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Structural and electronic properties of Eu- and Pd-doped ZnO.

Assadi MH, Zhang Y, Zheng RK, Ringer SP, Li S - Nanoscale Res Lett (2011)

Bottom Line: The ground state properties, equilibrium bond lengths, and band structures of both the ZnO:Eu and ZnO:Pd systems were also investigated.The total and partial densities of electron states were also determined for both systems.It was found that in the ZnO:Eu system, ambient ferromagnetism can be induced by introducing Zn interstitial which leads to a carrier-mediated ferromagnetism while the ZnO:Pd system possesses no ferromagnetism.PACS 31.15.E-, 75.50.Pp, 75.30Hx.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. sean.li@unsw.edu.au.

ABSTRACT
Doping ZnO with rare earth and 4d transition elements is a popular technique to manipulate the optical properties of ZnO systems. These systems may also possess intrinsic ferromagnetism due to their magnetic moment borne on 4f and 4d electrons. In this work, the structural, electronic, and magnetic properties of Eu- and Pd-doped ZnO were investigated by the ab initio density functional theory methods based on generalized gradient approximation. The relative stability of incorporation sites of the doped elements in the ZnO host lattice was studied. The ground state properties, equilibrium bond lengths, and band structures of both the ZnO:Eu and ZnO:Pd systems were also investigated. The total and partial densities of electron states were also determined for both systems. It was found that in the ZnO:Eu system, ambient ferromagnetism can be induced by introducing Zn interstitial which leads to a carrier-mediated ferromagnetism while the ZnO:Pd system possesses no ferromagnetism.PACS 31.15.E-, 75.50.Pp, 75.30Hx.

No MeSH data available.


Related in: MedlinePlus

The relaxed crystallographic structure of the ZnO:Eu systems. Representing (a) ZnO:EuZn, (b) ZnO:EuI, (c) ZnO:EuZn + VO, (d) ZnO:EuZn + ZnI systems. Red, blue, and gray balls represent the O, Zn, and Eu ions, respectively. For each system, the calculated length of the Eu bonds is presented along both the c direction (or [001]) and within the ab (basal) plane.
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Figure 1: The relaxed crystallographic structure of the ZnO:Eu systems. Representing (a) ZnO:EuZn, (b) ZnO:EuI, (c) ZnO:EuZn + VO, (d) ZnO:EuZn + ZnI systems. Red, blue, and gray balls represent the O, Zn, and Eu ions, respectively. For each system, the calculated length of the Eu bonds is presented along both the c direction (or [001]) and within the ab (basal) plane.

Mentions: The incorporation mechanism of Eu ions in ZnO's host lattice was investigated by calculating the Ef of the substitutional Eu (EuZn) and interstitial Eu (EuI) in the stochiometric ZnO as presented in Table 1. It was found that the Ef of EuZn is -2.391 eV while the Ef of EuI is 1.429 eV. Such a large difference in Ef indicates that Eu ions favorably substitute Zn ions rather than taking the interstitial sites of the ZnO lattice. The local geometry of the EuZn and EuI is presented in (a) and (b). Figure 1a shows that the length of Eu-O bond along c direction (ab plane) has increased to 2.280 Å (2.260 Å) in the ZnO:EuZn system. The increase of the bond lengths is approximately equivalent to an expansion of 14% along the c direction and 13% within the ab plane with respect to the Zn-O bond length in an undoped ZnO. On the other hand, in the ZnO:EuI system, in which EuI binds to three Zn and three O ions, the length of the Eu-O and Eu-Zn bonds were found to be 2.323 and 2.857 Å comprising an expansion of 16% and 24%, respectively compared to the unrelaxed structure. In the ZnO:EuZn system, although the length of the Eu bonds is also substantially expanded, the expansion is much smaller than that in the ZnO:EuI system. As a result, the ZnO:EuZn system reaches the structural stability with less lattice distortion.


Structural and electronic properties of Eu- and Pd-doped ZnO.

Assadi MH, Zhang Y, Zheng RK, Ringer SP, Li S - Nanoscale Res Lett (2011)

The relaxed crystallographic structure of the ZnO:Eu systems. Representing (a) ZnO:EuZn, (b) ZnO:EuI, (c) ZnO:EuZn + VO, (d) ZnO:EuZn + ZnI systems. Red, blue, and gray balls represent the O, Zn, and Eu ions, respectively. For each system, the calculated length of the Eu bonds is presented along both the c direction (or [001]) and within the ab (basal) plane.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211447&req=5

Figure 1: The relaxed crystallographic structure of the ZnO:Eu systems. Representing (a) ZnO:EuZn, (b) ZnO:EuI, (c) ZnO:EuZn + VO, (d) ZnO:EuZn + ZnI systems. Red, blue, and gray balls represent the O, Zn, and Eu ions, respectively. For each system, the calculated length of the Eu bonds is presented along both the c direction (or [001]) and within the ab (basal) plane.
Mentions: The incorporation mechanism of Eu ions in ZnO's host lattice was investigated by calculating the Ef of the substitutional Eu (EuZn) and interstitial Eu (EuI) in the stochiometric ZnO as presented in Table 1. It was found that the Ef of EuZn is -2.391 eV while the Ef of EuI is 1.429 eV. Such a large difference in Ef indicates that Eu ions favorably substitute Zn ions rather than taking the interstitial sites of the ZnO lattice. The local geometry of the EuZn and EuI is presented in (a) and (b). Figure 1a shows that the length of Eu-O bond along c direction (ab plane) has increased to 2.280 Å (2.260 Å) in the ZnO:EuZn system. The increase of the bond lengths is approximately equivalent to an expansion of 14% along the c direction and 13% within the ab plane with respect to the Zn-O bond length in an undoped ZnO. On the other hand, in the ZnO:EuI system, in which EuI binds to three Zn and three O ions, the length of the Eu-O and Eu-Zn bonds were found to be 2.323 and 2.857 Å comprising an expansion of 16% and 24%, respectively compared to the unrelaxed structure. In the ZnO:EuZn system, although the length of the Eu bonds is also substantially expanded, the expansion is much smaller than that in the ZnO:EuI system. As a result, the ZnO:EuZn system reaches the structural stability with less lattice distortion.

Bottom Line: The ground state properties, equilibrium bond lengths, and band structures of both the ZnO:Eu and ZnO:Pd systems were also investigated.The total and partial densities of electron states were also determined for both systems.It was found that in the ZnO:Eu system, ambient ferromagnetism can be induced by introducing Zn interstitial which leads to a carrier-mediated ferromagnetism while the ZnO:Pd system possesses no ferromagnetism.PACS 31.15.E-, 75.50.Pp, 75.30Hx.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. sean.li@unsw.edu.au.

ABSTRACT
Doping ZnO with rare earth and 4d transition elements is a popular technique to manipulate the optical properties of ZnO systems. These systems may also possess intrinsic ferromagnetism due to their magnetic moment borne on 4f and 4d electrons. In this work, the structural, electronic, and magnetic properties of Eu- and Pd-doped ZnO were investigated by the ab initio density functional theory methods based on generalized gradient approximation. The relative stability of incorporation sites of the doped elements in the ZnO host lattice was studied. The ground state properties, equilibrium bond lengths, and band structures of both the ZnO:Eu and ZnO:Pd systems were also investigated. The total and partial densities of electron states were also determined for both systems. It was found that in the ZnO:Eu system, ambient ferromagnetism can be induced by introducing Zn interstitial which leads to a carrier-mediated ferromagnetism while the ZnO:Pd system possesses no ferromagnetism.PACS 31.15.E-, 75.50.Pp, 75.30Hx.

No MeSH data available.


Related in: MedlinePlus