Preparation And Up-Conversion Luminescence Properties Of K₂O-ZnO-P₂O₅-SiO₂ Glass Ceramics

Rare earth ions doped up-conversion luminescent materials have a wide range of applications in the fields of display,photovoltaic,sensors,all-solid-state lasers and medicine.In this thesis,the optimal composition of K₂O-Zn O-P₂O₅-Si O₂ system precursor glass was determined by controlling variable method.A series of Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺doped KZn PO₄ crystal phase transparent glass ceramics were prepared by melting-solidification-crystallization method.The phase composition,microstructure,optical transmittance,up-conversion emission spectrum and chromaticity coordinates of glass ceramics were studied.The prepared glass ceramics were tested by X-ray diffraction（XRD）,and the obtained data were compared with the standard card to determine the precipitation of KZn PO₄crystal phase in the glass ceramics.Combined with differential scanning calorimetry（DSC）curve,XRD,scanning electron microscope（SEM）photos and light transmittance curve,the optimum heat treatment conditions of Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺doped glass ceramics were determined to be 670℃/60 min,660℃/60 min and 650℃/60 min respectively,and the light transmittance in the visible range reached about 80%,79%and75%,respectively.The luminescence properties of Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺doped glass ceramics with different doping concentrations were studied by up-conversion emission spectra under 980 nm excitation.By calculating the critical distance,the reason for the concentration quenching was the electrical multipole interaction.The optimum doping concentrations of Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺were determined to be 0.5%-1.0%,0.3%-0.8%and 0.3%-0.8%,respectively.According to the relationship between the pump power and the emission intensity,the up-conversion luminescence mechanism and the energy transfer between rare earth ions are studied.It is determined that there is energy transfer from Yb³⁺to Er³⁺,Tb³⁺and Ho³⁺.The up-conversion processes of Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺are two-photon processes.The CIE chromaticity coordinates of0.5%Er³⁺-1.0%Yb³⁺,0.3%Tb³⁺-0.8%Yb³⁺and 0.3%Ho³⁺-0.8%Yb³⁺doped glass ceramics were calculated by CIE chromaticity coordinate software.The chromaticity coordinates are in the green light region,and the color purity is 88.51%,75.64%,and 82.22%,respectively.The results show that Er³⁺-Yb³⁺,Tb³⁺-Yb³⁺and Ho³⁺-Yb³⁺doped transparent glass ceramics containing KZn PO₄ crystalline phase have broad application prospects in the fields of all-solid-state green lasers,printing and lighting.