Apatite Oxide Multilayer Body for Thermal Expansion Matching
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Solution Overview
Problem
Cracks occur between substrates and solid electrolytes due to thermal expansion differences, reducing the performance and reliability of electrochemical devices.
Innovation Solution
A layered body with a substrate and an oxide portion containing rare-earth elements, silicon, and oxygen, exhibiting a diffraction peak at 2θ = 51.9° ± 0.9° and a controlled thermal expansion ratio of 0.15 to 1.45, ensuring high ion conductivity and minimizing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the solid electrolyte is heated to cause sufficient ion conductivity, then ion conductivity is improved, but cracks occur between the substrate and solid electrolyte due to thermal expansion difference
Solution Approach 1:
The patent modifies the thermal expansion coefficient of the solid electrolyte by changing its chemical composition (adding specific oxides like Al2O3, SiO2, or adjusting rare earth element ratios) to match the substrate's thermal expansion coefficient. This parameter adjustment prevents thermal stress-induced cracks during heating while maintaining high ion conductivity.
Solution Approach 2:
The patent employs composite material design by combining the solid electrolyte with specific oxide additives or creating a multi-layer structure that includes buffer layers. This composite approach allows the material to exhibit both high ion conductivity and matched thermal expansion properties, resolving the contradiction between conductivity and structural integrity.
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 layered structure effectively suppresses crack formation during thermal cycling, maintaining high ion conductivity and device reliability.
Implementation Method 1
a ratio of linear expansion coefficient of the oxide that is contained in the oxide portion in an a-axis direction relative to linear expansion coefficient of the substrate is 0.15 or more and 1.45 or less
Data Source
Figure 1
AI summary
A layered body (10) includes: a substrate (11); and an oxide portion (13) positioned on the substrate (11). An oxide that constitutes the oxide portion (13) contains at least two or more rare-earth elements: silicon; and oxygen. The oxide that is conatined in the oxide portion (13) exhibits a diffraction peak derived from a (004) plane at a position of 2θ = 51.9° ± 0.9° in an X-ray diffraction pattern, and has an apatite crystal structure. The ratio of linear expansion coefficient of the oxide that constitutes the oxide portion (13) in an a-axis direction relative to linear expansion coefficient of the substrate (11) is 0.15 or more and 1.45 or less.