Qinglin Guo

Luminescent characteristics of Ba3 Y2(BO3)4:Eu3+ phosphor for white LED

Abstract The Ba 3 Y 2 (BO 3 ) 4 :Eu 3+ phosphor was synthesized using a high temperature solid-state reaction method and the luminescent characteristics were investigated. The emission spectrum exhibited one strong red emission at 613 nm, corresponding to the electric dipole 5 D 0- 7 F 2 transition of Eu 3+ , under 365 nm excitation. The excitation spectrum of 613 nm indicated that the Ba 3 Y 2 (BO 3 ) 4 :Eu 3+ phosphor was effectively excited by ultraviolet (UV) (254, 365 and 400 nm) and blue (470 nm) light. The effect of Eu 3+ concentration on the 613 nm emission of the Ba 3 Y 2 (BO 3 ) 4 :Eu 3+ phosphor was measured. The results showed that the emission intensity increased with increasing Eu 3+ concentration, and then decreased. The CIE color coordinates of Ba 3 Y 2 (BO 3 ) 4 :Eu 3+ phosphor were x =0.641 and y =0.359 at 15 mol.% Eu 3+ .

Luminescent characteristics of LiCaBO3:Eu3+ phosphor for white light emitting diode

Abstract LiCaBO 3 :Eu 3+ phosphor was synthesized by high solid-state reaction method, and its luminescent characteristics were investigated. The emission and excitation spectra of LiCaBO 3 :Eu 3+ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet (400 nm) and blue (470 nm) light, and emitted red light. The effect of Eu 3+ concentration on the emission spectrum of LiCaBO 3 :Eu 3+ phosphor was studied. The results showed that the emission intensity increased with increasing Eu 3+ concentration, and then decreased because of concentration quenching. It reached the maximum at 3mol.% Eu 3+ , and the concentration self-quenching mechanism was the d-d interaction according to the Dexter theory. Under the conditions of charge compensator Li + , Na + or K + incorporated in LiCaBO 3 , the emission intensities of LiCaBO 3 :Eu 3+ phosphor were enhanced.

Luminescent properties of Eu3+-doped BaZrO3 phosphor for UV white light emitting diode

Abstract A novel orange phosphor Eu3+ doped barium zirconate (BaZrO3) was synthesized by conventional solid state reaction method and its crystal structure and luminescent properties were investigated in this paper. The X-ray diffraction patterns (XRD) showed that simple BaZrO3 phase was obtained. Monitoring at 596 nm, the excitation spectrum consisted of a broad band and a series of narrow bands and the stronger excitation peaks located at 275 and 393 nm, respectively. The emission spectrum excited by 393 nm UV light was composed of four narrow bands. The strongest emission was located at 596 nm. The appropriate concentration of Eu3+ was 0.025 (molar fraction) for the highest emission intensity at 596 nm. The H3BO3 and ammonium were added as flux and the results showed that 2 wt.% NH4F ions was the optimal flux for BaZrO3:Eu3+.

Effect of charge compensation on emission spectrum of Ca2SiO4: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.

Bandgap control for the lattice-matched InGaAs/InAlAs/InP single quantum wells

In0.53Ga0.47As/In0.52Al0.48As single quantum well (SQW) grown by molecular-beam epitaxy on the InP (001) substrate is investigated by using photoluminescence (PL) spectroscopy and time-resolved photoluminescence (TRPL). At the low temperature of 8 K and excitation intensity of 1 W/cm2, the emitting wavelength of QWs shifts from 1387 nm to 1537 nm when the well width increases from 5 nm to 50 nm, approaching the emitting wavelength of bulk In0.52Al0.48As. The emitting wavelength of QWs can be flexibly tailored by varying the thickness of the InGaAs layer.