Tunable photoluminescence from rare earth and transition metal ions activated silicate glasses and glass ceramics
The motivation of this thesis is given in the introduction, followed by the corresponding background. The second chapter gives the results and discussions in the form of publications. Firstly, dual-mode PL of mixed valence Eu3+/Eu2+ doped glass ceramics are investigated. During the crystallization processes, Eu3+ ions are partially incorporated into crystalline phases, and gradually reduced to Eu2+. It is investigated how to control the blue PL of Eu2+ and red PL of Eu3+ in these glass ceramics. Secondly, tunable IVMn2+/VIMn2+ PL of Li2ZnSiO4 glass ceramics are displayed. The Mn2+ ions are octahedrally coordinated in the SLZAKP glass. After crystallization, Mn2+ can be partially incorporated into the crystalline phase. Consequently, the ratio of IVMn2+/VIMn2+ and the emission color can be tailored by annealing temperature. Thirdly, broadband PL of V5+ doped SLZAKP glasses and corresponding Li2ZnSiO4 glass ceramics are studied. The PL from [VO4]3– is centered at 550–590 nm. After crystallization, a tenfold increase in the emission intensity is observed. Fourthly, broadband NIR PL of VINi2+ doped Ba-Al titanate glass ceramics is investigated. Ni2+ ions are tetrahedrally coordinated in precursor glasses, whereas Ni2+-species are incorporated into the crystalline environment in octahedral sites. The broadband NIR PL of VINi2+ spans the spectral range of 1.0–1.6 μm. Decay kinetics of the emission band can be adjusted. Lastly in this chapter, DC of one blue photon to two NIR photons is obtained from the Pr3+/Yb3+ co-doped SLABS glasses and Mn2+/Yb3+ do-doped Zn2GeO4. Pr3+ ions act as sensitizers by absorbing 415–505 nm photons and transferring the absorbed energy to Yb3+ ions in a cooperative down-conversion process. In the Zn2GeO4 lattice, intrinsic defect transitions and Mn2+ ions act as broadband spectral sensitizers by absorbing UV-Vis photons. The absorbed energy is transferred to Yb3+ ions in a cooperative DC process. The third chapter summarizes the thesis.