Perovskite Solid Solutions with Indifferent Melting Points
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Solution Overview
Problem
There is a lack of commercially viable substrates with cubic perovskite crystal structures having lattice parameters between 0.387 nm and 0.412 nm, which hinders the growth of epitaxial perovskite crystals with good lattice match, leading to challenges in achieving uniform and large-scale crystal growth.
Innovation Solution
The development of single-crystal perovskites as substrates with solid solutions having indifferent melting points at temperature minima in pseudo-binary phase diagrams, allowing for the growth of epitaxial crystals with perovskite structures within the specified lattice parameter range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional substrates are used for epitaxial growth, then existing manufacturing processes can be maintained, but lattice mismatch causes high strain and limits crystal size and uniformity
Solution Approach 1:
The patent changes the lattice parameter of substrates by developing perovskite solid solutions with compositions tuned to achieve lattice parameters between 0.387 nm and 0.412 nm. This allows matching the lattice constants of epitaxial perovskite crystals, reducing strain and enabling large-scale uniform growth.
Solution Approach 2:
The patent uses composite perovskite solid solutions formed by combining multiple perovskite compounds (e.g., Pb1-xLaxZr1-yTiyO3 and Pb1-xLaxZr1-ySryO3) to create substrates with tailored lattice parameters. These composite materials provide both the desired lattice match and cubic crystal structure at room temperature.
2Stability of the object's composition
If epitaxial growth is attempted without suitable substrates, then crystal uniformity and size can be improved, but lattice strain increases and growth fails
Solution Approach 1:
By precisely controlling the composition parameters of perovskite solid solutions (varying x, y, z parameters in formulas like Pb1-xLaxZr1-yTiyO3), the patent tunes the lattice parameters of substrates to match epitaxial crystals, minimizing lattice strain while maintaining composition uniformity.
Solution Approach 2:
The patent creates an equipotential lattice interface between substrate and epitaxial crystal by matching their lattice constants. This eliminates misfit dislocations and strain at the interface, allowing uniform crystal growth without compositional instability.
3Productivity
If perovskite solid solutions with indifferent melting points are used, then epitaxial crystal growth is enabled, but substrate synthesis complexity increases
Solution Approach 1:
The patent exploits phase transition behavior by selecting perovskite solid solution compositions that exhibit indifferent melting points (congruent melting). This allows the substrates to be grown from their own melt without decomposition, simplifying the synthesis process despite the complexity of achieving the right composition.
Solution Approach 2:
The perovskite solid solution substrates are designed to be self-supporting during growth, utilizing their own melt as the growth medium. This eliminates the need for external fluxes or complex carrier systems, reducing synthesis complexity while enabling high-quality crystal growth.
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 production of single-crystal perovskites with cubic structures at room temperature, facilitating the growth of epitaxial crystals with reduced lattice strain and expanded size and cost-effectiveness, addressing the dearth of suitable substrates for perovskite crystal growth.
Implementation Method 1
Single-crystal perovskites with an indifferent point for epitaxial growth of single crystals
Implementation Method 2
good lattice match, leading to challenges in achieving uniform and large-scale crystal growth
Implementation Method 3
indifferent melting point that occurs at a temperature minimum in a melting curve in a pseudo-binary phase diagram
Implementation Method 4
nucleate and grow the perovskite single crystal
Data Source
AI summary
Growth of single crystal epitaxial films of the perovskite crystal structure by liquid- or vapor-phase means can be accomplished by providing single-crystal perovskite substrate materials of improved lattice parameter match in the lattice parameter range of interest. Current substrates do not provide as good a lattice match, have inferior properties, or are of limited size and availability because cost of materials and difficulty of growth. This problem is solved by the single-crystal perovskite solid solutions described herein grown from mixtures with an indifferent melting point that occurs at a congruently melting composition at a temperature minimum in the melting curve in the pseudo-binary molar phase diagram. Accordingly, single-crystal perovskite solid solutions, structures, and devices including single-crystal perovskite solid solutions, and methods of making single-crystal perovskite solid solutions are described herein.