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Study Of Rare Earth Doped AlN Luminescent Nanomaterials

Posted on:2018-08-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:W WangFull Text:PDF
GTID:1311330515474278Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
White light emitting diodes?White LEDs?is the main direction of energy-saving light emitting device in the future,owing to these features like low energy consumption,high brightness,no environmental pollution and long operation time and so on.Rare earth?RE?ions doped AlN based luminescent nanomaterial perfectly combine the properties of AlN host with the luminescence characteristics of RE ions,holding potential utilization in White LEDs.But the relatively harsh synthesis conditions for AlN nanomaterial limit the development of AlN based luminescent nanomaterial.Consequently,it is of great importance to seek a simple and flexible chemical route to synthesize AlN nanomaterial at low temperature.The study subject of our paper is RE ions doped AlN based luminescent nanomaterial.The main content works of this paper are as follows: 1.We explored a simple chemical route to synthesize AlN nanomaterial using organic nitrogen source?such as urea and its derivatives?other than ammonia gas as N source.AlN nanomaterial with good crystallinity was successfully synthesized at relatively low temperature of 850 ? through this route.Firstly,the preparation conditions were confirmed by adjusting the ratio of nitrogen source to aluminum source and temperatures.We put forward the nucleation mechanism of AlN nanomaterial by detailed characterization methods,such as X-ray powder diffraction,transmission electron microscopy,X-ray energy spectrum and Thermogravimetric-differential scanning calorimetry analysis,Fourier transform infrared spectrophotometer and Photoluminescence spectrum.The as-synthesized AlN nanomaterial exhibited irregular morphology and blue light emission centered at 450 nm,which is derived from the oxygen defects in the AlN host.2.AlN:Tb luminescent nanomaterial was synthesized by solid state route using Tb3+ as activator.The effect of doping of Tb3+ ions into AlN host on the structure,morphology and photoluminescence properties was investigated.With the aid of photoluminescence spectra,the optimal doping concentration of Tb3+ is determined to be 0.3 % and the luminescence mechanism of AlN:Tb is provided.In addition,the photocatalytic property of AlN:Tb for hydrogen generation from water splitting was studied,showing an excellent photocatalytic property of 68 ?mol g-1 h-1.3.AlN:Dy luminescent nanomaterial was synthesized using the same route.The influence of the Dy3+ doping concentration and calcination temperature on the structure and photoluminescence properties of AlN:Dy were investigated.The results reveal that the Dy3+ doping concentration and calcination temperature rarely affected the structure and morphology of AlN:xDy,but had great impact on the photoluminescence properties.Besides,the emission spectra of AlN:xDy were comprised of characteristic emission of Dy3+ and emission from AlN host.Owing to the good thermal stability and chemical stability of AlN,a post-thermal treatment under air atmosphere was employed to the as-synthesized AlN:xDy samples.The results show that the post-thermal treatment would not change the crystal structure of AlN,and enhance the photoluminescence intensity significantly,making the light emission of AlN:Dy more close to white light.4.To better investigate the properties of RE ions co-doped AlN,we synthesized AlN:Ce,Tb and AlN:Ce,Dy luminescent nanomaterial.Results indicate that the co-doping of Ce3+ ions can dramatically improve the intensity of Tb3+ and Dy3+ emission.Moreover,AlN:Ce,Tb and AlN:Ce,Dy show red-shift excitation wavelength as compared with AlN:Tb and AlN:Dy,which is more suitable for application in White LEDs.5.At last,the as-synthesized AlN:Ce,Tb luminescence nanomaterial was used as fluorescent mark for manifesting latent fingerprint.The phosphor-marked fingerprints on various substrates can be clearly manifested with good contrast,high practicability and weak background inference,holding significant applications in the forensic field.
Keywords/Search Tags:Aluminum nitride, Solid state route, Rare earth ions, Tb, Dy, Ce, Photoluminescence, Manifest latent fingerprint
PDF Full Text Request
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