Bismuth Oxide Optical Glass for Precision Molding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical glasses with high refractive index and dispersion often contain lead oxide, leading to mold contamination and environmental toxicity, while lead-free alternatives face challenges in achieving low glass transition points and high transparency in the visible region.
Innovation Solution
An optical glass composition with a high amount of Bi2O3, combined with other oxides, achieving a refractive index of 1.85 or greater and an Abbe number of 10 to 30, while maintaining a glass transition point of 480°C or lower, suitable for precision mold pressing and high transparency in the visible region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If lead oxide is used to achieve high refractive index and dispersion, then optical performance is improved, but mold contamination and environmental toxicity occur
Solution Approach 1:
The patent removes lead oxide from the glass composition entirely, extracting the harmful substance while maintaining the desired optical properties through alternative oxide combinations (Bi2O3, B2O3, SiO2, GeO2, Ga2O3, TiO2, Nb2O5, Ta2O5, WO3, ZrO2, HfO2, La2O3, Y2O3, Gd2O3, Lu2O3, Al2O3, In2O3, SnO2, Pb-free analogues). This extraction eliminates mold contamination and environmental toxicity while preserving high refractive index (1.85 or greater) and dispersion (Abbe number 10 to 30).
Solution Approach 2:
The patent changes the chemical composition parameters by replacing lead oxide with specific combinations of other oxides. By adjusting the proportions of Bi2O3 (25-80%), B2O3 (3-60%), SiO2 (3-60%), and other metal oxides, the glass achieves the required optical constants without lead. The composition ranges are optimized to maintain Tg ≤ 480°C while achieving nd ≥ 1.85 and νd between 10-30.
2Object-affected harmful factors
If phosphate-based glass is used to avoid lead oxide, then environmental toxicity is reduced, but glass transition point becomes too high and devitrification resistance decreases
Solution Approach 1:
The patent employs a composite oxide system combining multiple glass-forming oxides (B2O3, SiO2, GeO2, Ga2O3, TiO2, Nb2O5, Ta2O5, WO3, ZrO2, HfO2, La2O3, Y2O3, Gd2O3, Lu2O3, Al2O3, In2O3, SnO2) with network modifiers (Bi2O3, Pb-free analogues, RO, Rn2O). This composite approach creates a synergistic effect that lowers Tg to 480°C or lower while maintaining chemical stability and devitrification resistance, overcoming the limitations of single-system phosphate-based glasses.
3Object-affected harmful factors
If phosphate-based glass is used to avoid lead oxide, then environmental toxicity is reduced, but transparency in visible region is lost
Solution Approach 1:
The patent optimizes the optical parameters by selecting specific oxide combinations and their proportions. By controlling the composition within defined ranges (Bi2O3: 25-80%, B2O3: 3-60%, SiO2: 3-60%, and other oxides), the glass achieves absorption edge ≤ 450 nm, ensuring high transparency in the visible region (400-700 nm). The optical constants are precisely tuned to achieve nd ≥ 1.85 and νd between 10-30 while maintaining excellent visible light transmittance.
Data Source
AI summary
Optical glass having a refractive index (nd) of 1.85 or greater, and an Abbe number (νd) falling within the range of 10 to 30, which is suited for molding by precision mold press is provided. The optical glass is characterized by including B2O3+SiO2 in an amount of 3 to 60%, Bi2O3 in an amount of 25 to 80%, RO+Rn2O in an amount of 5 to 60% (wherein R represents one or more selected from a group consisting of Zn, Ba, Sr, Ca, and Mg; and Rn represents one or more selected from a group consisting of Li, Na, K, and Cs), with each component in the range expressed in oxide-based mole percentage, and is characterized in that transparency in the visible region is high, and that the transition point (Tg) is 480° C. or lower. The optical glass is characterized by having a spectral transmittance of 70% or greater at a wavelength of 600 nm for a thickness of 10 mm.