Beta-Eucryptite Lithium Tantalate Composite for Low Thermal Expansion
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Solution Overview
Problem
Current low thermal expansion materials exhibit limited temperature range stability and high bulk density, making them unsuitable for applications requiring low weight and high rigidity, such as optical components for space exploration, where they must maintain low thermal expansion properties over a wide temperature range without generating by-products that affect thermal expansion behavior.
Innovation Solution
A complex material comprising a β-eucryptite crystal phase and a lithium tantalate crystal phase, with a volume ratio of 90% or more β-eucryptite and 10% or less lithium tantalate, which maintains crystal states and does not generate additional phases, allowing for controlled thermal expansion and high rigidity while minimizing bulk density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low thermal expansion glass (β-eucryptite complex) is used, then low thermal expansion properties are achieved, but bulk density becomes high and temperature range stability is limited
Solution Approach 1:
The patent creates a composite material consisting of β-eucryptite crystal phase and lithium tantalate crystal phase. This composite structure allows combining the low thermal expansion properties of β-eucryptite with the high rigidity and lower density characteristics of lithium tantalate, achieving a balance between thermal stability and weight reduction.
Solution Approach 2:
The patent optimizes the compositional parameters by controlling the volume ratio of β-eucryptite (90% or more) to lithium tantalate (10% or less). This parameter optimization ensures that the composite maintains low thermal expansion coefficients while reducing bulk density to 3 g/cm³ or less, resolving the contradiction between thermal stability and weight.
2Strength
If conventional low thermal expansion materials are used, then thermal expansion control is achieved, but high rigidity and low weight cannot be simultaneously obtained
Solution Approach 1:
The composite of β-eucryptite and lithium tantalate crystal phases leverages the complementary properties of both materials. Lithium tantalate contributes high rigidity and piezoelectric properties, while β-eucryptite provides low thermal expansion. The resulting composite achieves high rigidity with reduced bulk density, overcoming the limitations of conventional single-phase materials.
Solution Approach 2:
The patent maintains the crystal states of both components locally within the composite structure, allowing each phase to retain its inherent properties. The β-eucryptite domains provide low thermal expansion while lithium tantalate domains provide high rigidity, achieving local optimization of properties that translates to overall material performance.
3Ease of manufacture
If additional crystal phases or glass phases are generated in the complex, then material formation is complete, but thermal expansion behavior becomes unpredictable and reliability decreases
Solution Approach 1:
The patent establishes specific compositional parameters (β-eucryptite: 90% or more, lithium tantalate: 10% or less by volume) and controls sintering conditions to prevent the formation of unwanted phases. By optimizing these parameters, the material achieves complete reaction between components while maintaining only the desired crystal phases, ensuring predictable thermal expansion behavior and high reliability.
Solution Approach 2:
The patent selectively removes or prevents the formation of unwanted by-product phases through controlled composition and sintering parameters. By extracting the harmful variable (uncontrolled phase formation) from the system, the material achieves phase purity with only β-eucryptite and lithium tantalate crystal phases, ensuring consistent thermal expansion properties.
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 complex material achieves low thermal expansion coefficients near zero over a wide temperature range (0-50°C) with a bulk density of 3 g/cm3 or less, enhancing its suitability for lightweight, high-rigidity applications like optical components for space exploration.
Implementation Method 1
β-eucryptite exhibits negative thermal expansion behavior
Implementation Method 2
lithium tantalate exhibits positive thermal expansion behavior
Data Source
AI summary
A complex according to the present disclosure contains a β-eucryptite crystal phase and a lithium tantalate crystal phase. In a temperature range of 0 to 50° C., a coefficient of thermal expansion calculated for each 1° C. is within 0±1 ppm/K. Calcium is contained in the lithium tantalate crystal phase. The volume ratio of the β-eucryptite crystal phase to the lithium tantalate crystal phase is from 90:10 to 99.5:0.5.