Dissertation > Excellent graduate degree dissertation topics show

Study on the Structure and Magnetic Properties of K-doped SnO2 and V-doped ZnO Diluted Magnetic Semiconductor Powders

Author: TangXiaoMei
Tutor: WuPing
School: Tianjin University
Course: Materials Physics and Chemistry
Keywords: Diluted magnetic semiconductor Sol-gel method K -doped SnO2 V -doped ZnO Ferromagnetism
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 64
Quote: 1
Read: Download Dissertation

Abstract


Diluted magnetic semiconductors (DMSs) refers to the non-magnetic semiconductor material substrate (usually AB) through the incorporation of a small amount of magnetic transition metals or rare earth element to obtain the magnetic properties of a new class of functional materials. Currently, DMSs materials discovered many new physical phenomena, such as giant Faraday effect, giant Zeeman splitting, anomalous Hall effect, giant negative magnetoresistance, magneto-insulator-metal transition and so on. Using these effects, can be prepared a variety of new functional devices, for a number of conditions for the development of science and technology. Therefore, much of this new material research attention. In this paper, the sol - gel method was successfully prepared a series of K-SnO 2 and V-ZnO diluted magnetic semiconductor nano powder. Using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and physical performance tester (PPMS-9) in the sample vibrating magnetometer (VSM) on the structure and magnetic properties of the sample characterized. In the K-SnO 2 system, all samples are tin dioxide rutile structure, particle size of about several nanometers; K elements a price exists; samples with room temperature ferromagnetism, and the saturation magnetization With the increase of the doping concentration increased. The K doping concentration of 4% of the samples and pure SnO 2 samples annealed in an oxygen doped sample still has a temperature of K ferromagnetism is not caused by oxygen vacancies, so the main source of ferromagnetism. When an Sn K in a position substituted, as K, Sn different valence, a hole will produce three anionic, cationic occurs through these holes indirect exchange interaction, resulting in ferromagnetic magnetic specific mechanisms can be used RKKY model to explain. In the V-ZnO system, V is the doping concentration of less than 5%, the sample has a polycrystalline ZnO wurtzite structure, particle size is about twenty to thirty nanometers; V element valence of pentavalent; sample showing temperature iron magnetic, and the saturation magnetization of the samples with increasing concentration of V-Doped enhanced dopant concentration of 3% of the sample at different temperatures (500 ℃, 600 ℃, 700 ℃) after annealing for 1h under an air saturation magnetization As the annealing temperature strength is enhanced. We believe that the ferromagnetic sample is the main source of oxygen vacancies and defect density caused by the specific magnetic mechanism can be used to explain the bound magnetic polaron model.

Related Dissertations

  1. Sol - gel method p -type ZnO films,O484.1
  2. Doped ZnO thin film magnetic materials Preparation and magnetic properties at room temperature,O484.1
  3. Hydrogen AlN and ZnO-based diluted magnetic semiconductor materials First-principles study,O471
  4. Hydroxyapatite Coating Prepared on Porous Titanium Substrate by Sol-gel,R318.08
  5. Investigations on V-doped ZnO by First-principles Calculations,TN304.7
  6. Preparation and Quantitative Analysis of Tetragonal Nano-ZrO2 Powder,TB383.1
  7. Preparation and Characterization of Electrochromic TiO2 Thin Films Dipped by Ce/Sm,TB383.2
  8. Preparation and Characteristics of SrHfO3 :Ce Scintillator Ceramics,TQ174.1
  9. Research on the Preparation and the Photocatalytic Activity of Doped TiO2,O614.411
  10. Preparation and Catalytic Performance Research of LaCoO3 Rare-earth Perovskite Catalysts,O643.36
  11. Studies on the Resistive Switching Properties of SrTiO3 Films,TP333.5
  12. Ⅲ - Ⅴ semiconductors AlAs transition metal clusters in first-principles study,TN304.23
  13. Research on Production of High-containing C/C Composites by Mean of Sol-gel Method,TB332
  14. Effect of Cobalt Doping on the Morphology and Magnetism of ZnO Crystals,TB34
  15. Technical Study on the Synthesis of Mullite Powder and Whisker via Non-Hydrolytic Sol-Gel Route,TQ110.6
  16. Preparation and Characteristization of Zinc and Molybdenum Diluted Magnetic Semiconductor Compound,TN304.2
  17. The Magnetic Study of Zinc Oxide-based Diluted Magnetic Semiconductors,O482.5
  18. Preparation and Properties of Glycerol-based Phase Change Materials,TB34
  19. Study on the Synthesis Bi3.25La0.75Ti3O12（BLT） Nanotubes and Nano Wires,TB383.1
  20. Preparation of Perovskite-Type Lean-Burn NSR Catalysts BaFeO3 and Their NOx Storage and Sulfur-Resistance Performance,O643.36

CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
© 2012 www.DissertationTopic.Net  Mobile