The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective...The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)<sub>2</sub> was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.展开更多
Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-po...Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)展开更多
文摘The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)<sub>2</sub>) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)<sub>2</sub> was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.
文摘Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)
