The Jamesian style of poise and exquisiteness, and his notion of structural balance and his superb craftsmanship, is bril-liantly exemplified by The Portrait of a Lady, a work to be appreciated endlessly. This paper s...The Jamesian style of poise and exquisiteness, and his notion of structural balance and his superb craftsmanship, is bril-liantly exemplified by The Portrait of a Lady, a work to be appreciated endlessly. This paper studies the artistic genius of HenryJames, as it attains a great height in this early masterpiece.展开更多
In many database applications, ranking queries may reference both text and numeric attributes, where the ranking functions are based on both semantic distances/similarities for text attributes and numeric distances fo...In many database applications, ranking queries may reference both text and numeric attributes, where the ranking functions are based on both semantic distances/similarities for text attributes and numeric distances for numeric attributes. In this paper, we propose a new method for evaluating such type of ranking queries over a relational database. By statistics and training, this method builds a mechanism that combines the semantic and numeric distances, and the mechanism can be used to balance the effects of text attributes and numeric attributes on matching a given query and tuples in database search. The basic idea of the method is to create an index based on WordNet to expand the tuple words semantically for text attributes and on the information of numeric attributes. The candidate results for a query are retrieved by the index and a simple SQL selection statement, and then top-N answers are obtained. The results of extensive experiments indicate that the performance of this new strategy is efficient and effective.展开更多
A white emitting phosphor of YAl33(BO3)4:Ce+,Dy3+is synthesized by a solid state reaction,and its luminescent properties are investigated.Its phase formation is carried out with X-ray powder diffraction analysis,and t...A white emitting phosphor of YAl33(BO3)4:Ce+,Dy3+is synthesized by a solid state reaction,and its luminescent properties are investigated.Its phase formation is carried out with X-ray powder diffraction analysis,and there is no crystalline phase other than YAl3(BO3)4.YAl3(BO3)4:Ce3+can produce 422 nm blue emission under 367 nm excitation.The emission spectrum of YAl33(BO3)4:Dy+shows several emission peaks under 350 nm excitation,and the peaks locate at485 nm,575 nm and 668 nm,respectively.Emission intensities of Ce3+and Dy3+in YAl3(BO3)4 are influenced by their concentrations,and the concentration quenching effect is observed.Energy transfer from Ce3+to Dy3+in YAl3(BO3)4 is validated and proved to be a resonant type via a quadrupole-quadrupole interaction,and the emission color can be tuned from blue to white by tuning the ratio of Ce3+/Dy3+.Moreover,the critical distance(Rc)of Ce3+to Dy3+in YAl3(BO3)4 is calculated to be 1.904 nm.展开更多
A white emitting phosphor Ba2Ca(BO3)2:Dy3+ was synthesized via a high temperature solid state reaction at 1000℃ for 5 h. The luminescence, mole fraction quenching and thermal stability of Ba2Ca(BO3)2:Dy3+ were invest...A white emitting phosphor Ba2Ca(BO3)2:Dy3+ was synthesized via a high temperature solid state reaction at 1000℃ for 5 h. The luminescence, mole fraction quenching and thermal stability of Ba2Ca(BO3)2:Dy3+ were investigated. According to the phase composition analyzed by X-ray powder diffraction, there is no crystalline phase except Ba2Ca(BO3)2 in the sample. Ba2Ca(BO3)2:Dy3+ can produce white emission under 348 nm excitation. The emission intensities of Ba2Ca(BO3)2:Dy3+ are affected by Dy3+ concentration. The concentration quenching effect was analyzed, and the concentration quenching mechanism was verified as dipole-dipole interaction. The critical distance(R c) obtained based on the crystal structure data is 2.911 nm. At 150℃, the emission intensity of Ba2Ca(BO3)2:Dy3+ is 68.0% of the initial value at room temperature. The activation energy for the thermal quenching calculated is 0.202 e V. Moreover, the CIE chromaticity coordinates of Ba2Ca(BO3)2:Dy3+ locate in the white region of(0.319, 0.356).展开更多
A series of Sr3Y(PO4)3:Eu2+ samples are synthesized by the high temperature solid-state method. Sr3Y(PO4)3:Eu2+shows an asymmetrical emission band under excitation of 350 nm. The emission peaks at 426 nm and 497 nm ar...A series of Sr3Y(PO4)3:Eu2+ samples are synthesized by the high temperature solid-state method. Sr3Y(PO4)3:Eu2+shows an asymmetrical emission band under excitation of 350 nm. The emission peaks at 426 nm and 497 nm are assigned to the nine-coordination Eu2+ and six-coordination Eu2+, respectively. The effects of Eu2+ doping content on the emission intensity and color are observed, and the concentration quenching effect is also observed. For two different Eu2+ luminescence centers, the quenching mechanisms are dipole-dipole interaction and quadrupole-quadrupole interaction, respectively. And the critical distance of energy transfer is calculated by concentration quenching and turns out to be about 3.67 nm. The results above show that the asymmetrical emission band of Sr3Y(PO4)3:Eu2+ comes from two different Eu2+ luminescence centers in the lattice.展开更多
A series of Ce^(3+),Eu^(2+) and Ce^(3+)-Eu^(2+) doped Ca_9Al(PO_4)_7 phosphors are synthesized by a high temperature solid-state method.Under 291 nm excitation,Ca_9Al(PO_4)_7:Ce^(3+) has one emission band at 356 nm,wh...A series of Ce^(3+),Eu^(2+) and Ce^(3+)-Eu^(2+) doped Ca_9Al(PO_4)_7 phosphors are synthesized by a high temperature solid-state method.Under 291 nm excitation,Ca_9Al(PO_4)_7:Ce^(3+) has one emission band at 356 nm,which is attributed to4f°5d^1→4f^1 transition of Ce^(3+).Under 305 nm excitation,Ca_9Al(PO_4)_7:Eu^(2+) presents one emission band at 445 nm,which is assigned to 4f^65d^1→4f^7 transition of Eu^(2+).Energy transfer from Ce^(3+) to Eu^(2+) in Ca_9Al(PO_4)_7 is validated and proved to be a resonant type via a quadrupole-quadrupole interaction.Critical distance(R_c) of Ce^(3+) to Eu^(2+) in Ca_9Al(PO_4)_7 is calculated to be 1.264 nm.Moreover,the emission intensity of Ca_9Al(PO_4)_7:Ce^(3+),Eu^(2+) can be tuned by properly adjusting the relative doping composition of Ce^(3+)/Eu^(2+).展开更多
SrZn2(PO4)2:Sm3+ phosphor was synthesized by a high temperature solid-state reaction in atmosphere. SrZn2(PO4)2:Sm3+ phosphor is efficiently excited by ultraviolet(UV) and blue light, and the emission peaks are assign...SrZn2(PO4)2:Sm3+ phosphor was synthesized by a high temperature solid-state reaction in atmosphere. SrZn2(PO4)2:Sm3+ phosphor is efficiently excited by ultraviolet(UV) and blue light, and the emission peaks are assigned to the transitions of 4G5/2-6H5/2(563 nm), 4G5/2-6H7/2(597 nm and 605 nm) and 4G5/2-6H9/2(644 nm and 653 nm). The emission intensities of SrZn2(PO4)2:Sm3+ are influenced by Sm3+ concentration, and the concentration quenching effect of SrZn2(PO4)2:Sm3+ is also observed. When doping A+(A=Li, Na and K) ions, the emission intensity of SrZn2(PO4)2:Sm3+ can be obviously enhanced. The Commission Internationale de l'Eclairage(CIE) color coordinates of SrZn2(PO4)2:Sm3+ locate in the orange-red region. The results indicate that the phosphor has a potential application in white light emitting diodes(LEDs).展开更多
In this paper, we propose a new method based on index to realize IR-style Chinese keyword search with ranking strategies in relational databases. This method creates an index by using the related information of tuple ...In this paper, we propose a new method based on index to realize IR-style Chinese keyword search with ranking strategies in relational databases. This method creates an index by using the related information of tuple words and presents a ranking strategy in terms of the nature of Chinese words. For a Chinese keyword query, the index is used to match query search words and the tuple words in index quickly, and to compute similarities between the query and tuples by the ranking strategy, and then the set of identifiers of candidate tuples is generated. Thus, we retrieve top-N results of the query using SQL selection statements and output the ranked answers according to the similarities. The experimental results show that our method is efficient and effective.展开更多
Blue emitting phosphor SrZn_2(PO_4)_2:Eu^(2+) is synthesized by a high temperature solid state method,and the luminescent properties are investigated.At the 330 nm radiation excitation,SrZn_2(PO_4)_2:Eu^(2+) presents ...Blue emitting phosphor SrZn_2(PO_4)_2:Eu^(2+) is synthesized by a high temperature solid state method,and the luminescent properties are investigated.At the 330 nm radiation excitation,SrZn_2(PO_4)_2:Eu^(2+) presents an emission band at 416 nm,which is assigned to the 4f^65d^1→4f^7 transition of Eu^(2+) ion.The concentration quenching effect of Eu^(2+) in SrZn_2(PO_4)_2has been validated and proved to be a resonant type via a dipole-dipole interaction.The critical distance(R_c) of Eu^(2+) in SrZn_2(PO_4)_2 is calculated to be 3.244 nm.The Commission International de I'Eclairage(CIE) chromaticity coordinates of SrZn_2(PO_4)_2:Eu^(2+) locate at the blue region,such as(0.150,0.072).The results indicate that the SrZn_2(PO_4)_2:Eu^(2+)phosphor may have potential applications in white light emitting diodes(LEDs).展开更多
A series of Eu^(3+) or Tb^(3+) doped Ba_2Ca(BO_3)_2 phosphors were synthesized by a high temperature solid state method, and the luminescence properties are investigated. Ba_2Ca(BO_3)_2:Tb^(3+) can show an obvious gre...A series of Eu^(3+) or Tb^(3+) doped Ba_2Ca(BO_3)_2 phosphors were synthesized by a high temperature solid state method, and the luminescence properties are investigated. Ba_2Ca(BO_3)_2:Tb^(3+) can show an obvious green emission, and the peak locates at 551 nm, which corresponds to the 5D34→7F5 transition of Tb^(3+). Ba_2Ca(BO_3)_2:Eu+ can present the characteristic emission of Eu^(3+), and the peak locates at 600 nm, which is ascribed to the 5D70→F2 transition of Eu^(3+). In order to achieve the emission-tunable phosphors, the Eu^(3+)/Tb^(3+) co-doped Ba_2Ca(BO_3)_2 are synthesized. When tuning the Eu^(3+) or Tb^(3+) concentration, Ba_2Ca(BO_3)_2:Eu^(3+), Tb^(3+) can both show the tunable emission, which may be induced by the energy transfer from Tb^(3+) to Eu^(3+).展开更多
A series of Tb3+ doped Na Y(Mo O4)2 are synthesized by a solid-state reaction at 550 °C for 4 h, and their luminescent properties are investigated. The phase formation is carried out with X-ray powder diffraction...A series of Tb3+ doped Na Y(Mo O4)2 are synthesized by a solid-state reaction at 550 °C for 4 h, and their luminescent properties are investigated. The phase formation is carried out with X-ray powder diffraction analysis, and there is no other crystalline phase except Na Y(Mo O4)2. Na Y(Mo O4)2:Tb3+ can produce the green emission under 290 nm radiation excitation, and the luminescence emission peak at 545 nm corresponds to the 5D4→7F5 transition of Tb3+. The emission intensity of Tb3+ in Na Y(Mo O4)2 is enhanced with the increase of Tb3+ concentration, and there is no concentration quenching effect. The phenomena are proved by the decay curves of Tb3+. Moreover, the Commission International de I'Eclairage(CIE) chromaticity coordinates of Na Y(Mo O4)2:Tb3+ locate in the green region.展开更多
A novel white-bluish emitting phosphor of (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ is synthesized by the solid state reaction. (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ can be effectively excited by 370 nm ultraviolet (UV) light, and ex...A novel white-bluish emitting phosphor of (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ is synthesized by the solid state reaction. (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ can be effectively excited by 370 nm ultraviolet (UV) light, and exhibits two emission bands at 430 nm and 522 nm which are attributed to the d-f transitions of the Eu2+ ions in two different cation sites in the host lattices. And the chromaticity coordinate of (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ phosphor is (0.29, 0.25).展开更多
For enhancing the emission intensity and broadening the excitation region of Ba_3Eu(PO_4)_3(BEP),Sm^(3+) is doped as sensitizer in this paper.BEP:Sm^(3+) can produce an obvious red emission at near ultraviolet(n-UV) r...For enhancing the emission intensity and broadening the excitation region of Ba_3Eu(PO_4)_3(BEP),Sm^(3+) is doped as sensitizer in this paper.BEP:Sm^(3+) can produce an obvious red emission at near ultraviolet(n-UV) radiation.An effective energy transfer from Sm^(3+) to Eu^(3+) is proved.The commission international de I'Eclairage(CIE) chromaticity coordinates of BEP:Sm^(3+) locate at red region.When the environment temperature is 150℃,the emission intensity of BEP:0.10Sm^(3+) is decreased to 76%of the initial one at room temperature,and the activation energy is calculated to be0.164 eV,which can prove the good thermal stability of BEP:Sm^(3+).The results indicate that BEP:Sm^(3+) may have potential applications in white light emitting diodes(LEDs).展开更多
文摘The Jamesian style of poise and exquisiteness, and his notion of structural balance and his superb craftsmanship, is bril-liantly exemplified by The Portrait of a Lady, a work to be appreciated endlessly. This paper studies the artistic genius of HenryJames, as it attains a great height in this early masterpiece.
文摘In many database applications, ranking queries may reference both text and numeric attributes, where the ranking functions are based on both semantic distances/similarities for text attributes and numeric distances for numeric attributes. In this paper, we propose a new method for evaluating such type of ranking queries over a relational database. By statistics and training, this method builds a mechanism that combines the semantic and numeric distances, and the mechanism can be used to balance the effects of text attributes and numeric attributes on matching a given query and tuples in database search. The basic idea of the method is to create an index based on WordNet to expand the tuple words semantically for text attributes and on the information of numeric attributes. The candidate results for a query are retrieved by the index and a simple SQL selection statement, and then top-N answers are obtained. The results of extensive experiments indicate that the performance of this new strategy is efficient and effective.
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province in China(Nos.A2014201035 and E2014201037)the Education Office Research Foundation of Hebei Province in China(Nos.ZD2014036 and QN2014085)
文摘A white emitting phosphor of YAl33(BO3)4:Ce+,Dy3+is synthesized by a solid state reaction,and its luminescent properties are investigated.Its phase formation is carried out with X-ray powder diffraction analysis,and there is no crystalline phase other than YAl3(BO3)4.YAl3(BO3)4:Ce3+can produce 422 nm blue emission under 367 nm excitation.The emission spectrum of YAl33(BO3)4:Dy+shows several emission peaks under 350 nm excitation,and the peaks locate at485 nm,575 nm and 668 nm,respectively.Emission intensities of Ce3+and Dy3+in YAl3(BO3)4 are influenced by their concentrations,and the concentration quenching effect is observed.Energy transfer from Ce3+to Dy3+in YAl3(BO3)4 is validated and proved to be a resonant type via a quadrupole-quadrupole interaction,and the emission color can be tuned from blue to white by tuning the ratio of Ce3+/Dy3+.Moreover,the critical distance(Rc)of Ce3+to Dy3+in YAl3(BO3)4 is calculated to be 1.904 nm.
文摘A white emitting phosphor Ba2Ca(BO3)2:Dy3+ was synthesized via a high temperature solid state reaction at 1000℃ for 5 h. The luminescence, mole fraction quenching and thermal stability of Ba2Ca(BO3)2:Dy3+ were investigated. According to the phase composition analyzed by X-ray powder diffraction, there is no crystalline phase except Ba2Ca(BO3)2 in the sample. Ba2Ca(BO3)2:Dy3+ can produce white emission under 348 nm excitation. The emission intensities of Ba2Ca(BO3)2:Dy3+ are affected by Dy3+ concentration. The concentration quenching effect was analyzed, and the concentration quenching mechanism was verified as dipole-dipole interaction. The critical distance(R c) obtained based on the crystal structure data is 2.911 nm. At 150℃, the emission intensity of Ba2Ca(BO3)2:Dy3+ is 68.0% of the initial value at room temperature. The activation energy for the thermal quenching calculated is 0.202 e V. Moreover, the CIE chromaticity coordinates of Ba2Ca(BO3)2:Dy3+ locate in the white region of(0.319, 0.356).
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province of China(Nos.A2014201035 and E2014201037)the Education Office Research Foundation of Hebei Province of China(Nos.ZD2014036 and QN2014085)
文摘A series of Sr3Y(PO4)3:Eu2+ samples are synthesized by the high temperature solid-state method. Sr3Y(PO4)3:Eu2+shows an asymmetrical emission band under excitation of 350 nm. The emission peaks at 426 nm and 497 nm are assigned to the nine-coordination Eu2+ and six-coordination Eu2+, respectively. The effects of Eu2+ doping content on the emission intensity and color are observed, and the concentration quenching effect is also observed. For two different Eu2+ luminescence centers, the quenching mechanisms are dipole-dipole interaction and quadrupole-quadrupole interaction, respectively. And the critical distance of energy transfer is calculated by concentration quenching and turns out to be about 3.67 nm. The results above show that the asymmetrical emission band of Sr3Y(PO4)3:Eu2+ comes from two different Eu2+ luminescence centers in the lattice.
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation ofHebei Province in China(Nos.A2014201035 and E2014201037)the Education Office Research Foundation of Hebei Province in China(Nos.ZD2014036 and QN2014085)
文摘A series of Ce^(3+),Eu^(2+) and Ce^(3+)-Eu^(2+) doped Ca_9Al(PO_4)_7 phosphors are synthesized by a high temperature solid-state method.Under 291 nm excitation,Ca_9Al(PO_4)_7:Ce^(3+) has one emission band at 356 nm,which is attributed to4f°5d^1→4f^1 transition of Ce^(3+).Under 305 nm excitation,Ca_9Al(PO_4)_7:Eu^(2+) presents one emission band at 445 nm,which is assigned to 4f^65d^1→4f^7 transition of Eu^(2+).Energy transfer from Ce^(3+) to Eu^(2+) in Ca_9Al(PO_4)_7 is validated and proved to be a resonant type via a quadrupole-quadrupole interaction.Critical distance(R_c) of Ce^(3+) to Eu^(2+) in Ca_9Al(PO_4)_7 is calculated to be 1.264 nm.Moreover,the emission intensity of Ca_9Al(PO_4)_7:Ce^(3+),Eu^(2+) can be tuned by properly adjusting the relative doping composition of Ce^(3+)/Eu^(2+).
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province in China(Nos.A2014201035 and E2014201037)the Education Office Research Foundation of Hebei Province in China(Nos.ZD2014036 and QN2014085)
文摘SrZn2(PO4)2:Sm3+ phosphor was synthesized by a high temperature solid-state reaction in atmosphere. SrZn2(PO4)2:Sm3+ phosphor is efficiently excited by ultraviolet(UV) and blue light, and the emission peaks are assigned to the transitions of 4G5/2-6H5/2(563 nm), 4G5/2-6H7/2(597 nm and 605 nm) and 4G5/2-6H9/2(644 nm and 653 nm). The emission intensities of SrZn2(PO4)2:Sm3+ are influenced by Sm3+ concentration, and the concentration quenching effect of SrZn2(PO4)2:Sm3+ is also observed. When doping A+(A=Li, Na and K) ions, the emission intensity of SrZn2(PO4)2:Sm3+ can be obviously enhanced. The Commission Internationale de l'Eclairage(CIE) color coordinates of SrZn2(PO4)2:Sm3+ locate in the orange-red region. The results indicate that the phosphor has a potential application in white light emitting diodes(LEDs).
文摘In this paper, we propose a new method based on index to realize IR-style Chinese keyword search with ranking strategies in relational databases. This method creates an index by using the related information of tuple words and presents a ranking strategy in terms of the nature of Chinese words. For a Chinese keyword query, the index is used to match query search words and the tuple words in index quickly, and to compute similarities between the query and tuples by the ranking strategy, and then the set of identifiers of candidate tuples is generated. Thus, we retrieve top-N results of the query using SQL selection statements and output the ranked answers according to the similarities. The experimental results show that our method is efficient and effective.
基金This work has been supported by the Natural Science Foundation of Hebei Province in China (Nos.D2012201115 and A2011201010), the Guide Project of University Science & Technology Research in Hebei Province in China (No.Z2011266), the Scientific Research Project of Hebei Province Education Department (No.20052021), and the Guide Project of Bureau of Science and Technology of Baoding in Hebei Province in China (No. 12ZR057).
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province of China(Nos.A2014201035 and E2014201037)the Education Office Research Foundation of Hebei Province of China(Nos.ZD2014036 and QN2014085)
文摘Blue emitting phosphor SrZn_2(PO_4)_2:Eu^(2+) is synthesized by a high temperature solid state method,and the luminescent properties are investigated.At the 330 nm radiation excitation,SrZn_2(PO_4)_2:Eu^(2+) presents an emission band at 416 nm,which is assigned to the 4f^65d^1→4f^7 transition of Eu^(2+) ion.The concentration quenching effect of Eu^(2+) in SrZn_2(PO_4)_2has been validated and proved to be a resonant type via a dipole-dipole interaction.The critical distance(R_c) of Eu^(2+) in SrZn_2(PO_4)_2 is calculated to be 3.244 nm.The Commission International de I'Eclairage(CIE) chromaticity coordinates of SrZn_2(PO_4)_2:Eu^(2+) locate at the blue region,such as(0.150,0.072).The results indicate that the SrZn_2(PO_4)_2:Eu^(2+)phosphor may have potential applications in white light emitting diodes(LEDs).
基金supported by the China Postdoctoral Science Foundation(No.2015M581311)the College Students Innovation and Entrepreneurship of Hebei University in China(Nos.2014041 and 2015063)
文摘A series of Eu^(3+) or Tb^(3+) doped Ba_2Ca(BO_3)_2 phosphors were synthesized by a high temperature solid state method, and the luminescence properties are investigated. Ba_2Ca(BO_3)_2:Tb^(3+) can show an obvious green emission, and the peak locates at 551 nm, which corresponds to the 5D34→7F5 transition of Tb^(3+). Ba_2Ca(BO_3)_2:Eu+ can present the characteristic emission of Eu^(3+), and the peak locates at 600 nm, which is ascribed to the 5D70→F2 transition of Eu^(3+). In order to achieve the emission-tunable phosphors, the Eu^(3+)/Tb^(3+) co-doped Ba_2Ca(BO_3)_2 are synthesized. When tuning the Eu^(3+) or Tb^(3+) concentration, Ba_2Ca(BO_3)_2:Eu^(3+), Tb^(3+) can both show the tunable emission, which may be induced by the energy transfer from Tb^(3+) to Eu^(3+).
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province(Nos.A2014201035 and E2014201037)the Education Office Research Foundation of Hebei Province(Nos.ZD2014036 and QN2014085)
文摘A series of Tb3+ doped Na Y(Mo O4)2 are synthesized by a solid-state reaction at 550 °C for 4 h, and their luminescent properties are investigated. The phase formation is carried out with X-ray powder diffraction analysis, and there is no other crystalline phase except Na Y(Mo O4)2. Na Y(Mo O4)2:Tb3+ can produce the green emission under 290 nm radiation excitation, and the luminescence emission peak at 545 nm corresponds to the 5D4→7F5 transition of Tb3+. The emission intensity of Tb3+ in Na Y(Mo O4)2 is enhanced with the increase of Tb3+ concentration, and there is no concentration quenching effect. The phenomena are proved by the decay curves of Tb3+. Moreover, the Commission International de I'Eclairage(CIE) chromaticity coordinates of Na Y(Mo O4)2:Tb3+ locate in the green region.
基金the Natural Science Foundation of Hebei Province in China (No.D2012201115)
文摘A novel white-bluish emitting phosphor of (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ is synthesized by the solid state reaction. (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ can be effectively excited by 370 nm ultraviolet (UV) light, and exhibits two emission bands at 430 nm and 522 nm which are attributed to the d-f transitions of the Eu2+ ions in two different cation sites in the host lattices. And the chromaticity coordinate of (Ba0.49Sr0.49)2B2P2O10:0.02Eu2+ phosphor is (0.29, 0.25).
基金supported by the National Natural Science Foundation of China(No.50902042)the Natural Science Foundation of Hebei Province in China(Nos.A2014201035 and E2014201037)+1 种基金the Education Office Research Foundation of Hebei Province in China(Nos.ZD2014036 and QN2014085)the College Students Innovation and Entrepreneurship of Hebei University in China(Nos.2014041 and 2015063)
文摘For enhancing the emission intensity and broadening the excitation region of Ba_3Eu(PO_4)_3(BEP),Sm^(3+) is doped as sensitizer in this paper.BEP:Sm^(3+) can produce an obvious red emission at near ultraviolet(n-UV) radiation.An effective energy transfer from Sm^(3+) to Eu^(3+) is proved.The commission international de I'Eclairage(CIE) chromaticity coordinates of BEP:Sm^(3+) locate at red region.When the environment temperature is 150℃,the emission intensity of BEP:0.10Sm^(3+) is decreased to 76%of the initial one at room temperature,and the activation energy is calculated to be0.164 eV,which can prove the good thermal stability of BEP:Sm^(3+).The results indicate that BEP:Sm^(3+) may have potential applications in white light emitting diodes(LEDs).