2024-03-28T20:29:02Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/757602022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Combustion synthesis of Ca-alpha-SiAlON:Eu2+ phosphors with different Ca concentrations and diluent ratiosSaito, GenkiKunisada, YujiSakaguchi, NorihitoNomura, TakahiroAkiyama, TomohiroPhosphorOxynitrideSiAlONCombustion synthesis573Yellow Ca-alpha-SiAlON:Eu2+ phosphors for white light-emitting diodes (LEDs) were synthesized by a facile combustion synthesis method using CaO, Eu2O3, alpha-Si3N4, Si, and Al as raw materials. Ca concentrations and diluent ratios were optimized to improve their luminescence properties. The lattice constant and luminescence properties improved as x increased from 0.4 to 1.2 in Ca(x)Si(12-(m+n))Al(m+n)OnN(16-n):En(0.06). The optimum value was x = 1.2. Scanning transmission electron microscopy combined with energy dispersive X-ray analysis detected segregation of Ca and Eu at grain boundaries, which decreased luminescence behavior in the x = 1.4 sample. The influence of Si and Si3N4 diluents was investigated by varying the diluent ratio phi = (CaO + Eu2O3 + alpha-Si3N4)/(CaO + Eu2O3 + a-Si3N4 + Al + Si). Changes in temperature and flame propagation speed were measured during combustion synthesis using two thermocouples. When phi, was less than 0.5, the combustion temperature exceeded 1600 degrees C and the synthesized material contained an amount of the high-temperature beta-SiAlON phase. At phi > 0.7, the reaction temperature fell below 1200 degrees C, and unreacted raw materials remained. The optimum value of phi was 0.6. The internal quantum efficiency of the product synthesized at x = 1.2 and (I, = 0.6 was approximately 35% under 450-nm excitation. According to electron probe X-ray microanalysis, composition varied within individual synthesized particles, which may explain the decrease in emission behavior relative to a commercial product.ElsevierJournal Articleapplication/pdfhttp://hdl.handle.net/2115/75760https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/75760/1/SiAlON_v11-1.pdf0272-8842Ceramics international431512396124012017-10-15enginfo:doi/10.1016/j.ceramint.2017.06.106© 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/author