Gd2O3 nanopowders doped with different concentrations of Er3+ and Yb3+ were synthesized using the combustion method. The starting reagents‚ Gd(NO3)3 6H2O‚ Er(NO3)3 5H2O‚ Yb(NO3)3 xH2O and NH2CH2COOH (glycine)‚ which was used as a fuel in reaction‚ of an analytical grade were purchased from Sigma Aldrich and Alfa Aesar. The ratio of glycine to nitrate was kept as 0.56 [31‚ 32]. The appropriate amounts of the starting reagents were dissolved in a minimum amount of deionized water. The solution was
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CH1105: Materials Science Crystal Structure Assoc/Prof Timothy Tan Office: N1.2 B2-34 B2Tel: 6316 8829 E-mail: tytan@ntu.edu.sg Semester 1‚ 2013-2014 2013School of Chemical and Biomedical Engineering Why study structure of crystalline solids? To understand how atoms assemble geometrically into solid structures To describe the structure of solids To relate material properties to its structure 2 Energy and Packing Dense‚ regular packing Energy typical neighbor bond length typical
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characterized in terms of their crystalline structure (Powder X-Ray Diffraction)‚ microstructural behavior (Scanning electron microscopy)‚ Dielectric property (Permittivity analyzer) and crystal lattice vibration (Fourier-Transform Infrared Spectroscopy). In the X-Ray diffraction spectra‚ it is expected to observe the presence of a doublet peak from the reflection of (002) and (200) planes in tetragonal BT and an increase in its diffraction angle due to shorter distance between crystal planes.
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furnace. In this study‚ induction stress relieving is compared with the conventional method for plain carbon steels. Technical comparison between the two methods is conducted by mechanical properties measurement and residual stress analysis by X-ray diffraction method. Introduction: Residual stress is a macroscopic stress that is set up within a metal during non-uniform plastic deformation‚ as in cold drawing or thermal gradients‚ as in quenching or welding. Up to 45% area reduction is employed
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moved from a higher energy state back down to a lower energy level. Using a spectrometer with diffraction grating‚ a hydrogen lamp was observed and emission wavelengths compared with the known wavelength values. Flames from ignited sodium chloride were also observed and wavelengths calculated. To calculate the
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produce a diffraction pattern. If the crystal is pure enough and the diffraction pattern is developed very carefully‚ it is possible to reconstruct the positions of the atoms in the molecules that contain the basic unit of the crystal called the unit cell. By the early 1950s‚ scientists were just learning how to do this for biological molecules as complex as DNA. After discovering the existence of the A and B forms of DNA‚ Rosalind Franklin went on to achieve excellent X-ray diffraction patterns
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Optics (a) Interference Interference of light-Young’s experiment‚ Newton’s rings‚ interference by thin films‚ Michelson interferometer. Multiple beam interference and Fabry-Perot interferometer. Holography and simple applications. (b) Diffraction Fraunhofer diffraction-single slit‚
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room temperature around 34C‚ the solubility was found to be 92.41 gm/50 ml. The FT-IR spectroscopy was performed on pure zinc sulphate crystals to identify the presence of functional groups. The grown crystals have been subjected to powder X-ray diffraction to determine the unit cell dimensions and the crystal structure. The lattice parameters are found to be‚ a = 9.9810 Å‚ b = 7.2500 Å and c = 24.2800 Å‚ respectively. The values were in good agreement with those of the reported values. The TGA and
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characteristics of a periodic signal 3.Define funamental frequency 4.What is attenuation? 5.Describe the components of optical fiber cable. 6.Indicate some significant differences between broadcast radio and microwave. 7.What is the difference between diffraction and scattering? 8.List and briefly define important factors that can be used in evaluating or comparing the various digitial-to-digital encoding techniques. 9.What function doeas a modem perform? 10.What is QAM? Differentiate between guided
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pairs are involved in bonding‚ and that these electron pairs will keep as far away from each other‚ due to electron-electron repulsion. DETERMINING MOLECULAR GEOMETRY The molecular geometry can be determined by various spectroscopic methods and diffraction
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