Ultrasound - Microwave Chemical Co-precipitation Method To Prepare Ito And Cio Nanopowder

Transparent conductive oxide(TCO)material exhibits outstanding optical and electrical properties,such as low resistance,high permeation of the visible range light etc,because of high carrier concentration and wide optical band gap.As a kind of wide band gap semiconductor,TCO has been becoming one of a significant part of fundamental materials in modern optoelectronic industry,especially in liquid crystal display device,solar cell,heat insulation glass,electro-chromic,electromagnetic shielding,radar shielding protection,new type lighting,energy-saving building, anti-electrostatic industries.And it has brought great economic benefit for our society. TCO can be divided into two types,n-type and p-type,according to electric conduction property.At present,n-type TCO in the material system includes:In₂O₃,SnO₂,ZnO and doping system of In₂O₃:Sn(ITO),In₂O₃:Mo(IMO),SnO₂:Sb(ATO),SnO₂: F(FTO),ZnO;Al(ZAO)etc.p-type TCO in the material system includes:CuMO₂(M can represents Al,Ga,In,Sc,Y,Cr,La,etc.)and delafossite structured CuAlO₂(CAO) and CuInO₂(CIO)etc.As the excellent property,ITO,one of the n-type TCO materials, has been extensively applied in various areas,especially for the real application in liquid crystal display and solar cell.As the low resistance and high light permeation, CIO,one of the p-type TCO materials,has drawn extensive attention,and also applied in solar cell range.If solar photovoltaic energy system can plus the n-type and p-TCO material together as transparent cathode and anode,it will greatly improve the efficiency of photo-induced device such as power generation multi-function window, transparent emitting diode etc.The solar cell with transparent and conductive oxide film,combined by ITO and CIO have the semi-conductive property—bipolar.ITO and CIO are important materials for solar cell.At present,there are lots of methods in preparing ITO nano-powder,which mainly includes homogeneous co-precipitation,chemical co-precipitation,electrolysis,sol-gel, spray heating decomposition,machine grinding method,etc.Among these methods, the chemical co-precipitation has been concentrated much attention.Because of the exterior adding ammonia way and the advantages of simplified process,short production cycle,easy in operation,low requirement for the equipment,low cast investment and low production cost this method has been extensively accepted as it's suitable for large-scale production.However,this method could cause re-agglomerations of nano-particles in its preparation process.At present,the preparation of p-type transparent conducting CIO nano-powder mainly involves solid posture reaction,cation exchange reaction and sol-gel method.While,some real problems of these methods are the high heating temperature,long heat holding time, difficult amplification of the process,high energy consummation and requiring organic reagents,etc.To solve the existing problems in chemical co-precipitation method and other preparation methods for nanometer ITO powder and CIO powder,this paper creatively brings forward using ultrasonic wave chemical co-precipitation—combination drying of microwave method to prepare ITO and CIO powder.Through application of effective coupling and integration properties of the ultrasonic wave and microwave technologies to enhance the chemical co-precipitation and transferring processes,the original individual process technologies is well combined.This selected process has its optimized property,as high technical level,lower equipment investment,simplified process flow,easy in operation and producing the stable and qualified product.This paper has offered a novel process and taken out a new preparation approach in preparation nanometer ITO and CIO powders.The purpose in applying the ultrasonic wave and microwave method in the whole process of the preparation of ITO and CIO powders is to create a distinctive environment by ultrasonic cavitations,which can effectively control or reduce the agglomeration of nanometer powders.The eventually good result is reduction of the reaction temperature in co-precipitation,saving the reaction time and additionally without any adding disperses.By using the effective characters of microwave method as high heating efficiency,short reaction time,low energy consumption,easy to control,not easy in agglomeration of the materials,good quality production,simplified in operation etc,the processes of drying and roasting for ITO and CIO by microwave method has greatly shortened the whole preparation cycle time.The powder,dried by microwave,has its own advantages,such as loose structure, easy to mill,small particle size,and fast in heating,and also the drying time can reduced by over 50%by contrast to electro drying method,the calcination temperature by microwave can also be decreased compare to the traditional methods and the made product doesn't bring any pollution potentiality.To obtain spherical nano-powder ITO,the metals of In and Sn with over 4N purity are directly dealt with by concentrated sulfuric acid leaching,ammonia titration, ultrasonic dispersion and centrifugal separation,which effectively avoids the corrosion of equipment and taking any environmental consideration,as not using HCl and HNO₃ in its leaching process.As its not requiring to add sulfate additionally,the impurity contamination is decreased,and the washing solution with SO₄^2-can be returned electrolysis system with ZnSO₄ and In₂(SO₄)₃ for recycling utilization.According to the theoretical calculation,In³⁺concentration,ammonia concentration,temperature and PH of the reaction system,reaction time,disperse agent and mixing speed in ITO preparation by ultrasonically chemical co-precipitation method and the effect of ITO property by ultrasonic have been comprehensively discussed;The effect of ITO property by the parameters of material weight, micro-wave power,time,temperature,heating efficiency and roasting condition in ITO powder preparation by micro-wave drying and roasting method has also been extensively discussed.Through the ultrasonically chemical co-precipitation-microwave drying and calcining combined method,using the raw materials of self made copper solution or the bought CuCl,CuCl₂ over 4N metal indium,NaOH,HCl,NaCl etc.the best CIO powder preparation reaction parameters of In³⁺concentration,reaction time,reaction temperature,pH at reaction end time,NaOH concentration,disperse agent,material weight,microwave power,calcination time and temperature have been analyzed.The prepared CIO powder by the ultrasonically chemical co-precipitation-microwave drying and calcining combined method makes up the deficiency of the cation exchange reaction method and solid state method,this new method for CIO powder preparation has its own predominance,compared with the cation exchange reaction method and solid state method.With the modern analysis methods of TEM,SEM.EDS,XRD,BET,TG-DTA, UV-2401(PC),FT-IR,ICPS-1000â…¡etc,the prepared ITO and CIO powder under ultrasonic and microwave conditions has been tested in its configuration,appearance, constitution,particle size,purity and photoelectrical property.The engineering parameters of the preparation processes of these two nanometer powders have also been optimized,and the suitable particle size and distribution and large surface area ITO and CIO powders have been eventually produced.The experimental result shows:in this experimental ITO powder preparation,(1) Under ultrasonically chemical co-precipitation method,the optimized control conditions are:60-75℃in reaction temperature,In³⁺concentration＜160g/L,ammonia concentration <380g/L and pH of reaction end time is 6.5 to 7.5.With acute mixing, gentle titration,settle for 30min under 50℃,ultrasonic dispersing,ethanol treatment, the qualified pre-powder could be achieved;(2)The optimized microwave conditions are material weight 10g,microwave drying power 700W,drying time 8mins;(3)The optimized conditions of roasting of IYO powder by microwave are material weight 10g, microwave power 700W,calcination time 7-8mins.The ITO powder structure,made by the upper three processes,has cubic crystals form,no-porous,high density,particle as spherical form and low agglomeration occurrence,good disperse and particle distribution,narrow particle distribution,purity＞4N,average particle size as 15nm, surface area as 54.73m²/g,the weight proportion of In₂O₃:SnO₂ is 90:10 and colored as light green.The optical property of nanometer ITO powder is:strange absorption in UV range(100-400nm);high light permeation in visible light range(400-800nm)and high reflectivity in infrared range(800-3500nm),which greatly over passes the optically technical standard.The electric property of ITO powder is low resistance.Preparation of nanometer CIO powder;(1)(1)Under ultrasonically chemical co-precipitation method,the optimized control conditions are:30-55℃in reaction temperature,In³⁺concentration＜150g/L,NaOH concentration＜250g/L and pH of reaction end time is 10-11.5.With acute mixing,gentle titration,settle for 30min under 50℃,ultrasonic dispersing,ethanol treatment,the qualified pre-powder could be achieved;(2)The optimized microwave conditions are material weight 5g,microwave drying power 540W,drying time 5mins;(3)The optimized conditions of calcining of ITO powder by microwave are material weight 5g,microwave power 700W, calcination time 5-7mins.With Ar addition in microwave oven in heating temperature and calcining for 7mins,the nanometer CIO powder could be produced as 27.83nm average particle size,42.06 m²/g and the weight proportion of Cu₂O:In₂O₃ is70:30. This Powder particle forms spherical,low agglomeration,good dispersing condition and colored as palm black.The optical property of nanometer CIO powder is:strange absorption in UV range(100-400nm);high light permeation in visible light range (400-800nm)and high reflectivity in infrared range(800-3500nm),which greatly over passes the optically technical standard.The electric property of CIO powder is low resistance.Compared with the traditional methods,ITO and CIO powders prepared by ultrasonically chemical co-precipitation- microwave drying and calcining combined method have short experiment time period,low cost,limited equipment occupation area,non-pollution,good quality product,high photoelectric property,and it is an ideal method in replacing the traditional preparation technologies.These prepared ITO and CIO powders are good transparent and conductive film,solar cell and infrared shielding materials.