LMO Substrate Doping for Superconducting Wire Rod Crystal Orientation
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Solution Overview
Problem
The challenge is to lower the phase transition temperature at which the crystal lattice of LaMnO3+δ (LMO) becomes cubic, allowing for epitaxial growth of another oxide thin film while maintaining the mechanical strength of the superconducting wire rod, as higher growth temperatures reduce mechanical strength and make it difficult to achieve biaxial orientation.
Innovation Solution
A substrate with an oxide layer composed of Laz(Mn1−xMx)wO3+δ, where M represents Cr, Al, or Ti, and δ is an oxygen non-stoichiometric amount, is used, with x ranging from 0 to 1, to lower the phase transition temperature and enhance crystal orientation, thereby reducing strain and maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the growth temperature of the oxide layer including LMO is set high (above phase transition temperature) to enable epitaxial growth and cubic crystal structure, then the crystal orientation is improved, but the mechanical strength of the superconducting wire rod deteriorates
Solution Approach 1:
The patent modifies the compositional parameters of LMO by doping with Cr, Al, Co, or Ti at the Mn site, which changes the phase transition temperature parameter. This allows the material to maintain cubic crystal structure at lower temperatures, enabling epitaxial growth without exposing the superconducting wire rod to high temperatures that would compromise mechanical strength
Solution Approach 2:
The patent creates a composite oxide layer by combining LMO with dopant elements (Cr, Al, Co, or Ti) at the Mn site. This composite material exhibits modified phase transition behavior, maintaining cubic structure at lower temperatures while still enabling effective epitaxial growth of subsequent oxide layers, thus resolving the contradiction between crystal orientation and mechanical strength
2Temperature
If the phase transition temperature of LMO is lowered through doping, then the growth temperature can be reduced preserving mechanical strength, but the crystal structure stability may deteriorate
Solution Approach 1:
The patent carefully controls the doping concentration parameter (x in Laz(Mn1-xMx)wO3+δ) to achieve the desired phase transition temperature reduction while maintaining crystal structure stability. The specific dopant elements (Cr, Al, Co, Ti) are selected for their ability to stabilize the cubic structure at lower temperatures without introducing excessive lattice distortion
Solution Approach 2:
The doping is applied locally at the Mn site within the LMO structure, allowing precise control over the phase transition temperature and crystal structure properties. This localized modification enables tailoring of the material properties to achieve both lower phase transition temperature and maintained stability
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 allows for epitaxial growth of oxide thin films at lower temperatures, preserving the mechanical strength of the superconducting wire rod and enabling efficient crystal orientation, thus improving the superconducting properties.
Implementation Method 1
LMO, which has a phase transition point that is accompanied by a change in the crystal structure (crystal lattice)... the crystal lattice of LMO changes from orthorhombic to cubic when the temperature of LMO is about 800 K (phase transition temperature T1) or higher
Implementation Method 2
the thin film undergoes epitaxial growth in which the crystal orientation of the growing thin film inherits the crystal orientation of the substrate or an underlying thin film layer, which serves as a template
Data Source
AI summary
The phase transition temperature, at which the crystal lattice of LMO that constitutes an oxide layer as an intermediate layer or as a part of an intermediate layer becomes cubic, is lowered. A substrate for a superconducting wire rod includes an oxide layer (LMO layer (22)) which contains, as a principal material, a crystalline material represented by the compositional formula: Laz(Mn1−xMx)wO3+δ (wherein M represents at least one of Cr, Al, Co or Ti, δ represents an oxygen non-stoichiometric amount, 0<w/z<2, and 0<x≦1).