Luminescence Properties Of Er³⁺/Yb³⁺ Codoped And Er³⁺ Doped Molybdate Phosphors

Upconversion luminescence materials are one kind of light-emitting materials with the feature of emitting short wavelength photons while excited by long wavelength photons. Most of them are inorganic materials doped with rare earths. These materials can emit different color visible lights under the excitation by 980 nm infrared laser. The upconversion luminescence materials doped with rare earthe have been intensively studied because of their potential applications in many fields, such as laser, three-dimensional displays, medical diagnostics and optical amplifiers.Due to the special electron configuration at 4f level,4f5d energy level and charge transfer band structure of rare earth elements, their absorption spectra, excitation and emission spectra show a wide range and rich connotation luminescence properties. The wavelengths of the spectroscopy range from the vacuum ultraviolet to IR. Because the visible light materials doped rare earth ions have the properties of the large light emission intensity and high absorption luminous efficiency, they have been widely studied and used in a variety of display, lighting, X-ray intensifying screens, detecting and recording in nuclear physics and radiation field, and medical radiology imaging in various photographic techniques. In addition, they are also generally concerned used in fiber-optic communications, laser source, biosensors and fluorescence immunoassay and other fields.In this thesis, Er3+/Yb3+ codoped and Er3+ doped NaGd(MoO4)2 phosphors were synthesized via solid-state reaction method. Their down-converting and up-converting properties were investigated. The obtained results are described as follows:(1) Er3+ doped NaGd(MoO4)2 phosphors were synthesized via olid-state reaction method. The structure of the samples was investigated. It was found that the samples are the pure NaGd(Mo04)2 phosphors.(2) Er3+ doped NaGd(MoO4)2 phosphors’ luminescence properties in NIR were investigated according to the fluorescence spectra. The emission spectra excited by 532 nm. And their NIR properties were achieved.(3) Er3+/Yb3+ codoped NaGd(MoO4)2 phosphors were synthesized via olid-state reaction method. The structure of the samples was investigated. It was found that the samples are the pure NaGd(MoO4)2 phosphors.(4) Er3+/Yb3+ codoped NaGd(MoO4)2 phosphors’ down-converting properties were investigated with to the fluorescence spectra. We achieved the excitation spectra of 553 nm and the emission spectra of 274 nm and 380 nm respectively.(5) The dependence of UC emission intensity on the LD working current was also discussed. The two-photon process is responsible for both red and green upconversion emissions in the samples. The effects of LD pump current and dopant concentrations on upconversion luminescence were studied, and no concentration quenching was observed.