Piezoelectric Actuator PbTiO3 Layer PZT Grain Control
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Solution Overview
Problem
Existing liquid discharge apparatuses using piezoelectric actuators face challenges in achieving high dielectric strength and reliable operation due to small particle sizes of lead zirconate titanate (PZT) particles, leading to low dielectric breakdown voltage and increased leakage current.
Innovation Solution
The use of a lead titanate (PbTiO3) layer to control the crystallization of PZT particles, with an average diameter of 40 nm or more, and optimizing the thickness of the PbTiO3 layer to enhance grain size and orientation, thereby improving dielectric strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particle size of PZT is reduced to improve piezoelectric characteristics, then the piezoelectric properties are enhanced, but the dielectric strength decreases and leakage current increases
Solution Approach 1:
The patent changes the particle size parameter of PZT to be 40 nm or more (instead of smaller particles), which resolves the contradiction by finding an optimal parameter range that maintains both piezoelectric characteristics and dielectric strength
Solution Approach 2:
The patent uses a composite structure consisting of a PbTiO3 layer and a PZT layer, where the PbTiO3 layer acts as a seed layer to control crystal grain growth. This composite approach enables the PZT particles to achieve both small size (for piezoelectric properties) and controlled grain boundaries (for dielectric strength)
2Reliability
If the particle size of PZT is reduced to improve piezoelectric characteristics, then the piezoelectric properties are enhanced, but the leakage current increases
Solution Approach 1:
The patent specifies PZT particle size of 40 nm or more to optimize the balance between piezoelectric characteristics and leakage current suppression
Solution Approach 2:
The PbTiO3/PZT composite structure with controlled grain boundaries reduces leakage current while maintaining piezoelectric performance
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 effectively increases the average particle diameter of the PZT particles, enhancing dielectric strength and maintaining good piezoelectric properties, ensuring stable and reliable operation of the liquid discharge apparatus.
Implementation Method 1
The use of a lead titanate (PbTiO3) layer to control the crystallization of PZT particles
Implementation Method 2
there is known, for example, an inkjet recording apparatus including a liquid discharge head that discharges liquid such as ink. For such a liquid discharge head, there are known technologies of using a piezoelectric body as a drive source of an actuator
Data Source
AI summary
An actuator includes a substrate, a diaphragm over the substrate, a lower electrode over the diaphragm, a lead titanate (PbTiO3) layer over the lower electrode, a piezoelectric body over the PbTiO3 layer, and an upper electrode over the piezoelectric body. The piezoelectric body comprises particles of lead zirconate titanate (PZT). An average diameter of the particles of the PZT is 40 nm or more. The average diameter is measured by capturing an electron backscatter diffraction image of the piezoelectric body in an image area of 20 μm×20 μm, fitting each of the particles in the image area, and determining an average value of diameters of the circles.