The effect of flux addition to Eu²⁺-doped Ca-α-SiAlON phosphor

Abstract

A yellow-emitting Eu 2+ -doped Ca-¡-SiAlON phosphor is a promising candidate to make white LEDs by combining with blue LED. In the current research, the effect of flux (NH 4 Cl or NH 4 F) addition on the Ca-¡-SiAlON:Eu 2+ phosphor was investigated. The formation of both the compound and liquid phase between the flux and raw materials resulted in the decreased photoluminescence (PL) intensity in the early stage. However, the subsequent melting of second phases and retarded crystallization enhanced the PL intensity with increasing the synthesis temperature and time. The increased PL intensity for the flux-added compositions is attributed to the less surface damages due to grinding of as-synthesized agglomerate-like phosphors. Further, the flux addition enhanced the particle growth by forming agglomerates in the early stage and it also influenced the particle morphology from the typical acicular shape to pseudo-equiaxed shape.

Study on Sulfur Transfer Behavior during Refining of Rejected Electrolytic Manganese Metal

“…A BN crucible, which contained 180 g scrap of the rejected EMM, was first placed in the center of the Al2O3 tube in the furnace [15]. By flowing the high-purity (99.999%) argon gas at a rate of 5 NL/min, the furnace was heated to a specified temperature, ranging from 1773 K to 1923 K, at a The initial compositions of the rejected EMM and the slag are listed in Tables 1 and 2.…”

“…The melt process was kept in the furnace for 10 min at 1773 K. The quenched slag was thoroughly ground and then decarburized by heating in a muffle furnace (Wuhan Dianlu Factory, Wuhan, China) for about 10 h at 1273 K. The carbon content in the decarburized slag was confirmed to be lower than 0.001 mass%. A BN crucible, which contained 180 g scrap of the rejected EMM, was first placed in the center of the Al 2 O 3 tube in the furnace [15]. By flowing the high-purity (99.999%) argon gas at a rate of 5 NL/min, the furnace was heated to a specified temperature, ranging from 1773 K to 1923 K, at a heating rate of 10 K/min.…”

The Effect of Pretreatment of Raw Powders on the Photoluminescence of Ca-α-SiAlON:Eu2+Phosphor

“…1,2) On top of their excellent thermal quenching property, Eu 2+ -doped SiAlON phosphors are attractive due to their wide emission range, which covers band from green to red. [3][4][5][6][7][8][9][10][11] The fabrication and analysis of both the green-emitting β-SiAlON:Eu 2+ phosphor 3,4) and the yellow-emitting Ca-α-SiAlON:Eu 2+ phosphor [5][6][7][8][9][10][11] were well documented.…”

“…In the research laboratory as well as in the industry, chemically stable CaCO 3 is frequently adopted as a source of Calcium for α-SiAlON phosphors. [5][6][7][8][9] Therefore, the formation of agglomerates by CaO-containing eutectics and the decomposition of CaCO 3 to CaO is expected to occur in the course of heating.…”

Microstructure and Thermal Conductivity of Sintered Reaction‐Bonded Silicon Nitride: The Particle Size Effects of MgO Additive

“…Notably, it has also been proved that the grain size is a dominant microstructural factor with regard to the thermal conductivity of SRBSN [16,17]. First, the selfpurification of Si 3 N 4 grains with the exclusion of lattice oxygen generally occurs with the grain growth via a solutionreprecipitation process [18]. Secondly, because the intrinsic thermal conductivity of the glassy intergranular phase is much lower than that of Si 3 N 4 grains, the elimination of the grain boundaries with grain growth would be beneficial when attempting to realize high thermal conductivity [5,15].…”