Preparation Of Nanometer Complex Oxides By Sol-gel-auto-combustion Method And The Research On Their Properties

Nanometer complex oxides are one kind of very useful nano-materials. Because of the quantum size effect,small size effect,surface effect and macro-quantum tunnel effect,its property is obviously superior to the counterpart bulk materials.In this paper,the research situation of the Ce-Mg-O complex nano-oxides and the copper ferrite are introduced,some frequently-used methods of preparing nanometer complex oxides are enumerated,and their advantages and drawbacks are analyzed.The said two kinds nanometer complexes are prepared using sol-gel auto-combustion method.The structure and composition of the as-prepared nano-oxides were characterized and the reaction condition was improved and optimized and their some application was analyzed.Ce-Mg-O nano-powders are prepared by sol-gel method using Ce(NO₃)₃6H₂O,(MgCO₃)₄Mg(OH)₂5H₂O and malic acid as raw materials. According to different molar ratios of Ce to Mg,five different kinds of nano-powders are prepared.The constituents and the thermal decomposition process of the precursor were studied by FT-IR,TG-DTA,and XRD.The morphology and Uv-shielding property were characterized by TEM and Uv-vis respectively.The influence of ratio of the raw materials,reaction time, calcined temperature and time on the particle size and morphology of the sample was analyzed.The results show that the molar ratio of metal ions to malic acid being 1:2,the pH value of the mixed solution being about 8.0, calcined temperature at 600℃,calcined for 3h were the best reaction conditions.A Uv-vis spectrum shows that the nanometer Ce-Mg-O complex oxides have strong absorption at ultraviolet region and they have excellent Uv-shielding property,so they can be used to prevent rubber from aging and to synthesis Uv-shielding materials. According to different molar ratios of Ce to Mg,three different kinds of nano-powders are prepared by auto-combustion method using Mg(NO₃)₂5H₂O,Ce(NO₃)₃6H₂O and malic acid as raw materials.Using this method,the samples can be obtained via heated the precursor on a hot plate up to about 240℃,without calcining the precursor at high temperature.This method is simple,inexpensive equipment,economy,high quality and in keeping with industrialization produce.The constituents and the thermal decomposition process of the precursor were studied by FT-IR,TG-DTA and XRD.The morphology of the particles was characterized by TEM.The results show that the particles' size is small and uniform,its average size is 8 to 10nm,and there is no apparent agglomeration.The influence of experiment conditions have been investigated and optimized.The results show that the molar ratio of metal ions to malic acid being 1:1,reaction time being 3～4h,the pH value of the mixed solution being about 3.0,drying temperature at 80℃for 6h were the best reaction conditions.The reacting mechanism was analyzed.Copper ferrite nano-powders are prepared by auto-combustion method, using Cu(NO₃)₂5H₂O,Fe(NO₃)₃6H₂O and malic acid as raw materials.The constituents and the thermal decomposition process of the precursor were studied by FT-IR,TG-DTA and XRD.The morphology of the particles was characterized by TEM.The results show that the samples' average size is about 26nm.There is slight agglomeration among particles,which associates to the magnetism of ferrite.The influence of experiment conditions have been investigated and optimized.The results show that the molar ratio of metal ions to malic acid being 1:1.25,reaction time being 3～4h,the pH value of mixed solution being about 8.0,drying temperature at 80℃for 6h were the best reaction conditions.Copper ferrite nano-powders have high catalytic activity,because there are lattice defects in copper ferrite nano-powders.The performances of copper ferrite nano-powders on the thermal decomposition of ammonium perchlorate(AP)were investigated.The results show that the as-burnt copper ferrite nano-powders have high catalytic activity on the thermal decomposition of AP,and the thermal decomposition temperature of AP shift 105℃downward with the effect of nanometer copper ferrite.With the content of CuFe₂O₄ increasing,the effect of catalysis enhances,when the content comes to 5%,the catalysis effect arrives to summit.The catalytic mechanism of copper ferrite nano-powders was analyzed.