| Transparent conductive thin film?TCO?is widely used in life because of its excellent photoelectric properties.The high quality TCO requires high quality sputtering target.At present,the preparation technology for high-quality target materials in our country is relatively backward.Therefore,it is of great significance to prepare ZnO targets with excellent properties.In this paper,the purpose is preparing ZnO target,mainly explored the basic process and method for preparing ZnO powder by ultrasonic-assisted direct precipitation method.The effects of the precipitant,type and amount of surfactant,calcining temperature,solvent and pre-calcination on the morphology,particle size and sintering activity of the powder were analyzed.The sintering process for the preparation of ZnO targets by atmospheric pressure sintering was studied systematically.The effects of initial powder,sintering temperature and holding time on the microstructure,electrical conductivity and relative density of ZnO targets were analyzed.The main findings are as follows:?1?The type of precipitant and the type and amount of surfactant mainly affect the morphology and dispersibility of the powder.With NaOH as precipitant,the powder was short rod-like and agglomerated;with NH3·H2O as precipitant,the powder had different morphology,good dispersion and wide particle size distribution;?NH4?2·CO3as precipitant,powder The body is discoid and agglomerated;with?NH4?2·CO3 as precipitant,3%wt PEG-400,1%wt TEA surfactant is added,and the powder is spherical with good dispersibility and particle size distribution.Evenly,this kind of powder has the best sintering performance in the sintering experiment.The calcination temperature and pre-calcination mainly affect the powder morphology.With the increase of temperature,the powder adheres to the rod shape.After pre-calcining,the ZnO powder grows like a rod in the[0001]direction.The length is about 1?m.The ethanol content in the solvent mainly affects the grain size.With the increase of ethanol content,the particle size first decreases and then increases.When the ethanol content is 60%,the particle size is the smallest.?2?The initial powder properties and sintering process have a great influence on the sintering performance of the target.Under the same sintering process.The initial powder prepared with different precipitants has a relatively large difference in the relative density he powder with the?NH4?2·CO3 as precipitant and PEG-400 and TEA as surfactants had the highest target relative density of 99%.At the same time,the sintering temperature can effectively improve the performance of the target.With the increase of sintering temperature,the number of stomata in the target first decreased and then increase;the relative density increased first and then decreased,and the weight loss rate increased slowly with the increase of temperature,and the shrinkage rate first slowly increased,and it rose sharply at 1450°C,after 1450°C tends to be flat;the resistivity of the target decreases first and then increases.Finally,a target with a relative density of 99.12%and a resistivity of 5.6×10-2?·cm was prepared at 1450°C.In addition,the holding time has a great influence on the closing of the pores and the coarsening of the grains.Prolonging the holding time can increase the density of the target material.However,if the time is too long,the coarsening of the crystal grains will be promoted and the performance of the target material will be degraded.Finally,the powder prepared with?NH4?2·CO3 as the precipitant and 3%wt PEG-400 and 3%wt TEA was added,and the target was sintered at 1450?,for 6 h,and the highest density was 99.35%.The rate is 3×10-2?·cm.?3?The process of densification:0?-1000?is in the initial stage of sintering,the contact area of the particles in the green body becomes large,and a distinct neck begins to form,the degree of densification is not high;1000°C-1250°C is in the middle of sintering,continuous holes closed,the body began to densification,volume shrinkage,grain growth 2-3um;1250°C-1350°C in the late sintering period,the densification rate at this stage is relatively slow,rapid grain growth,the relative density of more than 90%.At 1450°C-1550°C,grains grow abnormally,secondary recrystallization occurs,the green body burns and swells,and Zn volatilizes,resulting in an increase in porosity,which decreases the relative density and resistivity. |
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