张洪生
,
张玥
,
郭卫红
,
王晓光
,
李滨耀
,
吴驰飞
高分子材料科学与工程
通过红外光谱证明在加工过程中,SEBS-g-MA的酸酐基团与PET的端羟基发生反应生成了共聚物,研究了SEBS-g-MA用量对共混物的流动性和动态力学性质的影响,MFR分析结果表明,随着SEBS-g-MA用量增加,共混物的流动性呈现先升高后降低趋势,DMA分析结果表明,SEBS-g-MA用量为10%(质量分数)时,共混物的储能模量和损耗模量与未添加SEBS-g-MA的共混物的结果接近,且SEBS-g-MA用量对共混物的tanδ无影响.
关键词:
回收对苯二甲酸二乙酯
,
线性低密度聚乙烯
,
SEBS-g-MA
,
动态力学性质
Communications in Theoretical Physics
By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d(3) electronic configuration, the values of the parameters in the expressions of thermal shift (TS) from EPI for the ground level, R level and R line of SrTiO3:Mn4+ have been evaluated; the R-line TS and various contributions to it have been calculated in the low-temperature region. It is found that all the three terms of R-line TS from EPI relevant to the lattice vibration are red shifts. The Raman term is the largest, the neighbor-level term is the second, and the optical-branch term is very small over the range of T less than or equal to 80 K. The contribution to R-line TS from thermal expansion has been approximately neglected in this work. The very strong EPI relevant to its lattice vibration for SrTiO3:Mn4+ causes its R-Line TS to be an unusually large red-shift. Only by taking into account the strong softening of the low-frequency acoustic modes of the lattice vibration at low temperatures, can we successfully explain the variation of R-line TS of SrTiO3:Mn4+ with temperature.
关键词:
crystal fields;optical properties;electron-phonon interaction;thermal;shift;softening of acoustic modes
Communications in Theoretical Physics
The local impurity-vibration modes (especially, the low-frequency one) of SrTiO3:Cr3+ cause a very large R-line blue-shift; while the Raman term, neighbor-level term and optical-branch term relevant to the lattice vibration cause small red shifts. The algebraic sum of them gives rise to the observed unusual and large R-line thermal shift (blue-shift) of SrTiO3:Cr3+. By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d(3) electronic configuration, the values of the parameters in the expressions of thermal shift (TS) from EPI for the ground level, R level and R line of SrTiO3:Cr3+ have been evaluated; the R-line TS and various contributions to it have been calculated in two temperature ranges (30 K less than or equal to T less than or equal to 80 K and 130 K less than or equal to T less than or equal to 300 K). The contribution to R-line TS from thermal expansion has been approximately neglected in this work. Furthermore, the improvement on simplified approximation of adopting a single low-frequency impurity-mode and neglecting its hardening in low-temperature region has been made.
关键词:
crystal fields;optical properties;thermal shift;electron-phonon;interaction;impurity modes;softening and hardening
Communications in Theoretical Physics
The unified theoretical calculation of thermal shifts (TS) of R-1 and R-2 lines and thermal broadenings (TB) of R, R' and B lines for ruby was carried out for the first time. The calculated results are in very good agreement with a great number of experimental data. Especially by using quantum theory and taking into account all the admixtures of wavefunctions within d(3) electronic configuration, all the Gamma M in electron-phonon interaction (EPI), the electronic energy spectrum and lattice-vibration Spectrum, the very important contributions to TS and TB from single-phonon direct process were theoretically calculated in detail. The microscopic essentials of various contributions are revealed, and the mistakes in previous work are remedied.
关键词:
diamond anvil cell;pressure measurement;spectroscopy;temperatures
Journal of Applied Physics
Electron-doped perovskite manganite Ca(0.9)R(0.1)MnO(3) (R= La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb) polycrystalline samples were prepared and their transport and thermoelectric properties were studied from room temperature to 1000 K. The transport behavior for all the samples is adiabatic small polaron hopping mechanism below 600 K but changes to metallic conductivity at higher temperature. Above 600 K, more 3d electrons of Mn(3+) ions will occupy e(g) orbitals, resulting in the variation in thermoelectric power values. For all the samples, thermoelectric power is only determined by carrier concentration, but resistivity also rests with effective bandwidth. The size matching between Ca(2+) and R(3+) ions together with heavier R(3+) doping can improve thermoelectric performance evidently. Combining these two factors, Ca(0.9)Dy(0.1)MnO(3) and Ca(0.9)Yb(0.1)MnO(3) reach ZT=0.2 at 1000 K, suggesting that they can be efficient high temperature n-type thermoelectric oxide materials. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.3003065]
关键词:
transport-properties;oxide;system;performance;fabrication;antimonides;manganites;ca3co4o9;physics;camno3
王海
,
魏芬绒
,
崔文俊
,
樊亚军
,
陈志宏
,
朱峰
钛工业进展
对用来加工手表盖的Gr2纯钛棒材生产过程中发现的端面点状缺陷进行了分析，通过对典型缺陷的显微组织及硬度进行检测，发现缺陷处晶粒更加细小，呈条带状，且显微硬度高于基体；对缺陷区域进行能谱分析，未发现明显的成分差异；最后对缺陷区域进行电子探针显微分析，发现其N元素含量远高于基体，属于N富集造成的局部冶金缺陷。通过对纯钛铸锭的真空电弧熔炼过程进行分析，得出产生该问题的原因为：一是海绵钛里混入TiN颗粒，熔炼时未剔除干净；二是在电极焊接时未采取有效的保护措施，焊接时有大气介质导致N元素含量增加。后期针对上述问题进行改善，有效避免了Gr2纯钛棒材出现此类冶金缺陷。
关键词:
Gr2纯钛
,
点状缺陷
,
电子探针显微分析
,
显微硬度
