Study On Optical And Magnetic Properties Of Mn Doped ZnO

1.Preparation and Characterization of Mn doped ZnOWhen we prepared the sample quality such as Zn Zn(CH3COO)2?2H2O ,NaHCO3 and the molar ratio of 18% MnSO4 full grinding at room temperature.Mixture in the tube furnace at 160℃, 180℃, 200℃, 250℃, 300℃thermal decomposition under 2 hours and cooled to room temperature.Washed with deionized water to filter and dried at 100℃for 2 hours.XRD on Rigaku RU200B X-ray diffractometer for testing, using Cu Kαλ= 1.5406?.We use the JEOL-2010 type transmission electron microscope TEM images obtained samples of the actual measured particle radius compared with the results, accelerating voltage of 200 kV.Scherrer formula which we use the average size of ZnO nanocrystals. The formula is: D = 0.9λ/Bcosθ. Figure 1 is calculated with the Scherrer particle size of the sample preparation temperature dependence, from the figure we can clearly see: Preparation of the sample size grew from 8nm to 18nm or so.Figure 2 shows left and right panel 200℃300℃TEM sample preparation and electron diffraction images can be seen from the graph for the 12nm and 20nm particle size were about basically consistent with the XRD results. Figure 2 at different temperatures in the TEM of nanocrystalline ZnO And electron diffraction photograph Left:200℃,Right:300℃We are testing samples for chemical composition, with Thermo's TN-5502 X-ray analyzer that tested samples EDS, with Cu Kαas excitation source, accelerating voltage of 20kV.Produced by the British VG Escalb MarkⅡelectron spectroscopy, X-ray excitation source was monochromatic Al (Kα) tested samples of X-ray photoelectron spectroscopy (XPS). Measuring pressure of 5 * 10-8 mbar. Resolution of 0.3eV.。2. optical and magnetic properties of Mn doped ZnOIn order to study Mn-doped optical properties of nano-ZnO, including the measurement of samples at different temperatures X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy. Crystal material to conduct fingerprint identification and crystal structure determination, must be X-ray diffraction, that is, to measure X-ray diffraction patterns of samples (XRD).Figure 3 shows the XRD curve, we can see that all the samples there is a clear crystalline ZnO and the diffraction peaks corresponding to.With the sample preparation temperature, XRD peaks gradually increase and gradually narrow half-width, indicating that ZnO the grain size.To test the chemical composition of samples, we measured samples of the energy dispersive spectroscopy (EDS), energy dispersive analysis in the micron or nanometer scale of the scanning electron microscope or transmission electron microscope by electron impact within the generated energy X-ray measurements todetermine the chemical composition of the analysis. Preparation of samples there are only O, Zn, Mn three elements of the electron scattering peak, indicating that the samples contained only O, Zn, Mn component, while excluding other impurities.One 1600C Mn samples prepared weakest element of the electron scattering peak, indicating that sample preparation may 1600C Mn element content at least.In order to study the chemical structure of the sample surface preparation, we measured samples of X-ray photoelectron spectroscopy (XPS), XPS is a kind of material composition and structure of the physical approach to the role of a certain energy X-rays in the sample, the sample surfaceelectronic excitation of different atoms into free electrons, these electronic information with the sample surface, and characteristic energy.Collected and studied their electronic energy distribution, not only can determine what elements of atoms present in the compound, you can also study the chemical structure of the sample.As Mn doped ZnO the XPS study less, so as we study the XPS Mn doped ZnO may be on its valence state and chemical environment of the analysis has some reference value.Reference to the data standards, the graphite C1s peak time for the 284.8eV, ZnO in the O1s peak for the 530.40eV, Zn2p3 / 2 peak position for the 1021.75eV.Our samples are prepared for the C1s peak of 284.6eV as a standard, so the Zn2p, O1s peaks before to add 0.2eV compared with the standard value.Since XPS can only be qualitative (semi-quantitative) analysis of the content of each element, according to Mn (2p3 / 2) peak of the main peak intensity of Zn (2p3 / 2) peak intensity approximate estimate samples Mn, Zn content, because of largeadsorbed oxygen or CO, there is no estimate on the O levels.Photoluminescence spectra showed that the prepared samples showed a strong ultraviolet emission, and 1600C, 1800C, 2000C prepared samples appeared very weak visible emission, 2500C and 3000C samples prepared almost no visible emission, which indicates that a large number of Mn on the surfaceplayed a role in surface passivation, it leads to visible emission is very weak or even quenching.We measured the samples at room temperature, magnetic.Measurement results show that, 1600C samples prepared at room temperature with weak ferromagnetism, with the sample preparation temperature, the ferromagnetism is getting worse, 3000C when the performance of the paramagnetic.3. Defects of Mn doped ZnOAs the nano-material itself has a large surface ratio, so a large number of nano-surface defects and dangling bonds, dangling bonds or defects of these will transition metal magnetic materials doped ZnO has a great influence, but also has a very uniqueThe optical and electrical properties, and the next generation of spin quantum spin devices such as quantum computers need high-quality magnetic semiconductor nanostructures (nano-thin films, quantum wells, nanorods, nanotubes, quantum dots and their arrays, etc.). We prepared material for the single Mn doped ZnO nanocrystals in the preparation of lower temperature (160 degrees Celsius), the sample size small (8nm), they found a weak magnetic at room temperature.The theoretical results show that a single Mn doped ZnO is difficult to be ferromagnetic above room temperature, so we should be prepared ferromagnetic samples from the defect.The particle size of 8nm Nano particles, about 4600 ZnO molecules on the ZnO surface, the number of molecules (about 1500) is about 33% of the total number of molecules, so the surface of a large number of dangling bonds and defects and these dangling bondsdefects will Mn2 + ion confinement in a certain area, its magnetic moment tends to spin the same direction, making it more stable (compared to spin in the opposite direction).