Preparation Of Magnesium Titanium Oxide Electroceramics By Combustion Method

Mg₂TiO₄ has minor dielectric constant , dielectric spoilage and excellent microwave dielectric properties, but researches on Mg₂TiO₄ used as electroceramics are still very few , literatrues about the luminescent properties haven't been found. In the dissertation , Mg₂TiO₄ of high purity and better luminescent effect can be synthesized at 900℃by combustion method using urea as the fuel , the temperature can be reduced by 400℃compared with the temperature 1300℃of solid state reaction in literature , so the cost can be greatly reduced.In the dissertation , the magnesium titanium oxide(Mg₂TiO₄) electroceramics powders has been synthesized via combustion method by using tetra-n-butyl titanate and magnesium nitrate as raw materials, citric acid and urea as the fuels respectively. And also, researches on technological conditions of the synthesis of Mg₂TiO₄ electronic ceramics are studied , simultaneously , phase composition, construction, particle size, appearance and other microscopic features are characterized and analysized by XRD and SEM. The influence of the factors on the properties of Mg₂TiO₄ are studied , such as the variety of the doping ions and its doping amount , the sort of fuels , calcination temperature , the holding time , the amount of ethylene glycol and the quantity of citric acid , and also the luminescent properties are investigated by the fluorescence spectrophotometer.The XRD shows that the kinds of fuels have the greatest influence on the phase composition. When using urea as the fuel , Mg₂TiO₄ of high purity can be synthesized , and the phase composition is pure Mg₂TiO₄ , and its PCPDF card number is 25-1157 ; but when using citric acid as the fuel , the sample is constitued by Mg₂TiO₄ , little MgTiO₃ and MgO . Calcination temperature , heat holding time also infulences the phase of the sample , when citric acid is used as the fuel , the diffraction peak of Mg₂TiO₄ is sharper and the intensity is stronger as the temperature and the heat preservation time raises , the effect is obvious ; when urea is used as the fuel , the diffraction peak of Mg₂TiO₄ is visible as the temperature raises , but isn′t apparent as the heat preservation time prolongs. So, raising temperature and prolonging heat preservation time help to get purier Mg₂TiO₄ for the system of magnesium titanate .The SEM photos show that the kind of fuels has the greater influence. When urea is used as the fuel , the appearance is regiment and when using citric acid as the fuel , the micro- appearance is schistose .The FL spectrums show that the excitation spectrum of Mg₂TiO₄ is a broad-band spectrum , and the peak value is 338nm , the emission peaks are located at 400nm and 661 nm , they are the intrinsic emission of Mg₂TiO₄ , the peak at 400 nm is the main emission peak , which is located in purple light region, and the peak at 661 nm is the secondary emission peak ,which is located in red light region, so the color of the Mg₂TiO₄ is reddish purple. The variety of the doping ions and its doping amount ,the sort of fuels ,calcination temperature ,the holding time ,the amount of ethylene glycol and the quantity of citric acid all have effects on the luminescent properties of Mg₂TiO₄. We find that the doping of rear earth ions helps to enhance the properties of luminescence of Mg₂TiO₄. The samples doped by Dy³⁺ and Nd³⁺ have the best luminescent effect, doping Dy³⁺ , Nd³⁺and Tb³⁺ favor for the purple light emission of 400nm , doping Pr³⁺ is in favor of the red light emission of 661 nm . The system that uses urea as the fuel have the better luminescent brightness and intensity compared with the system using citric acid as the fuel. The properties of luminescence is better and better as the calcination temperature ,heat preservation time and the amount of doping concentration raises , but it has a quench temperature 900℃, quench concentration 0.05moL%, an optimal heat preservation time 20min. The results show that the better technological conditions of preparing Mg₂TiO₄ electronic ceramics powders by combustion can be got when the ratio of urea to [Mg+Ti] , ethylene glycol to urea is respectively 1.5 and 4.0, the doping amount of rear earth ions equals to 0.05moL% , the calcining temperature is 900℃, heat preservation time lasts 20 minutes.Therefore, researches on Mg₂TiO₄ have great importance. The preparation technology , properties and application is still a new field , it will be very important practical to the development of the open up of application field and the development of new products ,and also it has great practical significance to develop new industries using the rich resources of titanium and magnesium . Simultaneously, we have the advantage of resources to develop metal materials of titanium and magnesium,magnesuim titanate electronic ceramics materials , optical functional materials and so on .