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Microstructure and Magnetic and Optical Properties of Mn2+-doped MgxZn1-xO Powders

Author: CuiHaiTao
Tutor: LiuYuXue
School: Northeast Normal University
Course: Condensed Matter Physics
Keywords: MgxZn1-xO Mn XRD SQUID Raman spectroscopy Absorption spectrum Photoluminescence spectra
CLC: O482
Type: Master's thesis
Year: 2010
Downloads: 19
Quote: 0
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Abstract


Magnetic doped sol - gel method of the of Mg x Zn 1-x O, Mg and Mn doping concentration is 3%. And using X-ray diffraction, Raman spectroscopy, and superconducting quantum interference magnetometer and light-induced luminescence spectrometer characterized samples, committed Mn2 doped the the of Mg x Zn 1-x O optical and magnetic properties. XRD patterns of analysis, all samples emerged hexagonal structure. Unreduced samples, in addition to the diffraction peaks of ZnO, still 2θ = 29.95 ° and 2θ = 43.17 °, the location of the discovery of two diffraction peaks, after comparison the drawn the former belongs ZnMn 2 O 4 of the diffraction peak, and the latter from the MgO. Restored after the samples still showed wurtzite structure, but does not appear ZnMn 2 O 4 , MgO diffraction peaks. We believe that this introduction of O vacancies (Vo) and restore the relevant. After calculation, it is found that the lattice constant of the sample after doping larger description of the Mn2 alternative Zn 2 into the lattice. The Mn doping usually introduce defect states, and XRD to characterize the defects can not be, so we do Raman test. Raman spectroscopy, unreduced samples of ZnMn 2 O 4 Raman peak appears at 680 cm-1, this peak disappeared after reduction treatment this The XRD results are consistent Mn 2 into the lattice. Appears at 526 cm-1, a strong Raman peak, which is caused due to the ZnO bulk oxygen vacancies, interstitial zinc defects, after reduction, the Raman peak enhancement after reduction treatment does the sample The increase in oxygen vacancies. Appears in the tape at the end of (410 nm) in the absorption spectrum, in addition to the absorption edge of the ZnO, an obvious absorption peak After the reduction was significantly enhanced, consistent with this and other reported in the literature. The literature suggests that this is caused by the introduction of impurity level due to Mn ion doping, further illustrating the Mn ions into the crystal lattice, and this is consistent with the results of XRD. Was observed in the PL spectra, ultraviolet and visible light-emitting. Under normal circumstances, the ratio of the intensity of ultraviolet and visible light can be reflected to the crystallinity of the sample. By calculating the ratio of the reduced samples is far less than the unreduced samples described restore the sample after the crystallization becomes weak, this is consistent with the Raman spectra. By magnetic measurements, the unreduced samples did not appear the ferromagnetic at room temperature, and restored after the sample appeared relatively weak ferromagnetism. We believe this is due to the introduction of O vacancies formed Mn 2 -Vo-Mn 2 the superexchange role.

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