High Temperature Superconductive Films Bi-Layered Structure
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Solution Overview
Problem
Current methods for growing high-temperature superconductive films on substrates face challenges in achieving thick, high critical current density layers, particularly in forming two-side coated structures on polycrystalline metallic substrates, which are costly and inefficient due to thermal conductance and AC losses issues.
Innovation Solution
A bi-layered structure is formed using a thin, non-superconductive YBCO template layer on a substrate with a YSZ buffer layer, allowing a thick superconductive YBCO layer to grow, enabling two-side coating on sapphire substrates, which reduces thermal conductance and AC losses, and increases critical current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thick superconductive layer is grown directly on a substrate, then the critical current density increases, but the layer quality and superconductive properties deteriorate due to lattice mismatch and defects
Solution Approach 1:
The superconductive layer is divided into two segments: a thin template layer (5-50 nm) with optimized lattice parameters for quality growth, and a thick superconductive layer (100-1000 nm) for high critical current density. This segmentation allows each layer to be optimized for its specific function without compromising the other.
Solution Approach 2:
A template layer acts as an intermediary between the substrate and the thick superconductive layer. This intermediate layer has lattice parameters that are intermediate between the substrate and the final superconductive layer, enabling epitaxial growth of high-quality thick layers that would otherwise be impossible to grow directly on the substrate.
2Adaptability or versatility
If polycrystalline metallic substrates are used for two-side coating, then the manufacturing complexity increases, but thermal conductance and AC losses worsen
Solution Approach 1:
Sapphire substrates provide a homogeneous, single-crystal surface that enables identical superconductive layers to be grown on both sides with consistent properties. This homogeneity reduces defects and improves superconductive performance compared to polycrystalline substrates, while still allowing two-side coating capability.
3Quantity of substance
If a thin template layer is used to enable thick superconductive layer growth, then the manufacturing process complexity increases, but the critical current density improves
Solution Approach 1:
A thin template layer is deposited in advance on the substrate to prepare the surface for subsequent thick superconductive layer growth. This preliminary action creates the necessary lattice structure and surface conditions that enable high-quality thick layer formation, which would be impossible to achieve by direct deposition.
Solution Approach 2:
The lattice parameters of the template layer are specifically optimized to be intermediate between the substrate and the final superconductive layer. By changing the lattice parameters of the intermediate layer, the system enables epitaxial growth of thick superconductive layers with high critical current density that would otherwise suffer from lattice mismatch defects.
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 approach results in a superconductive layer with high critical current density and reduced thermal conductance, lowering costs and maintenance needs in applications like MRI machines and particle accelerators by allowing efficient two-side coating and improved insulation.
Implementation Method 1
both YSZ and YBCO layers were grown by off axis dc magnetron sputtering from stoichiometric single targets
Implementation Method 2
The substrate was heated by IR radiation and its temperature was estimated as 750° C
Implementation Method 3
An annealing process in pure oxygen was performed for 16 hours at approximately 500° C
Data Source
AI summary
Described is a superconductive layered structure and an article including this superconductive layered structure on a substrate structure. The superconductive layered structure comprises a stack including at least one bi-layered assembly formed by first and second layers of similar superconducting material compositions, the second layer being superconductive at predetermined temperature condition, the first layer being a substantially thin layer and having a c lattice parameter selected in accordance with those of the substrate structure and the second layer, such that said first layer is non-superconductive at said predetermined temperature condition thereby allowing the second superconductive layer to be desirably thick to provide high critical current density of the superconductive layer.