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.     

ZrO2（Y2O3）团聚状态对ZrO2增韧金刚石—SiC超硬复相陶瓷结构,性？…

用恒沸水解方法（ＢＨ）制备了颗粒度均一（０．１μｍ）的纳米晶（９ｎｍ）２．２ｍｏｌ％Ｙ２Ｏ３－ＺｒＯ２（以下简称：２．２Ｙ－ＺｒＯ２），用化学共沉淀方法（ＣＰ）制备了松散团絮状的纳米晶（２０ｎｍ）２．２Ｙ－ＺｒＯ２。对这两类ＺｒＯ２粉体增韧ＳｉＣ中介金刚石超硬复相陶瓷进行了ＸＲＤ、ＳＥＭ、及韧性、耐磨性分析测定。结果表明，超高压烧结后，水解法ＺｒＯ２在ＳｉＣ是介相内以均一的粒度（０．１μｍ）均匀分     

纳米晶ZrO2:Tm3+制备与发光性质研究

本文用共沉淀法制备了纳米晶ZrO2∶Tm3 荧光粉,并对它的晶体结构、颗粒大小和光致发光性质进行了表征。XRD测试结果表明:以此工艺制备的纳米晶ZrO2:Tm3 含有单斜相和四方相两种微观结构,四方相的含量与热处理的温度有关,Tm3 离子的掺入有稳定ZrO2四方晶相的作用。测量了各样品的荧光激发和发射光谱,当以264nm(3H6→3P2)和359nm(3H6→1D2)光激发分别得到Tm3 的355nm(1I6→3H4或3P0→3H4)和459nm(3P0、1I6→3F4或1D2→3H4)的较强荧光发射。通过对荧光强度与激活离子Tm3 浓度的关系研究发现:荧光强度先随浓度提高而增强,在浓度达1%摩尔数时达到最大,然后又随之降低。     

ZrO2:Tb3+纳米晶的制备与发光研究

本文用共沉淀法制备了纳米晶ZrO2:Tb3+荧光粉,并对它的晶体结构、颗粒大小和光致发光性质进行了表征.XRD测试结果表明:以此工艺制备的纳米晶ZrO2:Tb3+含有单斜相和四方相两种微观结构,四方相所占比例随着Tb3+离子浓度的提高而提高,Tb3+离子的掺入有稳定ZrO2四方晶相的作用.纳米晶ZrO2:Tb3+粉体中Tb3+的强室温特征发射的两个主发射带为5D3→7F1和5D4→7F1的跃迁.荧光强度与Tb3+浓度的关系研究表明:5D3和5D4能级有不同的猝灭规律,由于(5D3,7F6)→(5D4,7Fo)的交叉弛豫,使得5D3→7F5跃迁的猝灭浓度较低,在我们的实验中,掺1.5;摩尔分数Tb3+时5D3→7F1跃迁发射最强,掺6;摩尔分数Tb3+时5D4→7F1跃迁发射最强.     

ZrO2对热压AlN陶瓷的显微结构与力学性能的影响

通过添加纳米ZrO2粉体,并结合Y2O3烧结助剂,采用热压烧结制备了AlN陶瓷.结果表明,加入ZrO2后,热压AlN陶瓷的物相包含AlN主相、Al5Y3O12晶界相以及ZrN新相.随着ZrO2的加入,热压AlN陶瓷的维氏硬度基本没有变化,然而其断裂韧性逐渐提高.这主要是由于添加的ZrO2与AlN发生高温反应生成了ZrN,导致AlN陶瓷从单一的沿晶断裂模式转变为包含沿晶和穿晶的混合断裂模式,强化了晶界,进而改善了断裂韧性.     

退火温度对纳米晶ZrO2发光和ZrO2:Pr3+能量传递的影响

利用共沉淀法制备了纳米晶ZrO2和ZrO2:Pr3+,通过XRD对材料的晶体结构、颗粒尺寸进行了表征,研究了退火温度对纳米晶ZrO2发光性质的影响,探讨了ZrO2的发光机制,研究了退火温度对ZrO2∶ Pr3+能量传递的影响,给出了基质ZrO2与Pr3+离子间的能量传递模型.结果表明:随着退火温度的提高,纳米晶ZrO2由四方相转变为单斜相,颗粒尺寸增大;ZrO2的发射谱是一个中心位于470 nm的宽带,发光强度随退火温度升高而增强;基质ZrO2向激活离子Pr3+的能量传递方式为无辐射过程,高温退火有利于基质向Pr3+离子的能量传递,这种现象与退火温度对纳米晶ZrO2发光性质的影响有关.     

ZrO2陶瓷流延浆料的流变特性的研究

本文探索了纳米ZrO2粉的流延浆料的流变特性.以体积比为1:1的丙酮和无水乙醇为混合溶剂,粘结剂选用聚乙烯缩丁醛(PVB),分散剂选用甘油三酯(TG),邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二辛酯(DOP)为增塑剂配置了ZrO2陶瓷浆料.研究了浆料的固相体积以及各种有机添加剂的添加量对其流变性能的影响.结果表明:固相含量为60wt;,分散剂量为1wt;,粘结剂添加量为5wt;,增塑剂与粘结剂的质量比为1～1.3,浆料流变性能良好,浆料粘度达到了2200 mPa·s左右;制备出良好无缺陷ZrO2陶瓷基片.     

不同表面活性剂对纳米ZnO/ZrO2的制备和脱硫性能的影响

研究不同表面活性剂对采用共沉淀-真空冷冻干燥法制备的ZnO/ZrO2纳米催化剂的结构和物相变化的影响,并在模拟烟气中利用气相色谱仪进行脱除SO2性能的测定.结果表明,表面活性剂的引入可以降低纳米ZrO2的平均晶粒度.与吐温80、PEG-400和PVA相比,柠檬酸铵和DBS抑制晶核生长的能力更大,从而纳米ZrO2的平均晶粒尺寸更小,脱硫率更高;由于PEG-400具有络合正离子的能力,可防止纳米活性组分的团聚和长大,其催化吸收SO2的性能最好.     

LiNO3熔盐辅助煅烧制备高分散纳米ZrO2粉体

以可溶性锆盐溶液反向滴定氨水溶液成功地制备了纳米ZrO2粉体,系统研究了反应物浓度与煅烧温度对产物粒径和形貌的影响;在反应过程中加入表面活性剂,并采用正丁醇共沸蒸馏干燥和LiNO3熔盐辅助煅烧等方法,以控制粒径、减少团聚.通过热重-差热分析(TG-DTA)、透射电镜(TEM)、X射线衍射(XRD)、比表面积分析(BET)等对样品进行了形貌表征、晶型及粒径分析.结果表明:上述多种方法联合使用能够有效控制粒径、减少团聚,制备出的纳米ZrO2粉体分散性优异,为立方晶相结构,粒径15 nm左右.     

Graphene/ZrO2复合陶瓷材料的热导性能研究

采用3Y-ZrO2粉体和石墨烯(Graphene)为原料,利用放电等离子体烧结技术(SPS),烧结制备了Graphene/ZrO2复合陶瓷材料.利用SEM、HRTEM、XRD、激光热导仪等研究了烧结温度和石墨烯含量对Graphene/ZrO2复合陶瓷材料的显微结构、物相和热传导性能的影响.研究结果表明,引入石墨烯不但可以抑制ZrO2晶粒的生长,而且对复合材料的热传导性有着显著的影响;相对于单相ZrO2陶瓷,随着石墨烯的引入, Graphene/ZrO2复合陶瓷材料扩散系数反而降低,其原因可以归结于三个方面:首先,石墨烯含量比较低(0.5~1.5wt;),其次,石墨烯与ZrO晶粒界面处产生的强声子散射作用导致热导下降,最后是Graphene/ZrO2复合陶瓷材料没有完全致密.     

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.     

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)     

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)     

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...     

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.     

Crystal structure of bis 4-benzyl piperidinium monohydrogenmonophosphate pentahydrate, [C6H5CH2CHCH2CH2NH2CH2CH2]2HPO4·5H2O

The salt bis 4-benzyl piperidinium monohydrogenmonophosphate pentahydrate is orthorhombic with the following unit cell dimensions: a = 11.235(2) Å, b = 27.924(6) Å, c = 9.321(4) Å space group Pca2₁ with Z = 4. The structure was solved by the Patterson method and refined to final R value of 0.049 for 1802 independent reflections. The flack parameter is 0.14 with an e.s.d. of 0.23. The structure consists of infinite parallel two-dimensional [110] planes built of mutually connected ions and water molecules by strong O—H,...,O and N—H,...,O hydrogen bonding. There are no contacts other than normal van der Waals interactions between the layers.