Piezoelectric Single Crystal Composition for High Temperature Operation
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Solution Overview
Problem
Perovskite-type piezoelectric single crystals have limitations due to low phase transition temperatures, coercive fields, and mechanical properties, restricting their use in high-temperature applications and fabrication processes, and are costly due to the inclusion of expensive elements like Sc and In.
Innovation Solution
Development of piezoelectric single crystals with a Perovskite structure containing Zr, using a solid-state crystal growth method, which excludes expensive elements and incorporates reinforcing second phases like metals and oxides to enhance mechanical properties and stability, allowing for high-temperature operation and cost-effective mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rhombohedral piezoelectric single crystals are used to achieve high dielectric and piezoelectric characteristics, then dielectric constant and piezoelectric constants are improved, but phase transition temperature becomes low limiting usable temperature range
Solution Approach 1:
The patent changes the compositional parameters of the piezoelectric single crystal by incorporating specific ratios of Pb(Mg1/3Nb2/3)O3, PbTiO3, and PbZr1-xYxO3 to adjust the phase transition temperature while maintaining high dielectric and piezoelectric characteristics. By varying the mole fractions of these components, the Curie temperature can be tuned to desired values.
Solution Approach 2:
The patent creates a composite piezoelectric single crystal system combining multiple perovskite materials (PMN-PT-PZY) to achieve synergistic effects. The composite structure allows simultaneous optimization of dielectric properties, piezoelectric coefficients, and phase transition temperature that cannot be achieved with single-component materials.
2Reliability
If expensive elements like Sc and In are included to improve piezoelectric characteristics, then dielectric constant and piezoelectric constants are improved, but production cost increases
Solution Approach 1:
The patent replaces expensive rare earth elements (Sc, In) with more economical alternatives (Yb, Zn, Nb) that can achieve similar or superior piezoelectric performance. This substitution significantly reduces raw material costs while maintaining high d33 and k33 values.
Solution Approach 2:
The patent extracts and eliminates the expensive Sc and In elements from the composition, retaining only the essential functional components needed for high piezoelectric performance. The simplified composition reduces material costs and simplifies the manufacturing process.
3Reliability
If low phase transition temperature and coercive field are present, then dielectric characteristics are improved, but mechanical strength and stability deteriorate causing easy depoling
Solution Approach 1:
The patent employs a composite perovskite structure combining PMN, PT, and PZY phases to achieve a balance between soft dielectric characteristics and mechanical stability. The multi-phase composite provides both high dielectric constant and adequate coercive field for mechanical stability.
Solution Approach 2:
The patent adjusts the compositional parameters and processing conditions to optimize the balance between dielectric softness and mechanical stability. By controlling the mole ratios and heat treatment parameters, the material achieves appropriate coercive field strength while maintaining high dielectric properties.
4Reliability
If Bridgman method or flux method is used to grow single crystals, then high dielectric and piezoelectric characteristics are achieved, but production cost and complexity increase
Solution Approach 1:
The patent extracts the crystal growth process from complex melt-based methods (Bridgman, flux) and replaces it with solid-state sintering. This simplification eliminates the need for precise temperature gradient control and flux chemistry while achieving sufficient single crystal or dense polycrystal quality for high performance.
Solution Approach 2:
The patent adopts a simpler, more economical solid-state sintering process that uses conventional ceramic processing equipment and procedures. This approach sacrifices some crystal perfection but achieves adequate material quality at significantly reduced process complexity and cost.
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 resulting piezoelectric single crystals exhibit high dielectric and piezoelectric constants, elevated phase transition temperatures, and improved mechanical strength, enabling their use in high-temperature ranges and reducing production costs, thus facilitating their commercialization and application in various devices.
Implementation Method 1
piezoelectric single crystals having a Perovskite-type crystal structure, which have high dielectric constant K3T, high piezoelectric constants (d33 and k33)
Implementation Method 2
high dielectric constant K3T
Implementation Method 3
high phase transition temperatures [Tc (Curie temperature or phase transition temperature between tetragonal and cubic phases) and TRT (phase transition temperature between rhombohedral and tetragonal phases)]
Data Source
AI summary
A piezoelectric single crystal and piezoelectric and dielectric application parts using the same are provided, which have all of high dielectric constant K3T, high piezoelectric constants (d33 and k33), high phase transition temperatures (Tc and TRT), high coercive electric field Ec and improved mechanical properties and thus can be used in high temperature ranges and high voltage conditions. Furthermore, the piezoelectric single crystals are produced by the solid-state single crystal growth adequate for mass production of single crystals and the single crystal composition is developed not to contain expensive raw materials so that the piezoelectric single crystals can be easily commercialized. With the piezoelectric single crystals and piezoelectric single crystal application parts, the piezoelectric and dielectric application parts using the piezoelectric single crystals of excellent properties can be produced and used in the wide temperature range.