOB crystal.The melting point of YCOB crystal is 1510℃,and Pt crucible less than 1.0mm thick was chosen.The temperature of the furnace was controlled from 1560℃ to 1650℃.Owing to the extremely high melting points of both Y 2O 3 and CaO,the feed material had been heated at the above temperature for more than 10 hours before growth so that it melts thoroughly.The growth rate of 0.2-0.6mm/h and the temperature gradient near the solid-liquid interface of 40-60°C/cm were chosen.The Crack free and transparent YCOB crystals with 25mm in diameter and 50mm long have been grown in near sealed Pt crucibles under the above growth condition,which suggests that the vertical Bridgman method is suitable for the growth of YCOB crystal.展开更多
Two alkali-metal sulfamates nonlinear optical(NLO)crystals,Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3)),have been obtained through the facile evaporation method.Li(NH_(2)SO_(3))crystallizes in the polar space group Pca2_(1)(N...Two alkali-metal sulfamates nonlinear optical(NLO)crystals,Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3)),have been obtained through the facile evaporation method.Li(NH_(2)SO_(3))crystallizes in the polar space group Pca2_(1)(No.29).The structure of Li(NH_(2)SO_(3))can be described as a 3D network formed by[LiO_(4)]^(7-)polyhedral connecting with NH_(2)SO_(3)^(-)tetrahedra through corner-sharing.Na(NH_(2)SO_(3))crystallizes in the polar space group P2_(1)2_(1)2_(1)(No.19).The structure of Na(NH_(2)SO_(3))can be described as a 3D network formed by distorted[NaO_(6)]^(11-)octahedral connecting with NH_(2)SO_(3)^(-)tetrahedra through corner-sharing.The UV-Vis-near-infrared spectra demonstrate that Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3))possessed large optical band gaps of 5.25 and 4.81 eV,respectively.Powder second-harmonic generation(SHG)measurements demonstrate that the SHG intensity of Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3))were 0.32 times and 0.31 times that of KH_(2)PO_(4),respectively.First-principles calculations confirm the nonlinear optical performance mainly derived from the synergistic effect of amino sulfonate anions and alkali metal oxide anionic polyhedra.CCDC:2339109,Li(NH_(2)SO_(3));2339110,Na(NH_(2)SO_(3)).展开更多
基金Project(50375156) supported by the National Natural Science Foundation of China
文摘A theoretical model of relationship between subsurface damage and surface roughness was established to realize rapid and non-destructive measurement of subsurface damage of ground optical materials.Postulated condition of the model was that subsurface damage depth and peak-to-valley surface roughness are equal to depth of radial and lateral cracks in brittle surface induced by small-radius(radius≤200 μm)spherical indenter,respectively.And contribution of elastic stress field to the radial cracks propagation was also considered in the loading cycle.Subsurface damage depth of ground BK7 glasses was measured by magnetorheological finishing spot technique to validate theoretical ratio of subsurface damage to surface roughness.The results show that the ratio is directly proportional to load of abrasive grains and hardness of optical materials,while inversely proportional to granularity of abrasive grains and fracture toughness of optical materials.Moreover,the influence of the load and fracture toughness on the ratio is more significant than the granularity and hardness,respectively.The measured ratios of 80 grit and 120 grit fixed abrasive grinding of BK7 glasses are 5.8 and 5.4,respectively.
文摘Ca 4YO(BO 3) 3(YCOB) which possesses good NLO properties and chemical stability,is an excellent candidate for frequency conversion crystals to produce green and blue light (SHG and THG of Nd∶YAG laser).In this paper,preparation of the feed material and the vertical Bridgman growth condition for YCOB crystal is reported for the first time to our knowledge. YCOB crystals have been grown from the feed materials composed of Y 2O 3(4N),CaCO 3/CaO (A.R.) and H 3BO 3/B 2O 3(4N)by vertical Bridgman method.Since Ca 4YO(BO 3) 3 melts congruently,the feed material should be prepared in the stoichiometric composition.The evaporation of B 2O 3 at high temperature and the hygroscopicity of CaO,B 2O 3 and Y 2O 3 were carefully considered.It was showed by experiments that the feed material prepared by directly and thoroughly mixing together stoichiometric amount of Y 2O 3,CaO and B 2O 3 is suitable for the Bridgman growth of YCOB crystal.The melting point of YCOB crystal is 1510℃,and Pt crucible less than 1.0mm thick was chosen.The temperature of the furnace was controlled from 1560℃ to 1650℃.Owing to the extremely high melting points of both Y 2O 3 and CaO,the feed material had been heated at the above temperature for more than 10 hours before growth so that it melts thoroughly.The growth rate of 0.2-0.6mm/h and the temperature gradient near the solid-liquid interface of 40-60°C/cm were chosen.The Crack free and transparent YCOB crystals with 25mm in diameter and 50mm long have been grown in near sealed Pt crucibles under the above growth condition,which suggests that the vertical Bridgman method is suitable for the growth of YCOB crystal.
文摘Two alkali-metal sulfamates nonlinear optical(NLO)crystals,Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3)),have been obtained through the facile evaporation method.Li(NH_(2)SO_(3))crystallizes in the polar space group Pca2_(1)(No.29).The structure of Li(NH_(2)SO_(3))can be described as a 3D network formed by[LiO_(4)]^(7-)polyhedral connecting with NH_(2)SO_(3)^(-)tetrahedra through corner-sharing.Na(NH_(2)SO_(3))crystallizes in the polar space group P2_(1)2_(1)2_(1)(No.19).The structure of Na(NH_(2)SO_(3))can be described as a 3D network formed by distorted[NaO_(6)]^(11-)octahedral connecting with NH_(2)SO_(3)^(-)tetrahedra through corner-sharing.The UV-Vis-near-infrared spectra demonstrate that Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3))possessed large optical band gaps of 5.25 and 4.81 eV,respectively.Powder second-harmonic generation(SHG)measurements demonstrate that the SHG intensity of Li(NH_(2)SO_(3))and Na(NH_(2)SO_(3))were 0.32 times and 0.31 times that of KH_(2)PO_(4),respectively.First-principles calculations confirm the nonlinear optical performance mainly derived from the synergistic effect of amino sulfonate anions and alkali metal oxide anionic polyhedra.CCDC:2339109,Li(NH_(2)SO_(3));2339110,Na(NH_(2)SO_(3)).
