γ-CuⅠ晶体生长和红光发射的抑制机理

Growth and Red Luminescence Suppression of γ-CuⅠ Single Crystal

以乙腈为溶剂、γ-CuⅠ粉末为原料,采用溶剂蒸发法,通过工艺优化,生长出了尺寸约为9mm×9mm×1mm的透明γ-CuⅠ闪烁晶体。卢瑟福背散射谱(RBS)实验结果表明,所生长的γ-CuⅠ晶体中铜和碘元素的比例分别为53.1和46.9mol%。在生长溶剂中掺入适量碘可提高γ-CuⅠ晶体中碘的比重,所获得晶体中铜和碘元素的比例被调整为50.4和49.6mol%。光致发光谱(PL)的结果表明,所生长的γ-CuⅠ晶体存在有410nm发射峰和720nm附近的宽发射带,掺碘后720nm的宽发射带得到了较大幅度的抑制,但同时也会在424和474nm处出现两个相对较弱的发射峰;X射线激发发射谱(XEL)显示,所生长的CuⅠ晶体存在有435nm发射峰和720nm附近的宽发射带,掺碘后720nm的宽发射带得到了较大抑制。综合掺碘前后γ-CuⅠ晶体的发射光谱可以发现:碘元素有助于抑制γ-CuⅠ晶体的红光发射,其原因来自于碘元素的体掺杂造成晶体中碘空位的减少,而非由晶体表面的吸附碘。

Transparent γ-CuⅠ crystal with size about 9 min× 9 mm× 1 mm was grown by using optimized solvent evaporation method with γ-CuⅠ powders as raw material and acetonitrile as solvent. The results of Rutherford backscattering spectrometry （RBS） showed that the proportions of copper and iodine in as-grown γ-CuⅠ crystal were 53.1 and 46.9mol%, respectively. By iodine doping into growth solution, the proportions of copper and iodine were adjusted to 50. 4 and 49.6 mol%, respectively. Photolumineseence （PL） showed that the as-grown γ-CuⅠ crystal had an emission at 410 nm and an emission band around 720 nm. After iodine doping, the emission band around 720 nm was suppressed while other two weak emissions at 424 and 474 ran appeared. X-ray excited luminescence （XEL） showed that the as-grown γ-CuⅠ crystal had an emission at 435 nm and an emis-sion band around 720 nm. After iodine doping, the emission band around 720 nm was suppressed. Comparing the emission spec-tra before and after iodine doping, it is clear that red luminescence in γ-CuⅠ crystal could be suppressed by iodine doping. The effect originated from the reduction of iodine vacancy in the crystal, but not from the iodine adsorbtion on the surface.