Papers by Keyword: Flux Method

Abstract: The crystals of aluminium metaphosphate Al(PO₃)₃ are synthesized by flux method. The photoluminescence properties of Al(PO₃)₃ are studied under the vacuum ultra violet (VUV) synchrotron excitations. The electronic structure of Al(PO₃)₃ crystal is calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. The photoluminescence (PL) emission spectra of of aluminium metaphosphate reveal emission bands in the ultraviolet-blue and in the yellow-red spectral regions. Obtained results point to an active role of the electronic states of phosphate groups in the processes of intrinsic luminescence in Al(PO₃)₃ crystals.

Abstract: PrFe₄P₁₂ shows an anomalously phase transition from a heavy fermion (HF) state to a non-magnetic ordered state. We prepared single crystal sample of Pr (Fe_1-xCo_x)₄P₁₂ by Sn-flux method to investigate the effects of electron doping. The distinct change of magnetic property was observed. The phase transition of PrFe₄P₁₂ rapidly disappears when doped rate x=0.03. This result indicates that the d-electron plays an important role in formation of Low-temperutre phase and HF state of PrFe₄P_12.

Abstract: The flux growrh method is employed to grow the Yb:LuPO4 crystal using lead pyrophosphate Pb2P2O7 as the high-timperature solvent. The infrared spectroscopy(IR) was tested to determine the purity of the obtained crystal. The absorption spectra of the 5% Yb-doped Yb:LuPO4 crystal was measured at room temperature. Three absorption peaks that located on 985nm, 976nm and 953nm were found, and the absorption cross sections on the absorption peaks were calculated respectively. The results shows that Yb:LuPO4 crystal has potential to be applied as laser material.

Abstract: Lead free piezoelectric single crystals of sodium potassium niobate (K _0.5Na_0.5)NbO₃ single crystals were grown by high-temperature solution method using B₂O₃ flux The KNN crystals grown by without B₂O₃ flux and with B₂O₃ flux are referred to as samples A and B respectively. It was found that additions of small amounts of boron oxide B₂O₃ further lower the melting temperature of the eutectic mixture and exhibits excellent dielectric properties. Phase analysis showed that all samples crystallized in pure orthorhombic perovskite phase. AFM morphological studies show that the root mean square (rms) roughness values were measured to be, 5.3nm and 6.96nm for the sample A and sample B crystal respectively. A slight decrease in the orthorhombic to tetragonal phase transition temperature T_OT> and Curie temperature T_c has been observed in sample B when compared with sample A.

Abstract: Ba2B5O9Cl whiskers with uniform morphology were synthesized by a simple flux method, using BaCl2•2H2O, H3BO3 as the starting materials, and KCl as the flux. The products were characterized by X-ray diffraction (XRD) and scanning electron microcopy (SEM), and the optimum conditions for preparing high quality Ba2B5O9Cl whiskers were studied. Results show that a sintering temperature around 700 °C, an Ba/B mole ratio of 1:3 and a raw materials to flux mass ratio of 1:2 lead to uniform orthorhombic Ba2B5O9Cl whiskers with a diameter of 0.4-1.0 µm and a length of 10-25 µm.

Abstract: Magnesium borate (Mg₂B₂O₅) whisker was successfully synthesized by high temperature flux method using Magnesium chloride, boric acid, sodium hydroxide and sodium chloride as raw materials.The as-prepared product was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy(SEM), Transmission Electron Microscope (TEM) and X-Ray Photoelectron Spectrometry (XPS). The results showed that the as-prepared sample had triclinic structure and consisted of whisker-like particles with an average diameter about 1.25 μm and length up to 40μm. XPS results confirmed that the molar ratio of each atom agreed with the stoichiometric composition of Mg₂B₂O₅. The growth mechanism was briefly discussed.

Abstract: Up-conversion luminescent materials of Y₂O₂S: Yb, Tm with different doping concentrations of Tm³⁺ ion (0.5 mol%–4 mol %) and Yb³⁺ ion (4 mol%–16 mol %) were prepared by flux method. As Tm³⁺ doping concentration was 1 mol% and Yb³⁺ doping concentration was 8 mol%, the blue and red up-conversion luminescent intensity reached the maximum. The concentration quenching of Tm³⁺ was due to the reducing of the distance between Tm³⁺ ions and the cross-relaxation increasing. The concentration quenching of Yb³⁺ was attributed to increasing of nonradiative transition. The blue emission intensity of ¹G₄→³H₆ was always weaker than the red emission intensity of ³F₃→³H₆, and the blue emission intensity of ¹G₄→³H₆ is similar with the red emission intensity of ¹G₄→³F₄.

Abstract: Up-conversion luminescent materials of Y2O2S:Yb, Er with different doping concentrations of Er3+ ion (1 mol%–6 mol%) and Yb3+ ion (4 mol%–16 mol%) were prepared by flux method. As Yb3+ doping concentration was fixed at 8 mol%, when Er3+ doping concentration was 2 mol%, the green and red up-conversion luminescent intensity reached the maximum. As Er3+ doping concentration was fixed at 2 mol%, when Yb3+ doping concentration was 4 mol%, the green and red emission intensity reached the maximum. The up-conversion luminescent colours were adjustable.

Abstract: 0.999Bi0.5Na0.5TiO3-0.001BaTiO3 (BNT-0.1%BT) single crystals with a maximum size of 1×1×1 mm3 were successfully grown by a flux method using BNT-6%BT powder and Bi2O3 as a flux. The crystals showed a remanent polarization of 33 μC/cm2 and coercive electric field of 40 kV/cm along [100]Cubic. Electric-field induced strain measurements along [100]Cubic revealed an effective piezoelectric strain constant d33 * of 80 pm/V.

Abstract: Sr or Ba filled type-I Ge clathrate single crystals were prepared using high pure elemental Ga, Ge, and Sr or Ba as the starting materials, and Ga as a flux. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC) were used to characterize the crystals, respectively. The results show that large and well-crystallized single crystals can be prepared under optimum synthesis condition. The composition of the crystals is in good agreement with the nominal composition (M8Ga16Ge30, M=Sr, Ba). Raman spectra of the single crystals were studied at room temperature and several of the Raman active vibrational modes in the crystals have been identified.