Piezoceramic Composition Stability via A-Site Defect Control
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Solution Overview
Problem
Manufacturing alkaline niobate-piezoceramic compositions faces challenges in achieving stability and reproducibility of piezoelectric properties due to hydroscopic properties of potassium and volatilization issues during sintering, leading to unevenness and increased costs.
Innovation Solution
A piezoceramic composition with a perovskite structure, comprising potassium, sodium, and lithium as A-site elements and niobium, tantalum, and antimony as B-site elements, with a heterogeneous phase AsBtOu, optimized to maintain a specific A/B ratio and defect tolerance, and incorporating bismuth and iron to enhance piezoelectric properties, while using X-ray diffraction to adjust composition ratios and sintering conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkaline niobate-piezoceramic composition is manufactured using conventional methods, then piezoelectric products can be produced, but stability and reproducibility of piezoelectric property deteriorate due to hydroscopic property of potassium material and potassium volatilization during sintering
Solution Approach 1:
The patent applies preliminary action by pre-mixing potassium-containing materials with barium titanate powder before sintering. This preliminary mixing ensures uniform distribution of potassium compounds throughout the ceramic matrix, preventing localized potassium deficiency that would occur due to volatilization during sintering. The pre-prepared green body is then sintered in a controlled atmosphere to maintain composition stability.
Solution Approach 2:
The patent employs an inert atmosphere (nitrogen or oxygen) during the sintering process to prevent potassium volatilization and oxidation of other components. By controlling the atmospheric environment, the patent maintains the intended stoichiometry and achieves reproducible piezoelectric properties across multiple batches.
2Manufacturing precision
If A-site defects are increased to improve piezoelectric property, then radial electromechanical coefficient improves, but manufacturing precision deteriorates due to difficulty in controlling defect amount
Solution Approach 1:
The patent utilizes parameter changes by adjusting the A/B ratio (ratio of A-site to B-site elements) and controlling the sintering temperature and atmosphere to achieve the desired amount of A-site defects. By systematically varying these parameters, the patent optimizes the radial electromechanical coefficient while maintaining manufacturing control. The key is to create a controlled non-stoichiometric composition with slight A-site deficiency.
3Reliability
If composition ratio is adjusted to achieve desired A-site defects, then piezoelectric property improves, but manufacturing cost increases due to difficulty in achieving desired ratio
Solution Approach 1:
The patent achieves cost-effective manufacturing by optimizing the A/B ratio parameter within a specific range (0.98-1.02) rather than requiring precise control. This parameter optimization allows for normal manufacturing tolerances while still achieving the desired piezoelectric properties, thereby reducing manufacturing cost.
Solution Approach 2:
The patent implements feedback control by measuring the actual composition and piezoelectric properties of each batch, then adjusting subsequent batches accordingly. This feedback mechanism ensures consistent quality while minimizing material waste and rework, thereby controlling manufacturing costs.
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 a stable and reproducible piezoelectric composition with a radial electromechanical coefficient of 0.4 or more, reducing unevenness and manufacturing costs by controlling A-site defects and composition ratios, enabling efficient mass production.
Implementation Method 1
an X-ray diffraction profile of the powder sample that is crushed until the particles of the piezoceramic composition are 10 μm or less in diameter
Data Source
AI summary
A piezoceramic composition comprises, as the main phase, a crystalline phase of a perovskite structure signified as formula ABO3, with Element A consisting of one or more elements selected from among K (potassium), Na (sodium) and Li (lithium) and with Element B consisting of one or more elements selected from among Nb (niobium), Ta (tantalum) and Sb (antimony), with Elements A and B comprising other elements as additives. An X-ray diffraction profile of crushed particles of the piezoceramic composition that are 10 μm or less in diameter has a diffraction peak indicating the presence of the main (single) phase as well as a heterogeneous phase of a crystalline structure signified as formula AsBtOu (s<t<u) but not belonging to the perovskite structure.