Piezoceramic Material with Cryolite Phase for Thermal Stability
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Solution Overview
Problem
Existing piezoceramic materials face challenges in achieving optimal thermal and temporal stability, as well as large deflections under moderate electrical fields, while maintaining high reliability and adequate thermal stability, which is difficult to achieve with traditional compositions of lead zirconate titanate (PZT) ceramics.
Innovation Solution
The development of a ceramic material with a perovskite structure, incorporating mixed crystals and aliovalent substitutions, including rare earth elements and cryolite compounds, to adjust the Zr/Ti ratio and create vacancies, enhancing grain growth and piezoelectric properties, and incorporating cryolite phases to manage oxygen vacancies for improved sinter compaction and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional PZT compositions are used, then thermal stability is maintained, but deflection amplitude under moderate electrical fields is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of PZT by incorporating rare earth elements (La, Nd, Sm, Eu, Gd, Er, Yb, Lu) at the A-site and transition metals (Nb, Ta, Sb) at the B-site of the perovskite structure. This compositional parameter change enables achieving both high deflection amplitude (d33 ≥ 400 pm/V) and thermal stability (Curie temperature ≥ 300°C) simultaneously, resolving the contradiction between deflection performance and thermal stability.
Solution Approach 2:
The patent creates a composite ceramic material by combining PZT base phase with rare earth-doped perovskite phases. The multi-phase composite structure integrates the thermal stability of traditional PZT with the enhanced piezoelectric response from rare earth doping, achieving both high deflection amplitude and thermal stability that cannot be obtained with single-phase traditional PZT.
2Reliability
If additives are added to adapt functional properties, then piezoelectric characteristics are improved, but Curie temperature decreases
Solution Approach 1:
The patent carefully controls the concentration parameters of additive components to maintain Curie temperature ≥ 300°C. By optimizing the doping levels of rare earth elements and transition metals within specific ranges, the patent achieves improved piezoelectric characteristics (d33 ≥ 400 pm/V) while preventing excessive reduction of Curie temperature, thus resolving the contradiction between piezoelectric performance and thermal stability.
3Reliability
If Zr/Ti ratio is adjusted to MPB, then piezoelectric properties are optimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent shifts from relying solely on precise Zr/Ti ratio control at MPB to a multi-element doping strategy. By incorporating rare earth elements and transition metals, the patent achieves enhanced piezoelectric properties through compositional parameter changes that are more tolerant to manufacturing variations, reducing the stringency of Zr/Ti ratio control requirements while maintaining d33 ≥ 400 pm/V.
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
This approach results in piezoceramics with enhanced dielectric constants, large deflection amplitudes, and improved long-term stability, allowing for the production of both soft and hard piezoceramics with tailored properties suitable for various applications, including actuators.
Implementation Method 1
incorporating compounds with cryolite structure, which encourages sinter compaction and grain formation
Implementation Method 2
a partial substitution of PbII and ZrIV/TiIV in the Pb(Zr, Ti)O3 ceramic with ions of comparably ionic radius, such as AII cations (AII: Ba, Sr, Ca) at the A-sites and BIV cations (BIV: Sn) at the B-sites of the perovskite structure
Data Source
AI summary
A ceramic material includes first and second ceramic materials. The first ceramic material has a perovskite structure and defines a host lattice. The first ceramic material contains lead, zirconium and titanium, e.g., lead zirconate titanate. The second ceramic material has a cryolite structure. The ceramic material may be part of a piezo-actuator containing ceramic layers formed of the ceramic material.