Multilayer Seed Epitaxial Growth for ReBCO Superconducting Crystals
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Solution Overview
Problem
Existing methods struggle to grow high-temperature superconducting single crystals containing two or more types of rare-earth metals due to significant differences in lattice constants between the precursor and the seed, which hinders epitaxial growth.
Innovation Solution
A method involving the use of a multilayer seed with a staircase-like structure and buffer crystals to reduce the lattice constant difference between the rare-earth barium copper oxide (ReBCO)-based precursor and the seed, facilitating epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-layer seed is used for crystal growth, then the structure is simple and easy to manufacture, but the lattice constant difference between the precursor and seed cannot be reduced, preventing successful epitaxial growth of high-temperature superconducting single crystals containing multiple rare-earth metals
Solution Approach 1:
The seed structure is divided into multiple layers with different materials, each having different lattice constants. The multilayer seed includes a first seed layer and a second seed layer, where each layer is designed to bridge the lattice constant difference between the precursor and the final crystal structure, enabling step-by-step epitaxial growth
Solution Approach 2:
The multilayer seed acts as an intermediary structure between the precursor and the target single crystal. Each seed layer serves as a transitional interface that reduces the lattice mismatch, allowing the crystal to grow epitaxially by providing intermediate lattice constant steps rather than requiring a direct interface between materials with large lattice differences
2Productivity
If the precursor is cooled rapidly to room temperature, then the crystal growth process is fast and productive, but the crystal orientation cannot be properly matched with the seed, resulting in poor quality single crystals
Solution Approach 1:
The cooling process is divided into multiple stages with different cooling rates. A first cooling rate is applied initially, followed by a second cooling rate at a different magnitude. This periodic variation in cooling rate allows the crystal to properly orient itself with the seed at higher temperatures, then rapidly cool to complete the growth process efficiently
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 successful growth of high-quality high-temperature superconducting single crystals with improved critical current density, enhancing magnetic field capabilities and power density.
Implementation Method 1
melting a portion of the precursor by heating the precursor to a peritectic temperature thereof or higher
Implementation Method 2
growing a single crystal by cooling the precursor to a crystal growth temperature thereof to match a crystal orientation of the seeds
Data Source
AI summary
A method of forming a high-temperature superconducting single crystal is capable of facilitating a high-temperature superconducting single crystal containing rare-earth metals to grow using a multilayer seed. The method includes: preparing a rare earth barium copper oxide (ReBCO)-based precursor containing rare-earth metals; preparing a plurality of seeds that differ in lattice constant; placing the prepared seeds on top of the precursor through stacking; melting a portion of the precursor by heating the precursor to a peritectic temperature thereof or higher; and growing a single crystal by cooling the precursor to a crystal growth temperature thereof to match a crystal orientation of the seeds. Despite being used to increase the area and maintain the soundness of the single-crystalline specimen in most single-crystal growth, a buffer herein is to facilitate a single crystal of a new composition to grow.