Lead-Free Dielectric Thin Film With (100) Orientation for Higher d33

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Solution Overview

Problem

Dielectric thin films made from [(Na, Bi)1-xBax]TiO3 crystals with only the (001) plane oriented lack sufficient dielectric property.

Innovation Solution

A dielectric thin film with a metal oxide composition of (1−x)(Bi0.5Na0.5)TiO3-xBaTiO3, where x satisfies 0.15≤x≤0.40, is developed. This film includes tetragonal crystals with a perovskite structure, and the (100) plane of at least a part of the tetragonal crystal is oriented in the normal direction of the film surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If only the (001) plane of [(Na, Bi)1-xBax]TiO3 is oriented, then the piezoelectric material can be formed, but the dielectric property is insufficient

Engineering Contradiction:

Improvedielectric propertyVSAvoidcrystal orientation control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the crystal orientation parameter from (001) plane orientation to (100) plane orientation of the tetragonal crystal structure. This parameter change in crystal orientation fundamentally improves the dielectric property while maintaining the piezoelectric characteristics of the [(Na, Bi)1-xBax]TiO3 material system.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite approach by combining specific composition control (x value between 0.05 and 0.40) with crystal structure control (tetragonal phase with (100) orientation) to achieve both excellent dielectric and piezoelectric properties in the lead-free material system.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If lead-free piezoelectric material is used to replace PZT, then environmental harm is reduced, but dielectric property becomes insufficient

Engineering Contradiction:

Improveenvironmental harm from leadVSAvoiddielectric property

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent optimizes multiple parameters including the compositional parameter (x value), crystal structure parameter (tetragonal phase), and crystal orientation parameter ((100) plane orientation) to achieve excellent dielectric property in lead-free [(Na, Bi)1-xBax]TiO3 material, resolving the trade-off between environmental friendliness and performance.

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 dielectric thin film exhibits excellent dielectric properties and improved piezoelectric characteristics, including increased piezoelectric constant d33 and reduced dielectric loss.

Implementation Method 1

a piezoelectric actuator converts a voltage into a force by an inverse piezoelectric effect of deforming the piezoelectric material by applying a voltage to the piezoelectric material

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the piezoelectric sensor converts a force into a voltage by a piezoelectric effect of deforming the piezoelectric material by applying a pressure to the piezoelectric material

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12329036B2Dielectric thin film, dielectric thin film element, piezoelectric actuator, piezoelectric sensor, head assembly, head stack assembly, hard disk drive, printer head and inkjet printer device

Publication Date: 2025.06.10 TDK CORP

AI summary

Provided is a dielectric thin film including a metal oxide. The metal oxide includes bismuth, sodium, barium, and titanium, at least a part of the metal oxide is a tetragonal crystal having a perovskite structure, and a (100) plane of at least a part of the tetragonal crystal is oriented in a normal direction of a surface of the dielectric thin film.