过渡金属Co2+离子掺杂ZnS硫化物纳米晶制备与中红外发光特性研究

利用不含有机相的简单水热法制备了Co^2+∶ZnS纳米晶,纳米晶具有立方闪锌矿结构,平均晶粒尺寸约为8.3 nm,在808 nm激光泵浦下具有2~5μm波段的中红外荧光发射,中心波长位于3400 nm和4700 nm,分别对应Co^2+离子的4T2(F)→4 A 1(F)和4T1(F)→4T2(F)的能级跃迁.进一步将制备的纳米晶在还原气氛下进行800℃热处理,获得立方闪锌矿和纤锌矿混合晶型的纳米晶,平均晶粒尺寸增大到22.5 nm左右,热处理后的纳米晶表面羟基含量更低,中红外荧光发射强度显著提高.该Co^2+∶ZnS纳米晶的制备方法简单、在制备过程中不引入有机相等荧光淬灭中心,同时证明通过后热处理过程可以进一步减少表面缺陷及羟基含量,使荧光强度得到大幅提升.

Preparation and Mid-infrared Luminescence Properties of Transition Metal Co2+ Doped ZnS Sulfide Nanocrystals

Co^2+∶ZnS sulfide nanocrystals are prepared by a simplified hydrothermal method without organic materials.These nanocrystals have a cubic sphalerite structure with an average grain size of around 8.3 nm.Mid-infrared fluorescence emissions at 3400 nm and 4700 nm were detected under 808 nm laser pumping.By heat treatment at 800℃ in a reducing atmosphere,the prepared nanocrystals transfered to cubic sphalerite and wurtzite mixed crystal forms,and the average grain size increaes to 22.5 nm.After the heat treatment,the nanocrystals possess lower hydroxyl content on surface,therefore exhibit stronger mid-infrared fluorescence.This method is facile and aviods the introduction of organic mid-infrared fluorescence quenching centers during the preparation of Co^2+∶ZnS nanocrystals.The surface defects and hydroxy content of Co^2+∶ZnS nanocrystals were reduced and more stronger mid-infrared fluorescence was obtained after heat treatment.