Growth And Characterization Of CuI Crystal In Ionic Liquids

In recent years, scintillation crystals materials have became a hot subject in the Materialscience. Which owing to scintillation properties with fast dedaying time and high density, potentialapplication value in safety inspection and medical imaging. γ-cuprous iodide(CuI) crystal in cubicsystem with space group F-43m, the cell parameter of a=6.04, b=6.04, c=6.04, α=β=γ=90°. It has been considered to be an excellent scintillating crystal with fast dedaying time, bigphotoyield.Ionic liquids were used as good solvents for its low volatility, good thermal stability, strongsolubility characteristics. In this paper, we chose green organic solvents ionic liquids as solvent,studying solution conditions, optimizing growth parameters for growth of CuI-type crystal bysolution method.Halogenated n-butane and N-methyl imidazole have been used as reaction materials. Threekinds of ionic liquids of chloride1-butyl-3-methylimidazolium ([BMIm]Cl), bromide1-butyl-3-methylimidazolium ([BMIm]Br), iodide1-butyl-3-methylimidazolium ([BMIm]I) have beenselectively synthesized, refluxed and heated under nitrogen atmosphere. The relationship havebeen studied between the reaction temperarure, time and yield, purity by IR,1H-NMR, TG-DTA.The experimental results are as follows: reaction time and temperature affectted yield and purity, sothe appropriate synthesis time of [BMIm]Cl was12hours; the best temperature of [BMIm]I was100C.Selecting the appropriate solvent was critical. We studied the solution state of CuI in thesethree ionic liquids by measuring viscosity, conductivity and analyzing X ray photoelectronspectroscopy. The results showed that: the system of [BMIm]Cl and CuI、[BMIm]Br and CuIwere suitable solutions with moderate viscosity and little effect on CuI crystal purity of chlorideand bromine.In this experiment, we determined solubility curve of CuI in [BMIm]Br, studied the influenceof oxygen, moisture, reductant and acid-base properties on the solution state. Growing CuI singlecrystal by the solution cooling, the temperature difference method. Solution growth conditionswere: controlling solution temperature at160C under nitrogen protection, copper as reducingagent; dissolved of stirring speed was130r/min, growth of50r/min; cooling rate was1~1.2C/d. CuI crystal in size of10mm×7mm×2mm has been obtained. Polycrystalline of CuI was grown bytemperature difference method without in-depth study. Characterization of crystal: XRD showed γ-CuI; TG-DTA curves showed phase transition temperature was377C and405C, decompositionpeak at606C; UV absorption curve showed energy gap of CuI crystal was2.9eV.