H.N.M.Ekramul Mahmud
,
Anuar Kassim
,
Zulkarnain Zainal
,
Wan Mahmood Mat Yunus
材料科学技术（英文）
The electrochemical preparation of polypyrrole-carboxymethylcellulose (PPY-CMC) conducting polymer composite films on indium tin oxide (ITO) glass electrode from an aqueous solution containing pyrrole monomer, $p$-toluenesulfonate electrolyte and carboxymethylcellulose insulating polymer is reported. The characterization by Fourier transform infrared spectroscopy (FT-IR) shows that carboxymethylcellulose (CMC) has been successfully incorporated into polypyrrole structure forming PPY-CMC polymer composite films. The conductivity of the prepared composite films was found to increase with increaseing CMC concentration in pyrrole solution. The optical microscopic results show the influence of CMC concentration in the pyrrole solution over the morphological changes of the prepared films. The dynamic mechanical analysis (DMA) on the prepared PPY-CMC film reveals the higher plastic property of the PPY-CMC composite film.
关键词:
Conducting polymer
,
null
,
null
Y.B. Hou
金属学报(英文版)
In this paper, the PMMA films doped with N,N'-diphenyl-N,N'-di(m-tolyl)-benzidineand rubrene were fabricated by spin coating, and the effect of photooxidation onthe photoluminescence of the doped PMMA thin films was investigated. The resultsshowed that under the irradiation of 350nm UV light, N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine can sensitized rubrene and results in the enhancement in the photooxrationof rubrene. The effect of photooxidation on the photoluminescence from rubrene w asmore obvious. Both lifetime measurement and in situ measurement of photolumines-cence showed that rubrene molecules exist in two chemical surroundings.
关键词:
photoluminescence
,
null
HL. Huang
,
J.H Xing
,
G.L. Liu and G.Y Zhang(Department of Electrouic Science and Engineering
,
Liaoning University Shenyang 110036
,
China)(Department of Physics
,
Liaoning University Shenyang 110036
,
China)(Shenyang Polytechnic University Shenyan 110023
,
China)(Northeast Microelectronic Institute of Ministry of Electronic Industry Shenyang 110032
,
China)
金属学报(英文版)
The electronic structures of (CdSe)n/(ZnSe)m strained-lager soperfattice (SLS) were investigated by the recursion method in the tight-bindiop opproximation. The total,local, and partial density of states were calculated for n=1, m=5.The total density of states (TDOS) for bulk CdSe, ZnSe and n=1, 3, m=1, 3, 5, for SLS were investigated.Fermi energy, the band gap, the valence of an atom, and the ionization potential and the electron affinity were discassed.
关键词:
density of state
,
null
,
null
,
null
,
null
解凤霞
,
张欣欣
,
张丹
,
华敏
,
张逢星
人工晶体学报
以Ln(NO3)3·6H2O[Ln=Ce(1),Nd(2)]、间苯二甲酸(m-H2bdc)为原料,用水-DMF溶剂热合成法合成了两个异质同构的新型三维孔洞稀土金属配位聚合物{ Ln2 (m-bdc)3(H2O)2}π[Ln=Ce(1),Nd(2)],晶体结构经X射线单晶衍射仪分析确定,两种配合物的晶系均为单斜晶系,P21/c空间群,配位聚合物1:a=1.35428(11) nm,b=1.45987(11) nm,c=1.67101(10) nm,β=127.750(4)°,V=2.6122(3)nm3,Z=4,Dc=2.056 g·cm-3.配位聚合物2:a=1.34364(3) nm,b=1.45406(3) nm,c=1.66669(5) nm,β=127.382(2)°,V=2.5875(11) nm3,Z=4,Dc=2.097 g·cm-3.对配位聚合物1和2进行了元素分析、热重、红外光谱等表征,同时对标题配位聚合物的热稳定性及动力学进行了分析.
关键词:
稀土
,
羧酸
,
配合物
,
水热合成
自然科学进展﹒国际材料（英文）
The phase relations at the 600 degreesC and 700 degreesC isothermal sections of the ternary systems R-Co-B for R Nd, Pr and R = Sm, Cd respectively were summarized in this paper. For Rm+nCo5m+3nB2n, two new types of compounds R3Co13B2 ( R = Pr, Nd, Sm, Gd, Dy, Ho, Er, Y) (m = 2, n = 1) and R5Co19B6 (R = Pr, Nd) (m = 2, n = 3) were synthesized by utilizing the principle of structural combination. Their crystal* structures and easy magnetization direction were determined by X-ray powder diffraction, and structures were refined by the Rietveld method. The Curie temperature T-C, saturation magnetization M-s and anisotropic field H-A of the new compounds were measured using a vibrating-sample magnetometer, an extraction sample magnetometer and M(H) - H curves of samples in different magnetization directions respectively. The T-C and M-s of Rm+nCo5m+3nB2n increase with increasing values of m at a given n value. H-A increases with an increase in n when m is kept invariable. The effects of the substitution of Ni for Co on the magnetic properties of Nd13Co15-xNixB2 were also investigated. It was found that T-SR decreased monotonously as the concentration of Ni increased, and at x = 3 the easy magnetization direction becomes axial at room temperature. The relations between crystal structure and magnetic properties of Rm+nCo5m+3nB2n and the possible routes of synthesizing permanent magnetic materials are also discussed.
关键词:
R-Co-B ternary systems;R3Co13B2;P5Co19B6;crystal structure;magnetic;properties;co-b;phase relation;permanent-magnets;nd;borides;sm;gd;fe
Journal of Applied Physics
Using the full potential linearized augmented plane wave method based on the spin density functional theory, we investigate the ferromagnetic properties, the electronic structure, and the formation energy of Ga(0.9375)M(0.0625)N (M=vacancy, Ca). The calculations indicate that both cases prefer ferromagnetic ground state. The magnetic moments mainly come from the N atoms surrounding the defect centers, which are different from the conventional diluted magnetic semiconductor. High formation energy for the Ga vacancy Suggests that the defect concentration is too low to result in the ferromagnetic GaN. The formation energy for the two substitutional (Ca(Ga),Ca(N)) and two interstitial sites (tetrahedral T, Ca(i-T) and octahedral O, Ca(i-O)) doped configurations indicates that Ca prefers the substitutional Ga in GaN. The defect concentrations for the Ga(0.9375)Ca(0.0625)N under thermal equilibrium N-rich and N-realistic growth conditions are also discussed, respectively. The calculations show that defect concentration under N-rich condition can readily reach 7%, while under N-realistic growth condition, the maximum defect concentration is as low as 1.71% when the growth temperature increases to 1100 K (melting point of GaN). These results suggest that it would be a little difficult to achieve ferromagnetic state for Ga(0.9375)Ca(0.0625)N using the chemical-equilibrium fabrication method, such as chemical precipitation. Using the same method as that for Cu-doped ZnO [L. H. Ye et al., Phys. Rev. B 73, 033203 (2006)], the transition temperature of Ga(0.9375)Ca(0.0625)N may be close to room temperature. (C) 2008 American Institute of Physics.
关键词:
generalized gradient approximation;doped zno;gan;semiconductors;calcium;systems;origin
Journal of Physics-Condensed Matter
From the physical point of view, the cohesive energy of a reactant is preferable to its formation energy for characterizing its influence on the reaction processes from the reactants to the products. In fact it has been found that there is a certain correlation between the experimental hydrogen desorption temperature and the cohesive energy calculated by a first principles method for a series of A(m)(MH(4))(n) (A = Li, Na, Mg; M = Be, B, Al) light complex hydrides (including Na(2)BeH(4), Li(2)BeH(4), NaAlH(4), LiAlH(4), Mg(AlH(4))(2), LiBH(4) and NaBH(4)), which suggests that cohesive energy may be a useful physical quantity for evaluating the hydrogen desorption ability of complex hydrides, especially in cases when dehydrogenation products have unknown crystal structures, or may even be unknown. To understand this correlation more deeply, the ionic interaction between A and the MH(4) complex and the covalent interaction between M and H were calculated and their contributions to the cohesive energy evaluated quantitatively. The calculated results show that the covalent M-H interaction in the MH(4) complex is the dominant part of the cohesive energy E(coh) (up to more than 75%) and hardly changes during high-pressure structural transitions of A(m)(MH(4))(n). It was also found that low electronegativity of M or high electronegativity of A is responsible for the weak covalent M-H interaction and finally leads to the low thermodynamic stability of A(m)(MH(4))(n), suggesting that complex hydrides A(m)(MH(4))(n) can be destabilized by partial substitution of M (A) with an element with electronegativity lower (higher) than Ms (As). This conclusion has been confirmed by lots of experimental results and may be a useful guideline for the future design of new complex hydrides of the type A(m)(MH(4))(n).
关键词:
reversible hydrogen storage;doped naalh4;mechanochemical synthesis;lithium borohydride;metal hydrides;ti;transition;libh4;sc;1st-principles
