Gd2Ti2O7/ZrO2（3Y）陶瓷制备及力学性能研究

用共沉淀法合成Gd2Ti2O7纳米粉体,经真空烧结制备不同ZrO2(3Y)含量的Gd2Ti2O7/ZrO2(3Y)陶瓷。用XRD、SEM和力学性能试验等测试手段研究样品的物相、形貌和力学性能。结果表明:Gd2Ti2O7/ZrO2(3Y)陶瓷的力学性能随ZrO2(3Y)含量增加显著提高,ZrO2(3Y)含量为90vol%时,样品的维氏硬度、抗弯强度和断裂韧性最大值分别达到20.95GPa、199.21MPa和8.17MPa·m1/2。其原因是ZrO2(3Y)固溶导致晶粒尺寸减小,过饱和析出ZrO2(3Y)的颗粒弥散增韧,以及ZrO2(3Y)应力诱导相变增韧作用。     

共沉淀法制备Gd2Zr2O7纳米粒子

采用反向滴定共沉淀法制备了Gd2Zr2O7纳米粒子,用XRD、SEM、TEM、TG-DTA等测试手段分析了煅烧温度和时间、体系温度、pH值、初始浓度、表面活性剂含量(SDBS)对前驱体的物相、形貌及晶粒大小的影响。结果表明:五种因素分别对Gd2Zr2O7相变化无影响,以氨水做沉淀剂经反向滴定,当体系温度为0℃、母盐溶液初始浓度为0.01mol/L、pH值为11、SDBS含量2wt%时,在1100℃煅烧3 h制备出近球形的Gd2Zr2O7纳米粒子,粒径约40 nm。     

水热-固相法制备Gd2Zr2O7纳米粒子

以Gd2O3和ZrOCl2.8H2O为原料,氨水为矿化剂,在200℃和12～30 h的水热条件下合成的前驱体,经固相反应获得Gd2Zr2O7纳米粒子。用X射线衍射(XRD)、热重差热(TG-DTA)、傅立叶变换红外光谱(FT-IR)、扫描电镜(SEM)等测试手段分析了样品合成过程的物相变化、产物结构及形貌特征。结果表明:在n(Gd)∶n(Zr)=1∶1,水热合成温度200℃,pH=11,保温24 h,合成的前驱体经1000℃、2 h煅烧获得分散性好、形貌近球形、粒径约23nm的Gd2Zr2O7纳米粒子。     

柠檬酸铵辅助溶胶-凝胶法制备Gd2Zr2O7纳米粉体及其表征

以Gd(NO3)3·6H2O、Zr(NO3)4·6H2O为原料,无水柠檬酸(C6H8O7)为螫合剂,无水乙醇做溶剂,采用柠檬酸铵(C6H17N3O7)分散剂辅助溶胶凝胶法合成分散好的Gd2Zr2O7纳米粉体.通过TG-DSC、XRD、SEM、TEM测试方法对合成的粉体进行了表征.结果表明:添加的柠檬酸铵与无水柠檬酸的摩尔量之比为1时,其溶胶的pH值为2.8左右,所制得的Gd2Zr2O7前驱体在空气中900℃煅烧4h后得到分散均匀、团聚程度轻、结晶良好的纯相Gd2Zr2O7纳米粉体,样品为缺陷型萤石结构,平均晶粒尺寸约为33 nm.     

Gd2Zr2O7纳米晶的制备及表征

以柠檬酸(CA)为螯合剂,乙二醇(EG)为分散剂,通过Pechini法合成出Gd2Zr2O7纳米晶,讨论了pH值、分散剂含量以及热处理温度对样品物相和形貌的影响,采用SEM、TG-DTA、XRD和TEM等测试手段对样品进行了表征。结果表明:溶胶pH值=6,乙二醇含量为柠檬酸的2倍,经900℃煅烧2 h获到Gd2Zr2O7样品结晶度高、晶型完整,为缺陷型萤石结构,属于Fm3m空间群,且粒度均匀,粒径约50 nm,d111面间距为0.304 nm。     

共沉淀法制备Al2O3-ZrO2复合纳米粉体

以ZrOCl2·8H2O、Al(NO3)3·9H2O、Y(NO3)3为原料,NH4HCO3 (AHC)为络合剂,采用共沉淀法制备Al2 O3-ZrO2复合纳米粉体.利用X射线衍射分析(XRD)、扫描电镜(SEM)、透射电子显微镜(TEM)、激光粒度分析仪等对Al2 O3-ZrO2复合粉体进行测试表征,详细研究了pH和AHC/Zr摩尔比对复合粉体的影响.结果表明,当前驱体的煅烧温度低于1200℃时,只形成t-ZrO2相,当煅烧温度达到1300℃时,α-Al2O3相开始形成;沉淀反应的pH和AHC/Zr摩尔比对Al2O3-ZrO2复合粉体的产率有很大的影响.在pH7、AHC/Zr =4.5:1的条件下制备前驱体,经过1300℃煅烧2h得到两相纯度高,分散性能好,粒度分布窄,平均粒径为0.75 μm的Al2O3-ZrO2复合粉体.     

Al2O3-ZrO2-YAG复相粉末的低温合成研究

用低温原位合成技术制备了Al2O3-ZrO2-YAG复相粉末,在1100℃,5h热处理后,Al-Zr-Y-O体系中的主相为ZrO2四方相,其余为无定形相,表明ZrO2抑制了Al2O3和YAG晶粒的生长,同时Al2O3和YAG抑制了ZrO2从四方相向单斜相的转变.在1580℃,1h热处理后,Al-Zr-Y-O体系中的复相组成为(115+90x)Al2O3+54(Y2O3)x·ZrO2+(32-36x)YAG,其中0 ≤x＜0.88(mol).     

ZrO2 (Y2O3) 增韧SiC中介结合的金刚石聚晶烧结体的相结构与性能

本文采用恒沸腾水解法制备了颗粒度均一的亚微米晶ZrO2 (Y2O3)粉体,并以其为增韧相,在高温(1350℃)超高压(5GPa)条件下制备ZrO2 (Y2O3)+SiC+金刚石的聚晶烧结体(PCD).用XRD、SEM背散射分析、冲击韧性测定和磨耗比测定研究了不同含量Y2O3稳定的ZrO2粉体对SiC-金刚石聚晶烧结体结构及机械性能的影响,结果表明:ZrO2 (Y2O3)粉体中Y2O3含量＜2.2mol;时,ZrO2以四方t相+单斜m相的混合相形式存在于烧结体的结合剂基体上,t相量随Y2O3含量增加而增加,对SiC-金刚石聚晶烧结体的增韧来源于相变增韧和微裂纹增韧的叠加,当Y2O3含量＞2.2mol;时,ZrO2以100;t相存在,增韧机制为相变增韧.在2.0mol;～2.2mol;Y2O3含量范围内,PCD可获得较高的磨耗比和冲击韧性.     

碳酸氢铵共沉淀法制备(Y,Gd)2O3: Eu3+纳米材料及光谱特性

以碳酸氢铵作沉淀剂采用共沉淀法制备了(Y,Gd)2O3: Eu3+纳米粉体.用FT-IR、DTA/TG、XRD和SEM对样品进行了表征,并用荧光光度计分析了样品的发射光谱.结果表明:碳酸氢铵为沉淀剂,先驱沉淀物经150 ℃干燥,800 ℃煅烧保温2 h时,合成了近似球形、粒径均匀、约为15～20 nm、分散性好的(Y,Gd)2O3: Eu3+纳米粒子.随着掺入Eu3+浓度的增加, 发射峰强升高;当掺入5 mol;的Eu3+时,峰强最大; 当Eu3+的含量高于5 mol;时出现了浓度猝灭,峰强反而降低.     

Y2O3/ZrO2复合泡沫陶瓷烧结的初步研究

本文采用有机泡沫浸渍法制备了Y2O3/ZrO2双层复合、Y2O3/Y2O3-ZrO2/ZrO2三层复合及Y2O3和ZrO2单相泡沫陶瓷,分析了两种复合泡沫陶瓷层间的结合及各层显微结构随烧结温度的变化,并与单相氧化物陶瓷进行了对比。结果表明:双层复合陶瓷层间有较大缝隙,这是因为两种氧化物陶瓷烧结不同步造成的。三层复合陶瓷中Y2O3-ZrO2混合中间层的存在减弱了Y2O3、ZrO2烧结不同步引起的层间应力,层间结合明显改善,并大大减少了泡沫陶瓷表面宏观裂纹。两种复合陶瓷的ZrO2内层的烧结程度都低于单相ZrO2,这主要是因为先于ZrO2烧结的Y2O3外层阻碍了内部气体的排出从而阻碍ZrO2的烧结所致。     

Crystal structure of Rb2[GeO2(OH)2]·2H2O

Single crystals of Rb₂[GeO₂(OH)₂] · 2H₂O are studied by X-ray diffraction. The crystals belong to the orthorhombic system, sp. gr. Pna2₁, a = 13.523(6) Å, b = 8.143(4) Å, c = 13.407(6) Å, Z = 8, R ₁ = 0.0506. In [GeO₂(OH)₂]^2? anions, the Ge-O distances (1.71–1.73(1) Å) are shorter than the Ge-OH distances (1.76–1.80(1) Å). Anions are linked to each other by pairs of hydrogen bonds to form infinite chains. The chains are linked by hydrogen bonds involving water molecules to form a 3D structure. The assignment of the bands in the IR spectrum of the compound under study is performed.     

通过SiO2涂层改善BaSi2O2N2∶Eu2荧光粉的热性能

本文研究了SiO2涂层对BaSi2O2N2∶ Eu2蓝绿色荧光粉发光性能和热性能的影响.采用溶胶-凝胶法制备了SiO2包覆的BaSi2O2N2∶Eu2+蓝绿色荧光粉.实验结果表明,最佳镀膜量为6wt;,当镀膜量大于此值时,荧光粉亮度迅速降低.涂覆SiO2后,在150℃下BaSi2O2 N2∶Eu2荧光粉的热猝灭性能提高了2.4;,在500℃热降解后荧光粉的发光性能提高了15;.SiO2涂层显著提高了BaSi2O2N2∶Eu2+荧光粉的热稳定性.SiO2涂层的作用机理是在荧光粉表面和氧化气氛之间形成阻挡层,保护Eu2的发光中心在热加热过程中不被氧化.     

Identification of a new family of diphosphate compounds, AI2BII3(P2O7)2: Structures of Ag2Co3(P2O7)2, Ag2Mn3(P2O7)2, and Na2Cd3(P2O7)2

Syntheses and single-crystal X-ray structural results are reported for three new mixed diphosphates of the family A^I ₂B^II ₃(P₂O₇)₂; Ag₂Co₃(P₂O₇)₂ (I), Ag₂Mn₃(P₂O₇)₂ (II), and Na₂Cd₃(P₂O₇)₂ (III). All crystallize in the triclinic system, space group P1 bar: (I) a = 5.351(4), b = 6.375(4), c = 16.532(4) Å, = 80.83(6) = 81.45(4), = 72.87(5)°, V = 528.9(6) ų, Z = 2, D _calc = 4.649 mg/m³, R/Rw = 0.0428/0.0548 for 3949 obs. reflns; (II) a = 5.432(7), b = 6.619(6), c = 16.51(3) Å, = 80.78(8) = 82.43(9), = 72.82(7)°, V = 557.7(13) ų, Z = 2, D _calc = 4.338 mg/m³, R/Rw = 0.0679/0.1303 for 2100 obs. reflns and (III) a = 5.67(3), b = 7.08(4), c = 7.90(4) Å, = 77.0(2), = 82.5(2), = 67.8(2)°, V = 286(3) ų, Z = 2, D _calc = 4.249 mg/m³, R/Rw = 0.0307/0.0342 for 1945 obs. reflns. (I) and (II) are isostructural but (III) is of a different type. All three structures are characterized by layers of P₂O₇ groups alternating with layers of mixed metal atoms. Differences are seen in the conglomerate bonding patterns of B atoms and in the irregular geometry of Ag in (I) and (II) compared to the octahedral bonding seen for Na in (III). The differences in structure may be understood in terms of the ratios of the ionic radii of A and B atoms.     

Dissociation of LiAlO2 and LiGaO2

The thermodynamic calculations of dissociation of LiAlO₂ and LiGaO₂ as function of temperature and oxygen pressure are presented. It has been found that LiGaO₂ evaporates congruently at the melting point under the oxygen pressure equal to 1 · 10^—5 atm. LiAlO₂ evaporates incongruently, the equilibrium oxygen partial pressure at the melting point is equal to 9.6 · 10^—5 atm and the partial pressure of Li and Al oxides decrease with increasing of oxygen pressure.     

Ru掺杂MoS2对SO2F2和H2S气体吸附的第一性原理研究

本文基于第一性原理探讨了Ru掺杂的单层MoS₂(Ru-MoS₂)的结构及其对SF₆绝缘设备中的两种主要分解气体SO₂F₂和H₂S的传感和吸附行为。Ru原子进入硫空位从而产生Ru-MoS₂,结果表明，Ru-MoS₂对SO₂F₂和H₂S气体的吸附能(E_ad)分别为-1.52和-2.11 eV,属于化学吸附。通过能带分析(BS)和态密度(DOS)分析进一步证明了两个体系的吸附性能，并阐述了Ru-MoS₂用于电阻式气体传感器时的气体吸附传感机制。除此之外，本文在理论上探索了不同温度下Ru-MoS₂解吸附SO₂F₂和H₂S的恢复时间，在598 K温度下，SO₂F₂吸附体系的恢复时间为6...     

Synthesis and characterization of (NH4)2CuBr2Cl2·2H2O crystals

Single crystals of a new compound, (NH₄)₂CuBr₂Cl₂.2H₂O, were grown from saturated aqueous solution at room temperature by slow evaporation method. The grown crystals were characterized through elemental, powder XRD, thermal and DSC analyses and FTIR and far IR spectra. The elemental analysis and the decomposition pattern formulated using the TG‐DTG studies confirm the stoichiometry of the compound. The crystallinity of the compound is confirmed from the powder XRD pattern. A preliminary single crystal X‐ray diffraction structural analysis reveals that the title compound belongs to the orthorhombic system with a = 7.7466 Å, b = 7.783 Å and c = 8.1211 Å. The low temperature DSC shows thermal anomalies at –161.1, –156.5, –152.4, –145.2, –134, –18.5, and 1.4°C during the heating run and at –4.3, –54.8, –66.1, –90.6, –109.7 and –147.2 °C during the cooling run. The thermal hysterses indicate first order phase transitions in the title compound at these temperatures. The FTIR spectra were used to assign the characteristic vibrational frequencies due to NH₄⁺, CuX₄^2– ions and other chemical bonds. The effect of substitution of two bromine atoms on the phase transitions of a closely related crystal, diammonium tetrachloro cuprate dihydrate is also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical properties of the germanate melilites Sr2MgGe2O7, Sr2ZnGe2O7 and Ba2ZnGe2O7

Refractive indices and their dispersion in the wavelength range from 365 nm to 2325 nm and transmission ranges of the tetragonal melilite‐type germanates Sr₂MgGe₂O₇, Sr₂ZnGe₂O₇ and Ba₂ZnGe₂O₇ were determined. The uniaxial positive crystals Sr₂MgGe₂O₇ and Ba₂ZnGe₂O₇ both offer the possibility for phase matched second harmonic generation, a detailed analysis of phase matching conditions is given. The refractive indices of Sr₂ZnGe₂O₇ show an isoindex (isotropic) point at 467 nm. The investigation was performed on Czochralski grown large single crystals. The crystal structure of all three germanates were determined by means of X ‐ray diffraction. The results corroborate unmodulated melilite‐type structures at room temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structure of {Pb[S2CN(C2H5)2]2(1,10-phenanthroline)}2

Lead (II) nitrate reacts with 1,10-phenanthroline and sodium diethyldithiocarbamate in water to produce yellow bisdiethyldithiocarbamata 1,10-phenanthroline lead(II). Crystals from water are triclinic, space group $P\bar 1$ (#2),a=10.53(2) Å,b=11.050(12)Å,c=24.74 (3) Å, α=94.71 (9)⁰, β=98.15(11)^o, γ=114.11(9)^o,V=2569(6) ų,Z=2. Each lead atom has approximate pentagonal pyramid coordination geometry through the nitrogens of a phenathroline and sulfurs of two dithiocarbamates. Additionally, complexes form loose dimers in which lead atoms are weakly coordinated to a sulfur in an adjacent complex. IR and proton nmr spectrum of the complex are consistent with the solid state structure.     

CaO-MgO-Al2O3-Fe2O3-B2O3-SiO2系微晶釉的制备

通过引入B2O3以降低烧成温度,利用赤泥中的Fe2O3为着色剂,在1150℃左右低温烧成制备了CaO-MgO-Al2O3-Fe2O3-B2O3-SiO2系微晶釉.赤泥的加入量为20;左右时,釉面具有良好的装饰效果和显微硬度.利用XRD、SEM研究了釉的物相及显微组织.结果表明,釉中析出的微晶是普通辉石,微晶的含量随MgO及CaO的含量增加而增加,而提高Al2O3含量则抑制微晶的析出.