Tunable Emission And Luminescent Performance Of Bi³⁺,Eu³⁺ Co-doped Phosphors

As we all know,white light emitting diodes（w-LEDs）have been widely concerned by researchers on account of the great advantages of low energy consumption,environmental friendliness,small size and long working lifetime,etc..Currently,commercial w-LEDs are prepared by YAG:Ce³⁺yellow emission phosphors and blue emission LED chip.Nevertheless,the light component of this type of w-LED lack of red light,which brings about the disadvantages of low color rendering index and high color temperature.Encapsulating near-ultraviolet LED chips with tricolor phosphors or directly exciting single-phase white light emitting phosphors by near-ultraviolet LED chips are two effective methods to solve this problem.Therefore,the exploitation of new single-phase white light emitting phosphors and red emission materials with excellent performances has become the current research hotspot.Whats more,because the non-contact optical thermometer with high sensitivity and rapid response time solves the defects of traditional contact temperature measurement（such as large error and rigorous environmental requirements）,the non-contact optical thermometer has gradually attracted extensive attention of researchers.In this text,Bi³⁺,Eu³⁺co-doped single-phase white light and red light emitting phosphors were synthesized successfully and the optical temperature measurement performance of Er³⁺ions in oxide host were investigated.1.Novel single-phase Na_3.6Y_1.8（PO₄）₃:Bi³⁺,Eu³⁺phosphor for tunable and white light emission:A series of Bi³⁺,Eu³⁺co-doped Na_3.6Y_1.8（PO₄）₃ phosphors were manufactured successfully,and its crystal structure,luminescent properties,luminescent mechanism and thermal stability were explored detailly.Under ultraviolet radiation,Na_3.6Y_1.8（PO₄）₃:Bi³⁺,Eu³⁺phosphors present adjustable emission of bluish green to white and blue to red.And the as-prepared white light emission sample possesses good quantum efficiency and thermal stability,which manifests that the target sample might have potential utilization value in the field of high power w-LEDs.2.Study on tunable luminescent properties of Y₄Ge O₈:Bi³⁺,Eu³⁺red phosphors:The crystal structure and luminescent properties of as-prepared phosphors were explored through X-ray diffraction and photoluminescence.In this host,adjustable emission of green to red can be obtained by adjusting doping content of Bi³⁺and Eu³⁺.And the quantum efficiency and thermal stability of the optimal red emission sample were explored in detail.Our results indicate that the red emission sample has potential value in w-LEDs.3.Up-conversion luminescence properties and temperature sensing performances of Ba₅Y₈Zn₄O₂₁:Yb³⁺,Er³⁺phosphors:A series of Ba₅Y₈Zn₄O₂₁:Yb³⁺,Er³⁺phosphors were carried out by traditional solid-state reaction method.Combining luminescence characteristics,energy lever structure and fluorescence decay curves,the up-conversion luminescence mechanism was deduced.And the reasons for the variation of luminescence intensity under different doping concentrations were elaborated in detail.In addition,the temperature sensing performances of optimal green emission sample were explored.Its maximum relative sensitivity is 1.36×10^-2 K^-1（at 293 K）.Hence,the Ba₅Y₈Zn₄O₂₁:Yb³⁺,Er³⁺phosphors have potential value in optical temperature sensing.