Dissertation > Excellent graduate degree dissertation topics show

The Study of the Infrared Spectra on the Electron Doped Superconductor Nd1.85-xRxCe0.15CuO4±δ （R=Gd and Sm）

Author: JiangChengZuo
Tutor: YangHongShun
School: University of Science and Technology of China
Course: Condensed Matter Physics
Keywords: Electronic -type high-temperature superconductors Doping effects Infrared Spectroscopy
CLC: O511.4
Type: Master's thesis
Year: 2011
Downloads: 18
Quote: 0
Read: Download Dissertation

Abstract


The transition metal compound contains many rich and exotic physical properties, and thus become one of the hot issues of the condensed matter physics research, such as of this thesis copper oxide high temperature superconductivity, the nature of the infrared spectrum. These exotic physical properties of the excited great interest and enthusiasm. So far, not yet a full fledged theory to explain the nature of these singular, thus the study of transition metal compounds has been widespread concern. The element substitution method plays a very important role in the study the physical properties of high-temperature superconductors, scientists have done a lot of work on E-superconductor doped research aimed to explore the mechanism of high-temperature superconducting temperature to suppress. In this paper, we e-type high-temperature superconductor Nd the 1.85-x R x Ce 0.15 of CuO 4 ± δ (R = Gd and Sm) single crystal X-ray diffraction spectrum, electrical resistivity, infrared spectroscopy, performed a series of research and exploration. The first chapter, we briefly crystal structure of copper-oxide high-temperature superconductors and superconducting phase diagram and anomalous behavior of the copper-oxide high-temperature superconductors and theoretical and experimental research progress in this regard. At the same time we also briefly element substitution on the nature of the copper oxide. The second chapter we introduce the principle of infrared (IR) spectroscopy and infrared spectroscopy, outlines the status and progress of the copper oxide high-temperature superconductors, infrared spectroscopy study. The third chapter introduces the Nd 1.85-x R x Ce 0.15 CuO 4 ± δ (R = Gd and Sm) single crystal growth method. X-ray diffraction pattern without any impurity peak, the FWHM of the peak is very small, suggesting that the preparation of single-crystal samples with high quality, laid an important foundation for our follow-up study. The fourth chapter studies the different doping concentration the the Nd of 1.85-x R x Ce 0.15 CuO 4 ± δ < / sub> (R = Gd and Sm) single crystal X-ray diffraction of the samples, Fourier transform infrared spectroscopy and resistivity was studied. Its purpose is to study with the doping concentration of the gradual increase in the infrared spectral changes, explore whether the infrared spectra help to reveal the reason of superconducting suppression. No other impurity peak and peak half-height width is very small, X-ray diffraction results show that the quality of single-crystal samples of the two doping system is very good. The lattice constant c of the two systems along with the increase in the doping amount of reduced, wherein the reduction rate of Gd doped system significantly larger than the SM. Gd doping, with increase in the doping amount of infrared spectrum is gradually moved to the high frequency, and Sm doped infrared spectral peaks remained almost unchanged. This indicates that with Gd substituted Nd causes the Cu-O bond becomes short, and substituted with Sm Nd Cu-O bond length almost unchanged. Gd doping, the decrease of the lattice constant c, and the Cu-O bond becomes short so that the cell volume at a reduced speed is greater than the Sm doping makes Gd doping Fermi surface state density lowers the rate is greater than the Sm-doped Miscellaneous. The Gd x the make Nd -1.85-x Ce 0.15 Nd of CuO 4 ± δ superconducting repression rate greater than < sub> 1.85-x Sm x Ce 0.15 CuO 4 ± δ become possible. Resistivity measurements, we compared the Gd x the Nd 1.85-x Ce 4 ± δ of CuO 0.15 and Nd -1.85-x Sm the x Ce 0.15 of CuO 4 ± δ superconducting transition temperature TC with doped miscellaneous changes, found that the superconducting transition temperature TC with increasing doping content between the two systems are suppressed, however, Gd doping, the superconducting transition temperature TC is intense repression, and for Sm doping, the superconducting transition temperature TC with doping reduce the relatively slow increase in the amount of two doping system in the unit cell volume and the density of states at the Fermi surface of this phenomenon with the doping amount of changes. This is taking a step forward to prove the above inference.

Related Dissertations

  1. Analysis of Infrared Spectral Features and Identification of Al-responsive Genes in Small Black Soybean with Aluminum Stress,S529
  2. Monitoring Leaf Nitrogen Status in Rice with Near Infrared Spectroscopy,S511
  3. Infrared spectroscopy surfactant aqueous two- phase system of,O647.2
  4. Influence of Doping Effect on Zinc Oxide by First Principles Studies,O614.241
  5. Experimental Study on the Ethylene/air Diffusion Flame Based on Near-infrared Emission Spectrometry Measurement,TK16
  6. Instrument-to-Instrument Calibration Transfer and Standardization of Spectra,O657.33
  7. Impact aerobic granular sludge formation and structural stability of the key components of extracellular polymer research,X703
  8. DSP FPGA -based near-infrared detector key technology research,TN791
  9. SBS Content Testing and Quality Evaluation of SBS Modified Asphalt,U414
  10. Clinic Study of the Composition of Encrustation on Double J Ureteral Stent,R699.4
  11. Research on the Method of Near-infrared Detection of E.coli,R378
  12. The Theoretical Prediction of Isomers and Infrared Spectrum of Interstellar Molecule SiC4H,O561.3
  13. Application of Two-Dimensional Infrared Correlation Spectroscopy in Starch Analysis,TS231
  14. Study on Identification of Cashmere and Wool Using Near Infrared Spectroscopy,TS131
  15. Study on Predict the Carcass and Beef Quality of Kerchin Cattle,TS251.52
  16. The Rapid Detection of Soil Moisture Based on Near-Infrared Spectroscopy and Machine Vision,S152.7
  17. The Research on Processing Method of NIR Diffuse Reflectance Spectral Signal Based on Wavelet Transform,TN911.74
  18. Study on Rapid Detection of Freshness of Raw Meat and Adulteration Meat by Near Infrared Spectroscopy Analysis,O657.33
  19. Application of Near Infrared Spectroscopy Conformity Test、 Correlation Coefficient and PLS to Identification and Quantitative Analysis of Traditional Chinese Medicine,O657.33
  20. Non-destructive Detection of Kiwifruits,peaches and Pears Quality Based on Near-infrared Spectroscopy Analysis,TS255.7
  21. The Study of the Algorithm of Infrared Spectrometry Quantitative Analysis on Aqueous Solution Using Wavelet Transform,O657.33

CLC: > Mathematical sciences and chemical > Physics > Low Temperature Physics > Superconductivity > Superconductors nature
© 2012 www.DissertationTopic.Net  Mobile