Preparation And Microwave Absorbing Properties Of Tetrapod-shaped Zinc Oxide Whisker Research

Tetrapod-like zinc oxide whisker (T-ZnOw) is a kind of single-crystal micro-fiber with peculiar three-dimensional tetra-needle-like shape. It not only has the excellent mechanical properties, but also has the properties of electrical conductivity and electromagnetic wave absorption. Preparation of raw material is non-toxic and harmless, the preparation method is simple, widely used in antistatic and conductive composite material, wave absorption, impact resistance, shock absorption, sound insulation material, reinforced composite material and antibacterial materials.In this paper, the relationship between morphology and the preparation condition of the whiskers was studied with the help of modern apparatus such as X ray diffraction (XRD), scanning electron microscopy (SEM), vector network analyzers, and other modern advanced characterization and detection means. The morphology and wave absorbing property was discussed.(1) Tetrapod-like zinc oxide whiskers were prepared by thermal evaporation method using metallic zinc as raw material, cylindrical activated carbon as catalyst in air environment. The structure and surface morphology of these whiskers were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the pure zinc oxide powders have a hexagonal structure, which grow well and regular appearance. The needle body is elongating, the ratio of length to diameter is large. The lengths of the whiskers are about 20μm, the widths are about 4μm.(2) Aluminum doping modification was adopted to improve the dielectric constants and enhance the electric loss of Tetrapod-like zinc oxide whisker.In this method, T-ZnOw was solid-state reacted with aluminum nitrate decomposed Al2O3 at high temperature. So T-ZnOw was doped by Al3+ and turned into n-type semiconductor.(3) Fe is one of the most common magnetic elements, which usually used in ferrite, polycrystalline iron fiber, ferrous titanate, hydroxyl iron powder and other types of radar wave absorbing materials. The Fe-doped T-ZnOw can also form trivalent ions, which plays a similar role as Al-doped. Therefore, the Fe element doping is expected to improve the tetrapod-like zinc oxide whisker's electric loss and magnetic loss and make it becoming the n-type magnetic semiconductor material.After the modification, the tetrapod-like zinc oxide whisker in 600-1500MHz microwave absorbing properties increase obviously, can reach above-4dB. Tetrapod-like zinc oxide whisker and its preparation of raw material is non-toxic and harmless, the preparation method is relatively simple. It can be used as mobile communication electromagnetic shielding materials.This article research the tetrapod-like zinc oxide whisker preparation and development of tetrapod-like zinc oxide whisker as microwave absorbing materials. It's scientific significance and application of reference value.