[Spectral characteristics of Ba3SiO4Cl2 : Eu2+ phosphor for white LED].

Ba3SiO4Cl2 : Eu2+ was synthesized by a high temperature solid state method. BaCO3 (A. R.), BaCl2 (A. R.), SiO2 (99.99%) and Eu2O3 (99.99%) were used as the raw materials. The final phase was checked with a conventional X-ray diffraction (XRD) (D/max-rA, CuKalpha, 40 kV, 100 mA, lambda = 0.154 06 nm). The spectral characteristics of the phosphors were performed by using a Hitachi F-4600 fluorescence spectrophotometer equipped with a 450 W Xe lamp. Ba3SiO4Cl2 : Eu2+ showed broad emission bands at 445 and 510 nm under the 365 nm radiation excitation. For the two emission peaks, the excitation spectra have two different spectral distributions, and the excitation peaks locate at 350 and 400 nm, respectively. The results indicate that different Eu2+ emission centres exist in Ba3SiO4Cl2. The emission intensity of the 445 and 510 nm peaks is influenced by Eu2+ doped content. With increasing its content, the emission intensity of 445 nm gradually increases, and that of 510 nm decreases. With washing the phosphor, the 445 nm emission peak disappears, and the emission spectrum has only the 510 nm emission band, and its intensity is lower than that of the original phosphor.

[Study on the spectral properties of Ca7(SiO4)2Cl6 phosphor for white LED].

A bluish green Ca7 (SiO4)2Cl6 : Eu2+ phosphor used for UV excited white LED was synthesized by high temperature solid state method. The XRD patterns and luminescence properties were investigated. The results indicated that the sample was single Ca7 (SiO4)2Cl6 phase; the emission spectrum included two emission peaks located at 418 and 502 nm, respectively. Monitoring for the two emission peaks, the excitation spectra were two broad band peaks centered at 290 and 360 nm respectively, which illustrated that Eu2+ ions located at two different crystal lattice sites. The influence of Eu2+ ions concentration on the luminescence intensity was studied and the optimal doping concentration was 0.75 mol%. The results showed that this phosphor was a better candidate bluish phosphor for UV based white LED.

[Influence of lighting sources spectra on the human visual brightness identification under the mesopic vision].

Based on the MOVE models and the measurement of emission spectra of various light sources, the photopic function weights x and the mesopic equivalent brightness of human visual spectral luminous efficiency in different background brightness were calculated. Results showed that in the mesopic scope, human visual function peak value gradually increases with the brightness decreasing, and is moving towards the short-wave direction. The change rate is inversely proportional to the s/p index. In the case of ambient brightness for 0.5 cd X m(-2), peak values increase by 30% compared to the photopic function. Compared to the traditional test results, the mesopic equivalent brightness of fluorescent lamp and other different color temperature white light LED showed a positive gain that reaches 40%. On the other hand, the high pressure sodium lamp showed a negative gain. Results also showed that there was a decreasing trend when the ambient light level increased, and once the brightness level reaches that when cone cells play a full role, the equivalent brightness will equal photopic brightness. The methods and conclusions of this paper can help evaluate light sources, light-emitting material spectrum and characteristics of apparent brightness.

[Fabrication and luminescent properties of Dy3+ doped Sr(1-x)Ca(x)MoO4].

Dy3+ doped Sr(1-x)CaxMoO4 phosphors were prepared by solid state method in the present paper. The crystal structure, luminescent properties and the effect of x on the luminescent properties were studied by XRD, SEM, excitation, emission and color parameters. The XRD patterns indicated that the samples were single phase of CaMoO4 and SrMoO4 when x=1 and x=0. It can be seen that the crystal size of samples prepared at 750 degrees C for 3 h were 0.2-1.0 microm, which was matched with solid state luminescent device. The excitation spectra monitored at 576 nm were composed of a broad band at 250-340 nm and a series of narrow band at 340-460 nm. The excitation peaks situation of CT transition and the excitation peaks intensity of narrow bands varied with Sr/Ca. The emission spectra excited by 350 nm were composed of two broad bands at 470 and 576 nm, which were attributed to the transition of 4F(9/2)-->(6)H(15/2) and (4)F(9/2)-->(6)H(13/2). The emission intensity of yellow and blue emission varied with the value of Sr/Ca.

[Spectral characteristics of Ba2B2P2O10 : Eu3+ phosphor].

Ba2B2P2O10 : Eu3+ phosphor was synthesized by high temperature solid-state method. BaCO3(A.R), NH4H2PO4 (A.R), H3BO3(A.R), Eu2O3 (99.99%), NH4Cl (A.R), Li2CO3 (A.R), Na2CO3 (A.R.) and K2CO3 (A.R.) were used for starting materials. After these individual materials were blended and grounded thoroughly in an agate mortar, the homogeneous mixture was heated at 1000 degrees C for 3 h, and the phosphors were obtained. The phase present of the samples were characterized by powder X-ray diffraction (XRD) (D/max-rA, Cu Kalpha, 40 kV, 40 mA, lamda = 0.15406 nm). The spectral characteristics of these phosphors were measured by a SHIMADZU RF-540 fluorescence spectrophotometer. Under the condition of 400 nm excitation, the emission spectrum of Ba2B2P2O10 : Eu3+ phosphor shows several bands at 600, 618, 627 and 660 nm respectively, which correspond to the electric dipole (5)D0-->(7)F1, (7)F2, (7)F3 and (7)F4 transitions of Eu3+. The effect of Eu3+ concentration or charge compensator on the emission intensity of Ba2B2P2O10 : Eu3+ phosphor was investigated, and the result shows that the emission intensity of the phosphor increases with increasing Eu3+ concentration, viz. the concentration quenching has not existed. And the emission intensity of the phosphor was enhanced by doping charge compensator. All the results illuminate that Ba2B2P2O10 : Eu3+ phosphor is a promising red phosphor for white LEDs.

[Spectral characteristics of Ce3+ in alkali-alkaline earth borate system].

Alkali-alkaline earth borate LiCaBO3 : Ce3+, LiSrBO3 : Ce3+ and LiBaBO3 : Ce3+ were investigated by solid-state method. CaCO3 (99.9%), SrCO3 (99.9%), BaCO3 (99.9%), Li2 CO3 (99.9%), Na2 CO3 (99.9%), K2 CO3 (99.9%), H3BO3 (99.9%) and CeO2 (99.9%) were used as starting materials, After these individual materials were blended and ground thoroughly in an agate mortar, the homogeneous mixture was heated at 700 degrees C for 2 h in a reduced atmosphere (5 : 95 (H2/N2)), and these three phosphors were obtained. The excitation and emission spectra of these phosphors were measured by a SHIMADZU RF-540 fluorescence spectrophotometer. The spectral characteristics of Ce3+ in alkali-alkaline earth borate LiCaBO3, LiSrBO3 and LiBaBO3 were investigated. The emission spectra of Ce3+ in these three phosphors all exhibited a dissymmetrical band, and the emission peaks were located at 428, 436 and 440 nm, respectively. The excitation spectra for 428, 436 and 440 nm emission of these three phosphors showed a dissymmetrical band at 364, 369 and 370 nm, respectively. The effects of Li+, Na+ and K+ on the emission intensities of these three phosphors were studied. The results show that the emission intensities of these phosphors were enhanced, and the maximal emission intensity of doping Li+ is higher than that of Na+ and K+.

[Study of spectra characteristics of Dy3+ -activated LiSrBO3 phosphor].

The LiSrBO3:Dy3+ phosphor was synthesized by solid-state method. SrCO2 (99.9%), Li2CO3 (99.9%), H3BO3 (99.9%) and Dy2O3 (99.9%) were used as starting materials. After these individual materials were blended and grounded thoroughly in an agate mortar, the homogeneous mixture was heated at 700 degrees C for 2 h in air, and LiSrBO3:Dy3+ phosphors were obtained. The phase present of the samples was characterized by powder X-ray diffraction (XRD) (D/max-rA, Cu Kalpha, 40 kV, 40 mA, lamda = 0.15406 nm). The excitation and emission spectra of these phosphors were measured by a RF-540 photoluminescence spectrophotometer. The emission spectrum of LiSrBO3:Dy3+ phosphor shows several bands at 486, 578 and 668 nm, respectively. The excitation spectrum for 578 nm emission has several excitation bands at 331, 368, 397, 433, 462 and 478 nm, respectively. The effect of Dy3+ concentration on the emission intensity of LiSrBO3:Dy3+ was investigated, and the result shows that the emission intensity of LiSrBO3:Dy3+ phosphor firstly increases with increasing Dy2+ concentration, then decreases, viz. the concentration quenching exists. And the Dy3+ concentration corresponding to the maximal emission intensity is 3 mol%, and the concentration quenching mechanisms are the d-d interaction by Dexter theory.

[Study of spectra characteristics of Ca3SiO5 : Eu2+ phosphor].

The Ca3SiO5 : Eu2+ phosphor was synthesized by the sol-gel reaction method. The emission spectrum was measured by a SPEX1404 spectrophotometer, and the excitation spectrum was measured by a SHIMADZU RF-540 ultraviolet spectrophotometer. All the characterization of the phosphors was conducted at room temperature. The results show that the emission spectrum of Ca3SiO5 : Eu2+ phosphor exhibits one asymmetry band centred at 505 nm under the 365 nm excitation, and the excitation spectrum for 505 nm indicates two bands centred at 374 and 397 nm, respectively. The above results indicate that the phosphor used for w-LEDs can be excited by UV light, and emit green light. The effect of synthesis condition, such as synthesis temperature, synthesis time and Eu2+ concentration, on the emission spectrum of Ca3SiO5 : Eu2+ phosphor was investigated. The results show that the emission peak intensity of Ca3SiO5 : Eu2+ phosphor firstly increases, then decreases with the increase in synthesis temperature or synthesis time or Eu2+ concentration, and reaches the maximum value at 1,100 degrees C, for 4 h and 0.5 mol% Eu2+.

[Effect of charge compensation on emission spectrum of Sr2SiO4 : Dy3+ phosphor].

The Sr2SiO4 : Dy3+ phosphor was synthesized by the high temperature solid-state reaction method in air. Dy2O3 (99.9%), SiO2 (99.9%), SrCO3 (99.9%), Li2CO3 (99.9%), Na2CO3 (99.9%) and K2CO3 (99.9%) were used as starting materials, and the Dy3+ doping concentration was 2 mol%. The emission spectrum was measured by a SPEX1404 spectrophotometer, and all the characterization of the phosphors was conducted at room temperature. The emission spectrum of Sr2 SiO4 : Dy3+ phosphor showed several bands centered at 486, 575 and 665 nm under the 365 nm excitation. The effect of Li+, Na+ and K+ on the emission spectra of Sr2SiO4 : Dy3+ phosphor was studied. The results show that the location of the emission spectrum of Sr2SiO4 : Dy3+ phosphor was not influenced by Li+, Na+ and K+. However, the emission spectrum intensity was greatly influenced by Li+, Na+ and K+, and the evolvement trend was monotone with different charge compensation, i. e. the emission spectrum intensity of Sr2SiO4 : Dy3+ phosphor firstly increased with increasing Li+ concentration, then decreased. However the charge compensation concentration corresponding to the maximum emission intensity was different with different charge compensation, and the concentration is 4, 3 and 3 mol% corresponding to Li+, Na+ and K+, respectively. And the theoretical reason for the above results was analyzed.

[Spectra characteristics of LiM (M = Ca, Sr, Ba) BO3 : Tb3+ phosphor].

LiM (M = Ca, Sr, Ba) BO3 : Tb3+ phosphors were synthesized by solid state reaction. The starting materials CaCO3, SrCO3, BaCO3, H3 BO3, Li2 CO3, Na2 CO3, K2 CO3 and Tb4 O7 (99.99% in mass) in appropriate stoichiometric ratio were mixed in the alumina crucible, then the mixed powders were calcined at 700 degrees C for 2 h, and LiCaBO3 : Tb3+, LiSrBO3 : Tb3+ and LiB-aBO3 : Tb3+ phosphors were obtained. The emission and excitation spectra were measured by a Shimadzu RF-540 ultraviolet spectrophotometer. All the photoluminescence properties of these phosphors were measured at room temperature. The emission spectra of LiM (M = Ca, Sr, Ba) BO3 : Tb3+ phosphors show several bands, and the main emission peaks correspond to the 5D4 --> 7F6(486, 486, 488 nm), 5D4 --> F5 (544, 544, 544 nm), 5D4 --> 7F4 (590, 595, 593 nm) and 5D4 --> 7F3 (620, 620, 616 nm) typical transitions of Tb3+, and the typical transitions of Tb3+ happens to split because of the effects of LiM (M = Ca, Sr, Ba) BO3 crystals field. The excitation spectra for the 544 nm green emission of LiM (M = Ca, Sr, Ba)BO3 : Tb3+ phosphors illuminate that these kinds of phosphors can be effectively excited by ultraviolet (350-410 nm) light, and emit green light, therefore, they are promising phosphors for white light emitting diodes. Effects of activation and charge compensation on the luminescence intensities of LiM (M = Ca, Sr, Ba) BO3 : Tb3+ phosphors were studied, and the results show that the intensities were obviously effected.

[Characteristic of optical emission spectrum in electron-assisted chemical vapor deposition of diamond].

The optical emission process of atomic hydrogen (Halpha, Hbeta, Hgamma), atomic carbon C(2p3s2p2 : lambda = 165.7 nm) and radical CH(A2delta --> X2II: lambda = 420-440 nm) in diamond film growth by electron-assisted chemical vapor deposition (EACVD) from a gas mixture of CH4 and H2 was studied by using Monte-Carlo simulation. The variation of the emission lines with gas pressure (0.1-12.5 kPa) of different substrate temperatures (573-1 173 K) was investigated. And the results show that at different substrate temperatures the intensity of all the emission lines increase with increasing gas pressure at first, whereas decreased afterward. Furthermore, the emission lines intensity decreases with increasing substrate temperature at a relative low gas pressure, while increases with increasing substrate temperature at the higher gas pressure.

[Effect of N+ (N = Li, Na, K) on the spectra of M3 (M = Ca, Sr, Ba) Y2 (BO3)4 : Eu3+ luminescent phosphor].

The M3 (M = Ca, Sr, Ba) Y2 (BO3)4 : Eu3+ red phosphor was synthesized by firing twice at 800 and 1 050 degrees C each for 4 h and 4 h in air, respectively. Y2O3 (99.9%), Eu2O3 (99.9%), H3BO3 (99.9%), CaCO3 (99.9%), SrCO3 (99.9%), BaCO3 (99.9%), Li2CO3 (99.9%), Na2CO3 (99.9%) and K2CO3 (99.9%) were used as starting materials, and the doping Eu3+ concentration was 3 mol%. The excitation spectrum was measured by a SHIMADZU RF-540 ultraviolet spectrophotometer. The emission spectrum was measured by a SPEX1404 spectrophotometer. All the luminescence characteristics of the phosphors were investigated at room temperature. The emission spectrum of M3 (M = Ca, Sr, Ba) Y2 (BO3)4 : Eu3+ phosphor exhibited a 613 nm red emission corresponding to the electric dipole 55D0 - 7F2 transition of Eu3+ under 365 nm excitation. The excitation spectrum for 613 nm indicates that the phosphor can be effectively excited by ultraviolet (UV) (254, 365 and 400 nm) and blue (470 nm) light. The effect of Li+ , Na+ and K+ on the excitation and emission spectra of M3 (M = Ca, Sr, Ba)Y2 (BO3)4 : Eu3+ phosphor was studied. The results show that the location of the excitation and emission spectrum of M3 (M = Ca, Sr, Ba) Y2 (BO3)4 : Eu3+ phosphor was not influenced by Li+, Na+ and K+. However, the excitation and emission spectrum intensities were greatly influenced by Li+, Na+ and K+, and the emission peak intensities were all enhanced. Under the condition of the same Li+, Na+ and K+ concentration, the emission peak intensities of M3 (M = Ca, Sr, Ba)Y2 (BO3)4 : Eu3+ phosphor were compared, and the result shows that the accretion effect of doping Li+ is the best. The effect of Li+ concentration on the emission peak intensity of Sr3 Y2 (BO3)4 : Eu3+ phosphor was studied. The results show that the emission peak intensity firstly increased with the increasing Li+ concentration, then decreased, and reached the maximum value at 5 mol% Li+, and the maximum value is about twice as much as the Li-undoped one.