Superconducting Wire Rod Reaction Suppressing Layer
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Solution Overview
Problem
The challenge in manufacturing superconducting wire rods lies in the difficulty of forming oxide superconductors with high crystalline orientation on substrates due to differences in thermal expansion and lattice constants, leading to impurity generation and adverse effects on superconducting properties, particularly when rare-earth elements in the cap layer react with Ba in the oxide superconducting layer during heat treatment.
Innovation Solution
A superconducting wire rod structure that includes a substrate, an intermediate layer, a reaction suppressing layer composed of polycrystalline SrLaFeO4+δ or CaLaFeO4+, and an oxide superconducting layer, where the reaction suppressing layer is formed between the intermediate layer and the oxide superconducting layer to prevent impurity formation, and a cap layer of CeO2 or PrO2 is used to enhance orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cap layer made of CeO2 or PrO2 is disposed directly below the oxide superconducting layer to enhance crystal orientation, then the biaxial crystal orientation is improved, but impurities such as BaCeO3 or BaPrO3 are generated due to reaction between the cap layer and oxide superconducting layer, which deteriorates superconducting properties
Solution Approach 1:
A reaction suppressing layer is introduced as an intermediary between the cap layer and the oxide superconducting layer. This intermediate layer prevents direct contact and chemical reaction between the cap layer materials (CeO2 or PrO2) and the oxide superconducting layer, thereby suppressing impurity generation while allowing the cap layer to maintain its crystal orientation function.
Solution Approach 2:
The interface structure between the cap layer and oxide superconducting layer is segmented into three distinct layers: the cap layer, the reaction suppressing layer, and the oxide superconducting layer. This segmentation separates the orientation-providing function from the reaction-preventing function, allowing each layer to perform its specific role without interference.
2Device complexity
If the oxide superconductor is formed directly on the substrate to simplify the structure, then the device complexity is reduced, but the differences in thermal expansion and lattice constants cause distortion or peeling-off during cooling, which deteriorates reliability
Solution Approach 1:
An intermediate layer is introduced between the substrate and the oxide superconducting layer as a buffer to accommodate differences in thermal expansion coefficients and lattice constants. This intermediate layer absorbs the mismatch stresses during cooling, preventing distortion and peeling-off of the oxide superconducting film, thereby ensuring film stability.
3Reliability
If the crystal axes a and b are oriented along the substrate surface to promote electricity flow, then the electrical conductivity is improved, but the crystal axis c must be oriented perpendicular to the substrate, which requires complex orientation control during deposition
Solution Approach 1:
The intermediate layer is prepared in advance with a specific crystal structure and orientation before depositing the oxide superconducting layer. This preliminary orientation of the intermediate layer serves as a template that guides the oxide superconducting layer to form with the desired crystal orientation (a and b axes in the plane, c axis perpendicular), simplifying the overall orientation control process.
Solution Approach 2:
The intermediate layer acts as an orientation mediator that translates the substrate's crystal structure into the required orientation for the oxide superconducting layer. It provides a crystallographic template that facilitates the formation of highly oriented oxide superconducting films with improved electrical conductivity without requiring complex direct orientation control.
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 configuration significantly reduces impurity formation, such as BaCeO3 or BaPrO3, thereby improving the superconducting properties and critical current of the wire rod by suppressing reactions between the cap layer and the oxide superconducting layer, resulting in enhanced crystal orientation and electrical conductivity.
Implementation Method 1
a reaction suppressing layer which is formed on the intermediate layer and mainly contains polycrystalline SrLaFeO4+δ1 or CaLaFeO4+δ2
Implementation Method 2
The oxide superconductor has electrical anisotropy such that the flow of electricity is promoted along the crystal axes a and b of the crystals itself, but the flow of electricity is impended along the crystal axis c of the crystals itself
Implementation Method 3
a superconducting wire rod obtained by depositing an oxide superconductor represented by a composition formula of REBa2Cu3O7−δ on a tape-shaped metal substrate
Data Source
AI summary
Impurities are reduced in an oxide superconducting layer and in an interface between the oxide superconducting layer and an intermediate layer. A superconducting wire rod 1 has a structure including a substrate (10), an intermediate layer (20) formed on the substrate (10), a reaction suppressing layer (28) formed on the intermediate layer (20) and mainly containing polycrystalline SrLaFeO4+δ1 or CaLaFeO4+δ2, in which the δ1 and the δ2 each represent an amount of non-stoichiometric oxygen, and an oxide superconducting layer (30) formed on the reaction suppressing layer (28) and mainly containing an oxide superconductor.