Ce:Y_3Al_5O_(12)透明陶瓷的制备和荧光性能的研究

以Ce(NO3)3.5H2O,Y(NO3)3.5H2O和A l(NO3)3.9H2O为原料,NH4HCO3为沉淀剂,采用醇水溶剂共沉淀法在弱还原气氛下1100℃煅烧2 h合成纯相1 at%Ce∶YAG纳米粉体,经1800℃真空烧结10 h后得到了Ce∶YAG透明陶瓷。通过XRD、TEM、SEM和荧光光谱仪对粉体和陶瓷进行了表征。结果表明:所制得的Ce∶YAG纳米粉体散均匀、团聚程度轻、结晶良好,平均晶粒尺寸约35 nm。Ce∶YAG透明陶瓷和纳米粉体的发射峰都在530 nm附近,但透明陶瓷的发射强度明显比纳米粉体强,且发射峰向长波方向移动。     

低温燃烧合成法制备纳米氧化镧

以六水硝酸镧、一水柠檬酸为原料,利用低温燃烧合成法制备了纳米La2O3粉体.利用XRD、TG-DTA和TEM等测试方法对干凝胶热分解过程及最终形成的纳米La2O3粉体进行了表征,并研究了前驱体溶液的pH值、物质的量配比、煅烧温度、煅烧时间对粉体粒径和形貌的影响.实验结果表明,在溶液的pH=2,La(NO3)3·6H2O:C6H8O7·H2O=6:7,煅烧温度在700~900 ℃,煅烧时间为1.5 h时,可获得粒径均匀的纳米La2O3粉体,且所得产物的粒径范围为50~100 nm.     

沉淀法制备纳米氧化铬粉体的影响因素

以Cr(NO3)3·9H2O为原料,以氨水为沉淀剂,聚乙二醇为分散剂,采用沉淀法制备了纳米Cr2O3粉体.研究了反应物浓度、分散剂用量、晶种、煅烧温度及保温时间等因素对合成纳米Cr2O3粉体晶粒度的影响,用场发射扫描电镜(FE-SEM)、X射线衍射仪(XRD)和比表面积测试仪(BET)等手段对其进行表征.结果表明:随反应物浓度(0.2～0.6 mol/L)的增加,纳米Cr2O3粉体的晶粒度增加;在反应物溶液中加入适量的分散剂及用加入1wt;的分散剂的去离子水洗涤前驱体,所得的纳米Cr2O3粉体的晶粒度减小;加入晶种有利于纳米Cr2O3粉体晶体的发育;随煅烧温度的升高及保温时间的延长,纳米Cr2O3粉体的晶粒度增加.在反应物浓度为0.4 mol/L、晶种加入量为1;、分散剂加入量为3;、煅烧温度为450 ℃及保温时间为1 h时可以得到晶粒度为20～50 nm,分散良好的纳米Cr2O3粉体.     

共沉淀法制备YAG纳米粉体影响因素的研究

本文采用Al(NO3)3.9H2O和Y(NO3)3·6H2O为母盐,碳酸氢铵为沉淀剂,利用共沉淀法制备YAG(Y3Al5O12)纳米粉体。利用XRD、SEM对YAG前驱体及煅烧纳米粉体进行了表征,并分析了母盐溶液的浓度、母盐溶液的滴加速度以及有机溶剂的种类对制备YAG纳米粉体的影响。结果表明:母盐溶液的浓度、滴加速度及有机溶剂种类对前驱体和煅烧粉体的分散性、组成及形貌有显著的影响。当母盐溶液浓度比较低时([Y3+]=0.08mol/L,[Al3+]=0.13mol/L),得到YAG纳米粉体的分散性较好,加入少量乙醇(乙醇与母盐溶液体积比为1∶5)更易获得纯相YAG粉体,快速加入母盐溶液比慢速滴入更易获得纯相YAG粉体。实验证实所制备的YAG粉体能够烧结出透明陶瓷,证明通过系统地控制上述3个因素可以得到具有良好烧结性的YAG纳米粉体。     

硅酸锶粉体的溶胶-凝胶制备工艺及机理

以正硅酸乙酯(TEOS)和Sr(NO3)2为原料,采用溶胶-凝胶法制备出高纯度的不规则形状硅酸锶粉体。利用X射线衍射仪、扫描电镜和差热-热重分析仪等研究了锶盐种类、水硅比和pH值对硅酸锶粉体的相结构、形貌和纯度的影响,探讨了溶胶-凝胶法制备硅酸锶粉体的反应过程与机理。结果表明:溶胶-凝胶法制备Sr2S iO4粉体的最佳工艺条件为:锶盐选择Sr(NO3)2,n(H2O)∶n(TEOS)∶n(EtOH)为24∶1∶5,pH值为3~4,煅烧温度为800℃。与传统高温固相反应法相比,该方法大幅度降低了煅烧温度,提高了粉体的纯度,同时能够减小最终获得的硅酸锶粉体粒径。     

熔盐法制备CuFeMnO4光吸热材料的研究

以KOH、KNO3为熔盐,Cu(NO3)2·3H2O、Fe(NO3)3·9H2O、50wt; Mn(NO3)2为原料,研究了金属离子配比及合成温度对熔盐法制备CuFeMnO4粉体的影响,采用XRD和FESEM进行物相及微观形貌的测试分析,利用自行设计测试装置对CuFeMnO4涂层的吸热性能进行评价.研究结果表明,CuFeMnO4粉体主晶相为尖晶石型,当金属离子配比为Fe3+∶ Cu2+∶ Mn2+=1∶0.5∶1时,可有效地抑制杂相的生成;合成温度为700℃时,晶体成核均匀,晶粒尺寸较小.该粉体制成涂料涂覆在铝板上,可使铝板的吸热温度提高22℃,增强了吸热效果.     

纳米Al2O3/GdAlO3共晶陶瓷复合粉体的醇-水加热法制备与表征

为制备分散均匀的纳米尺度的共晶陶瓷复合粉体,采用Al(NO3)3·9H2O和Gd2O3作为原材料,通过醇-水加热法制备了纳米尺度的Al2O3/GdAlO3共晶成分陶瓷粉体.研究了溶液初始浓度配比和pH值等对复合粉体粒径的影响.通过SEM、TEM、FT-IR和BET N2吸附法等手段表征了前驱体颗粒大小和分散性3确定最佳的前驱体制备工艺,对前驱体进行煅烧制得Al2O3/GdAlO3复合陶瓷粉体.结果表明,前驱体粒径和分散性受制备工艺影响较大;特别是,最佳工艺制备的前驱体平均粒径20 nm,分散性良好,形貌多呈球形;1250℃煅烧后得到的Al2O3/GdAlO3共晶陶瓷粉体的晶化良好、成分均匀,粉体粒径100～200 nm.     

共沉淀法制备Gd3（In,Al）5 O12∶Ce石榴石粉体

将Gd2O3、In2O3、NH4Al(SO4)2·12H2O和Ce2(CO3)3试剂溶入稀硝酸制取可溶盐混合溶液,采用NH3·H2O和NH4 HCO3混合溶液沉淀剂,通过共沉淀法获得碱式硫酸碳酸复合盐水合物前驱体,经950℃以上温度烧结处理制备出立方晶系GIAG∶Ce石榴石粉体。应用红外光谱和差热分析研究了前驱体所含特征官能团和热化学行为,应用X射线粉末衍射分析了前驱体经不同温度烧结所出现的物相变化,应用表面电镜和粒度分析表征了GIAG∶Ce粉体的SEM形貌和粒度分布,GIAG∶Ce粉体的荧光光谱呈现365 nm和450 nm两个发光峰,表明Ce3+离子已固溶进入粉体介质晶格。     

柠檬酸凝胶燃烧法制备Nd∶YAGG多晶粉体

采用柠檬酸凝胶燃烧法制备了Nd∶YAGG多晶粉体.将Nd2O3,Ga2O3,Y2O3和Al(NO3)3分别用稀硝酸溶解后,与柠檬酸溶液均匀混合并于100℃加热4h,可以得到棕黄色凝胶,凝胶自燃可获得干凝胶.干凝胶分别在500℃、700℃和900℃下进行煅烧获得Nd∶ YAGG多晶粉体.红外光谱测试表明NO、OH等在900℃已被分解完全;扫描电镜观察发现煅烧后的Nd∶ YAGG多晶粉体是由规则的球状颗粒组成,粒径约为30 nm;XRD测试表明900℃为Nd∶ YAGG多晶粉体的最佳煅烧温度;荧光光谱分析发现Nd∶ YAGG多晶粉体具有较好的荧光性能,荧光发射的最强峰位于1064.54 nm处,属于Nd3+的4F3/2-4I11/2能级跃迁.     

溶胶-凝胶自蔓延燃烧法合成LaFeO3纳米粉体

采用溶胶凝胶自蔓延法,以La2O3,和Fe(NO3)3·9H2O为原料,柠檬酸为络合剂,制备出纳米级别LaFeO3粉体.对制备的干凝胶和纳米粉体采用热分析(DTA/TG),X射线衍射仪(XRD),扫描电镜(SEM)和透射电镜(TEM)检测方法进行检测分析.分别探讨了溶液金属离子与柠檬酸比例对凝胶的形成影响,煅烧温度对LaFeO3晶相的形成及晶粒尺寸大小的影响.研究结果表明,当柠檬酸与金属离子摩尔比例为1:1时制备的干凝胶,引燃温度300℃,然后900℃保温1 h,可以得到尺寸大小在55～70 nm的单相LaFeO3纳米粒子.     

Crystal and molecular structures oftrans-dichloro-(ethylene) (4-methylpyridine)platinum(II) andtrans-dichloro(ethylene) (2,4,6-trimethylpyridine)platinum(II)

The crystal and molecular structures oftrans-[PtCl₂(C₂H₄)(4-MeC₅H₄N)] (I) andtrans-[PtCl₂(C₂H₄)(2,4,6-Me₃C₅H₂N)] (II) have been determined by single-crystal x-ray methods.I crystallizes in space groupP2₁/c witha= 4.991(1), b=21.658(3), c=10.675(3) Å, =110.17(2) °,Z=4;II is orthorhombic (Pbca) witha=10.295(6),b=12.393(8),c=20.370(10) Å,Z=8.Full-matrix least-squares refinements have given finalR factors of 0.053 (1520 reflections) forI and 0.042. (1412 reflections) forII. The intensities were recorded by counter methods, and only those reflections havingI>3(I) were used in the analyses.In both complexes, platinum is four-coordinate with the two chlorine atoms, the double bond of the ethylene, and the nitrogen atom of the substituted pyridine. The two structures are discussed in terms of the arrangement of the pyridine ligand with respect to the PtCl₂(C₂H₄) moiety.     

Synthesis, spectroscopy, and X-ray structures of fac-(CO)3(dppe)MnSC(S)H, fac-(CO)3(dppe)ReSC(S)H, fac-(CO)3(dppp)ReSC(S)H, and fac-(CO)3(dppb)ReSC(S)H

The monodentate dithioformato complexes, fac-(CO)₃(dppe)MnSC(S)H (1), fac- (CO)₃(dppe)ReSC(S)H (2), fac-(CO)₃(dppp)ReSC(S)H (3), and fac-(CO)₃ (dppb)ReSC(S)H (4), where dppe is 1,2-bis(diphenylphosphino)ethane, dppp is 1,3-bis(diphenylphosphino)propane, and dppb is 1,4-bis(diphenylphosphino)butane, were synthesized from the treatment of the corresponding hydrides, fac-(CO)₃ (P-P)MSC(S)H with CS₂. Compounds 1–4 crystallize in the monoclinic crystal system: for 1, space group = P2₁/c, a = 15.3139(3) Å, b = 9.7297(4) Å, c = 19.0991(6) Å, = 105.928(1), V = 2736.5 ų, Z = 4; for 2, space group = P2₁/c, a = 15.6395(8) Å, b = 9.8182(5) Å, c = 19.4153(11) Å, = 106.741(1), V = 2854.9(3) ų, Z = 4; for 3, space group = P2₁/n, a = 11.3570(10) Å, b = 19.465(2) Å, c = 15.5702(14) Å, = 104.776(2), V = 3328.3(5) ų, Z = 4; and for 4, space group = C2/c, a = 32.078(2) Å, b = 10.4741(6) Å, c = 19.0608(9) Å, = 94.315(2), V = 6386.1(6) ų, Z = 8.     

Structure of (chloranilato)bis(tri-n-butylphosphine)palladium(II)

(Chloranilato)bis(tri-n-butylphosphine)palladium(II), [Pd(C₆Cl₂O₄){P(C₄H₉)₃}₂] (chloranilic acid=2,5-dichloro-3,6-dihydroxy-p-benzoquinone): FW=718.02,P2₁/c,a=21.729(6),b=17.293(5),c=21.010(9) Å,=112.62(3)°,V=7287.42 ų,Z=8,D _c=1.309mg m^–3, Mo, =0.710730 Å,=0.76 mm^–1,F(000)=3008, finalR=0.087, 2594 observed reflections. Palladium is ligated by a distorted square planar P₂O₂ coordination sphere in the title compound. The two molecules per asymmetric unit differ in the arrangement of phosphine n-butyl chains, yielding two unique metal centers.     

Crystal structure of triphenylphosphine-(1-(di(trifluoromethyl)-hydroxymethyl)-cyclopentadienyl)-(1,2-di(carboxymethyl) ethylene-1-yl) ruthenium (0)

The structure of triphenylphosphine — (1 — (di(trifluoromethyl) — hydroxymethyl) — cyclopentadienyl) — (1,2 — di(carboxymethyl)ethylene — 1 — yl) — ruthenium (0) has been studied by single-crystal X-ray diffraction techniques. This compound, [C₅ H₄(CF₃)2 COH] Ru(PPh₃)C2(CO₂Me)₂H, crystallizes in the triclinic space groupP¯1 witha =10.131,b= 15.107,c= 10.798 Å, = 102.14, = 107.04, = 89.64° andZ = 2. The structure was refined by block-diagonal least-squares methods to a finalR value of 0.042, including hydrogen atoms. The compound contains a dicarboxymethylethylene ligand coordinated to ruthenium both through a ketonic oxygen and through a metal--carbon -bond. An intramolecular hydrogen bond is observed. Details of the structure are reported, and the structures of several Ru(0) complexes are compared.     

X-ray crystal structures ofcis-bis(diphenylphosphinamide)tetracarbonylmolybdenum(0) andtrans-bis(N-methyl diphenylphosphinamide)tetracarbonylmolybdenum(0)

The X-ray crystal structures ofcis-Mo(CO)₄(Ph₂PNH₂)₂,I, andtrans-Mo(CO)₄(Ph₂PNHMe)₂,II, are presented. ComplexI crystallizes in the monoclinic space groupP2₁/c(a=13.433(1),b=12.2719(8),c=17.318(2)Å;=109.79(1)°;V=2686.1(8)ų;Z=4). ComplexII crystallizes in the triclinic space groupP¯1 (a=6.9986(8),b=10.328(1),c=11.241(2)Å,=107.58(1)°,=91.76(1)°, =101.28(1)°,V=756.1(4)ų,Z=1). The molybdenum coordination geometry in each complex is a slightly distorted octahedron. The molybdenum-carbon bond lengths for the carbonyls trans to phosphorus in complexI are shorter than those the carbonyls trans to other carbonyls. The average molybdenum-phosphorus distance inI (2.525(5)Å) is similar to those in other diphenylphosphinamide complexes and longer than the molybdenum-phosphorus distance inII in 2.4585(7)Å). The distance between two nitrogen atoms incis Mo(CO)₄(Ph₂PNH₂)₂ (3.74(3)Å) is significantly larger than the sum of their van der Waals radii (3.10 Å) indicating that the two nitrogens are not hydrogen bonded.     

Crystal and molecular structures of trans-bis(acetonitrile)bis(bipyridine)ruthenium(II) perchlorate and trans-diamminebis(bipyridine)ruthenium(II) perchlorate

The structures of trans-[(MeCN)₂(bpy)₂Ru](ClO₄)₂(I) andtrans-[(NH₃)₂(bpy)₂Ru](ClO₄)₂(II) have been determined by single crystal X-ray diffraction methods. (I) forms monoclinic crystals in the space groupP2₁/c witha=8.399(2),b=10.406(2),c=15.590(3) Å,=93.78(2)° andZ=2 atT=293 K. The final refinement gaveR=0.040 for 2448 reflections withF _o ² >3(F _o ² ). (II) crystallizes in the triclinic space groupP¯1 witha=1.702(1),b=8.439(2),c=10.525(2) Å,=107.56(2),=104.63(1), =100.89(2)° andZ=1 atT=293 K. Refinement using 1878 reflections withF _o ² >3(F _o ² ) produced a finalR value of 0.036. Both of these structures have the ruthenium atom located on a crystallographic inversion center. The bipyridine ligands in both structures are in the bowed conformation as a means of circumventing the steric problems associated with the trans arrangement of the bipyridine ligands. The Ru-N(monodentate) distance is longer for the ammonia complex (2.106(3) Å) than for the acetonitrile complex (2.008(4) Å); there are no significant differences in the distances and angles of the two Ru(bpy)₂ frameworks.     

Structure of (N-(2-hydroxyphenyl)-salicylaldiminopiperidino) Ni(II) complex

The crystal and molecular structure of the title complex, C₁₈H₁₉N₂O₂Ni, has been determined by direct methods. The compound crystallizes in the monoclinic crystal system witha=22.973(1),b=5.212(1),c=27.076(1)Å, β=106.46(1)°, space groupC2/c,V=3109.1(6)ų, Z=8, andD _x=1.51g cm^?3. The nickel atom is in a slightly distorted square-planar environment of two oxygens [Ni(1)?O(1) 1.824(3) and Ni(1)?O(2) 1.856(3)Å] and two nitrogens [Ni(1)?N(1) 1.849(3) and Ni(1)?N(2) 1.932(3)Å] with O?Ni?N angles between 85.7(1) and 97.1(1)°. The nickel atom is 0.006 Å out of the plane of its ligands.     

X-ray structures of tris(0-cyclohexyl-dithiocarbonato)bismuth(III) and tris(0-benzyl-dithiocarbonato)bismuth(III)

The crystal structures of two Bi tris xanthates are reported, namely [Bi(S₂CO-c-C₆H₁₁)₃ J and [Bi(S₂COCH₂C₆H₅)₃]. They exist as centrosymmetric dimers, owing to the presence of bridging xanthate ligands, with seven-coordinate Bi atoms. The presence of a stereochemically active lonepair of electrons in each structure distorts the coordination geometry defined by seven S atoms and causes the elongation of some of the Bi-S bond distances. Crystals of both compounds are triclinic, space groupP¯1 with unit cell dimensions for [Bi(S₂CO-c-C₆H₁₁)₃]:a=12.417(3),b=13.571(3),c=9.681(4) Å;=102.30(2),=109.21(2), =66.23(2)° andZ=2; and for [Bi(S₂COCH₂C₆H₅)₃]:a=14.747(2),b=15.966(2),c=5.991(1) Å;=95.08(1),=98.51(1), =104.92(1)° andZ=2. The structures were refined by a full-matrix least-squares procedure to finalR=0.045 using 4274 reflections for [Bi(S₂CO-c-C₆H₁₁)₃] and toR=0.027 using 3993 reflections for [Bi(S₂COCH₂C₆H₅)₃].