超声—微波化学共沉淀法制备ITO和CIO纳米粉体的研究

【作者】 宋宁；

【导师】 戴永年；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2007， 博士

【摘要】 透明导电氧化物（TCO）材料因具有大的载流子浓度和光学禁带宽度,而表现出优良的光电特性,如低的电阻率和高的可见光透过率等。TCO作为重要的宽带半导体材料,已经成为现代光电子产业的基础材料之一,特别是在液晶显示、太阳能电池、隔热玻璃、电致变色、电磁屏蔽、雷达屏蔽保护、新型照明、节能建筑以及防静电等行业中占了重要的地位,给社会带来了巨大的经济效益。TCO材料根据导电特性可分为n型和p型两类。目前n型TCO材料体系包括:In₂O₃,SnO₂,ZnO及其掺杂体系In₂O₃:Sn（ITO）,In₂O₃:Mo（IMO）,SnO₂:Sb（ATO）,SnO₂:F（FTO）,ZnO:Al（ZAO）等。p型TCO材料体系包括通式为CuMO₂（其中M可以为Al、Ga、In、Sc、Y、Cr、La等元素）铜铁矿结构的CuAlO₂（CAO）和CuInO₂（CIO）等。n型TCO材料ITO因具有优良的特性,被广泛地应用于各种领域,特别作为透明电极在液晶显示和太阳能电池等领域得到实际应用。p型TCO材料CIO因具有低电阻率高透光率的优点而引起人们的极大兴趣,同样在太阳能电池领域得到应用。如果太阳光伏能源系统能够将n型和p型TCO材料迭加作为透明阴阳极,就能够大幅度地增加光致电压器件的效率,如发电多功能窗、透明二极管等。由ITO和CIO制成的透明导电氧化物薄膜太阳能电池就具有这种半导体性质—双极性,ITO和CIO是构成太阳能电池的重要材料。目前,国内外制备纳米ITO粉体的方法很多,主要有均相共沉淀法、水溶液共沉淀法、电解法,溶胶—凝胶法、喷雾热分解法和机械研磨法等。在这些方法中,水溶液化学共沉淀法是引人注目的一种方法,该方法采用从外部加氨水,其工艺简单、周期短,操作方便,对设备的要求不高,投资少,生产成本低,较适合于大规模生产而被广泛采用,但这种方法在具体的制备过程中存在着突出的团聚现象,即纳米粒子重新团聚成较大的粒子。而对于p型透明导电材料CIO纳米粉的制备,目前制备的主要方法有固相反应法、阳离子交互反应法和溶胶—凝胶法。这些方法存在加热温度高,保温时间长,工艺过程放大难,能耗高,需添加有机试剂等实际问题。本论文针对化学共沉淀法及其他制备纳米ITO和CIO粉体中存在的问题,创新性地提出,采用“超声—微波化学共沉淀法”新工艺来制备ITO和CIO纳米粉体,通过超声波、微波等技术的有效集成来强化共沉淀化学反应或传递过程,把单个的工艺技术有机地结合起来,使所选择的工艺技术含量高、稳定,设备易得,易操作,工艺简单,制得的产品质量好。在制备纳米ITO和CIO粉体的工艺方面具有新颖性,为高品质透明导电氧化物材料ITO和CIO纳米粉体提供了一种新的制备途径。将超声波和微波应用于制备纳米ITO和CIO粉体的整个过程中,其目的就是利用超声空化所产生的独特的反应环境,来控制或减少纳米ITO粉末的团聚,最终带来的好处是:共沉淀反应温度的降低,缩短反应时间,无需添加分散剂。利用微波具有加热效率高、时间短、能耗低、加热均匀、易控制、物料不易烧结、产品质量好、操作简单等特点,用于ITO和CIO粉前驱体的干燥和煅烧,大大地缩短了纳米ITO和CIO粉体的制备周期。微波干燥煅烧粉体结构疏松、易磨、颗粒小、加热速度快。其干燥时间较电热干燥缩短50%或更多,微波煅烧温度较常规方法有所降低,产品无污染。为获得球状纳米ITO粉,将＞4N的纯金属In、Sn直接采用浓H₂SO₄浸出、氨水滴定、超声分散、离心分离,避免了使用HCl浸出对设备的腐蚀及HNO₃浸出带来的环境压力。由于无需外加H₂SO₄盐,减少了添加试剂所带来的杂质污染,对含有SO₄^2-的洗涤液,返回ZnSO₄和In₂（SO₄）₃电解系统或循环利用。根据理论计算,讨论了在超声化学共沉淀法制备纳米ITO粉体前驱体中的In³⁺浓度、氨水浓度、反应体系的温度和pH值、反应时间、分散剂、搅拌速率、超声波的介入等因素对纳米ITO粉性能的影响。讨论了微波干燥煅烧制备纳米ITO粉体过程中的物料重量、微波功率、时间、温度、升温速率、煅烧气氛等因素对纳米ITO粉性能的影响。采用“超声—微波化学共沉淀法”,以自制的铜溶液或市售的CuCl和CuCl₂及＞4N金属铟、NaOH、HCl、NaCl等为原料,讨论了In³⁺浓度、反应时间、反应温度和反应终点pH值、NaOH浓度、分散剂及物料重量、微波功率、煅烧时间、煅烧温度等制备纳米CIO粉的最佳反应条件。采用“超声—微波化学共沉淀法”制备纳米CIO粉弥补了阳离子交互反应法和固相法的不足,此法较阳离子交互反应法和固相法具有优势。通过采用TEM、SEM、EDS、XRD、BET、TG-DTA、UV-2401（PC）、FT-IR、ICPS-1000Ⅱ等系列现代分析手段对超声波、微波等条件下制备的ITO和CIO纳米粉体的物相、形貌、组成、粒度、纯度、以及光电性能等进行表征,适时对两种纳米粉体制备工艺参数进行调整优化,最终制得粒径小、粒度分布均匀、分散性好和比表面积大的纳米ITO和CIO粉。实验结果表明:在本实验范围内制备纳米ITO粉,①超声波化学共沉淀最佳控制条件是反应温度为60-75℃,In³⁺浓度＜160g/L,氨水浓度＜380g/L,终点pH为6.5-7.5。通过剧烈搅拌,缓慢滴定,陈化30min（50℃）,超声分散,无水乙醇后处理,得到合格的前驱体。②微波干燥最佳条件是物料重量为10g,微波干燥功率为700W,干燥时间为8min。③微波煅烧纳米ITO粉的最佳工艺条件是物料重量10g,微波功率700W,煅烧时间7-8min。经上述三个过程所制得的纳米ITO粉体,在结构上具有立方晶系结构,无孔隙、致密、颗粒呈球状,并且团聚少、分散性好、粒度分布均匀、粒度分布窄、纯度＞4N,平均粒径为15nm,比表面积54.73m²/g,In₂O₃:SnO₂（重量）=90:10,颜色为浅绿色。纳米ITO粉光学性能表现为紫外区（100-400nm）具有强烈的吸收性,可见光区（400-800nm）具有高的透过性,红外区（800-3500nm）具有高的反射率,大大超过了光学性能技术指标。纳米ITO粉电学性能表现为具有低的电阻率。纳米CIO粉的制备,①超声波化学共沉淀最佳控制条件为反应温度30-55℃,In³⁺浓度＜150g/L,氢氧化钠浓度＜250g/L,终点pH为10-11.5。通过剧烈搅拌,缓慢滴定,陈化30min（50℃）,超声分散,无水乙醇后处理,得到合格的前驱体。②微波干燥最佳条件是物料重量为5g,微波干燥功率为540W,干燥时间为5min。③微波煅烧纳米CIO粉的最佳工艺条件是物料重量5g,微波功率700W,煅烧时间5-7min,在Ar保护条件下,所制得的纳米CIO粉平均粒径为27.82nm,比表面积42.06 m²/g,Cu₂O:In₂O₃（重量）=70:30,粉体颗粒均呈球状,团聚少,分散性好,颜色为棕黑色。纳米CIO粉光学性能表现为紫外区（100-400nm）具有强烈的吸收性,可见光区（400-800nm）具有高的透过性,红外区（800-3500nm）有高的反射率,也超过了光学性能技术指标。纳米CIO粉电学性能表现为具有低的电阻率。“超声—微波化学共沉淀法”新工艺制备纳米ITO和CIO粉,较其他常规方法实验周期短、成本低、设备占地面积小,无污染,产品纯质量好,光电性能高,是替代传统制备技术的理想方法。所制得的纳米ITO和CIO粉是制备透明导电薄膜材料、太阳能电池材料和红外屏蔽功能材料的理想材料。更多还原

【Abstract】 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-1000Ⅱetc,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.更多还原