Piezoelectric Ceramic Speaker Low-Temperature Sintering
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Solution Overview
Problem
Existing piezoelectric ceramics face challenges in achieving high kr and specific dielectric constants while maintaining low sintering temperatures and minimizing characteristic variations.
Innovation Solution
A piezoelectric ceramic with a primary phase of perovskite crystal structure composed of Pb, Nb, Zn, Ti, and Zr, and a secondary phase of sporadically distributed ZnO grains, allowing for sintering at 900°C or below and optimizing piezoelectric characteristics through controlled composition and grain size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If piezoelectric ceramics are sintered at low temperatures (900°C or below), then energy consumption is reduced and manufacturing cost decreases, but achieving high kr and high specific dielectric constant simultaneously becomes difficult
Solution Approach 1:
The invention uses a composite ceramic system comprising Pb(Zr, Ti)O3 (PZT) as the base material with Pb(Ni1/3Nb2/3)O3 (PNN) and Pb(Zn1/3Nb2/3)O3 (PZN) additives. This composite composition enables low-temperature sintering (900°C or below) while achieving high kr (electromechanical coupling coefficient) and high specific dielectric constant, resolving the contradiction between low sintering temperature and high piezoelectric performance
Solution Approach 2:
The invention optimizes the compositional parameters by controlling the ratios of PZT, PNN, and PZN components, and by adjusting the content of acceptor elements (Ni, Zn) to be in excess of stoichiometric composition. This parameter optimization allows the ceramic to achieve dense sintering and high piezoelectric characteristics at low temperatures (900°C or below), simultaneously improving both sintering temperature and piezoelectric reliability
2Temperature
If acceptor elements (Ni, Zn) are added in excess of stoichiometric composition to enable low-temperature sintering, then sintering temperature decreases, but characteristics variation increases
Solution Approach 1:
The invention precisely controls the compositional parameters by defining specific ranges for PNN and PZN content (0.01-0.30 mol ratio each) and setting the acceptor element excess within controlled limits. This parameter control, combined with optimized sintering conditions, achieves low-temperature sintering while minimizing characteristics variation through consistent microstructure formation
Solution Approach 2:
The invention implements process control by monitoring and adjusting the acceptor element content and sintering parameters to achieve the desired balance between low sintering temperature and minimal characteristics variation. The feedback mechanism ensures that the excess acceptor elements produce the intended low-temperature sintering effect without causing excessive characteristics variation
3Reliability
If B site components (Ti, Zr) are substituted with other atoms to improve piezoelectric characteristics, then kr increases, but sintering temperature decreases and characteristics stability worsens
Solution Approach 1:
The invention uses a composite system where PNN and PZN are combined with PZT in specific ratios. The PNN and PZN components provide acceptor doping effects that enhance piezoelectric characteristics (high kr) while their controlled composition and interaction with PZT matrix help maintain characteristics stability, resolving the contradiction between improved piezoelectric performance and composition stability
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 approach results in a high-performance piezoelectric ceramic with stable structure, high kr, and low temperature sintering, leading to improved piezoelectric speaker performance with reduced characteristic variations.
Implementation Method 1
Piezoelectric ceramics with a function to convert electrical energy to mechanical energy or mechanical energy to electrical energy (piezoelectric effect) have been applied to a number of electronic devices
Data Source
AI summary
A piezoelectric ceramic speaker includes a piezoelectric element using a vibration sheet formed with piezoelectric ceramic having a primary phase constituted by ceramic grains of perovskite crystal structure containing Pb, Nb, Zn, Ti, and Zr, and a secondary phase constituted by ZnO grains, wherein the primary phase is constituted by ceramic grains expressed by a composition formula Pb {(Zr(1-a)Tia)x·(Ni1/3Nb2/3)y·(Zn1/3Nb2/3)z}O3 (where 0<x≤0.85, 0≤y<1, 0<z<1, x+y+z=1, and 0.45≤a≤0.60); and an enclosure which encloses the piezoelectric element.