Lead-Free Piezoceramic Sintering Oxygen Atmosphere
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Solution Overview
Problem
Lead zirconate titanate ceramics pose environmental concerns due to lead oxide, and bismuth sodium titanate systems face challenges with oxygen vacancies and production complexities, including the need for ethanol as a solvent and high sintering temperatures.
Innovation Solution
A lead-free piezoceramic material using sodium bismuthate as the sodium and bismuth source in the Bi0.53+Na0.51+Ti4+O32− system, sintered in an oxygen-rich environment to minimize oxygen vacancies and reduce sintering temperature, with precursors mixed and ground in an aqueous system to avoid explosive material handling and environmental lead content issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free bismuth sodium titanate system is used to replace lead zirconate titanate ceramics, then environmental compatibility is improved, but oxygen vacancies increase during sintering which increases conductivity and makes polarization more difficult
Solution Approach 1:
The patent changes the sintering atmosphere parameter from conventional air or reducing atmosphere to oxygen-rich atmosphere. This parameter change suppresses oxygen vacancy formation during sintering, maintaining low conductivity and enabling effective polarization while preserving the environmental benefits of lead-free composition
Solution Approach 2:
The patent uses a composite precursor system containing multiple metal organic compounds (at least two different metal ions from groups 3-12) combined with bismuth sodium titanate. This composite approach allows optimization of sintering characteristics and electrical properties while maintaining lead-free composition, addressing both environmental compatibility and functional reliability
2Object-affected harmful factors
If bismuth sodium titanate is produced using conventional methods, then lead-free composition is achieved, but solubility of sodium carbonate in water causes homogeneity problems requiring ethanol solvent which increases safety and equipment complexity
Solution Approach 1:
The patent changes the solvent parameter from water or ethanol to carboxylic acid (C1-C6), particularly acetic acid. This parameter change improves homogeneity of the precursor mixture by better solubility characteristics, eliminates the need for explosive safety equipment required for ethanol, while maintaining lead-free composition
Solution Approach 2:
The patent employs readily available, inexpensive carboxylic acids (especially acetic acid) as solvents instead of requiring specialized equipment for ethanol handling. This substitutes complex safety infrastructure with simple, disposable chemical reagents that are easier and safer to handle in conventional laboratory equipment
3Ease of manufacture
If conventional sintering methods are used for bismuth sodium titanate, then material is formed, but high sintering temperatures are required which increase energy consumption
Solution Approach 1:
The patent performs preliminary formation of metal organic precursor complexes before sintering. This preliminary action creates a pre-organized structure that facilitates lower-temperature sintering, reducing energy consumption while ensuring proper material formation and phase development
Solution Approach 2:
The patent changes the sintering temperature parameter from conventional high temperatures (>900°C) to lower temperatures (700-850°C) by using metal organic precursors. This parameter change reduces energy consumption while maintaining ease of manufacture through the reactive nature of the organic precursor system
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 method produces a bismuth sodium titanate piezoceramic with reduced oxygen vacancies, lower sintering temperatures, and minimized lead content, enhancing energy efficiency and environmental compatibility for applications in sensors and actuators.
Implementation Method 1
Oxygen is liberated during sintering due to the reduction of Bi5+ to Bi3+
Implementation Method 2
Piezoelectric ceramics (piezoceramics) have a broad field of application in the areas of sensors (measuring forces, accelerations, and pressures) and actuators
Data Source
AI summary
The invention relates to a piezoelectric lead-free material based on bismuth sodium titanate, to a method for the production thereof, and to the use thereof.