Research Of Rare Earth Ions Doped La₂W₂O₉Red Luminous Phosphor

As a novel lighting source, white light LEDs have been rapidly developed andwidely used. Techniques for producing white light from LED methods vary.The whitelight LEDs generated from near ultraviolet（near-UV） light use tri-phosphor（red, green,and blue phosphors）. Where, red phosphors emit at low-frequency, and most of them areunstable sulfides. Consequently, to develop high active, stable red phosphors, which canbe used to generate white light LEDs from near-UV light, is significant.In this thesis, a new kind of red phosphor based on rare-earth-ion-doped tungstate isproposed. Eu³⁺ion’s main excitation peak is exactly in the near-UV bands for its special4f electron configuration. Incorporating Eu³⁺ions in tungstate matrices as activators, andunder near-UV light excitation, the⁵D₀â†'⁷F₂transitions of Eu³⁺can emit red light at616nm.High-temperature solid-phase method was used to produce the white light LED byusing the red phosphor La₂W₂O₉:Eu³⁺with urea as the fuel, and polyethylene glycol as adispersant. Influences of different experimental conditions on luminescent properties ofthis new phosphor were tested by using spectrophotometer while characterizing thephosphor by XRD and TEM respectively. The experiments show that this material is anew kind of red phosphor for producing white light. It can emit red fluorescence light ofgood monochromaticity. The luminous intensity of this material varies with the changesof density of Eu³⁺ions and preparation temperature.The fluorescence emission spectrum of red phosphor La₂W₂O₉:Eu³⁺was observed atlow temperature in high magnetic field. And its spectral characteristics under thiscondition are discussed in this thesis. Red shift and peak splitting appear in the spectrumat low temperature. The luminous intensity increases as the temperature decreases.