Experimental Study On Infrared Spectra Of Nano-MgO

It is very important for the development of modern stealthy technology and people's life to study and develop infrared stealthy materials. Recent researches have shown that nanometer metal oxides have special infrared properties, such as strong absorption, wide infrared bands and frequencies shift. In this thesis, experimental study on infrared spectra of nano-MgO has been carried out to explore the principle of the infrared absorption.The experimental part in this thesis is the study of nanometer MgO in detail. Nanometer MgO with different external morphology and grain sizes were prepared by liquid phase deposition-thermal decomposition, and were charactered by XRD,TEM and IR. The XRD results displayed that the grain sizes of the samples are 30nm～100nm. The infrared results show that nano-MgO with different external morphology and grain sizes have different infrared spectra. Compared to the normal MgO, the blue shift and broadening of absorption peak were observed. In certain range of grain sizes (100nm～50nm), blue shift were observed obviously with decreasing particle size; in certain range of grain sizes (50nm～30nm), red shift will happen with decreasing particle size. The particles of 50nm reached the limit of blue shift. The causes of these phenomena were discussed.Abnormal absorption of IR is impacted by many factors, including the lattice distortion, quantum size effect, surface effect and other factors. Which type of frequency shifts will happen depends on which factors playing a major role. In the latter part of the thesis, analysis shows that the existence of the interface leads to blue shift; lattice distortion of different parts in nano-particles made frequency shift non-monotonous.