Electron-phonon coupling （EPC） in cuprate and iron-based superconducting systems, as revealed by Raman scat- tering, is briefly reviewed. We introduce how to extract the coupling information through phonon lineshape...Electron-phonon coupling （EPC） in cuprate and iron-based superconducting systems, as revealed by Raman scat- tering, is briefly reviewed. We introduce how to extract the coupling information through phonon lineshape. Then we discuss the strength of EPC in different high-temperature superconductor （HTSC） systems and possible factors affecting the strength. A comparative study between Raman phonon theories and experiments allows us to gain insight into some crucial electronic properties, especially superconductivity. Finally, we summarize and compare EPC in the two existing HTSC systems, and discuss what role it may play in the HTSC.展开更多
The purpose of this note is to stimulate interest in measuring and characterizing the emitted ultraviolet frequencies in antimicrobial copper materials. Antimicrobial sanitizing materials are urgently needed to limit ...The purpose of this note is to stimulate interest in measuring and characterizing the emitted ultraviolet frequencies in antimicrobial copper materials. Antimicrobial sanitizing materials are urgently needed to limit the spread of COVID-19 virus. In the current pandemic, ultraviolet radiation is often used for sterilization. It is shown that 3<b><span "=""> </span></b><span>d-orbital capture in copper can result in radiation generated by copper materials. Since ultraviolet radiation is known to be effective in antimicrobial sterilization, it is logical to assume that the radiation formed by copper occurs in the ultraviolet region. Electron transitions in 3 d-orbital capture are expected to occur in this region. A description of the 3 d-orbital capture process, and the origin of the associated frequency, is given. It is shown that for Group 1B elements the strength of electron affinity in the d-orbital capture process increases with increasing Periodic Table period number, n. This is the opposite of other electron affinity properties for atoms that decrease wth an increase in n. A brief discussion of the relationship of d-orbital capture to the chemical inertness of gold is given. The same type of d-orbital capture process that occurs in antimicrobial copper occurs in high temperature superconducting cuprates.</span>展开更多
Polycrystalline YBa2Cu3O7-y （YBCO） and Y0.6Gd0.4Ba2-xNbxCu3O7-y （YGBNCO） compounds with 0≤x≤0.225 were synthesized using standard solid state reaction technique. The structure for all samples was characterized b...Polycrystalline YBa2Cu3O7-y （YBCO） and Y0.6Gd0.4Ba2-xNbxCu3O7-y （YGBNCO） compounds with 0≤x≤0.225 were synthesized using standard solid state reaction technique. The structure for all samples was characterized by X-ray difference （XRD） and scanning electron microscopy （SEM）. The transport properties were measured by the （FPP） method in the temperature range from 70 to 130 K. As the Nb content in the samples increased, a diffused phase indicating a niobium perovskite phase and a small amount of unidentified phase appeared. With the increase of Nb content, the superconducting transition temperature Tconset increased slowly with x≤0.125, and then it remained unchanged or slowly decreased with 0.125≤x≤0.225. It could be found that there was a slow decrease of zero-resistance temperature, Tcoffset, with the increase of Nb content. The larger transition width might result from the YBa2NbO6 phase, impurity and unidentified phases of the sample due to the Nb doping.展开更多
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00112 and 2012CB921701)
文摘Electron-phonon coupling （EPC） in cuprate and iron-based superconducting systems, as revealed by Raman scat- tering, is briefly reviewed. We introduce how to extract the coupling information through phonon lineshape. Then we discuss the strength of EPC in different high-temperature superconductor （HTSC） systems and possible factors affecting the strength. A comparative study between Raman phonon theories and experiments allows us to gain insight into some crucial electronic properties, especially superconductivity. Finally, we summarize and compare EPC in the two existing HTSC systems, and discuss what role it may play in the HTSC.
文摘The purpose of this note is to stimulate interest in measuring and characterizing the emitted ultraviolet frequencies in antimicrobial copper materials. Antimicrobial sanitizing materials are urgently needed to limit the spread of COVID-19 virus. In the current pandemic, ultraviolet radiation is often used for sterilization. It is shown that 3<b><span "=""> </span></b><span>d-orbital capture in copper can result in radiation generated by copper materials. Since ultraviolet radiation is known to be effective in antimicrobial sterilization, it is logical to assume that the radiation formed by copper occurs in the ultraviolet region. Electron transitions in 3 d-orbital capture are expected to occur in this region. A description of the 3 d-orbital capture process, and the origin of the associated frequency, is given. It is shown that for Group 1B elements the strength of electron affinity in the d-orbital capture process increases with increasing Periodic Table period number, n. This is the opposite of other electron affinity properties for atoms that decrease wth an increase in n. A brief discussion of the relationship of d-orbital capture to the chemical inertness of gold is given. The same type of d-orbital capture process that occurs in antimicrobial copper occurs in high temperature superconducting cuprates.</span>
基金Project supported by the Council of the Scientific Research Projects at Konya University
文摘Polycrystalline YBa2Cu3O7-y （YBCO） and Y0.6Gd0.4Ba2-xNbxCu3O7-y （YGBNCO） compounds with 0≤x≤0.225 were synthesized using standard solid state reaction technique. The structure for all samples was characterized by X-ray difference （XRD） and scanning electron microscopy （SEM）. The transport properties were measured by the （FPP） method in the temperature range from 70 to 130 K. As the Nb content in the samples increased, a diffused phase indicating a niobium perovskite phase and a small amount of unidentified phase appeared. With the increase of Nb content, the superconducting transition temperature Tconset increased slowly with x≤0.125, and then it remained unchanged or slowly decreased with 0.125≤x≤0.225. It could be found that there was a slow decrease of zero-resistance temperature, Tcoffset, with the increase of Nb content. The larger transition width might result from the YBa2NbO6 phase, impurity and unidentified phases of the sample due to the Nb doping.
