Discovery of novel phosphors is extremely important to target the ever change of the solid state lighting technology. In this paper, we present a high-speed way to discover new phosphors, namely single- particle-diagn...Discovery of novel phosphors is extremely important to target the ever change of the solid state lighting technology. In this paper, we present a high-speed way to discover new phosphors, namely single- particle-diagnosis approach. This approach is based on investigating the crystal structure and lumines- cence of a tiny single crystal, without the necessity of the growth of large-size single crystals or the preparation of single phase powder samples. The concept of the approach and some new nitride phosphors explored by this approach are shown in this paper.展开更多
Pure Ca-SiAlON:Eu2+ was synthesized by microwave sintering method at a relatively low temperature of 1550℃.Photoluminescence intensity of the resultant phosphor was higher than those of the samples synthesized by con...Pure Ca-SiAlON:Eu2+ was synthesized by microwave sintering method at a relatively low temperature of 1550℃.Photoluminescence intensity of the resultant phosphor was higher than those of the samples synthesized by conventional gas-pressure sintering technique at 1750℃.When it was excited at 450 nm,the as-prepared yellow Ca-SiAlON:Eu2+ sample had an external quantum efficiency of 42%,comparable to the sample synthesized at 1750℃ under 0.5 MPaN2 gas pressure by the GPS method reported in reference.The experimental results demonstrated that the microwave sintering method was also an interesting approach for synthesizing nitride phosphors,which promises lower firing temperature than those by carbothermal reduction and nitridation (CRN) methods,higher heating rate and shorter duration time compared with those by gas-pressure sintering.展开更多
Color rendition,luminous efficacy and reliability are three key technical parameters for white light-emitting diodes(wLEDs)that are dominantly determined by down-conversion phosphors.However,there is usually an inevit...Color rendition,luminous efficacy and reliability are three key technical parameters for white light-emitting diodes(wLEDs)that are dominantly determined by down-conversion phosphors.However,there is usually an inevitable trade-off between color rendition and luminescence efficacy because the spectrum of red phosphor(that is,spectral broadness and position)cannot satisfy them simultaneously.In this work,we report a very promising red phosphor that can minimize the aforementioned trade-off via structure and band-gap engineering,achieved by introducing isostructural LiSi_(2)N_(3) into CaAlSiN_(3):Eu^(2+).The solid solution phosphors show both substantial spectra broadening(88→117 nm)and blueshift(652→642 nm),along with a significant improvement in thermal quenching(only a 6%reduction at 150℃),which are strongly associated with electronic and crystal structure evolutions.The broadband and robust red phosphor thus enables fabrication of super-high color rendering wLEDs(Ra=95 and R9=96)concurrently with the maintenance of a high-luminous efficacy(101 lm W^(−1)),validating its superiority in highperformance solid state lightings over currently used red phosphors.展开更多
基金Project supported by National Natural Science Foundation of China(5157223,51561135015,51272259)Natural Science Foundation of Jiangsu Province(BK20170242)
文摘Discovery of novel phosphors is extremely important to target the ever change of the solid state lighting technology. In this paper, we present a high-speed way to discover new phosphors, namely single- particle-diagnosis approach. This approach is based on investigating the crystal structure and lumines- cence of a tiny single crystal, without the necessity of the growth of large-size single crystals or the preparation of single phase powder samples. The concept of the approach and some new nitride phosphors explored by this approach are shown in this paper.
基金supported by the National Natural Science Foundation of China(51102252 and 51272259)the Special Foundation for Young Scientists of Zhejiang Province(R12E020005)
文摘Pure Ca-SiAlON:Eu2+ was synthesized by microwave sintering method at a relatively low temperature of 1550℃.Photoluminescence intensity of the resultant phosphor was higher than those of the samples synthesized by conventional gas-pressure sintering technique at 1750℃.When it was excited at 450 nm,the as-prepared yellow Ca-SiAlON:Eu2+ sample had an external quantum efficiency of 42%,comparable to the sample synthesized at 1750℃ under 0.5 MPaN2 gas pressure by the GPS method reported in reference.The experimental results demonstrated that the microwave sintering method was also an interesting approach for synthesizing nitride phosphors,which promises lower firing temperature than those by carbothermal reduction and nitridation (CRN) methods,higher heating rate and shorter duration time compared with those by gas-pressure sintering.
基金the financial support from the JSPS KAKENHI(No.23560811)the National Natural Science Foundation of China(Nos.51272259,61575182,5157223 and 51561135015)+1 种基金the Natural Science Foundation of Zhejiang Province(No.Y16F050012)the Taiwan Science and Technology Authority(No.‘MOST’104-2113-M-002-012-MY3 and No.104-2119-M-002-027-MY3).
文摘Color rendition,luminous efficacy and reliability are three key technical parameters for white light-emitting diodes(wLEDs)that are dominantly determined by down-conversion phosphors.However,there is usually an inevitable trade-off between color rendition and luminescence efficacy because the spectrum of red phosphor(that is,spectral broadness and position)cannot satisfy them simultaneously.In this work,we report a very promising red phosphor that can minimize the aforementioned trade-off via structure and band-gap engineering,achieved by introducing isostructural LiSi_(2)N_(3) into CaAlSiN_(3):Eu^(2+).The solid solution phosphors show both substantial spectra broadening(88→117 nm)and blueshift(652→642 nm),along with a significant improvement in thermal quenching(only a 6%reduction at 150℃),which are strongly associated with electronic and crystal structure evolutions.The broadband and robust red phosphor thus enables fabrication of super-high color rendering wLEDs(Ra=95 and R9=96)concurrently with the maintenance of a high-luminous efficacy(101 lm W^(−1)),validating its superiority in highperformance solid state lightings over currently used red phosphors.
