Local structure and paramagnetic properties of Zn1-xMnxO

Abstract

Having based on x-ray absorption spectroscopy, we point out structural phase separation in polycrystalline Zn1-xMnxO ceramics prepared by solid-state reaction. The samples are single phase in the wurtzite structure as x < 0.04. A Mn-concentration increase with x ≥ 0.04 results in the formation of a secondary phase of tetragonal ZnMn2O4 spinel. The feature of x-ray absorption spectra for the Mn K edge reveals an existence of Mn2+ and Mn3+ ions in Zn1-xMnxO, which are responsible for room-temperature paramagnetism. Particularly, when Mn content is increased, there is a chemical shift of the absorption edge toward higher energies, indicating an increase in concentration of Mn3+ ions. Fourier analyses for the spectra of extended x-ray absorption fine structure (EXAFS) shows up the substitution of Mn for Zn sites in the ZnO host lattice. The parameters related to the local structure have been determined and discussed in detail.

Raman scattering and electrical properties of Zn1−xMnxO films

“…content increases, the E 2 (high) mode becomes very weak and broad. Such phenomena could be due to the broken symmetry induced by Mn dopants in the ZnO host lattice [10]. The Raman scattering results are well consistent with those of XRD.…”

“…might be ferromagnetic with Curie temperature (T C ) above room temperature (RT) [2,3], ZnO-based diluted magnetic semiconductors (DMSs) are attracting much more attention. This has led to a large number of experimental [4][5][6][7][8][9][10] and theoretical [11,12] studies of TM-doped ZnO. Specially, among all the TMs, the doping of Mn in ZnO is most encouraging because the ionic radius of Mn 2+ is similar to Zn 2+ and the substitutional Mn 2+ has the highest magnetic moment.…”

Correlation between oxygen vacancies and dopant concentration in Mn-doped ZnO nanoparticles synthesized by co-precipitation technique

“…4(a) and (b), M S of Zn 1−x Mn x O nanoparticles monotonously increases with increasing C Mn for x=0.08. However, Because ZnMn 2 O 4 appear in the Zn 0.9 Mn 0.1 O nanoparticles, the interaction between Mn 2+ and Mn 3+ ions within the ZnO matrix shows antiferromagnetism with anegative Curie-Weiss temperature[30] and the antiferromagnetic interaction suppresses ferromagnetic coupling of sample[31]. Thus, the M S value has resulted in Mn ion concentration, which can be attributed to the increase of oxygen vacancies in the samples…”

Ferromagnetism in Zn1–xMnxO Nanoparticles Prepared by Ball Milling

“…For the samples with d > 72 nm, there is no lattice distortion around the Zn sites. The ε increase is thus ascribed to oxygen-related defects because the intensity of the peaks in the Fouriertransformed XAFS spectra is dependent on atoms surrounding the absorbing Mn atom [5]. It has been shown that oxygen loss occurs during themilling in an Ar ambient, leading to the presence of oxygen vacancies (V O ) [9].…”

“…Annealing at temperatures higher than 700 o C usually leads to the paramagnetic (PM) behavior because of the coexistence of Mn 2+ and Mn 3+ ions [5].…”