Glass ceramic, method for their preparation and their use

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Solution Overview

Problem

Transparent, colored glass ceramics, particularly lithium aluminum silicate (LAS) glass ceramics, face challenges in achieving a neutral color point while maintaining high IR transmission and being easy to produce, with existing methods requiring precise control of process conditions and using expensive neodymium oxide (Nd2O3) that limits color neutrality and increases production complexity.

Innovation Solution

A glass ceramic with a light transmittance of 0.1% to 80% at 4 mm thickness, comprising between 0.003% and 0.4% by weight of MoOs and more than 0.2% by weight of Nd2O3, with a molar ratio of Nd2O3/MoO3 less than 15, which allows for reduced MoOs content while maintaining comparable visible transmission, enabling adjustable color neutrality and increased IR transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If transparent, colored glass ceramics are produced with high light absorption (1%-5% transmission) for aesthetic purposes and to prevent glare from heating elements, then operator safety is improved and aesthetic appearance is enhanced, but the glass ceramic exhibits chromatic coloration that distorts display colors and limits visibility of display elements

Engineering Contradiction:
Improveglare from heating elementsVSAvoidcolor accuracy of display elements
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent changes the chemical composition parameters by adding specific coloring agents (0.003-0.4% MoO3 and 0.05-1.0% Nd2O3) to the glass ceramic matrix. This composition modification alters the optical properties to achieve neutral coloration while maintaining the desired light absorption level of 1%-5% transmission, thereby preventing glare without distorting display colors.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite glass ceramic system combining multiple coloring agents (molybdenum trioxide and neodymium oxide) with the lithium aluminum silicate base material. This composite approach allows synergistic effects where the combination of coloring agents achieves superior color neutrality and display accuracy compared to single coloring agents alone.

Inventive Principle:
Principle #40Composite materials

2Loss of information

If neodymium oxide (Nd2O3) is added to achieve color neutrality and neutralize inherent yellow coloration, then color accuracy of display elements is improved, but production complexity increases due to precise control requirements and material costs

Engineering Contradiction:
Improvecolor neutralityVSAvoidproduction process control
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent optimizes the concentration parameter of neodymium oxide to a specific range (0.05-1.0%, preferably 0.1-0.5%) to achieve effective color neutrality without excessive complexity. This parameter optimization ensures sufficient neutralization of yellow coloration while maintaining production feasibility and reducing the stringency of process control requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces molybdenum trioxide as an intermediary coloring agent that works synergistically with neodymium oxide. This intermediary substance helps achieve color neutrality through a more robust mechanism that is less sensitive to precise process variations, thereby reducing production complexity while maintaining color accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Loss of information

If high Nd2O3 content is used to counteract yellow coloration and achieve neutral color point, then color neutrality is improved, but production cost increases and susceptibility to devitrification occurs

Engineering Contradiction:
Improvecolor neutralityVSAvoidresistance to devitrification
Core Design Contradiction:
Loss of informationVSReliability

Solution Approach 1:

The patent optimizes the Nd2O3 content parameter to a moderate range (0.05-1.0%) rather than using high concentrations, and combines it with MoO3 coloring agent. This parameter optimization achieves sufficient color neutrality while maintaining the glass ceramic's resistance to devitrification and reducing production costs by avoiding excessive rare earth oxide usage.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coloring system combining MoO3 and Nd2O3 where the two agents work synergistically. This composite approach distributes the coloring function between two substances, reducing the burden on each individual agent and thereby maintaining glass stability and resistance to devitrification while achieving color neutrality.

Inventive Principle:
Principle #40Composite materials

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 solution provides a glass ceramic that is color-neutral, allowing white light to be perceived as white, supports high-resolution displays, and offers improved operator safety with reduced susceptibility to devitrification and impurity effects, while being more cost-effective and easier to produce.

Implementation Method 1

These compounds absorb especially in the visible range

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP3747839B1Glass ceramic, method for their preparation and their use
Publication Date: 2023.08.16 SCHOTT AG
  • EP3747839B1 patent drawingFigure 1~2

AI summary

The invention relates to a glass ceramic, in particular a transparent, colored, especially volume-colored glass ceramic, specifically a transparent, colored, especially volume-colored glass ceramic with a neutral color point, as well as a method for producing such a glass ceramic and its use.