Piezoelectric Single Crystal Solid-Phase Growth Uniform Composition

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Solution Overview

Problem

Piezoelectric single crystals with perovskite type crystal structures face limitations due to low phase transition temperatures, coercive electric fields, and mechanical brittleness, restricting their application in high-performance components and requiring improvements in dielectric and piezoelectric characteristics, as well as uniform composition and high-temperature stability.

Innovation Solution

A piezoelectric single crystal with a compositional formula [A1−(a+1.5b)BaCb][(MN)1−x−y(L)yTix]O3, where A represents Pb or Ba, B includes elements like Ba, Ca, Co, Fe, Ni, and Sr, C includes elements like Co, Fe, La, and Lu, M includes Ce, Co, Fe, and Zn, and N includes Nb, Sb, and W, with specific ranges for a, b, x, and y, and a solid phase single crystal growth method to achieve uniformity and high mechanical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If piezoelectric single crystals are manufactured by conventional flux method or Bridgman method, then single crystal growth is achieved, but composition uniformity deteriorates due to composition gradient

Engineering Contradiction:
Improvecomposition uniformityVSAvoidcrystal growth process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of crystal growth method from liquid-phase (flux/Bridgman) to solid-phase growth. This parameter change enables composition uniformity to be improved because solid-phase growth avoids the composition gradient inherent in liquid-phase methods, while simplifying the process by eliminating flux removal steps and reducing overall process complexity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If complex chemical composition is used to improve piezoelectric characteristics, then dielectric constant and piezoelectric charge constant increase, but composition uniformity deteriorates

Engineering Contradiction:
Improvepiezoelectric performanceVSAvoidcomposition uniformity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the growth phase parameter from liquid to solid, which fundamentally alters how complex compositions are handled. In solid-phase growth, the complex multi-element composition remains uniform throughout the crystal because there is no liquid convection or segregation. This enables high piezoelectric performance from complex compositions while maintaining composition uniformity.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If phase transition temperature is increased to improve high-temperature stability, then workable temperature range expands, but coercive electric field may be affected

Engineering Contradiction:
Improvephase transition temperatureVSAvoidcoercive electric field
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent uses composite material strategy by combining multiple elements (Pb, Ba, Ca, Sr, Li, K, Nb, Ta, W, Mo) in specific ratios to create a perovskite structure with tailored properties. This composite approach enables simultaneous optimization of phase transition temperature and coercive electric field, achieving high-temperature stability while maintaining reliable piezoelectric switching characteristics.

Inventive Principle:
Principle #40Composite materials

4Ease of manufacture

If mechanical brittleness is reduced to improve processability, then ease of manufacture improves, but mechanical strength may be compromised

Engineering Contradiction:
ImproveprocessabilityVSAvoidmechanical strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the crystal growth phase parameter to solid-phase, which inherently produces crystals with fewer internal defects and more uniform microstructures. This parameter change improves both processability (reduced brittleness) and mechanical strength simultaneously, as the uniform growth eliminates weak points that would compromise strength while making the crystal easier to process.

Inventive Principle:
Principle #35Parameter changes

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 solution achieves high dielectric and piezoelectric constants, elevated phase transition temperatures, and enhanced mechanical characteristics, enabling the use of piezoelectric single crystals in a wide temperature range and high-precision applications with improved resistance to mechanical impacts.

Implementation Method 1

piezoelectric single crystal having a perovskite type crystal structure... high piezoelectric charge constant (d33≥1,400 to 6,000 pC/N)

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

high dielectric constant (K3T≥4,000 to 15,000)

Methodology Applied
Scientific EffectDielectric permittivity: Dielectric Permittivity

Implementation Method 3

manufactured by a solid phase single crystal growth method so that the uniform piezoelectric single crystal can be provided

Methodology Applied
Scientific EffectThermal energy: Heating

Data Source

PatentUS12031232B2Piezoelectric single crystal, fabrication method therefor, and piezoelectric and dielectric application parts using same
Publication Date: 2024.07.09 CERACOMP

AI summary

Provided is a piezoelectric single crystal, a method of manufacturing the piezoelectric single crystal, and piezoelectric and dielectric application components using the piezoelectric single crystal. The piezoelectric single crystal shows that characteristics of the piezoelectric single crystal are maximized through the control of composition concerning ions located at [A] from a perovskite type crystal structure ([A][B]O3), the single crystal of uniform composition can be provided without a composition gradient even in case of complex, chemical composition thanks to a solid phase single crystal growth method, and in particular, the piezoelectric single crystal is provided in a form which causes large resistance to a mechanical impact, and facilitates mechanical processing, so the piezoelectric single crystal can usefully be applied to the piezoelectric application component and the dielectric application component, like ultrasonic transducers, piezoelectric actuators, piezoelectric sensor, dielectric capacitors, using the piezoelectric single crystal pertain.