Study On Fabrication And Properties Of Phosphate Glass Ceramic Composite Materials For White LED

White LEDs have become the fourth generation of solid lighting source due to their outstanding performance such as high light efficiency,low energy consumption,long life.Phosphate luminescent glass has appropriate phonon energy,stable structure,high solubility of rare earth ions and excellent luminous properties,which are expected to be used as key conversion materials for white LEDs.Therefore,it is of great theoretical significance and application prospect to carry out the research of new phosphate luminescent materials for white LEDs.In this paper,a series of P-B-Sr-K?PBSK?phosphoborate matrix glasses with different B/P ratios were successfully prepared by melt quenching,and nanocrystalline glass ceramics were prepared by step temperature method.FT-IR,DSC,XRD and TEM were used to test and analyze the glass structure,crystallization behavior,and the structure of glass ceramics.The appropriate B/P ratio glass was selected as the matrix glass to prepare Tm³⁺/Dy³⁺co-doped and Tm³⁺/Tb³⁺/Mn²⁺tri-doped luminescent glass and glass ceramic.The optical properties and thermal stability of luminescent glass and glass ceramics were studied by relevant physical parameters,transmission spectrum,absorption spectrum,fluorescence spectrum,fluorescence lifetime,Inokuti-Hirayama model,CIE and temperature-depened spectrum.In addition,the YAG:Ce³⁺phosphor/glass composite?Pi G?was prepared by the secondary melting method.The physical and optical properties of Pi G were studied by density,transmission spectrum,fluorescence spectrum,external quantum efficiency and SEM.The comprehensive optical performance of the Pi G-type w-LED device was analyzed by the photoelectric test system.Through the careful study of the above glass,glass ceramics and Pi G,the main results are as follows:1.In the PBSK glass,[PO₄],[BO₄],and[BO₃]unites are bridged to form a chain structure containing P-O-B bonds through oxygen ions sharing a apex angle.Sr²⁺and K⁺ions are connected to form an amorphous layered structure.With the increase of the B element content,the[BO₃]trihedron in the glass network structure gradually changed to a more stable[BO₄]tetrahedron.The thermal stability of the phosphoborate glass gradually becomes stronger and then stabilizes.At the same time,the introduction of B₂O₃ is beneficial to the glass-forming ability and the crystallization ability.When B/P ratio is 0.4 and 0.8,the matrix glass can successfully precipitate glass ceramics with crystal phases of KSr PO₄ and Sr₁₀?PO₄?₆O,respectively.2.White light can be emitted by adjusting the excitation wavelength and the co-doping concentration of Tm³⁺/Dy³⁺.Tm³⁺transfers energy to Dy³⁺ions with electric dipole-electric dipole nonradiative transitions.When Tm³⁺and Dy³⁺ion doping concentrations are 0.2 mol%and 1.0 mol%,respectively,white light with a CIE of?0.324,0.333?and CCT of 5898.82 K can be emitted under the excitation wavelength of 354 nm.Luminous glass has good thermal stability.The step temperature mothed was used to successfully prepare the luminescent glass-ceramics with KSr PO₄ phase,which has good transparency;the emission spectral intensity of the luminescent glass-ceramics is significantly better than that of glass.3.Tm³⁺/Tb³⁺/Mn²⁺tri-doped PBSK5 matrix glass samples can emit white light when excited by near-UV light.When Tm³⁺/Tb³⁺/Mn²⁺ion doping concentration is 0.3/1.2/1.5mol%,the luminescent glass can emit white light with CIE of?0.337,0.353?and CCT of5312.35 K under 354 nm excitation wavelength.Both Tb³⁺and Tm³⁺ions have potential energy transfer to Mn²⁺ions.The luminescent glass ceramics with Sr₁₀?PO₄?₆O crystal phase has good transparency.The emission spectral intensity of the luminescent glass ceramics is significantly better than that of glass,and the color of the emitted light is almost unchanged.4.The P₂O₅-Zn O-Ba O-Na₂O phosphate low melting point matrix glass powder was prepared by the melt water quenching method and subsequent ball milling process,and the commercial YAG:Ce³⁺yellow phosphor was uniformly dispersed in the matrix glass by the secondary melting method to prepare the Pi G material.According to the optical properties,the optimal preparation process of Pi G materials was studied.YAG:Ce³⁺phosphor particles are uniformly dispersed and embedded in the matrix glass and maintain the original luminous performance.The Ce³⁺ions in Pi G materials can be effectively excited by 460 nm blue light and emit a broad yellow light emission band at 530 nm.Using 540 m A DC current to drive w-LED device obtained from a commercially available blue LED chip packaged with Pi G,which can emit white light with the power efficiency of 98 lm/W,the CIE of?0.300,0.339?,the CCT of 7125 K,and the CRI of 71.