Study On Reaction Mechanism Of Ba₅Li_xTi_xNb_10-xO₃₀ Synthesized In Millimeter Wave Field

In this paper, the theory progress of the microwave synthesis and millimeter wave synthesis was reviewed, after a analyzing the question found in microwave sintering and millimeter wave sintering, the study direction of millimeter wave sintering was clear.A new compound Ba5LixTixNb10-xO30 was synthesized by doping Li+ in the system BaO- TiO2- Nb2O5. It was found that the proper synthesis process was synthesized at temperature 1150℃ and 2 hours heating preservation. The crystal structure was determined by X-ray powder diffraction ,and it belongs to tetragonal tungsten bronze structure with space group P4bm and unit cell parameters : a=b=1.2512(2) (nm) ,c=0.4008(5) (nm) , and it belongs to relaxation ferroelectrics.XRD qualitative analysis was employed to study the process of the millimeter wave synthesizing BasLixTixNb10-xO30, By studying on the process parameters including synthesis temperature, heat preservation time, It was found that the proper synthesis process was synthesized at temperature 900 癈 , 8min heating preservation and with the slow cooling velocity. Because the ion diffusion was enhanced in the electric field, the reaction speed was faster. Comparing to conventional solid-state reaction, the reaction temperature is lower and the reaction time is shorter in the millimeter wave field.The product of the millimeter wave synthesis and conventional synthesis was compared. Microstructure of the products synthesized in different conditions was analyzed. The particle of millimeter wave synthesis had smaller size, narrower size distribution, better sinter-ability and without hard agglomeration than that of conventional synthesis. It is found that the particle size synthesized by millimeter wave is half of those by conventional synthesis. It is found that higherdensities than 95% of theoretical values can be obtained by millimeter wave sintering at 1100℃ for 120 min, The XRD qualitative analysis shows the reaction of Ba5LixTixNb10-xO30 in millimeter wave field is in good agreement with Carter equation. The constant of reaction speed in 900℃ is 10 times as conventional reaction.The study of interaction mechanism between millimeter wave and micro grain shows that the ability of diffusion and the reactive rate can be enhanced in the millimeter wave field.