纳米Si/C/N复相粉体的制备及其在不同基体中的微波介电特性

Preparation and Microwave Permittivity of Nano Si/C/N Composite Powders Suspended in Different Matrixes

以六甲基二硅胺烷（（Ｍｅ３Ｓｉ）２ＮＨ）（Ｍｅ：ＣＨ３）为原料，用双反应室激光气相合成纳米粉体装置制备了纳米Ｓｉ／Ｃ／Ｎ复相粉体．研究了纳米Ｓｉ／Ｃ／Ｎ复相粉体在不同基体中８．２～１２．４ＧＨｚ的微波介电特性，纳米粉体介电常数的实部（ε’）和虚部（ε”）随频率增大而减小，介电损耗（ｔｇδ＝ε”／ε’）较高·纳米Ｓｉ／Ｃ／Ｎ复相粉体中的ＳｉＣ微晶固溶了大量的Ｎ原子，在纳米Ｓｉ／Ｃ／Ｎ复相粉体中形成大量的带电缺陷；极化弛豫是吸收电磁波的主要原因．

The nano Si/C/N composite powders were synthesized from hexamethyldisilazane ((Me3Si)(2)NH) (Me:CH3) by a laser-induced gas-phase reaction. The powders are spherical, loosely agglomerate with sizes in range of 20 similar to 30nm. The laser synthesis reactor consists of two reaction zones, which can efficiently increase laser efficiency and production yield. The microwave permittivities of nano Si/C/N composite powders suspended in different matrixes were studied at the frequency range of 8.2-12.4GHz. The epsilon' and epsilon' of the nano Si/C/N composite powder decrease with frequency at the frequency range of 8.2-12.4GHz. The difference being the microwave resonance is not sharply peaked but rather smeared out over a large frequency range. The dissipation factors tg delta(epsilon'/epsilon') of the nano Si/C/N composite powders are high at the microwave frequencies. The SiC microcrystallines in the nano composite powders can dissolve a great deal of nitrogen, so charged defects and quasi-free electrons move in response to the electric field, diffusion or polarization current resulted from the field propagation. The high epsilon' and tg delta of nano Si/C/N composite powders are due to the dielectric relaxation. The unusual epsilon', epsilon' and tg delta of the nano Si/C/N composite powders suspended in different matrixes axe attributed to the interface effects between nano Si/C/N composite powders and matrixes.