Electronic structure and magnetism of transition metal doped Zn12O12 clusters: Role of defects

Ganguli, Nirmal; Dasgupta, Indra; Sanyal, Biplab

doi:10.1063/1.3525649

Cited by 25 publications

(19 citation statements)

References 32 publications

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“…This explains the magnetic behavior of ZnO clusters in presence of V Zn . The O-p states and the Zn-d states are the main contributors to the DOS at the E F , in line with the findings yielded by previous studies focusing on ZnO nanostructures, where V Zn was shown to introduce magnetism in an otherwise undoped ZnO system [12,19]. Figure 3 shows the electronic structure of ZnO cluster doped with Mg in three different cases, such as (a) without any additional defects (b) in presence of V O and (c) with V Z .…”

Section: Electronic and Optical Propertiessupporting

confidence: 90%

“…For the dopant transition metal atom, the onsite d-d Coulomb exchange interactions were described using U = 4.0 eV and J = 1.0 eV, while the parameters U = 7.0 eV and J = 0.75 eV were adopted for the Eu atom. The choice of Hubbard parameters are taken from standard literature where reliable results are produced with these values [12]. Further, For the Eu atom, we have tested different U and J combinations and used the values that could reproduce experimental values reliably.…”

Section: Computational Methodologymentioning

confidence: 99%

“…These properties can be harnessed in a variety of applications such as environmental sensors, photodetectors and transistors based on ZnO quantum dots (QDs) [4][5][6]. Rare earth (RE) dopants have been known to affect the electronic structures of semiconductors in general [7][8][9][10][11][12][13][14][15]. In addition, formation of defect complexes involving RE elements has been shown to play a key role in the optoelectronic properties of ZnO [5].…”

Section: Introductionmentioning

confidence: 99%

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Density Functional Theory Studies of Zn12O12 Clusters Doped with Mg/Eu and Defect Complexes

2020

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We report a density functional theory study of ZnO cluster doped with Eu and Mg along with native point defects using the generalized gradient approximation including the Hubbard parameter. The Zn atomic positions are found to be energetically more favorable doping sites than O. The Eu has a lower formation energy than Zn and O vacancies, helps in lowering the formation energy of point defects and induces spin polarization. Mg is less favorable dopant energetically and is not inducing any magnetism in the cluster. Presence of Eu and point defects along with Mg can help in sustaining spin polarization, implying that transition metal and rare earth dopant is a favorable combination to invoke desirable properties in ZnO based materials. Eu-Eu doping pair prefers ferromagnetic orientation and a spin flip is induced by Eu in the Eu-Mg configuration. Further, Eu doping increases the value of static refractive index and optical absorption in the UV region compared to the undoped ZnO cluster.

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Section: Electronic and Optical Propertiessupporting

confidence: 90%

Section: Computational Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Density Functional Theory Studies of Zn12O12 Clusters Doped with Mg/Eu and Defect Complexes

2020

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“…The endohedral bi-doped isomer, however, is found to be a stable local minimum. The structural and magnetic properties of (ZnO) 12 nanoclusters substitutionally doped with 3d transition-metals were also studied theoretically [17]. It was found that doping of TM at the Zn site is energetically more favorable than doping it at O site.…”

Section: Introductionmentioning

confidence: 99%

Second-Row Transition-Metal Doping of (ZniSi), i = 12, 16 Nanoclusters: Structural and Magnetic Properties

et al. 2013

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TM@Zn i S i nanoclusters have been characterized by means of the Density Functional Theory, in which Transition Metal (TM) stands from Y to Cd, and i = 12 and 16. These two nanoclusters have been chosen owing to their highly spheroidal shape which allow for favored endohedral structures as compared to other nanoclusters. Doping with TM is chosen due to their magnetic properties. In similar cluster-assembled materials, these magnetic properties are related to the Transition Metal-Transition Metal (TM-TM) distances. At this point, endohedral doping presents a clear advantage over substitutional or exohedral doping, since in the cluster-assembled materials, these TM would occupy the well-fixed center of the cluster, providing in this way a better TM-TM distance control to experimentalists. In addition to endohedral compounds, surface structures and the TS's connecting both isomers have been characterized. In this way the kinetic and thermal stability of endohedral nanoclusters is predicted. We anticipate that silver and cadmium endohedrally doped nanoclusters have the longest lifetimes. This is due to the weak interaction of these metals with the cage, in contrast to the remaining cases where the TM covalently bond to a region of the cage. The open-shell electronic structure of Ag provides magnetic properties to Ag@Zn i S i clusters. Therefore, we have further characterized (Ag@Zn 12 S 12) 2 and (Ag@Zn 16 S 16) 2 dimers both in the ferromagnetic and antiferromagnetic state, in order to calculate the corresponding magnetic exchange coupling constant, J.

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“…We note that Zn(II) and Mg(II) are diamagnetic ions and that they should not display a behavior consistent with ferromagnetic ordering, albeit, as we note, this effect was slight. Otherwise, recent studies for Zn n O n clusters and ZnO nanoparticles indicated the defect induced magnetism in ZnO clusters even without any transition metal dopants [55,56]. The extrapolation of these results to the reported MOF systems can suggest the impact of the defects in MOF structures to achieve and explain the origin of magnetic properties of the reported materials.…”

Section: Ferromagnetic Ordering Behavior: Little Field Dependence On mentioning

confidence: 68%

Tuning of Luminescent and Magnetic Properties via Metal Doping of Zn-BTC Systems

Wei

Ordonez

et al. 2018

Crystals

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In order to assess how metal doping affects the luminescence and magnetic properties of anionic Metal-Organic Frameworks (MOFs), seven single-metal doped MOFs {M-Zn-BTC}{Me 2 NH 2 + } (M = Co, Cu, Ni, Mn, Ca, Mg, Cd) and three dual-metal doped MOFs {Zn-M 1 -M 2 -BTC}{Me 2 NH 2 + } (M 1 = Co, Cu; M 2 = Ni, Co) were synthesized. Trace amounts of different metals were doped via addition of another metal salt during the synthetic process. All compounds retained the same crystal structure as that of the parent {Zn-BTC}{Me 2 NH 2 + } MOF, which was supported by single crystal and powder X-ray diffraction studies. Thermal Gravimetric Analysis (TGA) of these compounds also revealed that all MOFs had similar stability up to~450 • C. Solid state photoluminescent studies indicated that {Zn-Mn-BTC}{Me 2 NH 2 + }, {Zn-Cd-BTC}{Me 2 NH 2 + }, and {Zn-Ca-BTC}{Me 2 NH 2 + } had a significant red shifting effect compared to the original {Zn-BTC}{Me 2 NH 2 + } MOF. Applications of this doping method to other MOF systems can provide an efficient way to tune the luminescence of such systems, and to obtain a desired wavelength for several applications such as sensors and white light LED materials. Because Zn, Co, Cu, Ni, Mg have magnetic properties, the effect of the doping metal atom on the magnetism of the {Zn-BTC}{Me 2 NH 2 + } networks was also studied. To characterize the magnetic behavior of the synthesized MOFs, we conducted low-temperature (10 K) saturation remanence experiments in a 3 Tesla applied field, with the principal goal of identifying the domain state of the synthesized materials (Zn, Zn-Co, Zn-Cu-Co, Zn-Cu-Ni, Zn-Mg, Zn-Mn, Zn-Ni-Co, Zn-Ni). During room/low temperature saturation magnetization experiments, Zn, Zn-Co, Zn-Cu-Co, and Zn-Cu-Ni systems yielded data indicative of superparamagnetic behavior, yet during zero field and field cooled experiments Zn-Co showed a slight paramagnetic effect, Zn showed no temperature dependence on warming and Zn-Cu-Co and Zn-Cu-Ni demonstrated only a slight temperature dependence on warming. These behaviors are consistent with ferromagnetic ordering. Zero field and field cooled experiments indicate that Zn-Mg and Zn-Ni have a ferromagnetic ordering and Zn-Mn and Zn-Ni-Co show paramagnetic ordering behavior.

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Electronic structure and magnetism of transition metal doped Zn12O12 clusters: Role of defects

Cited by 25 publications

References 32 publications

Density Functional Theory Studies of Zn12O12 Clusters Doped with Mg/Eu and Defect Complexes

Density Functional Theory Studies of Zn12O12 Clusters Doped with Mg/Eu and Defect Complexes

Second-Row Transition-Metal Doping of (ZniSi), i = 12, 16 Nanoclusters: Structural and Magnetic Properties

Tuning of Luminescent and Magnetic Properties via Metal Doping of Zn-BTC Systems

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