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Studies on growth, characterization, thermal and dielectric properties of yttrium doped dysprosium phosphate crystal
|Krishan K. Bamzai , Nidhi Kuchroo , Vishal Singh , Shivani Suri|
CGMR Lab, Department of Physics, University of Jammu, Jammu 180006, India
Yttrium doped dysprosium phosphate with zircon structure was synthesized as single crystal at ambient temperature from aqueous solution using rare earth chloride, phosphoric acid and traces of ammonium hydroxides. The yttrium doping in dysprosium phosphate was about 2%. The prepared crystal was then anlaysed for their structural investigations using X-ray diffraction (XRD), energy dispersive X-ray anlysis (EDAX) and scanning electron microscopic (SEM) studies. X-ray studies establishes crystal belonging to tetragonal system with cell parameters as: a = b = 7.1208 Å, c = 6.8257 Å and α = β = γ = 89.990. EDAX establishes all the constituent elements like yttrium, dysprosium, phosphorous and oxygen in the proportion as was expected for this composition. The theoretical atomic and weight percentage calculated on the basis of the formula Y0.02Dy0.98PO4xH2O fits very well with the experimentally calculated values. SEM studies shows growth in the form of fibres. The spectroscopic investigations were done using Fourier tansformed infra-red spectroscopy which shows presence of various functional groups including the water molecules. Thermal behaviour was studied using thermo-gravimetric techniques like thermogravemtric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). TGA shows that this material is thermally stable up to a temperature of 2000C and then decomposition begins. The decomposition takes place in two different stages where in the phosphate gets converted in oxides. Solid state reaction kinetics for the two stages of the decomposition was studied using three models viz., Horowitz - Metzger, Coats - Redfern and Piloyan - Novikova. Using these three models various values like energy of activation (E), order of reaction (n) and frequency factor (Z) were calculated. The activation energy for the first stage of decomposition is higher as compared to the second stage, thus suggesting that the formation of by product in this stage is hard reaction. Electrical property in the form of dielectric constant (∈') was calculated for different temperature ranging of 40 - 5000C in the frequency range of 102 - 103 kHz. The maximum value of ∈' was found to 432 for 10 kHz at a temperature of 5000C. The detailed results will be presented and discussed.
Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 6, by Krishan K. Bamzai
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-04-12 11:00 Revised: 2013-04-12 11:00