Jin Man Han

Ca7.97-xMg(SiO4)4Cl2:Eu0.03,Dx (D=Y, Gd, Mn) Phosphor Particles Prepared by Spray Pyrolysis

Green-light-emitting Ca7.97-xMg(SiO4)4Cl2:Eu0.03,Dx (D=Y, Gd, Mn) phosphor particles were prepared by spray pyrolysis. The effects of the type of codopant on the morphology, crystallinity, and excitation and emission spectra of these particles were investigated. The codoped Ca8Mg(SiO4)4Cl2:Eu2+ phosphor particles obtained were fine and showed regular morphologies after post-treatment at 1100 °C for 3 h in a reducing atmosphere. The Ca7.97-xMg(SiO4)4Cl2:Eu0.03,Dx (D=Y, Gd, Mn) phosphor particles had broad excitation wavelengths that ranged from 260 to 450 nm. The improvements in their photoluminescence intensity were 29, 29, and 21% when the x values for the Y, Mn, and Gd codopants were 0.0075, 0.005, and 0.02, respectively.

Effects of Preparation Conditions in the Spray Pyrolysis on the Characteristics of Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ Phosphor

In spray pyrolysis, the effects of the preparation temperature, flow rate of the carrier gas and concentration of the spray solution on characteristics such as the morphology, size, and emission intensity of Ca Mg(SiO ) Cl :Eu phosphor powders under long-wavelength ultraviolet light were investigated. The phosphor powders obtained post-treatment had a range of micron sizes with regular morphologies. However, the composition, crystal structure and photoluminescence intensity of the phosphor powders were affected by the preparation conditions of the precursor powders. The Ca Mg(SiO ) Cl :Eu phosphor powders prepared at temperatures that were lower and higher than 700 C had low photoluminescence intensities due to deficiencies related to the of Cl component. The phosphor powders with the deficient Cl component had impurity peaks of Ca SiO . The optimum flow rates of the carrier gas in the preparation of the Ca Mg(SiO ) Cl :Eu phosphor powders with high photoluminescence intensities and regular morphologies were between 40 and 60 l/minute. Phosphor powders prepared from a spray solution above 0.5 M had regular morphologies and high photolu- minescence intensities.

Characteristics of Fe powders prepared by spray pyrolysis from a spray solution with ethylene glycol as the source material of heat pellet

Fe powders as the heat pellet material for thermal batteries are prepared from iron oxide powders obtained by spray pyrolysis from a spray solution of iron nitrate with ethylene glycol. The iron oxide powders with hollow and thin wall structure produce Fe powders with elongated structure and fine primary particle size at a low reducing temperature of 615 °C. The mean size of the primary Fe powders with elongated structure decreases with increasing concentration of ethylene glycol dissolved into the spray solution. The heat pellets prepared from the fine-size Fe powders with elongated structure have good ignition sensitivities below 1 watt. The heat pellets formed from the Fe powders obtained from the spray solution with 0.5 M EG have an extremely high burn rate of 26 cms−1.