Study On Preparation Of Phosphate Glass-Ceramics

In this work, series of P₂O₅-Al₂O₃-SiO₂ (PAS) glass and rare-earth doped phosphate glass were prepared by melting-quenching method. Combined with the glass structure and crystallization properties of phosphate glass systems, compositional effects on glass thermal stability, and other properties of advanced phosphate glasses were investigated.Results indicate that 15-28mol% P₂O₅ can form a stable glass in PAS system. With the increase of P₂O₅ content, the P-O- bond become weaker and the P=O bond strengthen, which means that P5+ exists in [PO4] tetrahedron with partial P=O bond. At higher P₂O₅ content, the glass structure which composd by [PO4] and [SiO4] tetrahedron doesn't change.The form ability of PAS glass and non-isothermal crystallization properties were investigated by non-isothermal DSC experiment and ?atava and Ozawa-Chen method,the crystallization parameter of glass is accounted. Results indicateΔT and H·are appropriate criterion. At higher P₂O₅ content, the stability of PAS glass decreases. The crystal growth factor match crystal growth pattern which observe by SEM. The best glass heat-treated system is crystallized at 670℃for 1.5h.In this work, RE2O3(RE³⁺=La³⁺,Pr³⁺,Sm³⁺,Gd³⁺,Er³⁺,Yb³⁺, x=0.5¹0) doped PAS galss were prepared. The influence of rare-earth oxides on glass structure, thermal stability, category and morphology of crystal were investigated. The results indicated that rare-earth oxides act as network modifier, in the interspace of glass structure, does not change the basic glass structure,At higher RE2O3 content, the stability of PAS glass increases and the crystallization tendency decreases. With the addition of Yb2O3, the stability of the glass enhances and the activation energy E for crystallization increases when Yb2O3 content is less than 1.5wt%. The stability of the sample is the best and E is the largest at 1.5wt% Yb2O3 doped, then both decrease when Yb2O3 content is over 1.5wt%. The crystal phases in P₂O₅-Al₂O₃-SiO₂ glass-ceramics keep the same after Yb2O3 doped. The primary crystal phase is AlPO4 and the subordinate is Mg3(PO4)2.When Yb2O3 doped the phosphate glass crystal on the surface exist with globosity,while the other rare-earth oxides doped the phosphate glass crystal on the surface exist with acerous.When rare-earth oxides doped the phosphate glass, with the increase of CFS,TEC decreases. With the increase of rare-earth oxides molecular weight, hardness and density of phosphate glass increases.