Coprecipitation method for preparing ultra fine zinc oxide powder possessing high electric conductivity

Abstract

The invention relates to a preparation method for preparing nano-scale oxidized zinc powder with high conductivity. The method simultaneously drip mixed salt solution of zincic soluble salt and doping elements such as aluminum, gallium, indium, Yt, scandium, tin, germanium, silicon, as well as precipitating agent into water, to generate coprecipitation to generate doped zinc bloom precursor basic zinc carbonate in condition of controlling temperature and PH value of entire reaction system, and at last, calcining the product in mixed gas atmospheres of hydrogen gas and argon gas, doped superfine zinc bloom conductive powder material can be obtained. The powder material prepared by the invention has small particle-size, uniform grain fineness distribution, and which mean particle diameter is about 10 to 80 nanometer. The electric volume resistivity of the powder can reach 2.5*10^-3 omega.cm, thus its electro conductivity is better than the sample prepared by plasma method and gas-phase method in current market. The preparation method further enhances whiteness degree and conductivity of the oxidized zinc powder, and further reduces the cost.

Description

technical field [0001] The invention relates to a method for preparing zinc oxide powder, in particular to a method for preparing nanoscale inorganic oxide powder with high electrical conductivity. Background technique [0002] With the rapid development of the electronics industry and the improvement of people's living standards, conductive powder, as a functional filler in the preparation process of plastics, coatings, fibers, etc., has antistatic, electromagnetic shielding and other properties, and has begun to attract people's attention. focus on. At present, conductive powders mainly include: metal powders such as silver, nickel, etc., non-metallic powders such as graphite, carbon black, etc., metal oxides such as zinc oxide, antimony oxide, etc., and composite powders and iodides such as SnO 2 -In 2 o 3 Coated mica or inorganic mineral powder, copper iodide, etc. Metal and carbon black materials have excellent electrical conductivity, but they are not easy to dispe...

AI Technical Summary

Problems solved by technology

The zinc oxide powder prepared by this method has a very high volume resistivity, which is greater than 1.0×10 in the best case. 1 Ω·cm, poor electrical conductivity, and the doping is obtained by sintering zinc oxide as the initial material at a high temperature greater than 750°C in a reducing atmosphere in the presence of hydrogen. Can not show enough whiteness, and the calcination at high temperature will make the zinc oxide particles grow up and lead to the formation of some coarse particles

This complex process makes it cost much more than the production cost of carbon black

The co-precipitation preparation method that appeared afterwards has also obtained a large amount of research ( Djega-Mariadasson, et al.US Patent: 4894185, 1990; Takao Hayashi, et al.US Patent: 5312614, 1994.), generally the mixed salt solution of zinc is directly added dropwise to the precipitant under the condition of preliminary control of the experimental conditions Co-precipitation occurs in the medium, although the doping effect can be obtained relatively better than the previous solid-phase mixing and sintering method, but it still causes the doping ions and zinc ions to not be completely and uniformly precipitated at the same time during precipitation, and the doping elements cannot be completely uniform Doped into the lattice of zinc oxide, although the obtained particles are more uniform than the previous method, the performance of the powder is also greatly improved compared with the performance of the powder prepared by the previous solid-phase mixing and sintering method, but The electrical conductivity of the finally obtained powder is still relatively poor (in the most ideal case, when the optimal doping content of the non-ferrous metal Sn and the rare earth element Ga is adopted, the powder synthesized at pH=9.0 is heated at 400 ° C under a hydrogen atmosphere. After sintering for 1 hour, a conductive zinc oxide powder with a volume resistivity of 7.4×10-1Ω·cm can be obtained), the particle size is relatively large, and there is a relatively serious agglomeration phenomenon

Conductive zinc oxide powder produced by gas phase method (Yoshimaru, et al. US Patent: 5560871, 1996) and plasma method (Yuan Fangli et al., Chemical Metallurgy, 1998, 19(3): 212-216) reported in previous years (The performance parameters of the powder are shown in Table 1) The performance has been greatly improved than before, but there are also problems such as whiteness and low electrical conductivity: the cost of preparing conductive zinc oxide powder by the gas phase method is low, but the particles The size is basically at the micron level, and its particle size is too large for the application in the field of nano-functional materials; while the conductive zinc oxide powder prepared by the plasma method has a relatively suitable particle size and good dispersion, but its preparation cost is high. very high

These existing problems have limited the application of current conductive zinc oxide powder to a large extent.