铁磁－铁电复合双性能材料的微波烧结特性及机理研究

It is very difficult to realize the high performance composite materials at low temperature with both magnetic and dielectric properties. And the reason lies in that how can we fabricated the composited materials with good magnetic, dielectric and low loss with low temperature sintering technique. In this project, the microwave sintering technology will be applied in fabrication of composite materials and the basic law and mechnism will be investigated. With the microwave singtering method,the electron field encourages vacancy disfusing from high concentration to low concentration and leads to decreasing of activation energy, then decrease the sintering temperature of composite materials. However, the different materials has the different absorbties and the effect of "thermal runaway" are always appearing in microwave heating process, which is leading to the complication of microwave sintering. The composition, conductivity, the temperature of phase transfer, sample shape and sample size are all the important effects which affecting the controling of microwave power. In this project, the microwave sintering model of composite material needs to be created and calculate the distribution of microwave power, realizes the composite materials with high performance from 1MHz to 4GHz at low temperature. Finally, the low pass filter will be design with the composite material to validate the success of composite material with microwave sintering method.

设计和制备出同时具有磁性－介电性能的复合双性能材料是目前国际无机非金属材料领域的难点问题。难度在于：如何在低温烧结工艺下实现同时具有良好的磁性、介电和低损耗的复合材料？本项目将采用微波烧结工艺探索制备复合材料的规律和机理。在微波烧结工艺中，电场促进了空位沿电场方向由高浓度向低浓度区扩散，降低了材料活化能，从而实现了复合材料的低温烧结。但由于材料对微波能量的吸收特性和机理的不同，以及微波烧结热失控效应等决定了微波烧结工艺的复杂性：材料配方、电导率、两相含量、转相温度、样品形状、体积等都会影响微波功率的控制。本项目拟通过对复合材料建立烧结动力学模型，分析计算微波功率分布，探索双性原子互掺杂机理，找到合适的微波烧结工艺参数，成功制备出在1MHz～4GHz频段的复合双性能低温共烧材料，并通过设计低通滤波器对双性材料进行验证。

摘要：微波烧结的均匀性问题一直是氧化物电子陶瓷绿色烧结工艺中的难题。本课题研究着力于解决困扰氧化物电子陶瓷的烧结技术，保证微波烧结的可靠性和重复性。从探索微波烧结的机理出发，选择了几组合适的磁性和介电材料配方，综合考虑两种材料的微波烧结匹配特性，并根据热传输能量、媒介、样品的导热特性、样品转相所需的激活能结合样品物理尺寸来确定了微波烧结曲线，并经过反复的工艺调整和完善，最终实现 2 种可用于 LTCC 工艺的性能优良的复合双性材料，并利用微波烧结工艺实现了X波段平面移相器。