Microwave Dielectric Property of Porous Silicon Nitride Ceramics
This paper presents the microwave dielectric property of porous silicon nitride ceramics at a frequency of 9360 MHz, which were fabricated by the nitridation of silicon powder. The porous ceramics with different volume fraction of porosity from 18.6% to 56.2% were produced by adding different amount of the pore-forming agent into the initial silicon powder. Microstructural analysis revealed a dense matrix containing large pores and cavities with needle-shaped and flaky β-Si3N4 grains distributing in it. The results showed that the dielectric constant of the ceramics reduces with the porosity increases. With the addition of α-Si3N4 powder in the raw silicon powder, the nitridation rate is raised, and the dielectric constant and the dielectric loss of the ceramics decrease notablely.
Wei Pan and Jianghong Gong
J. Q. Li et al., "Microwave Dielectric Property of Porous Silicon Nitride Ceramics", Key Engineering Materials, Vols. 336-338, pp. 307-309, 2007