Lead-Free Piezoelectric Ceramic Composition with CeO2 Additive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lead-containing piezoelectric ceramic compositions, such as PZT, pose environmental pollution risks due to lead leaching, and lead-free alternatives like (K,Na)NbO3-based ceramics suffer from poor sinterability, high dielectric loss, and narrow sintering temperature ranges, limiting their practical application.
Innovation Solution
A lead-free piezoelectric ceramic composition represented by the formula (Na0.475K0.475Li0.05)(Nb1-xAx)O3+yCeO2+zBO2, where 'A' represents Sb or Sb+Ta, and 'B' is a tetravalent transition metal, with CeO2 or CeO2-containing complex additives improving sinterability and dielectric/piezoelectric properties, eliminating the need for specialized sintering techniques like hot pressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric ceramics such as (K,Na)NbO3 are used to replace lead-containing PZT ceramics, then environmental pollution is reduced, but sinterability deteriorates and high dielectric loss occurs
Solution Approach 1:
CeO2 acts as an intermediary substance that facilitates sintering of (K,Na)NbO3-based ceramics. The CeO2 additive promotes mass transport and grain boundary migration during sintering, enabling dense microstructure formation without requiring hot pressing. This resolves the sinterability issue while maintaining the environmental benefit of lead-free composition.
Solution Approach 2:
The invention changes the chemical composition parameters by introducing CeO2 and BO2 additives in specific proportions (0.1-5 wt% CeO2, 0.1-3 wt% BO2). This compositional modification alters the sintering behavior, enabling conventional sintering processes to achieve dense microstructures that previously required complex hot pressing techniques.
2Reliability
If (K,Na)NbO3-based ceramics are used as lead-free alternative, then piezoelectric properties improve compared to other lead-free options, but sintering temperature range narrows and reproducibility deteriorates
Solution Approach 1:
CeO2 serves as a sintering aid that broadens the effective sintering temperature window. By promoting liquid phase formation and enhancing diffusion processes, CeO2 enables consistent dense microstructure formation across a wider temperature range, improving manufacturing reproducibility while preserving excellent piezoelectric properties.
Solution Approach 2:
The invention creates a composite system combining (K,Na)NbO3 base ceramic with CeO2 and BO2 additives. This composite approach leverages the beneficial effects of CeO2 (sintering promotion, grain growth control) and BO2 (dielectric loss reduction, stability enhancement) to achieve both excellent piezoelectric properties and improved manufacturing precision.
3Reliability
If hot pressing technique is used to form dense structure of (K,Na)NbO3, then piezoelectric properties improve, but manufacturing cost increases and efficiency decreases
Solution Approach 1:
CeO2 acts as a chemical mediator that enables conventional sintering to achieve density levels previously only attainable through hot pressing. The CeO2 additive promotes liquid phase sintering and grain boundary migration, allowing dense microstructure formation under conventional pressure and temperature conditions, thereby eliminating the need for costly and time-consuming hot pressing equipment and processes.
4Reliability
If alkali metal components (K, Na) are present in (K,Na)NbO3, then piezoelectric properties are enhanced, but volatility increases causing abnormal grain growth and sinterability deterioration
Solution Approach 1:
CeO2 acts as a protective intermediary that suppresses the volatility of alkali metal components during sintering. The CeO2 forms a protective atmosphere or surface layer that reduces K and Na evaporation, preventing abnormal grain growth caused by volatile component loss, while allowing the piezoelectrically active (K,Na)NbO3 phase to form with dense microstructure under conventional sintering conditions.
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 composition exhibits enhanced sinterability, density, and piezoelectric properties, making it suitable for replacing lead-containing ceramics in various applications without environmental pollution concerns and with improved manufacturing efficiency.
Implementation Method 1
The poor sinterability of (K, Na)NbO3 is due to the volatility of alkali metal components (K, Na) and a low melting point of KnbO3, which tend to cause abnormal growth of grains
Implementation Method 2
it is featured with high dielectric loss, narrow sintering temperature range and poor reproducibility. Practically, a hot pressing technique is required to form a highly dense structure of (K,Na)NbO3
Implementation Method 3
a piezoelectric ceramic composition with a suitable amount of CeO2 or CeO2-containing complex additives
Data Source
AI summary
The present invention provides a piezoelectric ceramic composition, especially a lead-free piezoelectric ceramic composition, with a suitable amount of CeO2 or CeO2-containing complex additives, which is represented by the following formula:(Na0.475K0.475Li0.05)(Nb1-xAx)O3+yCeO2+zBO2 wherein “A” represents Sb or Sb+Ta, “B” represents a tetravalent transition metal, 0≦x≦0.2, 0.2 wt %<y<1.2 wt % and 0≦z 1 wt %. Addition of CeO2 or CeO2-containing complex additives suppresses melting and abnormal grain growth of (Na0.475K0.475Li0.05)(Nb1-xAx)O3 during sintering, thereby improving sinterability and increasing the density of the composition. As a result, the dielectric and piezoelectric properties of the ceramics are enhanced. Furthermore, the represented compositions have a wide sintering temperature range so that the process for preparing such a lead-free piezoelectric ceramic composition has high degree efficiency.