Different amounts of AlON have been introduced in calcium hexaaluminate(CA_(6)) using two approaches, that is, one-step and twostep methods, to improve the slag resistance of CA_(6). A one-step method can directly sin...Different amounts of AlON have been introduced in calcium hexaaluminate(CA_(6)) using two approaches, that is, one-step and twostep methods, to improve the slag resistance of CA_(6). A one-step method can directly sinter the mixtures combining Al_(2)O_(3), CaCO_(3), and Al in flowing nitrogen, in which AlON clusters are always formed because of the poor wettability of Al by Al_(2)O_(3), leading to the high porosity of CA_(6)/AlON composite. In a two-step method, CA_(6)and AlON are prepared separately and then mixed and sintered in flowing nitrogen. Compared with the sample prepared by the one-step method, CA_(6)and AlON in composite by the two-step method are more uniformly distributed,and the optimized amount of AlON added is 10wt%. The slag corrosion and penetration test shows that the CA_(6)/AlON composite using the two-step method exhibits superior slag corrosion protection. The promoted effect of AlON on slag penetration and corrosion resistance is also discussed.展开更多
A novel red-emitting phosphor tantalate Ca_(2)YTaO_(6):Eu^(3+)was synthesized by a solid-state reaction.The purity and surface morphology of the phosphors were characterized.The Ca_(2)YTaO_(6):Eu^(3+)phosphors show a ...A novel red-emitting phosphor tantalate Ca_(2)YTaO_(6):Eu^(3+)was synthesized by a solid-state reaction.The purity and surface morphology of the phosphors were characterized.The Ca_(2)YTaO_(6):Eu^(3+)phosphors show a sharp emission peak at 612 nm under near-ultraviolet(n-UV) at 395 nm because of the ^(5)D0→^(7)F_(2) transition of Eu^(3+).The optimal Eu^(3+)doping concentration in Ca_(2)YTaO_(6) is 40 mol% and the critical energy-transfer distance of Eu^(3+)ions was calculated to be 0.9 nm.The emission spectra of Ca_(2)YTaO_(6):Eu_(3+)from 300 to 480 K were investigated.The thermal-quenching temperature(T_(0.5)) of Ca_(2)YTaO_(6):Eu^(3+)is above 480 K.The color purity of Ca_(2)YTaO_(6):40 mol%Eu^(3+)is as high as 99.8%.The luminescence lifetime of Ca_(2)YTaO_(6):40 mol%Eu^(3+)was also discussed.The high color purity and high thermal stability of Eu^(3+)-doped Ca_(2)YTaO_(6) phosphors contribute to its application value in white lightemitting diodes(w-LEDs).展开更多
Novel yellow-emitting phosphors of Dy^(3+)-doped double perovskite Ca_(2)MgTeO_(6) were synthesized by using a conventional high-temperature solid-state reaction.The phase purity,particle morphology,size distribution,...Novel yellow-emitting phosphors of Dy^(3+)-doped double perovskite Ca_(2)MgTeO_(6) were synthesized by using a conventional high-temperature solid-state reaction.The phase purity,particle morphology,size distribution,elemental composition,luminescence properties,and luminescence decay curves of the resulting products were then analyzed in detail.The Ca_(2)MgTeO_(6):Dy^(3+),Na^(+) phosphors show three emission peaks after near-ultraviolet excitation at 350 nm,which correspond to ^(4)F_(9/2)→^(6)H_(11/2),^(4)F_(9/2)→^(6)H_(13/2),and ^(4)F_(9/2)→^(6)H_(13/2) transitions,respectively.Among them,the strongest peak is observed at 573 nm.The best doping content of Dy^(3+)in Ca_(2)MgTeO_(6):xDy^(3+),xNa^(+) phosphors is x=5 mol%.The calculated critical distance of energy transfer between Dy^(3+) ions is 1.6 nm.Luminescence quenching is confirmed to be due to dipole-dipole interactions among Dy^(3+) ions.The phosphors show excellent thermal stability with high activation energy(0.27 eV).The Commission Internationale de l’Eclairage(CIE) chromaticity coordinates of the Ca_(2)MgTeO_(6) Dy^(3+),Na^(+) phosphors are located in the yellow region.White light-emitting diodes(w-LEDs) were fabricated with a high color rendering index(R_(a)) of 88 and a good correlated color temperature(CCT) of 5440 K.All observed properties indicate that Ca_(2)MgTeO_(6):Dy^(3+),Na^(+) phosphors have potential applications in display and photonic devices.展开更多
Hydrothermal treatment of calcium oxide and boric acid mixtures at temperaturesbetween 234 ℃ and 300 ℃ has produced a colorless, transparent, orthorhombic compound Ca2B6O11 · H2O. Of the seven known members of ...Hydrothermal treatment of calcium oxide and boric acid mixtures at temperaturesbetween 234 ℃ and 300 ℃ has produced a colorless, transparent, orthorhombic compound Ca2B6O11 · H2O. Of the seven known members of the series of hydrated dicalcium hexaborate containing boron-oxygen six-membered ring anionic group (B3O8)7, only the title compound has been found to have the nonlinear optical effect. The second harmanic generation (SHG) effect of its crystal is larger than that of KH2PO4 (KDP). The reflection spectrum has shown that this compound has no absorption in the experimental wavelength range (800-240 nm). Its crystal structure is favorable for generating the nonlinear optical effect.展开更多
基金financially supported by the National Science Fund for Distinguished Young Scholars (No. 52025041)the National Natural Science Foundation of China (Nos. 51904021, 51974021, 52174294, and 51902020)+2 种基金the Fundamental Research Funds for the Central Universities (No. FRF-TP-19-008A1)the Project of Liaoning Province’s “Rejuvenating Liaoning Talents Plan”, China (No. XLYC1902092)the Beijing Excellent Talents Foundation。
文摘Different amounts of AlON have been introduced in calcium hexaaluminate(CA_(6)) using two approaches, that is, one-step and twostep methods, to improve the slag resistance of CA_(6). A one-step method can directly sinter the mixtures combining Al_(2)O_(3), CaCO_(3), and Al in flowing nitrogen, in which AlON clusters are always formed because of the poor wettability of Al by Al_(2)O_(3), leading to the high porosity of CA_(6)/AlON composite. In a two-step method, CA_(6)and AlON are prepared separately and then mixed and sintered in flowing nitrogen. Compared with the sample prepared by the one-step method, CA_(6)and AlON in composite by the two-step method are more uniformly distributed,and the optimized amount of AlON added is 10wt%. The slag corrosion and penetration test shows that the CA_(6)/AlON composite using the two-step method exhibits superior slag corrosion protection. The promoted effect of AlON on slag penetration and corrosion resistance is also discussed.
基金financially supported by the National Natural Science Foundation of China (Grant No. 51862012)the Natural Science Foundation of Jiangxi Province (Grants No. 20202BAB204008, 20165ABC28010)the Innovation Leadership Program of Ganzhou。
基金The work was supported by Undergraduate Innovation Fund of Northwest A&F UniversityChina(201910712069)+3 种基金Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)the Construction Program of the key discipline in Hunan Provincethe Projects of the Education Department of Hunan Province(No.18A465)Science and Technology Plan Project of Chenzhou City(jsyf2017014)。
文摘A novel red-emitting phosphor tantalate Ca_(2)YTaO_(6):Eu^(3+)was synthesized by a solid-state reaction.The purity and surface morphology of the phosphors were characterized.The Ca_(2)YTaO_(6):Eu^(3+)phosphors show a sharp emission peak at 612 nm under near-ultraviolet(n-UV) at 395 nm because of the ^(5)D0→^(7)F_(2) transition of Eu^(3+).The optimal Eu^(3+)doping concentration in Ca_(2)YTaO_(6) is 40 mol% and the critical energy-transfer distance of Eu^(3+)ions was calculated to be 0.9 nm.The emission spectra of Ca_(2)YTaO_(6):Eu_(3+)from 300 to 480 K were investigated.The thermal-quenching temperature(T_(0.5)) of Ca_(2)YTaO_(6):Eu^(3+)is above 480 K.The color purity of Ca_(2)YTaO_(6):40 mol%Eu^(3+)is as high as 99.8%.The luminescence lifetime of Ca_(2)YTaO_(6):40 mol%Eu^(3+)was also discussed.The high color purity and high thermal stability of Eu^(3+)-doped Ca_(2)YTaO_(6) phosphors contribute to its application value in white lightemitting diodes(w-LEDs).
基金Project supported by the Natural Science Foundation of Shaanxi Province(2018JM5055)Hunan Provincial Key Laboratory of Xiangnan Rare-Precious Metals Compounds and Applications(2019XGJSKFJJ01)+2 种基金the Construction Program of the Key Discipline in Hunan Provincethe Projects of the Education Department of Hunan Province(18A465)Science and Technology Plan Project of Chenzhou City(jsyf2017014)。
文摘Novel yellow-emitting phosphors of Dy^(3+)-doped double perovskite Ca_(2)MgTeO_(6) were synthesized by using a conventional high-temperature solid-state reaction.The phase purity,particle morphology,size distribution,elemental composition,luminescence properties,and luminescence decay curves of the resulting products were then analyzed in detail.The Ca_(2)MgTeO_(6):Dy^(3+),Na^(+) phosphors show three emission peaks after near-ultraviolet excitation at 350 nm,which correspond to ^(4)F_(9/2)→^(6)H_(11/2),^(4)F_(9/2)→^(6)H_(13/2),and ^(4)F_(9/2)→^(6)H_(13/2) transitions,respectively.Among them,the strongest peak is observed at 573 nm.The best doping content of Dy^(3+)in Ca_(2)MgTeO_(6):xDy^(3+),xNa^(+) phosphors is x=5 mol%.The calculated critical distance of energy transfer between Dy^(3+) ions is 1.6 nm.Luminescence quenching is confirmed to be due to dipole-dipole interactions among Dy^(3+) ions.The phosphors show excellent thermal stability with high activation energy(0.27 eV).The Commission Internationale de l’Eclairage(CIE) chromaticity coordinates of the Ca_(2)MgTeO_(6) Dy^(3+),Na^(+) phosphors are located in the yellow region.White light-emitting diodes(w-LEDs) were fabricated with a high color rendering index(R_(a)) of 88 and a good correlated color temperature(CCT) of 5440 K.All observed properties indicate that Ca_(2)MgTeO_(6):Dy^(3+),Na^(+) phosphors have potential applications in display and photonic devices.
文摘Hydrothermal treatment of calcium oxide and boric acid mixtures at temperaturesbetween 234 ℃ and 300 ℃ has produced a colorless, transparent, orthorhombic compound Ca2B6O11 · H2O. Of the seven known members of the series of hydrated dicalcium hexaborate containing boron-oxygen six-membered ring anionic group (B3O8)7, only the title compound has been found to have the nonlinear optical effect. The second harmanic generation (SHG) effect of its crystal is larger than that of KH2PO4 (KDP). The reflection spectrum has shown that this compound has no absorption in the experimental wavelength range (800-240 nm). Its crystal structure is favorable for generating the nonlinear optical effect.
