菱面片层氧化镁的制备及晶格畸变与反常红外特性

PREPARING NANOMETER RHOMBUS FLAKE MgO AND IT′S DISTORTION OF CRYSTAL LATTICE AND ABNORMAL INFRARED BEHAVIOR

以低品位白云石为原料采用二次酸浸、EDTA-氨水沉淀法制备前驱体Mg（OH）2，经煅烧得到菱面片层状多空隙结构的纳米MgO晶体。通过X射线衍射（XRD）、高分辨率扫描电镜（HRSEM）及傅立叶红外光谱（FT—IR）等测试手段对所得产物的物相和形貌等进行了表征。分析表明：氧化镁为结晶良好、立方晶系，厚度约10～20nm，最大面积可达1μm^2左右的菱形纳米片层结构；XRD数据表明纳米氧化镁的微结构存在晶格畸变并导致XRD相位差发生变化；红外光谱表明，Mg-O键伸缩特征吸收峰向高波数方向移动（蓝移）了约84．82cm^-1，而弯曲特征吸收峰向低波数方向移动（红移）了约31．88cm^-1，并导致红外吸收光谱的宽频化。结合XRD数据分析结果和界面效应等物理现象讨论了反常红外吸收机理。

Rhombus magnesia flakes with multi interspaces were prepared by calcining magnesium hydrate powders which processed by twice-acid immersing and ammonia depositing method from low content dolomite. The structure, morphology and composition of the heat-treated materials were characterized by means of XRD , HRSEM and FT-IR spectra analysis. The results of the HRSEM and XRD analysis showed that the magnesia were of cubic crystal nanometer rhombus flakes with 10-20 nm in thickness and up to 1μm2 in acreage. The distortion of crystal lattice of flake magnesia which leaded to the variety of the phase difference can he observed from XRD data calculate results. The abnormal infrared behavior, which the FT-IR characteristic absorption peak of Mg-O bond stretching vibration moved to a higher wave direction on about 84.82 cm^-1 and the characteristic absorption peak of Mg-O bond bend vibration moved to a lower wave direction on about 31.88 cm^-1 , and a wider rang of frequencies of IR spectra can be observed. The mechanism and behavior of abnormal IR absorption of nano-crystal rhombus magnesia flakes were studied with the methods of XRD data analysis and physical phenomenon such as interface effect,shape effect.