The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, v...The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of Zn O nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved.The prepared nanostructures have been found to be nontoxic to SH-SY5 Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of Zn O nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.展开更多
The electronic structures and effective masses of the N mono-doped and Al N, Ga-N, In-N codoped ZnO system have been calculated by a first-principle method, and comparisons among different doping cases are made. Accor...The electronic structures and effective masses of the N mono-doped and Al N, Ga-N, In-N codoped ZnO system have been calculated by a first-principle method, and comparisons among different doping cases are made. According to the results, the impurity states in the codoping cases are more delocalised compared to the N mono-doping case, which means a better conductive behaviour can be obtained by codoping. Besides, compared to the Al-N and Ga-N codoping cases, the hole effective mass of In-N codoped system is much smaller, indicating the p-type conductivity can be more enhanced by In N codoping展开更多
We investigated the electronic and magnetic properties for O or Zn defect of (Cu, N) or (Cu, F)-co- doped ZnO with the concentration of 2.77% - 8.33% by using the first-principles calculations. The ferromagnetic coupl...We investigated the electronic and magnetic properties for O or Zn defect of (Cu, N) or (Cu, F)-co- doped ZnO with the concentration of 2.77% - 8.33% by using the first-principles calculations. The ferromagnetic coupling of Cu atoms in (Cu, N)-codoped ZnO can be attributed to the hole-mediated double-exchange through the strong 2p-3d coupling between Cu and neighboring O (or N) atoms. The ferromagnetism in Cu-doped ZnO is controllable by changing the carrier density. The Cu magnetic moment in low Cu concentration (2.77%) is increased by the N-doping, while for the F-doping it decreases. For two Cu atoms of Zn0.9445Cu0.0555O with O vacancy, the antiferromagnetic state is more energetically favorable than the ferromagnetic state.展开更多
The structural and magnetic properties of the Cu-doped ZnO(ZnO:Cu) under c-axis pressure were studied using first-principle calculations. It was found that the ZnO:Cu undergoes a structural transition from Wurtzit...The structural and magnetic properties of the Cu-doped ZnO(ZnO:Cu) under c-axis pressure were studied using first-principle calculations. It was found that the ZnO:Cu undergoes a structural transition from Wurtzite to Graphite-like structure at a c-axis pressure of 7–8 GPa. This is accompanied by an apparent loss of ferromagnetic stability, indicating a magnetic transformation from a ferromagnetic state to a paramagnetic-like state. Further studies revealed that the magnetic instability is closely related to the variation in crystalline field originated from the structural transition, which is in association with the overlapping of spin–charge density between the Cu^2+ and adjacent O^2-.展开更多
Aiming at developing p-type semiconductors and modulating the band gap for photoelectronic devices and band engineering, we present the ab initio numerical simulation of the effect of codoping ZnO with Al, N and Mg on...Aiming at developing p-type semiconductors and modulating the band gap for photoelectronic devices and band engineering, we present the ab initio numerical simulation of the effect of codoping ZnO with Al, N and Mg on the crystal lattice and electronic structure. The simulations are based on the Perdew-Burke-Ernzerhof generalised-gradient approximation in density functional theory. Results indicate that electrons close to the Fermi level transfer effectively when Al, Mg, and N replace Zn and O atoms, and the theoretical results were consistent with the experiments. The addition of Mg leads to the variation of crystal lattice, expanse of energy band, and change of band gap. These unusual properties are explained in terms of the computed electronic structure, and the results show promise for the development of next-generation photoconducting devices in optoelectronic information science and technology.展开更多
The effect of a second dopant on the magnetic property of Cu-doped ZnO by first-principles calculations based on the density functional theory was studied. It is found that the Cu-doped ZnO shows ferromagnetism due to...The effect of a second dopant on the magnetic property of Cu-doped ZnO by first-principles calculations based on the density functional theory was studied. It is found that the Cu-doped ZnO shows ferromagnetism due to the hybridization between Cu-3d and O-2p orbitals. When Na is introduced to the Cu-doped ZnO system, Cu cations tend to take on a bivalent state. Therefore, the magnetic moments on both Cu and coordinated oxygen sites increase due to Na doping. On the contrary, the magnetic moments decrease dramatically in the (Cu, A1) co-doped ZnO, which can be attributed to the fully occupied 3d states of Cu+ and O-2p states.展开更多
基金supported by Higher Education Commission of Pakistan, National Basic Research Program of China (2010CB934602)National Science Foundation of China (51171007 and 51271009)
文摘The modification of nanostructured materials is of great interest due to controllable and unusual inherent properties in such materials. Single phase Fe doped Zn O nanostructures have been fabricated through simple, versatile and quick low temperature solution route with reproducible results. The amount of Fe dopant is found to play a significant role for the growth of crystal dimension. The effect of changes in the morphology can be obviously observed in the structural and micro-structural investigations, which may be due to a driving force induced by dipole-dipole interaction. The band gap of Zn O nanostructures is highly shifted towards the visible range with increase of Fe contents, while ferromagnetic properties have been significantly improved.The prepared nanostructures have been found to be nontoxic to SH-SY5 Y Cells. The present study clearly indicates that the Fe doping provides an effective way of tailoring the crystal dimension, optical band-gap and ferromagnetic properties of Zn O nanostructure-materials with nontoxic nature, which make them potential for visible light activated photocatalyst to overcome environmental pollution, fabricate spintronics devices and biosafe drug delivery agent.
基金Project supported by the Special Foundation for Young Scientists of Anhui Province,China (Grant No. 2009SQRZ097ZD)the Foundation of Anhui University of Architecture (Grant No. 20070601)
文摘The electronic structures and effective masses of the N mono-doped and Al N, Ga-N, In-N codoped ZnO system have been calculated by a first-principle method, and comparisons among different doping cases are made. According to the results, the impurity states in the codoping cases are more delocalised compared to the N mono-doping case, which means a better conductive behaviour can be obtained by codoping. Besides, compared to the Al-N and Ga-N codoping cases, the hole effective mass of In-N codoped system is much smaller, indicating the p-type conductivity can be more enhanced by In N codoping
文摘We investigated the electronic and magnetic properties for O or Zn defect of (Cu, N) or (Cu, F)-co- doped ZnO with the concentration of 2.77% - 8.33% by using the first-principles calculations. The ferromagnetic coupling of Cu atoms in (Cu, N)-codoped ZnO can be attributed to the hole-mediated double-exchange through the strong 2p-3d coupling between Cu and neighboring O (or N) atoms. The ferromagnetism in Cu-doped ZnO is controllable by changing the carrier density. The Cu magnetic moment in low Cu concentration (2.77%) is increased by the N-doping, while for the F-doping it decreases. For two Cu atoms of Zn0.9445Cu0.0555O with O vacancy, the antiferromagnetic state is more energetically favorable than the ferromagnetic state.
基金supported by the National Natural Science Foundation of China(Grant Nos.51031004 and 51272078)the Natural Science Foundation of Guangdong,China(Grant No.S2012010008124)+3 种基金the National Basic Research Program of China(Grant No.2015CB921202)the Project for Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2014)International Science & Technology Cooperation Platform Program of Guangzhou,China(Grant No.2014J4500016)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT1243)
文摘The structural and magnetic properties of the Cu-doped ZnO(ZnO:Cu) under c-axis pressure were studied using first-principle calculations. It was found that the ZnO:Cu undergoes a structural transition from Wurtzite to Graphite-like structure at a c-axis pressure of 7–8 GPa. This is accompanied by an apparent loss of ferromagnetic stability, indicating a magnetic transformation from a ferromagnetic state to a paramagnetic-like state. Further studies revealed that the magnetic instability is closely related to the variation in crystalline field originated from the structural transition, which is in association with the overlapping of spin–charge density between the Cu^2+ and adjacent O^2-.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB606401)
文摘Aiming at developing p-type semiconductors and modulating the band gap for photoelectronic devices and band engineering, we present the ab initio numerical simulation of the effect of codoping ZnO with Al, N and Mg on the crystal lattice and electronic structure. The simulations are based on the Perdew-Burke-Ernzerhof generalised-gradient approximation in density functional theory. Results indicate that electrons close to the Fermi level transfer effectively when Al, Mg, and N replace Zn and O atoms, and the theoretical results were consistent with the experiments. The addition of Mg leads to the variation of crystal lattice, expanse of energy band, and change of band gap. These unusual properties are explained in terms of the computed electronic structure, and the results show promise for the development of next-generation photoconducting devices in optoelectronic information science and technology.
基金financially supported by the National Natural Science Foundation of China (Nos. 50831002, 51271020, 51071022, and 11174031)Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT) (No. IRT1106)+2 种基金Beijing Nova Program (No. 2011031)Beijing Natural Science Foundation (No. 2102032)the Fundamental Research Funds for the Central Universities
文摘The effect of a second dopant on the magnetic property of Cu-doped ZnO by first-principles calculations based on the density functional theory was studied. It is found that the Cu-doped ZnO shows ferromagnetism due to the hybridization between Cu-3d and O-2p orbitals. When Na is introduced to the Cu-doped ZnO system, Cu cations tend to take on a bivalent state. Therefore, the magnetic moments on both Cu and coordinated oxygen sites increase due to Na doping. On the contrary, the magnetic moments decrease dramatically in the (Cu, A1) co-doped ZnO, which can be attributed to the fully occupied 3d states of Cu+ and O-2p states.