2005, Vol.15, No.6

Journal of the Korean Crystal Growth and Crystal Technology 2023 KCI Impact Factor : 0.19

pISSN : 1225-1429 / eISSN : 2234-5078
https://journal.kci.go.kr/jkcgct

The evaporation amounts of volatile Cd, Pb and Zn were characterized by measuring their total concentrationsin the EAF dust-clay bodies with various mixing ratio and heat treatment temperature. TCLP test was conducted for evaluatingthe chemical stabilities of the heavy metal elements. Evaporation amounts and leaching concentrations of heavy metalcomponents were strongly dependent on the mixing ratio and heat treatment temperature. The evaporation of the heavymetal components were decreased with increasing clay content and temperature. 20 wt% EAF dust-80 wt% clay sampleshows nearly zero evaporation and leaching concentrations of heavy metal components. XRD analysis showed that peakintensities of major crystalline phases such as franklinite and quartz were decreased with increasing the heat treatmenttemperature which means that the stabilization mechanism of the heavy metals was related with the vitrification process ofthe SiO2 in the clay.

In spite of their superior optical and laser properties rare-earth orthovanadate single crystals have not been adopted yet into extensive industrial applications because of crystal growth difficulties. The edge-defined film-fed-growth (EFG) technique was applied successfully for the production of such crystals. At first time 1 inch LuVO4 single crystals were grown by the EFG technique using newly developed die construction of high porous iridium with the application of automatic diameter control system.

We have grown the long persistent SrAl2O4 :Eu2+, Dy3+ phosphor single crystal by Verneuil method. The obtainedsingle crystals were long persistent phosphorescence peaking at λ= 520 nm with a size of about 5 m diameter, 55 m length.The melting temperature of SrAl2O4 :Eu2+, Dy3+ measured Tmp=1968oC. The optimum composition was SrCO3 :Al(OH)3 :Eu2O3 :Dy2O3 = 1 : 2 : 0.015 : 0.02. Flow rate of H2 :O2 is about 4 : 1. Growthing rate is about 5 m/hr. The spectra of thephosphorescence from the crystals are quite similar to those obtained with sintered powders used for luminous pigments.The crystalline structure of long persistent SrAl2O4 :Eu2+, Dy3+ phosphor single crystal was determined by X-ray diffraction.