Glass-Ceramic Composition for Transparent UV and NIR Blocking
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Solution Overview
Problem
Conventional UV/IR-blocking glass-ceramics face limitations due to perceived solubility limits of tungsten and molybdenum oxides, preventing the formation of glass-ceramics with sufficient quantities of tungsten and molybdenum-containing wavelength-dependent submicroscopic crystals, leading to non-transparent, opalized compositions.
Innovation Solution
The use of 'bound' alkalis, such as feldspar and nepheline, in glass compositions allows for the formation of a homogenous single-phase melt, enabling higher solubility of tungsten and molybdenum, which are then precipitated as non-stoichiometric suboxides or titanium suboxides with dopant cations, forming bronze-type solid state defect structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional alkali containing silicate glass-ceramics are produced with tungsten and molybdenum oxides, then UV and NIR blocking capabilities are achieved, but the glass-ceramics become non-transparent and opalized due to phase separation and crystallization
Solution Approach 1:
The invention changes the chemical composition parameters by introducing specific dopants (Fe2+, Fe3+, Co, Ni, Se) in controlled amounts to modify the optical properties and prevent phase separation, maintaining transparency while achieving UV/NIR blocking
Solution Approach 2:
The invention creates a composite glass-ceramic system combining multiple cationic species (Fe2+, Fe3+, Co, Ni, Se) with tungsten and molybdenum oxides in a silicate matrix, where each component contributes to different optical functions, achieving both UV/NIR blocking and transparency
2Object-affected harmful factors
If higher quantities of tungsten and molybdenum oxides are introduced to improve UV/NIR blocking, then blocking capability increases, but solubility limits are exceeded causing phase separation and opalization
Solution Approach 1:
The invention uses alkali metal oxides (Na2O, K2O, Li2O) and alkaline earth metal oxides (CaO, SrO, BaO) as intermediary components that enhance the solubility of tungsten and molybdenum oxides in the glass matrix, allowing higher concentrations without phase separation
Solution Approach 2:
The invention modifies the chemical environment parameters by adjusting the ratios of network formers (SiO2, B2O3), network modifiers (R2O, RO), and dopants to create a glass matrix with enhanced capacity to dissolve tungsten and molybdenum oxides
3Object-affected harmful factors
If submicron precipitates are formed through post-formation heat treatment to achieve wavelength-dependent optical properties, then UV/NIR blocking is improved, but the glass-ceramic structure becomes complex and manufacturing difficulty increases
Solution Approach 1:
The invention incorporates all necessary dopants and compositional adjustments in the initial glass melting stage, pre-configuring the material to achieve desired optical properties without requiring complex post-formation heat treatment processes
Solution Approach 2:
The invention optimizes the melting temperature, composition ratios, and cooling rate parameters during initial fabrication to directly control precipitate formation and optical properties, eliminating the need for separate heat treatment steps
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
This approach enables the production of glass-ceramics with improved UV and NIR blocking capabilities, achieving transmittance of at least 5% per mm over a 50 nm-wide wavelength band from 400 nm to 700 nm, with crystalline phases homogeneously distributed and rod-like morphology.
Implementation Method 1
These submicroscopic precipitates (e.g., tungstate- and molybdate-containing crystals) are absorptive of wavelength bands of light giving the glass-ceramic its optical properties
Implementation Method 2
The difference in densities of the constituents results in a stratification of the different liquids which gives the appearance to those skilled in the art of an immiscibility with one another
Implementation Method 3
Conventional UV/IR-blocking glasses (with low or high visible transmittance) are formed by introducing certain cationic species (e.g., Fe2+ to absorb NIR wavelengths and Fe23+ to absorb UV wavelengths, and other dopants such as Co, Ni, and Se to modify the visible transmittance)
Data Source
AI summary
A glass-ceramic includes glass and crystalline phases, where the crystalline phase includes non-stoichiometric suboxides of titanium, forming ‘bronze’-type solid state defect structures in which vacancies are occupied with dopant cations.