Design, Temperature Sensing And Scintillating Properties Of Novel Fluoride Glass Ceramics

The thesis is focused on the design, preparation, temperature sensing and scintillating properties of novel fluoride glass-ceramics. The thesis mainly includes three parts:(a) The fabrication, up-conversion and temperature sensing properties of K3YF6:Er3+ and KYb2F7:Er3+ glass-ceramics (Chapters 2 and 3); (b) The fabrication, photoluminescence and scintllating properties of KLu2F7:Tb3+ and KTb2F7 glass-ceramics (Chapters 4 and 5); (c) The fabrication and up-conversion luminescence properties of self-crystallized KYbF4:Ho3+ glass-ceramics (Chapter 6);The main contents are listed as follows:(1) The fabrication, up-conversion and temperature sensing properties of KsYF6:Er3+ glass-ceramics (GC):K3YF6 GC doped with lanthanide ions were successfully manufactured via traditional melt-quenching route. K3YF6 nano-crystals were already formed before heat-treatment, which is benefical for the control of nano-crystals size and incorporation of rare earth ions into nano-crystals. Eu3+ion is used as spectral probe to investitated the change of local structure. After heat-treatment, the symmetry of the matrix is significantly improved. Their structural and luminescent properties were systemically investigated. Moreover, the optical thermometry based on the fluorescence intensity ratio (FIR) of green up-conversion emissions from the thermally coupled energy levels (TCEL) of Er3+-doped K3YF6 GC was investigated systematically. The high energy level difference and sensitivity is obtained. All results manifest that such K3YF6:Er3+ GC with higher energy level difference, fair sensitivity, good stability and repeatability could be excellent candidates for highly sensitive optical thermal sensors.(2) The fabrication, up-conversion and temperature sensing properties of Er3+-doped KYb2F7 glass-ceramics:KYb2F7:Er3+ GC were successfully manufactured via traditional melt-quenching route. Their structural and up-conversion luminescent properties were systemically investigated. The greatly enhanced up-conversion intensity and obvious Stark splitting reveal the incorporation of Er3+ ions into high symmetry, low-phonon energy KYb2F7 nano-crystals. Besides, the optical thermometry based on the FIR of green up-conversion emissions from the TCEL of Er3+-doped KYb2F7 GC was investigated systematically. And the high energy level difference and sensitivity is achieved. All results manifest that such KYb2F7:Er3+ GC could be excellent candidates for highly sensitive optical thermal sensors.(3) The fabrication, photoluminescence and scintillating properties of KLu2F7:Tb3+ glass-ceramics:KLu2F7 GC doped with Tb3+ ions were successfully fabricated via melt-quenching technique and systematically investigated. After thermal treatment, greatly enhanced emissions for both photoluminescence (PL) and X-ray excited luminescence (XEL) and prolonged lifetimes are observed. Our results indicate that KLu2F7:Tb3+GC present potential applications in X-ray imaging.(4) The fabrication, photoluminescence and scintillating properties of self-crystallized KTb2F7 glass-ceramics:Self-crystallized KTb2F7 GC were successfully fabricated and systematically investigated. KTb2F7 nano-crystals were already formed before heat-treatment. By taking Tb3+ as host in KTb2F7 GC, greatly enhanced emissions for both PL and XEL are observed after heat-treatment. Nevertheless, the lifetimes of 543nm of Tb3+ are gradually shortened. These phenomena show that the degree of crystallinity is further increased after thermal treatment. Our results indicate that KTb2F7 GC present potential applications in X-ray imaging, such as industrial radiography and X-ray intensifying screen. And our strategy that takes active ions as host may contribute to designing other fluoride GC by using active ions as host.(5) The fabrication and up-conversion luminescence properties of self-crystallized KYbF4:Ho3+ glass-ceramics:Ho3+ -doped GC containing KYbF4 nano-crystals were successfully manufactured via melt-quenching technique. Their structural and luminescent properties were systemically investigated. KYbF4 nano-crystals were already formed before heat-treatment, which is benefical for the control of nano-crystals size and incorporation of Ho3+ ions into KYbF4 nano-crystals. The great enhancement, prolonged lifetime and obvious Stark splitting confirm the incorporation of Ho3+ into KYbF4 nano-crystals with lower phonon energy. Our results indicate that such GC containing KYbF4 nano-crystals are excellent up-conversion luminescence materials.