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.     

1,2,3,4-丁烷四羧酸镧系络合物的制备及热重和红外光谱研究

1,2,3,4-丁烷四羧酸镧系(Ln=La,Ce,Pr,Nd,Yb)络合物为结晶固体,其通式:Ln4(C8H6O8)3·nH2O,Ln=Ce、Pr、Nd,n=8;Ln=La,n=7;Ln=Yb,n=11。在加热过程中,它们首先失去络合物中所含的水,再进一步加热,开始分一步(Ce,Pr)或两步(La,Yb,Nd,中间产物为Ln2O2CO3)热分解,最终生成镧系金属氧化物。红外光谱研究表明Ln4(C8H6O8)3·nH2O中羧酸盐基团为双齿配位螯合体。     

类球形氧化铈的制备及抛光性能

采用溶剂热法合成了粒径为200 nm左右的类球形Ce O2前驱体,在一定温度下煅烧得到抛光粉,采用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、电子衍射、激光粒度分析仪等对其进行了表征和观察;同时考察了溶剂热温度、分散剂种类和用量等因素对合成类球形Ce O2前驱体的影响,以及不同煅烧温度和煅烧时间对单晶硅片抛光性能的影响。结果表明:以氯化铈为铈源,以0.75 mol·L-1NH3·H2O为沉淀剂,乙二醇为溶剂,聚乙烯吡咯烷酮(PVP)为分散剂,搅拌30 min后得到浑浊液转移至50 ml内衬聚四氟乙烯(PTFE)反应罐中,在烘箱中于180℃反应24 h,沉淀分别用去离子水,无水乙醇各洗3次,放于60℃烘箱中烘干,得到氧化铈前驱体,经500℃煅烧2 h为D50=203 nm的类球形Ce O2粉体,粉体分散性好,配成质量分数为0.2%的抛光浆料对n(111)型单晶硅片抛光,得到较高抛光速率和超平整的抛光表面。     

机械活化-放电等离子烧结制备Y3Al5O12陶瓷

以高纯Y2O3和Al2O3粉体为原料,通过机械活化和放电等离子烧结制备Y3Al5O12(YAG)陶瓷.研究结果表明:机械活化Y2O3和Al2O3粉体,不但细化了Al2O3颗粒,而且使Y2O3发生了晶态转变,由立方晶转变为斜方晶,并最终非晶化;机械活化过程最终还合成了过渡产物YAlO3(YAP),但球磨5h后,继续延长球磨时间,会引入大量ZrO2杂质;球磨处理的Y2O3和Al2O3粉体具有很高的活性,能促进在较低温度下通过放电等离子烧结合成YAG.对球磨5h的粉体在不同温度进行放电等离子烧结的研究表明,在1000℃可获得纯YAG陶瓷,在1 400℃可得到相对密度为99.4%、晶粒大小为1～2μm的YAG陶瓷.     

Y_2W_3O_(12)和Yb_2W_3O_(12)的制备及其负热膨胀性能

利用液相沉淀法制备了Y2W3O12和Yb2W3O12粉体。经室温XRD测定,Y2W3O12(空间群为Pnca)和Yb2W3O12(空间群为Pbcn)皆为单一的正交相。在50-800℃温度区间对两种粉体进行高温XRD测试,并利用软件TOPAS3.0对其在不同温度下的XRD图谱进行精修,发现Y2W3O12和Yb2W3O12都具有较大的负热膨胀特性,经计算两者的线热膨胀系数(αl)平均值分别为-6.38×10-6℃-1和-4.18×10-6℃-1。与高温固相反应法相比,液相沉淀法大大缩短了粉体的合成周期,降低了合成温度。     

尿素浓度对均相沉淀法制备球形Y_2O_3的影响

以尿素为沉淀剂,通过均相沉淀法制备了粒径均一、分散性好的球形Y2O3粉体,测量了制备Y2O3前驱体过程中的p H值,分析了尿素浓度对Y2O3粒径和形貌的影响,结果表明,Y2O3的粒径均一性和分散性受尿素浓度的影响较大;当[尿素]/[Y3+]=35∶1时得到了最小平均粒径为109 nm的Y2O3。XRD、FTIR表征了前驱体和煅烧后的粉体,TGA-DSC考察了前驱体分解过程,结果表明前驱体主要化学成分为Y(OH)CO3·2H2O,前驱体在800℃煅烧2 h完成分解并形成立方晶型的Y2O3。     

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.     

抛光用Ce1-xZrxO2粉末合成工艺的优化及其性能

用共沉淀法、NH3·H2 O为沉淀剂 ,利用正交实验法对合成抛光用Ce1 -xZrxO2 粉末的工艺进行了优化 ,结果得出 :以nZrO(NO3) 2 ∶nCe(NO3) 3=3∶5 0的混合料液为原料 ,无水乙醇为分散剂 ,70 0℃煅烧可得粒度均匀、且中位粒径约 0 .45 μm的混合粉末。经激光粒度仪、XRD ,TG ,比表面积测定仪、拉曼光谱仪对优化工艺合成的Ce1 -xZrxO2 粉末的粒度、物相、热稳定性、比表面积、拉曼特征峰等进行了表征 ,同时用抛光机和表面粗糙度测试仪对用此粉末抛光后的玻璃进行了测试 ,证明抛光效果良好     

Al2O3的掺杂浓度对Ce0．8Y0．2O1．9电解质的性能影响研究

利用低温燃烧合成法制备了Al2O3掺杂浓度为0.5%～10%(摩尔分数,以下同)的Al2O3/Ce0.8Y0.2O1.9固体电解质复合材料。研究了Al2O3掺杂浓度对Ce0.8Y0.2O1.9固体电解质烧结及电性能的影响。试验结果表明,添加少量的Al2O3可以改善Ce0.8Y0.2O1.9固体电解质的烧结性能,当Al2O3的添加量为0.5%时,电解质粉体具有最佳的烧结性能,1350℃时的相对密度达到99%以上。当Al2O3的掺杂浓度超过其在Ce0.8Y0.2O1.9中的溶解极限时,随Al2O3掺杂量的继续增加,烧结体的相对密度开始下降。阻抗谱结果表明,在溶解极限范围内,Al2O3使Ce0.8Y0.2O1.9的电导率减小,电导活化能增加。Al2O3的掺杂浓度超过溶解极限时,Ce0.8Y0.2O1.9的晶粒电阻不变,由于Al2O3对晶界的"清洁"作用,晶界电阻减小;当Al2O3的掺杂浓度超过5%时,由于Al2O3颗粒对晶界的"阻塞"作用,晶界电阻增加。     

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.     

Effect of Sulfate Ions on YAG Powders Synthesized by Microwave Homogeneous Precipitation

Using Al(NO3)3·9H2O, NH4Al(SO4)2·12H2O, Y(NO3)3 as mother salts, and urea as precipitant, YAG nano-powders were synthesized by microwave homogeneous precipitation. The composition, morphology, and phase transformation of precursor were analyzed by IR, XRD and TEM. The size distribution of YAG powders was characterized using laser diffraction method. The results show that sulfate ions influence the dispersion, composition and morphology of the YAG precursors. The addition of moderate sulfate ions can produce YAG powders with nano size and excellent dispersion at 1100 ℃.     

Synthesis, Catalysis of Rare Earth Complexes with Aliphatic Noncyclic Polyether-Amino Acid Schiff Base

Coordination chemistry of rare earth with Schiffbase has developed rapidly in the last fewyears ,butthe majority of the complexes studied are derivedfromaromatic Schiff base .So far less papers of rare earthcomplex with aliphatic Schiff base have been rep…     

Studies on Heterobinuclear Complexes of Ln3 and Zn2 with Acyclic Polyether Schiff Base

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Preparation of Well Dispersed and Ultra-Fine Ce （Zr）O2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.     

甘氨酸硝酸盐法制备超细Mo-Cu粉末及烧结

以四水合钼酸铵（（NH4）6Mo7O24·4H2O）、硝酸铜（Cu（NO3）2·3H2O）、甘氨酸和乙二胺为原料采用甘氨酸硝酸盐法（GNP）制备前驱体粉末,经过700℃氢气还原2 h得到Mo-Cu 复合粉末,经压制后进行真空烧结,研究不同烧结温度对Mo-Cu 烧结体性能的影响.结果表明：甘氨酸-硝酸盐法（GNP）制备的超细Mo-Cu 复合粉末形状规则、大小均匀、钼铜两相弥散分布,颗粒大小平均为50~80 nm.在950~1250℃范围内,随着烧结温度的升高,烧结体的硬度增大,致密度、电导率和热导率在1150℃达到最大值.     

Synthesis, structures,thermal and magnetic properties of a series of lanthanide [Ln=Sm, Gd, Er, Yb] complexes with 4-quinolineacarboxylate

A series of lanthanide binuclear complexes, [Ln2(L)6(H2O)4]·2H2O (Ln=Sm(III), Gd(III), Er(III), Yb(III), HL=4-quinolineacarboxylic acid, were synthesized by reactions of corresponding rare earth salts with 4-quinolineacarboxylic acid at room temperature and were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. X-ray diffraction analyses showed that they exhibited the same binuclear architecture and crystallized in monoclinic system and P21/c space group. In four complexes, each metal center adopted nine-coordinated mode coordinated by nine O atoms from two H2O molecules and three carboxyls of three ligands, and HL showed three different coordination modes. The variable-temperature magnetic susceptibility showed that complex [Gd2(L)6(H2O)4]·2H2O performed very weak antiferromagnetic property at low temperature and exchange was almost paramagnetic at high temperature. Complexes [Er2(L)6(H2O)4]·2H2O and [Yb2(L)6(H2O)4]·2H2O performed dominating antiferromagnetic coupling.     

稀土上转光剂(Y3Al5O12∶Er^3+)复合TiO2光催化剂的制备及其催化性能的研究

采用溶胶-凝胶法、高温煅烧法和超声分散法制备了Y3Al5O12∶Er^3+/TiO2复合光催化剂,并对制备的样品进行了XRD和SEM表征。利用次甲基蓝水溶液模拟有机污染水,对比了单一TiO2,上转光剂Y3Al5O12∶Er^3+以及Y3Al5O12∶Er^3+/TiO2复合光催化剂的催化活性。同时讨论了煅烧温度、煅烧时间、光照射时间、光照强度以及光催化剂用量等因素对光催化剂性能的影响。结果表明,煅烧温度为550℃、煅烧时间为90 min,照射时间为150 min,光照强度为1.0 mW/cm2和催化剂的量为1.00 g/L时,Y3Al5O12∶Er^3+/TiO2复合光催化剂降解次甲基蓝表现出了最佳的催化效果。