Monoclinic Relaxor-PT Crystals for Stable Shear Piezoelectric Performance

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Solution Overview

Problem

Relaxor-PT single crystals exhibit significant temperature dependence in shear piezoelectric coefficients and low coercive fields, limiting their application in electromechanical devices due to increased piezoelectric coefficients with temperature and limited AC field drive capabilities.

Innovation Solution

Development of monoclinic/orthorhombic relaxor-PT single crystals with specific domain configurations and doping, such as '1O' and '2R' engineered domain states, which provide temperature-independent shear piezoelectric coefficients and high coercive fields, enabling stable performance under AC fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If relaxor-PT single crystals are used to achieve high piezoelectric coefficients, then the piezoelectric performance is improved, but the temperature stability deteriorates due to significant temperature dependence

Engineering Contradiction:

Improvepiezoelectric performanceVSAvoidtemperature stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the crystallographic phase parameters by transitioning from rhombohedral to monoclinic/orthorhombic phases through composition adjustment and heat treatment. This parameter change in the crystal structure fundamentally alters the temperature dependence of piezoelectric coefficients, achieving temperature-stable performance while maintaining high piezoelectric values.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite domain structures within the crystal, specifically engineered multi-domain configurations (1O, 2O, 2R) that combine different domain orientations. This composite domain architecture enables the material to maintain stable piezoelectric properties across temperature ranges by distributing stress and polarization across multiple domains.

Inventive Principle:

Principle #40Composite materials

2Reliability

If rhombohedral single domain PMN-PT crystals with engineered domain configuration are used to achieve high shear coefficients, then the shear piezoelectric coefficient is improved, but the temperature stability deteriorates due to significant increase with temperature

Engineering Contradiction:

Improveshear piezoelectric coefficientVSAvoidtemperature independence

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the crystallographic phase from rhombohedral to monoclinic/orthorhombic, which fundamentally alters the temperature dependence behavior of shear piezoelectric coefficients. This phase parameter change eliminates the significant temperature increase observed in rhombohedral crystals, achieving temperature-stable shear coefficients.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of accepting the inherent temperature dependence of rhombohedral crystals as a given, the patent inverts the approach by selecting monoclinic/orthorhombic phases that naturally exhibit temperature-stable shear coefficients. This inversion of the conventional choice reverses the temperature stability problem.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If relaxor-PT single crystals are used to achieve high piezoelectric coefficients, then the electromechanical coupling is improved, but the coercive field is reduced leading to limited AC field drive capabilities

Engineering Contradiction:

Improveelectromechanical couplingVSAvoidcoercive field

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent creates composite domain structures (multi-domain configurations) within the crystal that combine different domain orientations. This composite domain architecture increases the coercive field by distributing the depolarization stress across multiple domains, while maintaining high electromechanical coupling through the collective response of all domains.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent segments the crystal into multiple domains with different polarization orientations (1O, 2O, 2R configurations). This segmentation increases the coercive field by requiring higher fields to switch all domains simultaneously, while maintaining high piezoelectric response through the coordinated switching of segmented domains.

Inventive Principle:

Principle #1Segmentation

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 temperature-stable and AC field-stable high shear piezoelectric coefficients, suitable for applications in vector sensors, NDE transducers, and low-frequency sonar transducers with improved performance.

Implementation Method 1

Temperature and field stable relaxor-PT piezoelectric single crystals

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS9673380B2Temperature and field stable relaxor-PT piezoelectric single crystals

Publication Date: 2017.06.06 TRS TECH

AI summary

The application is directed to piezoelectric single crystals having shear piezoelectric coefficients with enhanced temperature and/or electric field stability. These piezoelectric single crystal may be used, among other things, for vibration sensors as well as low frequency, compact sonar transducers with improved and/or enhanced performance.