Effect of V2O5 colorant on the optical properties and crystallization behaviors of lithium disilicate glass-ceramics

摘要

To understand the coloration in glass-ceramics for dental application, the effect of V2O5 colorant on the optical properties and crystallization behaviors of lithium disilicate (LS2) glass-ceramics (GCs) has been investigated for two different systems of SiO2-Li2O-P2O5-K2O-ZnO and SiO2-Li2O-P2O5-K2O-Al2O3. For this study, the amount of V2O5, SiO2 + Li2O, and P2O5 were fixed to have 0.5, 93.5, and 1.5 mol%, respectively, while the ratios of both ZnO/K2O (Zn/K) and Al2O3/K2O (Al/K) were varied from 0.5 to 2. The GC samples were prepared by two-stage heat treatments of 500 degrees C for 1 h as a nucleation stage and 600, 700, and 800 degrees C for 2 h as a growth stage in air. The light green glass samples having only V5+ ion continuously changed to violet, blue, green, and brown for GC samples due to its reduction into V4+ and V3+ ions with progressing crystallization. TEM-EDS analyses revealed that a small amount of V5+ ion was incorporated into both LS2 and SiO2 crystalline phases, causing greenish fluorescence, while most of vanadium ions remained in a residual glassy matrix. At the growth temperature of 800 degrees C, while the growth rate of LS2 was increased by lowering the viscosity of the glass matrix, and thus the LS2 crystal size of the GVZ(1.5) and GVZ(3) samples became larger (similar to 1 mu m) compared with its size below 500 nm for the samples without V2O5 colorant. The GVAl(1.5) and GVAl(3) samples exhibited the smaller size (similar to 1 mu m) than GVZ(1.5) and GVZ(3) samples because of higher nucleation rate and lower growth rate, leading to undesirable high translucency for the dental application. (C) 2020 Elsevier B.V. All rights reserved.