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Study on the synthesis and properties of light-emitting and absorbing 3 Nd -doped BaTiO Nano

Author: XiongJian
Tutor: YangBingChu
School: Central South University
Course: Condensed Matter Physics
Keywords: BaTiO3 Nd-doping photoluminescence upconversion microwave absorbing
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 46
Quote: 0
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Abstract


BaTiO3 has excellent ferroelectric, dielectric and piezoelectric properties, as the base material of electronic components, optical and absorbing aspects is widely applied. In order to improve the performance of BaTiO3, doping is obviously very meaningful. High purity BaTiO3 and Nd-doped BaTiO3 nanocrystallines powder was prepared with sol-gel method. Composition, microstructure, photoluminescence and high-frequency electromagnetic properties of the as-synthesized nanocrystallines were characterized by X-ray diffraction (XRD), IR, fluorescence spectrum and vector network analyzer respectively, which focuses on analyzing the effecting Nd-doped on microstructure and high-frequency electromagnetic properties of BaTiO3 powder. Also, the up-conversion mechanism and the microwave absorbing properties of BaTiO3 powder were studied.Using Barium acetate (AR), tetrabutyl titanate (AR) as raw materials, Neodymium Nitrate (CR) as doped raw materials; acetylacetone as a chelating agent, acetic acid (AR) and ethanol (AR) as the solvent, the clear yellow BaTiO3 precursor sol was prepared by sol-gel method at 90℃. The high purity, good crystallinity, doped uniform BaTiO3 nanopowders were obtained by sintering at>60℃.X-ray diffraction and Fourier infrared spectral analysis showed that the samples were tetragonal phase structure and without other impurity except little BaCO3. Nd-doped can lead to the lattice size first decreases then increases. The length is shorted and the bond energy is enhanced of Ti-O bond.Fluorescence spectrum analysis shows that all visible bands light appear excited by 400nm. However, there was no obvious photoluminescence peak excited by 800nm. The phenomenon of up-conversion light appear under excited by 800nm. The strongest photoluminescence peak, whose intensity increased with the Nd content, appeared in 531.5 nm. Maximum quenches concentration reached 10%.The electromagnetic parameters analysis shows that Nd- doped led to electromagnetic parameters blue-shift, Nd-doped has obviously improved the electromagnetic reflection losses of the BaTiO3 through calculation according to electromagnetic parameters. The intensity of reflection losses peaks of Nd-doped BaTiO3 at 4.43GHz、7.14GHz、13.36GHz were increased 18.3 dB,14.3 dB,10.92 dB compare with pure BaTiO3, respectively. Lowest peak reached -29.7dB. Nd doped broaden bandwidth obviously, the most obvious place up to 7 times, the other mostly reached 4 times. In sum, Nd doping can obviously improve the microwave absorbing properties of BaTiO3.

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