A series of Y2.985Al5–xGaxO12:0.015Ce(YAGG:Ce,x=0,1,2,3,4,5)transparent ceramics were prepared via a solid-state reaction method.Two-step sintering technique was proved to be an effective approach to prepare function...A series of Y2.985Al5–xGaxO12:0.015Ce(YAGG:Ce,x=0,1,2,3,4,5)transparent ceramics were prepared via a solid-state reaction method.Two-step sintering technique was proved to be an effective approach to prepare functional ceramics with high Ga concentration,and Y3Ga5O12(YGG)transparent ceramic was successfully prepared for the first time.According to the variation of Al/Ga ratio,regulation of band structure and luminescence properties of YAGG:Ce transparent ceramics were effectively investigated.When Ga substitutes Al sites,the tetrahedral site is more favorable compared to the octahedral site for Ga to occupy according to the first-principle calculation.A continuous blue shift of the emission from 565 to 515 nm was achieved as Ga was gradually introduced into Y3Al5O12:Ce matrix.High quality green light was obtained by coupling the YAGG:Ce ceramics with commercial blue InGaN chips.Transparent luminescence ceramics accomplished in this work can be quite prospective for high power LED application.展开更多
We investigated photoluminescence （PL） and scintillation properties of Ce3＋-doped Y3A12Ga3OI2 （Ce：YAGG） trans- parent ceramics synthesized by vacuum sintering with different Ce3＋ concentrations （mol.%） from 0...We investigated photoluminescence （PL） and scintillation properties of Ce3＋-doped Y3A12Ga3OI2 （Ce：YAGG） trans- parent ceramics synthesized by vacuum sintering with different Ce3＋ concentrations （mol.%） from 0.3% to 1% （0.3%Ce：YAGG, 0.5%Ce：YAGG, 0.8%Ce：YAGG and I%Ce：YAGG）. The samples were synthesized by the vacuum sintering technique. The obtained samples showed a very strong and broad PL emission by the 5dl-4f transition of Ce3＋ in the wavelength range from 470 to 600 nm. The PL decay profiles were approximated by a single exponential decay function with the time constants of around 33-39 ns, Fur- thermore, the scintillation spectra induced by X-rays showed similar features with those observed in PL. The scintillation decay time profiles followed a second-order exponential decay function. The fast component group （ranged 3542 ns） were dominantly contrib- uted by the 5d1-4f transition of Ce3＋. The pulse height spectra utilizing the latter emissions showed a clear photoabsorption peak. Among those samples tested, 0.5%Ce：YAGG sample showed the highest scintillation light yield of 21,400 ph/MeV under 13VCs y-ray irradiation.展开更多
The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)phosphor.The successful incorporation of Na^(+)and Sr^(2+)wa...The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)phosphor.The successful incorporation of Na^(+)and Sr^(2+)was confirmed by the X-Ray Difiraction(XRD)results.All the samples show 5d-4f green persistent luminescence of Ce^(3+)after 450 nm excitation.The decay curves demonstrate that the persistent luminescence is efiectively enhanced with Na+and Sr2+doping.The thermoluminescence glow curves also show not only does the trap concentration increase,but also the distribution of trap depths is broadened.In addition,the air-and H_(2)/Ar-annealing treatments were conducted on every as-made sample.The experimental results prove that the increased traps after the Na^(+)/Sr^(2+)doping are mainly attributed to the oxygen vacancies,and the traps have a continuous and broad distribution of trap depths.We hope this work could give new inspiration for designing a high-performance persistent phosphor.展开更多
The structural and thermal properties of yttrium-aluminum-gadolinium-gallium (Y2.97Gd0.03Al2Ga3O12) single crystals doped with terbium (0.1%), cerium (0.01%) and co-doped with both terbium and cerium ((0.1, 0.01)%) we...The structural and thermal properties of yttrium-aluminum-gadolinium-gallium (Y2.97Gd0.03Al2Ga3O12) single crystals doped with terbium (0.1%), cerium (0.01%) and co-doped with both terbium and cerium ((0.1, 0.01)%) were investigated. All samples were heated (calcined) at 1400°C for 15 hours before crystallization. X-ray powder diffraction (XRD) patterns of all calcined samples showed the presence of yttrium gallium aluminate (Y3Al2Ga3O12) and gadolinium gallium oxide (Gd3GaO6) while the grown crystals were single phase of Y3Al2Ga3O12. The lattice parameter of the crystals decreased with Ce doping. The thermal conductivity of each sample was determined from 25°C to 300°C and found to decrease exponentially with increasing temperature. All doped crystals have different thermal conductivity, which is attributed to the crucial influence of crystals structures. 0.01% Ce:YAGG was found to be a strong candidate for scintillators and other lasing materials because of its good thermal behavior (10.71 W/m·K).展开更多
The persistent luminescence(PersL)dependence on the dopants and derived mechanism of trapping and de-trapping processes were investigated in Y3Al2Ga3O12(YAGG)based nanophosphor,doped with Ce^3+and/or Cr^3+.It is found...The persistent luminescence(PersL)dependence on the dopants and derived mechanism of trapping and de-trapping processes were investigated in Y3Al2Ga3O12(YAGG)based nanophosphor,doped with Ce^3+and/or Cr^3+.It is found that the presence of Cr^3+ions produce electron and hole traps and capture suitable charge after X-ray irradiation.The effect of irradiation on the carriers trapping and their pathways after excitation was studied by means of thermo luminescence technique.On the other hand,for blue light irradiation the mechanism seems to be different.In the latter case,the Ce^3+ions,having the position of energy levels in the conduction band,become sensitizers for the electrons and main emission centres for the PersL(de-trapping process goes through Ce^3+).展开更多
基金supported by the National Key R & D Program of China (2016YFC0101800)National Natural Science Foundation of China (51672286, U1832159, 51772185)Science and Technology Major Project of Ningbo Municipality (2017C110028)
文摘A series of Y2.985Al5–xGaxO12:0.015Ce(YAGG:Ce,x=0,1,2,3,4,5)transparent ceramics were prepared via a solid-state reaction method.Two-step sintering technique was proved to be an effective approach to prepare functional ceramics with high Ga concentration,and Y3Ga5O12(YGG)transparent ceramic was successfully prepared for the first time.According to the variation of Al/Ga ratio,regulation of band structure and luminescence properties of YAGG:Ce transparent ceramics were effectively investigated.When Ga substitutes Al sites,the tetrahedral site is more favorable compared to the octahedral site for Ga to occupy according to the first-principle calculation.A continuous blue shift of the emission from 565 to 515 nm was achieved as Ga was gradually introduced into Y3Al5O12:Ce matrix.High quality green light was obtained by coupling the YAGG:Ce ceramics with commercial blue InGaN chips.Transparent luminescence ceramics accomplished in this work can be quite prospective for high power LED application.
文摘We investigated photoluminescence （PL） and scintillation properties of Ce3＋-doped Y3A12Ga3OI2 （Ce：YAGG） trans- parent ceramics synthesized by vacuum sintering with different Ce3＋ concentrations （mol.%） from 0.3% to 1% （0.3%Ce：YAGG, 0.5%Ce：YAGG, 0.8%Ce：YAGG and I%Ce：YAGG）. The samples were synthesized by the vacuum sintering technique. The obtained samples showed a very strong and broad PL emission by the 5dl-4f transition of Ce3＋ in the wavelength range from 470 to 600 nm. The PL decay profiles were approximated by a single exponential decay function with the time constants of around 33-39 ns, Fur- thermore, the scintillation spectra induced by X-rays showed similar features with those observed in PL. The scintillation decay time profiles followed a second-order exponential decay function. The fast component group （ranged 3542 ns） were dominantly contrib- uted by the 5d1-4f transition of Ce3＋. The pulse height spectra utilizing the latter emissions showed a clear photoabsorption peak. Among those samples tested, 0.5%Ce：YAGG sample showed the highest scintillation light yield of 21,400 ph/MeV under 13VCs y-ray irradiation.
文摘The low-valence cations Na^(+)and Sr^(2+)were selected as the co-dopants to increase the vacancies concentration in the Y_(2.982)Ce_(0.018)Al_(2)Ga_(3)O_(12)phosphor.The successful incorporation of Na^(+)and Sr^(2+)was confirmed by the X-Ray Difiraction(XRD)results.All the samples show 5d-4f green persistent luminescence of Ce^(3+)after 450 nm excitation.The decay curves demonstrate that the persistent luminescence is efiectively enhanced with Na+and Sr2+doping.The thermoluminescence glow curves also show not only does the trap concentration increase,but also the distribution of trap depths is broadened.In addition,the air-and H_(2)/Ar-annealing treatments were conducted on every as-made sample.The experimental results prove that the increased traps after the Na^(+)/Sr^(2+)doping are mainly attributed to the oxygen vacancies,and the traps have a continuous and broad distribution of trap depths.We hope this work could give new inspiration for designing a high-performance persistent phosphor.
文摘The structural and thermal properties of yttrium-aluminum-gadolinium-gallium (Y2.97Gd0.03Al2Ga3O12) single crystals doped with terbium (0.1%), cerium (0.01%) and co-doped with both terbium and cerium ((0.1, 0.01)%) were investigated. All samples were heated (calcined) at 1400°C for 15 hours before crystallization. X-ray powder diffraction (XRD) patterns of all calcined samples showed the presence of yttrium gallium aluminate (Y3Al2Ga3O12) and gadolinium gallium oxide (Gd3GaO6) while the grown crystals were single phase of Y3Al2Ga3O12. The lattice parameter of the crystals decreased with Ce doping. The thermal conductivity of each sample was determined from 25°C to 300°C and found to decrease exponentially with increasing temperature. All doped crystals have different thermal conductivity, which is attributed to the crucial influence of crystals structures. 0.01% Ce:YAGG was found to be a strong candidate for scintillators and other lasing materials because of its good thermal behavior (10.71 W/m·K).
基金Project supported by the Polish National Science Centre(OPUS 11#2016/21/B/ST5/02385)
文摘The persistent luminescence(PersL)dependence on the dopants and derived mechanism of trapping and de-trapping processes were investigated in Y3Al2Ga3O12(YAGG)based nanophosphor,doped with Ce^3+and/or Cr^3+.It is found that the presence of Cr^3+ions produce electron and hole traps and capture suitable charge after X-ray irradiation.The effect of irradiation on the carriers trapping and their pathways after excitation was studied by means of thermo luminescence technique.On the other hand,for blue light irradiation the mechanism seems to be different.In the latter case,the Ce^3+ions,having the position of energy levels in the conduction band,become sensitizers for the electrons and main emission centres for the PersL(de-trapping process goes through Ce^3+).
