运用传统固相法合成了Re掺杂的Mo3-x Re x Sb7(x=0,0.05,0.10)系列化合物,并通过热压烧结得到了致密样品。采用X射线粉末衍射(XRD)和X射线能量色散谱(EDS)表征了样品的相成分,同时经过第一性原理计算分析了Re掺杂对Mo3Sb7能带结构的影响...运用传统固相法合成了Re掺杂的Mo3-x Re x Sb7(x=0,0.05,0.10)系列化合物,并通过热压烧结得到了致密样品。采用X射线粉末衍射(XRD)和X射线能量色散谱(EDS)表征了样品的相成分,同时经过第一性原理计算分析了Re掺杂对Mo3Sb7能带结构的影响,进而研究了Re掺杂对Mo3Sb7热电性能影响的规律。结果表明:当掺杂量x≤0.1时,Re均匀地掺杂于晶格中形成固溶体且所有样品均无第二相杂质生成,同时晶胞参数随着Re掺杂量的增长而减小。Mo3Sb7作为一种P型三维导电材料,当每化学单位的Mo3Sb7额外获得两个化学单位的价电子将由金属转变为半导体。在Re掺杂后Mo3Sb7费米面上移,这是因为Re比Mo多一个价电子,但由于固溶度的限制,Re掺杂并不能使其转化为半导体,且Re掺杂对于费米面处能带形状以及禁带宽度的影响也非常有限。由于Re较多的价电子,因此Re的引入降低了化合物Mo3Sb7的电导率,并提高了其热电势值,而电导率的降低也必然会减小载流子贡献的热导率,同时Re掺杂增加了晶格无序也降低了其晶格热导率,因此Mo3Sb7总的热导率得到了降低,最后其热电性能得到了提高。其中,经过Re掺杂后的化合物Mo2.90Re0.10Sb7在860 K下ZT值达到0.127,比化合物Mo3Sb7提高了23.3%。展开更多
The nonlinear second order optical susceptibilities ( β ) of a series of multi branched molecules with triphenylbenezene as π center have been calculated by means of a combination of intermediate neglect of diff...The nonlinear second order optical susceptibilities ( β ) of a series of multi branched molecules with triphenylbenezene as π center have been calculated by means of a combination of intermediate neglect of differential overlap Hamiltonian with the configuration interaction (INDO/SDCI) method combined with sum over states expression (SOS). The results show that the β values are increased by replacing benzene rings with thiophene rings in the branches, as well as by increasing the donating and accepting strength of the three terminal substituents. The properties of the intermolecular charge transfer were studied through the calculation of charge changes between the ground and the main excited states and the frontier orbitals of these molecules. The results also indicate that these molecules investigated here possess improved transparency nonlinearity properties.展开更多
The second-order nonlinear optical (NLO) properties of a series of benzothiazole derivatives were studied by use of the ZINDO-SOS method. These chromophores are formed by a donor-π-bridge-acceptor system, based on a ...The second-order nonlinear optical (NLO) properties of a series of benzothiazole derivatives were studied by use of the ZINDO-SOS method. These chromophores are formed by a donor-π-bridge-acceptor system, based on a nitro group connected with benzothiazole as the acceptor and a hydroxyl-functional amino group as the donor. For the purpose of comparison, we also designed molecules in which nitrobenzene is an acceptor. The calculation results indicate that benzothiazole derivatives exhibit larger second-order polarizabilities than nitrobenzene derivatives. In order to clarify the origin of the NLO response of these chromophores, their electron properties were investigated as well. The benzothiazole derivatives are good candidates for application in electro-optical device due to their high optical nonlinearities, good thermal and photonic stability.展开更多
Different types of stilbene derivatives (D-p-D, A-p-A, D-p-A) were investigated with AM1, and specially, equilibrium geometries of symmetrical stilbene derivatives (D-p-D) were studied using of PM3. With the same meth...Different types of stilbene derivatives (D-p-D, A-p-A, D-p-A) were investigated with AM1, and specially, equilibrium geometries of symmetrical stilbene derivatives (D-p-D) were studied using of PM3. With the same method INDO/CI, the UV-vis spectra were explored and the position and strength of the two-photon absorption were predicated by Sum-Over-States expression. The relationships of the structures, spectra and nonlinear optical properties have been examined. The influence of various substituents on two photon absorption cross-sections was discussed micromechanically.展开更多
The first hyperpolarizabilities of a series of novel azulenic-barbituric acid chromophores have been studied by using 12 excitation wavelengths, ranging from 900 to 1907 nm. The dispersion relation of the first hyperp...The first hyperpolarizabilities of a series of novel azulenic-barbituric acid chromophores have been studied by using 12 excitation wavelengths, ranging from 900 to 1907 nm. The dispersion relation of the first hyperpolariza-bilities of chromophores holds the same tendency as the experimental results. In addition, the static first hyperpo-larizability 0 of molecules was calculated by means of the Sum-Over-States (SOS) expression and the two-level formula respectively. The results show that these molecules possess large static first hyperpolarizabilities and the 0 value increases as the donor or acceptor strength enhances; the distorted degree of molecules has also an important influence on the 0 value.展开更多
We have theoretically investigated the one- and two-photon absorption properties of C60 and C70 using the ZINDO method. From the results it is suggested that the one-photon absorption spectra are in agreement with the...We have theoretically investigated the one- and two-photon absorption properties of C60 and C70 using the ZINDO method. From the results it is suggested that the one-photon absorption spectra are in agreement with the experimental observations. It is found that the maximum TPA cross section of C70 is more than twice that of C60, which is consistent with the experimental results. A notable point is that the TPA process of C60 is different from that of C70 as well as other ordinary conjugated molecules.展开更多
文摘运用传统固相法合成了Re掺杂的Mo3-x Re x Sb7(x=0,0.05,0.10)系列化合物,并通过热压烧结得到了致密样品。采用X射线粉末衍射(XRD)和X射线能量色散谱(EDS)表征了样品的相成分,同时经过第一性原理计算分析了Re掺杂对Mo3Sb7能带结构的影响,进而研究了Re掺杂对Mo3Sb7热电性能影响的规律。结果表明:当掺杂量x≤0.1时,Re均匀地掺杂于晶格中形成固溶体且所有样品均无第二相杂质生成,同时晶胞参数随着Re掺杂量的增长而减小。Mo3Sb7作为一种P型三维导电材料,当每化学单位的Mo3Sb7额外获得两个化学单位的价电子将由金属转变为半导体。在Re掺杂后Mo3Sb7费米面上移,这是因为Re比Mo多一个价电子,但由于固溶度的限制,Re掺杂并不能使其转化为半导体,且Re掺杂对于费米面处能带形状以及禁带宽度的影响也非常有限。由于Re较多的价电子,因此Re的引入降低了化合物Mo3Sb7的电导率,并提高了其热电势值,而电导率的降低也必然会减小载流子贡献的热导率,同时Re掺杂增加了晶格无序也降低了其晶格热导率,因此Mo3Sb7总的热导率得到了降低,最后其热电性能得到了提高。其中,经过Re掺杂后的化合物Mo2.90Re0.10Sb7在860 K下ZT值达到0.127,比化合物Mo3Sb7提高了23.3%。
文摘The nonlinear second order optical susceptibilities ( β ) of a series of multi branched molecules with triphenylbenezene as π center have been calculated by means of a combination of intermediate neglect of differential overlap Hamiltonian with the configuration interaction (INDO/SDCI) method combined with sum over states expression (SOS). The results show that the β values are increased by replacing benzene rings with thiophene rings in the branches, as well as by increasing the donating and accepting strength of the three terminal substituents. The properties of the intermolecular charge transfer were studied through the calculation of charge changes between the ground and the main excited states and the frontier orbitals of these molecules. The results also indicate that these molecules investigated here possess improved transparency nonlinearity properties.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 99730 10 )andtheKeyLabofSupramolecularStructureandMate rialofJilinUniversity .
文摘The second-order nonlinear optical (NLO) properties of a series of benzothiazole derivatives were studied by use of the ZINDO-SOS method. These chromophores are formed by a donor-π-bridge-acceptor system, based on a nitro group connected with benzothiazole as the acceptor and a hydroxyl-functional amino group as the donor. For the purpose of comparison, we also designed molecules in which nitrobenzene is an acceptor. The calculation results indicate that benzothiazole derivatives exhibit larger second-order polarizabilities than nitrobenzene derivatives. In order to clarify the origin of the NLO response of these chromophores, their electron properties were investigated as well. The benzothiazole derivatives are good candidates for application in electro-optical device due to their high optical nonlinearities, good thermal and photonic stability.
基金Project supported by the National Natural Science Foundation of China (Nos. 20273023 90101026) and the Key Laboratory for Supramolecular Structure and Material of Jilin University.
文摘Different types of stilbene derivatives (D-p-D, A-p-A, D-p-A) were investigated with AM1, and specially, equilibrium geometries of symmetrical stilbene derivatives (D-p-D) were studied using of PM3. With the same method INDO/CI, the UV-vis spectra were explored and the position and strength of the two-photon absorption were predicated by Sum-Over-States expression. The relationships of the structures, spectra and nonlinear optical properties have been examined. The influence of various substituents on two photon absorption cross-sections was discussed micromechanically.
基金the National Natural Science Foundation of China (Nos. 20273023 and 90101026) and the Kay Laboratory for Supramolecular Structure and Material of Ji
文摘The first hyperpolarizabilities of a series of novel azulenic-barbituric acid chromophores have been studied by using 12 excitation wavelengths, ranging from 900 to 1907 nm. The dispersion relation of the first hyperpolariza-bilities of chromophores holds the same tendency as the experimental results. In addition, the static first hyperpo-larizability 0 of molecules was calculated by means of the Sum-Over-States (SOS) expression and the two-level formula respectively. The results show that these molecules possess large static first hyperpolarizabilities and the 0 value increases as the donor or acceptor strength enhances; the distorted degree of molecules has also an important influence on the 0 value.
基金Project supported by the National Natural Science Foundation of China (Nos. 20273023 90101026) and the Key Laboratory for Supramolecular Structure and Material of Jilin University.
文摘We have theoretically investigated the one- and two-photon absorption properties of C60 and C70 using the ZINDO method. From the results it is suggested that the one-photon absorption spectra are in agreement with the experimental observations. It is found that the maximum TPA cross section of C70 is more than twice that of C60, which is consistent with the experimental results. A notable point is that the TPA process of C60 is different from that of C70 as well as other ordinary conjugated molecules.
