Wang Deyin from Lanzhou University @ Wang Yuhua LPR replaces BaLu2Al4SiO12 with Mg2+- Si4+pairs A new blue light excited yellow emitting fluorescent powder BaLu2 (Mg0.6Al2.8Si1.6) O12: Ce3+was prepared using Al3+- Al3+pairs in Ce3+, with an external quantum efficiency (EQE) of 66.2%. At the same time as the redshift of Ce3+emission, this substitution also widens the emission of Ce3+and reduces its thermal stability.
Lanzhou University Wang Deyin & Wang Yuhua LPR replaces BaLu2Al4SiO12 with Mg2+- Si4+pairs: A new blue light excited yellow emitting fluorescent powder BaLu2 (Mg0.6Al2.8Si1.6) O12: Ce3+was prepared using Al3+- Al3+pairs in Ce3+, with an external quantum efficiency (EQE) of 66.2%. At the same time as the redshift of Ce3+emission, this substitution also widens the emission of Ce3+and reduces its thermal stability. The spectral changes are due to the substitution of Mg2+- Si4+, which causes changes in the local crystal field and positional symmetry of Ce3+.
To evaluate the feasibility of using newly developed yellow luminescent phosphors for high-power laser illumination, they were constructed as phosphor wheels. Under the irradiation of a blue laser with a power density of 90.7 W mm − 2, the luminous flux of the yellow fluorescent powder is 3894 lm, and there is no obvious emission saturation phenomenon. Using blue laser diodes (LDs) with a power density of 25.2 W mm − 2 to excite yellow phosphor wheels, bright white light is produced with a brightness of 1718.1 lm, a correlated color temperature of 5983 K, a color rendering index of 65.0, and color coordinates of (0.3203, 0.3631).
These results indicate that the newly synthesized yellow luminescent phosphors have significant potential in high-power laser driven illumination applications.
Figure 1
Crystal structure of BaLu1.94(Mg0.6Al2.8Si1.6)O12:0.06Ce3+viewed along the b-axis.
Figure 2
a) HAADF-STEM image of BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+. Comparion with the structure model (insets) reveals that all positions of heavy cations Ba, Lu, and Ce are clearly imaged. b) SAED pattern of BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+and related indexing. c) HR-TEM of BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+. Inset is the enlarged HR-TEM. d) SEM of BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+. Inset is the particle size distribution histogram.
Figure 3
a) Excitation and emission spectra of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+(0 ≤ x ≤ 1.2). Inset are photographs of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+ (0 ≤ x ≤ 1.2) under daylight. b) Peak position and FWHM variation with increasing x for BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+ (0 ≤ x ≤ 1.2). c) External and internal quantum efficiency of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+ (0 ≤ x ≤ 1.2). d) Luminescence decay curves of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+ (0 ≤ x ≤ 1.2) monitoring their respective maximum emission (λex = 450 nm).
Figure 4
a–c) Contour map of temperature dependent emission spectra of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+(x = 0, 0.6 and 1.2) phosphor under 450 nm excitation. d) Emission intensity of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+ (x = 0, 0.6 and 1.2) at different heating temperatures. e) Configuration coordinate diagram. f) Arrhenius fitting of the emission intensity of BaLu1.94(MgxAl4−2xSi1+x)O12:0.06Ce3+ (x = 0, 0.6 and 1.2) as a function of heating temperature.
Figure 5
a) Emission spectra of BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+under blue LDs excitation with different optical power densities. Inset is photograph of the fabricated phosphor wheel. b) Luminous flux. c) Conversion efficiency. d) Color coordinates. e) CCT variations of the lighting source achieved by irradiation BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+ with blue LDs at different power densities. f) Emission spectra of BaLu1.9(Mg0.6Al2.8Si1.6)O12:0.1Ce3+ under blue LDs excitation with an optical power densities of 25.2 W mm−2. Inset is the photograph of the white light generated by irradiated the yellow phosphor wheel with the blue LDs with a power density of 25.2 W mm−2.
Taken from Lightingchina.com
Post time: Dec-30-2024