Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2 CO3 and NH4 Cl were used as the fluxes.The phase for...Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2 CO3 and NH4 Cl were used as the fluxes.The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photo luminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi2 O2 N2：Eu^2＋ phosphor can be improved effectively. The photoluminescence intensity of BaSi2 O2 N2：Eu^2＋ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2 CO3, NH4 Cl and without flux. The optimum content of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2 O2 N2：Eu^2＋ phosphor prepared with BaF2 flux rises to 141%,meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2 O2 N2：Eu^2＋ is sort of promising bluish-green phosphor for application in full-spectra LED.展开更多
This paper reports crystal structures, magnetic properties and thermal stability of TbCu7-type Sm（8.5）Fe（（85.8-x）Co（4.5）Zr（1.2）Nbx（x = 0-1.8） melt-spun compounds and their nitrides, investigated by means of...This paper reports crystal structures, magnetic properties and thermal stability of TbCu7-type Sm（8.5）Fe（（85.8-x）Co（4.5）Zr（1.2）Nbx（x = 0-1.8） melt-spun compounds and their nitrides, investigated by means of X-ray diffraction, vibrating sample magnetometer, flux meter and transmission electron microscope. It is found that the lattice parameter ratio c/a of TbCu7-type crystal structure increases with Nb substitution, which indicates that the Nb can increase the stability of the metastable phase in the Sm-Fe ribbons. Nb substitution impedes the formation of magnetic soft phase a-Fe in which reversed domains initially form during the magnetization reversal process. Meanwhile, Nb substitution refines grains and leads to homogeneous micro structure with augmented grain boundaries. Thus the exchange coupling pining field is enhanced and irreversible domain wall propagation gets suppressed. As a result, the magnetic properties are improved and the irreversible flux loss of magnets is notably decreased. A maximum value 771.7 kA/m of the intrinsic coercivity H（cj） is achieved in the 1.2 at% substituted samples.The irreversible flux loss for 2 h exposure at 120 ℃ declines from 8.26% for Nb-free magnets to 6.32% for magnets with 1.2 at% Nb substitution.展开更多
基金Project supported by the National Key Research and Development Program of China(2016YFB0701003)
文摘Eu^2＋ activated BaSi2 O2 N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2 CO3 and NH4 Cl were used as the fluxes.The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photo luminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi2 O2 N2：Eu^2＋ phosphor can be improved effectively. The photoluminescence intensity of BaSi2 O2 N2：Eu^2＋ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2 CO3, NH4 Cl and without flux. The optimum content of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2 O2 N2：Eu^2＋ phosphor prepared with BaF2 flux rises to 141%,meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2 O2 N2：Eu^2＋ is sort of promising bluish-green phosphor for application in full-spectra LED.
基金Project supported by the National Natural Science Foundation of China(51401028)
文摘This paper reports crystal structures, magnetic properties and thermal stability of TbCu7-type Sm（8.5）Fe（（85.8-x）Co（4.5）Zr（1.2）Nbx（x = 0-1.8） melt-spun compounds and their nitrides, investigated by means of X-ray diffraction, vibrating sample magnetometer, flux meter and transmission electron microscope. It is found that the lattice parameter ratio c/a of TbCu7-type crystal structure increases with Nb substitution, which indicates that the Nb can increase the stability of the metastable phase in the Sm-Fe ribbons. Nb substitution impedes the formation of magnetic soft phase a-Fe in which reversed domains initially form during the magnetization reversal process. Meanwhile, Nb substitution refines grains and leads to homogeneous micro structure with augmented grain boundaries. Thus the exchange coupling pining field is enhanced and irreversible domain wall propagation gets suppressed. As a result, the magnetic properties are improved and the irreversible flux loss of magnets is notably decreased. A maximum value 771.7 kA/m of the intrinsic coercivity H（cj） is achieved in the 1.2 at% substituted samples.The irreversible flux loss for 2 h exposure at 120 ℃ declines from 8.26% for Nb-free magnets to 6.32% for magnets with 1.2 at% Nb substitution.
