High Refractive Index Silicate Glass Composition Devitrification Control
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Solution Overview
Problem
Current high refractive index silicate glasses suffer from poor thermal stability, high dispersion, and iridescence issues, along with challenges in manufacturing due to devitrification and crystallization, which affect their optical performance and reliability in applications like microscopes and virtual reality devices.
Innovation Solution
A glass composition with specific weight percentages of SiO2, B2O3, Al2O3, Li2O, CaO, BaO, MgO, SrO, ZnO, ZrO2, TiO2, Nb2O5, Ta2O5, La2O3, and Y2O3 is developed, offering a refractive index of 1.74 to 1.80, low density, high thermal stability, and resistance to crystallization, allowing for controlled cooling rates and liquidus viscosity greater than 25 Poises to prevent devitrification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high refractive index glass compositions are used to achieve high optical corrections and minimum weight, then refractive index and density are improved, but thermal stability deteriorates and dispersion increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the glass system by incorporating specific combinations of metal oxides (Nb2O5, TiO2, La2O3, ZrO2, Ta2O5) in controlled proportions. This changes the physical and chemical parameters of the glass to achieve a refractive index of 1.74-1.80 while maintaining thermal stability and reducing devitrification kinetics, thereby resolving the contradiction between high refractive index and thermal stability.
Solution Approach 2:
The patent creates a composite glass material combining multiple oxide components (silica base with additions of boria, alumina, and various metal oxides including niobium oxide, titanium dioxide, lanthanum oxide, zirconium oxide, and tantalum oxide). This composite approach allows the glass to exhibit enhanced optical properties (refractive index 1.74-1.80) while maintaining improved thermal stability and reduced devitrification, thus resolving the contradiction between high refractive index and thermal stability.
2Illumination intensity
If high refractive index glass compositions are used to achieve high optical corrections, then optical performance is improved, but dispersion increases causing iridescence
Solution Approach 1:
The patent optimizes the compositional parameters by carefully controlling the weight percentages of various metal oxides (Nb2O5: 5-25%, TiO2: 2-15%, La2O3: 5-25%, ZrO2: 2-10%, Ta2O5: 0-5%) to achieve a refractive index of 1.74-1.80. This precise parameter control allows the glass to provide high optical corrections while minimizing dispersion and iridescence, thereby resolving the contradiction between optical performance and harmful dispersion effects.
3Ease of manufacture
If conventional glass compositions are used for manufacturing, then production process is simple, but devitrification and crystallization occur during cooling
Solution Approach 1:
The patent modifies the chemical composition parameters to include specific oxide combinations (Nb2O5, TiO2, La2O3, ZrO2, Ta2O5) in controlled proportions. This composition modification changes the devitrification kinetics and crystallization behavior of the glass, allowing it to maintain reliability and resist crystallization during the cooling process while remaining manufacturable with standard glass production techniques.
Solution Approach 2:
The patent employs a glass composition that is designed to be processed through standard manufacturing methods without requiring specialized equipment or complex processing protocols. The composition tolerates typical manufacturing variations and cooling rates, making it as easy to manufacture as conventional glasses while achieving superior resistance to devitrification and crystallization, thus resolving the contradiction between manufacturing simplicity and reliability.
4Reliability
If fast cooling rates are applied to prevent crystallization, then glass formation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the compositional parameters to include specific oxide additions (Nb2O5: 5-25%, TiO2: 2-15%, La2O3: 5-25%, ZrO2: 2-10%, Ta2O5: 0-5%) that modify the devitrification kinetics of the glass system. This composition modification allows the glass to maintain amorphous structure and achieve reliable glass formation even at slower, more manageable cooling rates, thereby reducing manufacturing complexity and cost while maintaining glass formation quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The glass composition provides improved optical performance, thermal stability, and manufacturing flexibility by preventing crystallization, ensuring consistent optical properties and reduced manufacturing costs, while being free from harmful components.
Implementation Method 1
high refractive index glasses also exhibit poor thermal stability... resistance to crystallization... preventing crystallization
Implementation Method 2
high refractive index (nD)... refractive index from about 1.74 to about 1.80
Data Source
AI summary
A glass composition is provided. The glass composition includes: 25-40 wt % SiO2; 2.5-10 wt % B2O3; 0-10 wt % Al2O3; 0-15 wt % Li2O; 0-16 wt % of Li2O, Na2O, and K2O in total; 10-25 wt % CaO; 0-15 wt % BaO; 0-5 wt % MgO; 0-5 wt % SrO; 10-30 wt % CaO, BaO, MgO, and SrO in total; 0-7 wt % ZnO; 2-10 wt % ZrO; 2-15 wt % TiO2; 5-25 wt % Nb2O5; 0-5 wt % Ta2O5; 5-25 La2O3; and 0-5 wt % Y2O3. The glass composition has a refractive index from about 1.74 to about 1.80, a density from about 3.5 g/cm3 to about 4.0 g/cm3, a critical cooling rate from about 1° C./min to about 50° C./min, and a liquidus viscosity greater than 25 Poises.