共沉淀法制备稀土石榴石Ln3Al5O12(Ln=Y, Ce, Yb)

以Y2O3、Yb2O3、Al(NO3)3.9H2O和Ce(NO3)3.6H2O为原料,NH4HCO3、NH3.H2O做复合沉淀剂,用共沉淀法制备纳米稀土石榴石Ln3Al5O12(LnAG,Ln=Y,Ce,Yb)粉体。用TG/DTA、XRD、SEM、TEM等手段对LnAG前驱体及煅烧后的粉体进行表征。结果表明,用上述方法在1 000℃煅烧3h可得到分散性好、形状规则且粒径为50nm左右的Y3Al5O12、Yb3Al5O12、Y2.9Ce0.1Al5O12石榴石粉体,但不能得到Ce3Al5O12石榴石,合成石榴石粉体的最佳煅烧温度为1 050℃以上。     

碳酸盐前驱体和CS_2硫化制备SrY_2S_4∶Eu~(2+)红色荧光粉及其表征

以Sr2+,Y3+和Eu3+的混合硝酸盐溶液为阳离子溶液,以(NH4)2CO3为沉淀剂,共沉淀法制备了碳酸盐前驱体,TG-DSC分析结果表明,随着(NH4)2CO3浓度的升高,前驱体组成由碱式碳酸盐向正盐转变。以CS2为硫化剂,高温煅烧前驱体合成了SrY2S4∶Eu2+红色荧光粉。XRD表明前驱体经800℃处理得到纯相SrY2S4。荧光光谱和SEM研究表明在[Sr(NO3)2+Eu(NO3)3]∶[Y(NO3)3]∶[(NH4)2CO3]=0.25∶0.50∶2.00(摩尔比)条件下制备前驱体,然后1050℃煅烧4 h所得荧光粉的发光强度最大,粒径小于1μm,粒子形貌呈椭球。Eu2+在SrY2S4基质中的最佳掺杂摩尔分数是0.6%。     

沉淀剂对ZrO_2(MgO)纳米粉体制备的影响

以ZrOCl_2·8H_2O、Mg(NO_3)_2·6H_2O为原料,分别以氨水、氨水+0.5 mol/L碳酸铵、氨水+0.5 mol/L碳酸氢铵为沉淀剂,采用化学共沉淀法制备ZrO_2(MgO)前驱体粉体.通过差热分析、X射线衍射、扫描电镜、红外光谱等对所得纳米粉体进行测定分析.结果表明:采用不同沉淀剂制得的ZrO2(MgO)纳米粉体平均晶粒尺寸都稍大于30 nm,用氨水+碳酸铵、氨水+碳酸氢铵为沉淀剂时,能够提高ZrO_2(MgO)纳米粉体的分散性能.     

超细γ-Al_2O_3粉体化学沉淀法的合成及表征

分别以碳酸氢铵和氨水作为沉淀剂,采用化学沉淀法制备超细Al2O3粉体。研究沉淀剂对制备氧化铝前驱体的影响,分散剂对颗粒尺寸和形貌的影响及煅烧温度对产物晶型和颗粒尺寸的影响。利用SEM、XRD、DSC对γ-Al2O3粉体的性能进行了表征。结果表明:以碳酸氢铵为沉淀剂制备出的Al2O3粉体的平均粒径最小;该方法制备出的氧化铝前驱体在900℃下煅烧保温2h可制备出粒径细小,粒径为70nm左右的Al2O3粉体。     

沉淀法制备ITO粉体及其性能研究

以InCl3、SnCl4、尿素和氨水为主要原料,采用化学共沉淀法制备出ITO粉体,探讨了沉淀剂种类和煅烧温度对ITO粉体性能的影响。结果表明：采用氨水可制备针状、粒度分布窄的纳米粉体,沉淀剂为尿素时则为块状、粒度分布较宽的微米粉体;随煅烧温度的提高,粉体的比表面积呈下降趋势,从700℃的28．65m2／g下降到900℃的12．23m2／g;氨水作沉淀剂且煅烧温度为700℃时可获得粒度均匀、分散性好、物相单一的纳米ITO粉。     

共沉淀法制备Nd:YAG纳米粉体及其表征

采用共沉淀法制备出尺寸小、团聚程度轻、单分散、貌似球形的Nd:YAG纳米粉体.借助IR、XRD、BET、SEM和荧光分析仪等测试手段对前驱体和Nd:YAG粉体进行了表征与分析.结果表明,共沉淀温度及煅烧温度对产物的物相有较大影响;在聚乙二醇存在的情况下, 900℃煅烧前驱体2h得到单分散纯相的Nd:YAG粉体,粉体颗粒尺寸为30nm左右,比表面积为40m2·g-1左右;激活离子Nd3+的存在使粉体具有较好的荧光性.     

碳酸盐前驱体和CS2硫化制备SrY2S4:Eu2+红色荧光粉及其表征

以Sr2＋, Y3＋和Eu3＋的混合硝酸盐溶液为阳离子溶液, 以（NH4）2CO3为沉淀剂, 共沉淀法制备了碳酸盐前驱体, TG-DSC分析结果表明, 随着（NH4）2CO3浓度的升高, 前驱体组成由碱式碳酸盐向正盐转变. 以CS2为硫化剂, 高温煅烧前驱体合成了SrY2S4：Eu2＋红色荧光粉. XRD表明前驱体经800 ℃处理得到纯相SrY2S4. 荧光光谱和SEM研究表明在[Sr（NO3）2＋Eu（NO3）3]：[Y（NO3）3]：[（NH4）2CO3]=0.25：0.50：2.00（摩尔比）条件下制备前驱体, 然后1050 ℃煅烧4 h所得荧光粉的发光强度最大, 粒径小于1 μm, 粒子形貌呈椭球. Eu2＋在SrY2S4基质中的最佳掺杂摩尔分数是0.6%.     

前驱体制备方法对电池正极材料电性能的影响

采用氢氧化物共沉淀法和碳酸盐共沉淀法制备4种三元LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2前驱体,然后再采用高温煅烧工艺制得LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2。碳酸盐共沉淀法采用碳酸氢钠作为沉淀剂,氢氧化物共沉淀法分别采用氢氧化钠(正向和逆向加入)、氢氧化钠和氨水作为沉淀剂。通过X射线衍射、扫描电子显微镜、电化学性能测试等方法系统地研究了前驱体制备方法对三元锂离子电池正极材料电性能的影响。结果表明:碳酸盐共沉淀法制得的LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2体颗粒呈现类球形,与有氨水参与的氢氧化物共沉淀法沉淀产物的形貌基本相似。在1 C、3~4.3 V下充放电,不同前驱体制备的LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2首次放电比容量依次为147.0,145.8,140.2,138.1 m A·h/g,循环50周后依次为135.2,131.1,119.3,113.6 m A·h/g,容量保持率为92.0%、89.9%、85.2%、82.1%。     

合成高活性Y_2O_3和Al_2O_3超细粉及Nd:YAG透明陶瓷

分别以Y(NO3)3和氨水、NH4Al(SO4)2·12H2O和碳酸氢铵为原料,采用化学沉淀法与碳酸铝铵分解法合成了高活性、平均粒径分别为39 nm和95 am的Y23和AlO3超细粉体.以Y2O3,Al2O3超细粉和商用Nd2O3粉体为原料,采用固相反应法,经1 700℃真窄烧结15 h,制备了Nd:YAG透明陶瓷.含x(Nd)=1%的YAG陶瓷在可见光区最大透光率约为53%.对YAG陶瓷的烧结过程和显微组织研究表明,Nd的引入明显地促进了陶瓷的烧结,同时晶粒得到细化.     

钛酸钡超细粉体的共沉淀法制备及陶瓷的性能研究

以TiCl4和BaCl2·2H2O为原料,NH4HCO3和NH3·H2O为沉淀剂,采用化学共沉淀方法制备钛酸钡粉体。研究了钛酸钡粉体的合成条件对产物纯度、颗粒粒径、颗粒形貌及瓷体介电特性等影响。使用X射线衍射仪、激光粒度仪、扫描电子显微镜等进行测试分析,找出了较佳的制备条件。结果表明:采用适宜的原料配比Ba/Ti=1:1、反应温度20℃、NH4HCO3/Ba2+值为1.2、煅烧温度950℃等条件,可制得颗粒质量中位径D50为270nm、粒度分布均匀的四方相钛酸钡粉体。瓷体的烧结温度为1260℃,烧结时间为2h时,瓷体的密度最大,常温介电常数达到1763。     

Preparation and characterization of Y3Al5O12:Ln（Ln=Eu,Ce） phosphor powders by ultrasonic atomization and co-precipitation process

A novel technique for YAG:Ln(Ln=Eu,Ce) phosphor powder synthesis with a nanocrystalline structure was developed.Nanocrystalline YAG:Ln powder was prepared by an ultrasonic atomization and co-precipitation method using a mixture solution of ammonium hydroxide(NH3·H2O) and ammonium hydrogen carbonate(NH4HCO3) as precipitant.The as-prepared nano-powders were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and fluorescence spectrometer.The obtained phosphor powders were homogenous and in size of 50-70 nm.The results demonstrated that by using ultrasonic atomization and co-precipitation process,we could synthesize a good quality YAG:Ln(Ln=Eu,Ce) phosphor powder that had many potential applications.     

Synthesis of La3+ and Nd3+ co-doped yttria nanopowder for transparent ceramics by oxalate precipitation method

Polycrystalline Nd3+ and La3+ co-doped yttria nanopowder Nd3+:Y1.90La0.10O3 for transparent ceramics was synthesized by co-precipitation method using oxalate acid as the precipitant and(NH4)2SO4 as the electrical stabilizer under ultrasonic radiation.Nanopowders calcined at different temperatures were characterized with thermal gravimetric-differential thermal analysis(TG/DTA),X-ray diffraction(XRD),transmitting electron microscopy(TEM),energy dispersive spectrometry(EDS) and spectral analysis techniques.Th...     

不同沉淀剂制备氧化铈抛光粉

氧化铈(CeO₂)抛光粉在光学玻璃、手机盖板、集成电路等领域内有着广泛的应用。合成高端CeO₂抛光粉主要采用液相沉淀得到前驱体,再经过煅烧转型制得CeO₂。前驱体是决定CeO₂抛光粉性质和性能的关键因素之一。通过模拟工业上常用的制备方法,以氯化铈(CeCl₃)为铈源,使用碳酸钠(Na₂CO₃)、碳酸铵[(NH₄)₂CO₃]、碳酸氢铵(NH₄HCO₃)、二水合草酸(H₂C2O₄·2H₂O)和氢氧化钠(NaOH)为沉淀剂,合成了一系列CeO₂抛光粉的前驱体。利用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、激光粒度仪等手段表征了前驱体的晶相、形貌、粒度等性质,并研究了前驱体煅烧转型后的CeO₂性质及其对K9光学玻璃的...     

Preparation and characterization of Y3Al5O12:Ln (Ln=Eu,Ce) phosphor powders by ultrasonic atomization and co-precipitation process

A novel technique for YAG:Ln (Ln=Eu, Ce) phosphor powder synthesis with a nanocrystalline structure was developed. Nanocrystalline YAG:Ln powder was prepared by an ultrasonic atomization and co-precipitation method using a mixture solution of ammonium hydroxide(NH₃·H₂O) and ammonium hydrogen carbonate(NH₄HCO₃) as precipitant. The as-prepared nano-powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and fluorescence spectrometer. The obtained phosphor powders were homogenous and in size of 50-70 nm. The results demonstrated that by using ultrasonic atomization and co-precipitation process, we could synthesize a good quality YAG:Ln (Ln=Eu, Ce) phosphor powder that had many potential applications.     

撞击流-活性炭吸附法制备氧化钇超细粉体

以Y( NO3)3·6H2O和碳酸氢铵为原料,在撞击流反应器中制备碳酸钇,经焙烧得到超细氧化钇粉体.考察了分散剂加入量、反应物摩尔比n( NH4HCO3)/n(Y(NO3)3)、活性碳用量、反应温度、反应时间、搅拌速度以及碳酸钇的焙烧温度和焙烧时间等因素对Y2O3粒径的影响,并用WJL激光粒度仪、TG、XRD和SEM等表征手段对产品进行表征,从而获得制备超细氧化钇的优化工艺条件为:PEG4000的质量为硝酸钇的3％,活性炭用量为0.025 mol·L-1,反应物摩尔比n( NH4HCO3):n(Y( NO3)3)为8:1,反应温度50℃,反应40 min,螺旋桨转速1000 r·min-1,800℃下焙烧1.5h,在此条件下制得球形氧化钇超细粉体,表观粒径小于0.5μm.     

Coating of SiC Powder with Nano YAG Phase

SiCceramiccompositeshavefoundextensiveap plicationsinmodernindustryduetotheirexcellentchemicalstabilityandwear resistance .Rodeghieroetal.[1～ 3 ] investigatedthefabricationofSiC Al2 O3 ce ramiccompositematerialsviaco precipitationcoatingandsol gelmethods…     

AACH在柠檬酸铝制备多孔氧化铝中的应用研究

针对从简单铝盐(AlCl3,Al(NO3)3等)体系中制备化学品氧化铝易发生凝聚而导致颗粒分散性差的问题,提出利用柠檬酸作为铝的络合剂,并采用碳酸铝铵(AACH)作为中间体制备多孔氧化铝的方法.将柠檬酸铝溶液调节到一定pH值后,滴加到碳酸氢铵溶液中可以得到结晶良好的AACH固体,再通过简单焙烧后即可得高比表面积的多孔球型Al2O3产品.通过对原料碳酸氢铵和柠檬酸铝的物质的量之比β、反应体系pH值、反应温度及陈化时间对铝转化率α的影响的研究发现,在β=2,pH =9,室温25℃,陈化8d,有50％的柠檬酸铝转化为AACH.同时推测出,由于AACH的形成受柠檬酸,铝酸钠,碳酸氧铵三重络合-缓冲体系的限制,首先需要调节柠檬酸铝,其pH值大于9后缓慢释放出Al(OH)4-,Al(OH)4-再同碳酸氢铵反应易得到结晶良好的AACH晶体.TG-DTA热分析和XRD测试表明:300℃下AACH可完全分解为不定型氧化铝,700和1400℃下焙烧可分别得到γ-Al2O3,α-Al2O3.SEM和TEM测试表明,所得AACH粒径约为15 μm,并由大量长度为500 nm左右的纳米棒组成,700℃焙烧后得到形貌不变,含有大量孔径为1～5nm微孔、BET比表面积为235 m2·g -1的多孔氧化铝.     

Synthesis and luminescent properties of Pr-doped Lu3Al5O12 translucent ceramic

Lutetium aluminum garnet (LuAG) precursors doped with different Pr3+ concentration (0.25at.%, 0.5at.%, 1.0at.%, 3.0at.%, 5.0at.%) were synthesized via a co-precipitation method using ammonium hydrogen carbonate as precipitant. The phase evolution and mor-phology of the precursor were characterized with X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The resultant LuAG:Pr3+ powder was sintered into translucent ceramic without any additives in vacuum at 1150℃ and then in nitrogen atmosphere at 1700℃. Photohiminescence spectra of LuAG:Pr3+ powder and ceramic were measured at room temperature in vacuum ultraviolet (VUV) and ultraviolet (VU) region. For the 5d-4f transition of Pr3+ ions, dominant emission of ceramic samples peaking round 311 nm had higher lumines-cence intensity. And the host absorption in ceramic samples was not as intensive as that in powder samples. The luminescent intensity of LuAG:Pr3+ varied with the Pr3+ contents and the quenching concentration was about 1.0at.% for ceramic and 3.0at.% for powder, which was much higher than 0.24at.% for LuAG:Pr3+ single crystals. This phenomenon showed that the ceramic had some superiority over single crystals.     

Synthesis and characterization of YAG:Ce³⁺ fluorescence powders by co-precipitation method

YAG:Ce3+(Yttrium aluminum garnet) fluorescence powders were successfully prepared by co-precipitation method using aluminum nitrate,yttrium nitrate,cerous nitrate as the starting materials and ammonium carbonate as precipitant.The products were characterized by X-ray powder diffraction,luminescence spectrometer,transmission electron microscope(TEM).The XRD results showed that the obtained YAG:Ce3+ fluorescence powders had the crystalline structures of YAG at calcinations temperature of 900 oC and the TEM results showed that the grain diameters were about 100 nm.The YAG:Ce3+ fluorescence powders,synthesized by co-precipitation method,had the best luminescence property when the Ce doping amount was x=0.06 in the molecular formula of Y3-xCexAl5O12,the calcinations time was 2 h and the calcinations temperature was 1000 °C.