DIELECTRIC PROPERTIES OF POROUS Si3N4-SiO2-BN COMPOSITES

摘要：

Porous Si3N4-SiO2-BN composites were prepared by adding starch as both pore former and consolidator. Bruggeman effective-medium model, Maxwell-Garnett model and logarithmic model were used to describe and predict the dielectric constant of porous Si3N4-SiO2-BN ceramics. Relative dielectric constant of porous Si3N4-SiO2-BN composites decreases with the increase of apparent porosity within limits, and these models can forecast the change of the dielectric constant of the porous ceramics quite well. The minimum relative dielectric constant is 2.5 at the apparent porosity of 0.555 at room-temperature. The relationship between dielectric constant and temperature were investigated. It was found dielectric constant varied a lot with the increase of temperature, and Debye relaxation theory was employed to explain the variation of the dielectric constant with temperature increment. But the Debye relaxation theory can not explain the reason of variation of dielectric constant at the temperature range from 300℃ to 900℃. To ascertain the cause of changes of dielectric constant at this temperature region, differential scanning calorimentry (DSC) measurement was performed. In this temperature region, phase transition behavior occurs at nearly 300℃ in the porous composites. The new phase probably has a tidy large dielectric constant, and the dielectric constant increases sharply.

关键词： Dielectric constant silicon nitride composites

作者: YINBAO SUN YUMIN ZHANG DIHONG LI JIECAI HAN

作者单位: Center for Composites, Haerbin Institute of Technology, Yi Kuang Street 2, Haerbin, Heilongjiang 150 School of Material Science and Engineering, Haerbin Institute of Technology, Xi da zhi Street 90, Ha

会议类型: 国际会议

会议名称: 第五届先进材料与加工国际会议(Fifth International Conference on Advanced Materials and Processing ICAMP-5)

会议地点: 哈尔滨

会议语种:英文

页码: 1879-1884

在线出版日期: 2008-09-03（万方平台首次上网日期，不代表论文的发表时间）