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81.
Y2O3和CeO2复合掺杂ZrO2纳米晶的制备与表征 总被引:2,自引:0,他引:2
以ZrOCl2.8H2O,Y2O3,Ce(NO3)3.5.5H2O为原料,NH3.H2O作沉淀剂,少量表面活性剂PE作分散剂,采用反向共沉淀-喷雾干燥法,结合物理、化学分散技术,成功地制备了Y2O3,CeO2复合掺杂ZrO2纳米粉末。通过DSC-TG,XRD,XPS,BET和SEM等方法对所制得粉末进行了表征。结果表明:以Ce0.1Y0.1Zr0.8O1.95化学计量比制备的多元氢氧化物胶体经过喷雾干燥处理后,在500℃基本完成水合氧化物的分解,577℃附近完成由非晶相向立方相的转变;经过580-1000℃煅烧后,CeO2和Y2O3已经完全固溶到ZrO2中,形成类质同相体,该粉末系列均属于立方相萤石结构;掺杂进入ZrO2晶格中的Ce呈+4价形式存在;比表面积由22.0 m^2.g^-1(580℃煅烧)减至4.97 m^2.g^-1(1000℃煅烧);SEM结果显示800℃煅烧的该粉末颗粒尺寸分布均匀,多呈类球状,且粒径在50-80 nm。 相似文献
82.
The enthalpies of mixing of glycine, l-α-alanine, l-γ-aminobutyric acid, l-α-valine, l-α-serine and l-α-threonine with cyclohexanone in aqueous solutions and their respective enthalpies of dilution have been measured by calorimetry at 298.15 K. Experimental enthalpies of dilution and mixing have been correlated with the virial expansion equation that was obtained with the McMillan-Mayer theory. The enthalpic interaction parameters hxy, hxxy and hxyy of the amino acids studied with cyclohexanone in aqueous solutions have been evaluated, and the heterotactic enthalpic pair interaction coefficients (hxy) are discussed in terms of solute-solute interactions. 相似文献
83.
合成子Ni替代铁酸稀土复合氧化物LaF31-xNixO3(x=0.1-0.6),对样品进行了XRD、IR及Mossbauer谱测试,结果表明:x=0\1,0\2,0\3的样品为正交相,x=0.5,0.6的样品为菱方相;伴随相结构从正交向菱方结构的转变,IR谱上Fe(Ni)-O键伸振动谱带向高频移动近20cm^-1,Mossbauer谱测试表明Fe均处于+3自旋态,Ni离子以+3价进入晶格。 相似文献
84.
Although heme protein-based, amperometric nitric oxide (NO) biosensors have been well documented in previous studies, most have been conducted in anaerobic conditions. Herein we report a novel hemoglobin-based NO biosensor that is not only very sensitive but also usable in air. The heme protein was entrapped in a sodium montmorillonite film, which was immobilized at a pyrolytic graphite electrode surface. Film-entrapped hemoglobin can directly exchange electrons with the electrode, and this process has proven to favor the catalytic reduction of oxygen. In addition, NO induced a cathodic potential shift of the catalytic reduction peak of oxygen. This potential shift was proportional to the logarithm of NO concentration ranging from 4.0 × 10−11 to 5.0 × 10−6 mol/L. The detection limit has been estimated to be 20 pM, approximately four orders lower than previously reported amperometric detectors. 相似文献
85.
Jia-Heng Lei Dan Liu Li-Ping Guo Xue-Min Yan Hui Tong 《Journal of Sol-Gel Science and Technology》2006,39(2):169-174
Large-sized, optical transparent mesostructured Brij 56/silica monolith has been fabricated using a lyotropic liquid crystal
of Brij 56 (C16EO10) as a template and TMOS as a silica source, combined with a optimizing sol-gel process and a hydrothermal aging process.
By programmed temperature drying and calcinations, translucent mesoporous silica monolith with two-dimensional hexagonal structure
(P6mm) has bee obtained. The ordered mesoporous silica monoliths have been characterized by small-angle X-ray diffraction, transmission
electron microscopy (TEM), and nitrogen adsorption, which shows that the materials have a highly ordered two-dimensional hexagonal
mesostructure with the high specific surface area of 837 m2 · g−1 and narrow pore distribution with a mean BJH pore diameter of 2.73 nm. Based on calculations and differential scanning calorimetry
and thermogravimetric analyses, the action mechanism of the hydrothermal aging process has been proposed: the 100°C hydrothermal
conditions and autogenous 2.3 atm pressure promote the condensation and dehydration of silanol groups, with the result that
cross-linking degree, the flaws and moisture content in gels are reduced notably. Those processes guarantee the integrity
of gels in the following drying process. 相似文献
86.
Li Pang Edwin A. C. Lucken Gérald Bernardinelli 《Journal of inclusion phenomena and macrocyclic chemistry》1992,13(1):63-76
NQR spectroscopy and X-ray crystallography have been jointly applied to the study of the small guest molecules CH2Cl2, CHCl3, CCl4, CBr2Cl2, C(CH3)2Cl2 etc. in the Werner host complex Ni(SCN)2(3-methylpyridine)4. Specific host-guest dipole-dipole interactions play an important role in order-disorder effects for guest molecules in the cavities of orthorhombic system,Fddd. Thus a weakly polar molecule such as CBr2Cl2 exhibits a disordered alternation, both the bromine and the chlorine atoms occupying the two possible sites in theC
2 cavity, whereas for the polar molecule C(CH3)2Cl2, an ordered structure is observed. In addition, two new types of crystal structures,C2/c andP
, are reported here for dichloromethane and chloroform clathrates. 相似文献
87.
Chao Chen Yu-Lin Yang Kun-Lin Huang Zhen-Hua Sun Wei Wang Zhuo Yi Yun-Ling Liu Wen-Qin Pang 《Polyhedron》2004,23(18):3033-3042
With a hydrothermal technique, a layered titanium phosphate with the formula Ti2(H2PO4)(HPO4)(PO4)2 · 0.5C6N2H16 (denoted TP-J2) has been prepared by treating the Ti/H3PO4/H2O/1-methylpiperazine system directly. The as-synthesized products were characterized by powder X-ray diffraction, CP-MAS solid-state 31P NMR spectroscopy, thermogravimetric and differential thermal analyses (TG-DTA). The structure was solved by single-crystal X-ray diffraction analysis and it presents an extended γ-phase intercalated with organic amine. Crystal data: triclinic, , a = 8.106 (2) Å, b = 8.197 (2) Å, c = 11.658 (2) Å. = 78.32 (3)°, β = 80.85 (3)°, γ = 77.90 (3)°, Z = 2. Additionally, the intercalation behavior of TP-J2 with n-alkyl monoamine (n = 2, 3, 4, 6, 8, 10 and 12) was investigated. Owing to the strong brønsted base, N,N′-dimethylpiperazine, resides in the interlayer, it presented unusual features of TP-J2 in contrast with that of γ-Tip. 相似文献
88.
A series of spiropyrans with a polyaromatic or heteroaromatic pendant was synthesized conveniently.Their photochromic behaviors were investigated with the aid of absorption spectral measurements.The results indicated that the compounds with the same parent spiropyran but different aromatic pendant show significantly different photochromic properties.This may be due to the π-π orbital interaction between the polyaromatic pendant and the open photomerocyanine form of spiropyran.The results obtained are very useful in the molecule design area. 相似文献
89.
Jong-Shi Pang 《Mathematical Programming》1979,16(1):111-126
The present paper studies the linear complementarity problem of finding vectorsx andy inR
+
n
such thatc + Dx + y 0,b – x 0 andx
T
(c + Dx + y) = y
T
(b – x) = 0 whereD is aZ-matrix andb > 0. Complementarity problems of this nature arise, for example, from the minimization of certain quadratic functions subject to upper and lower bounds on the variables. Two least-element characterizations of solutions to the above linear complementarity problem are established first. Next, a new and direct method to solve this class of problems, which depends on the idea of least-element solution is presented. Finally, applications and computational experience with its implementation are discussed.Research partially supported by the National Science Foundation Grant MCS 71-03341 A04 and the Air Force Office of Scientific Research Contract F 44620 14 C 0079. 相似文献
90.
This paper concerns the existence of positive stationary solutions for a diffusive variable-territory prey–predator model, and completely settles an open problem of Wang and Pang (2009). The main result closes a gap in an earlier result (2011) by the authors. 相似文献