Lead Metaniobate Piezoelectric Ceramic Densification via Pb Vacancy Control
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Solution Overview
Problem
The challenge is to achieve high densification and prevent sintering cracking in lead metaniobate (PbNb2O6) piezoelectric ceramics while maintaining a high Curie temperature, as they exhibit low density and are prone to cracking due to abnormal grain growth and phase transformation during high-temperature sintering.
Innovation Solution
Introducing a specific proportion of Pb vacancy in the chemical composition Pb1-xNb2O6, where x is between 0.03 and 0.20, to inhibit phase transformation and internal stress, promoting uniform grain growth and higher density, and maintaining the Curie temperature through controlled sintering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sintering process is used for PbNb2O6 piezoelectric ceramics, then the material can be formed, but abnormal grain growth and phase transformation occur causing low density (relative density about 80%) and sintering cracks
Solution Approach 1:
The patent introduces Pb vacancies by controlling the Pb content to be less than the stoichiometric ratio (Pb1-xNb2O6 where x>0), which changes the compositional parameter to inhibit phase transformation and abnormal grain growth during sintering, thereby improving density and eliminating cracks
Solution Approach 2:
The patent preemptively introduces Pb vacancies before sintering to prevent the occurrence of harmful phase transformation and abnormal grain growth that would otherwise cause cracking and low density during the sintering process
2Manufacturing precision
If doping methods such as replacing Pb2+ with Ca2+ and Ba2+ are used to inhibit grain growth and increase density, then processing feasibility is improved, but Curie temperature is significantly reduced
Solution Approach 1:
Instead of changing the chemical composition by doping with other elements, the patent changes the stoichiometric parameter by controlling Pb content to create vacancies, which achieves density improvement without the harmful side effect of Curie temperature reduction
3Shape
If quenching method is used to restrain abnormal grain growth, then grain growth is inhibited, but the process complexity increases making it unsuitable for mass production
Solution Approach 1:
The patent performs preliminary action by introducing Pb vacancies into the composition before sintering, which pre-establishes conditions to inhibit abnormal grain growth during sintering, eliminating the need for post-sintering quenching treatments and simplifying the overall process
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 PbNb2O6 piezoelectric ceramics with a relative density of 93% to 99%, reduced cracking, and a Curie temperature of 554 to 560° C., along with decreased dielectric loss, enhancing their piezoelectric properties and mechanical stability.
Implementation Method 1
the phase transformation occurring at about 1,230° C. during a high-temperature sintering process of lead metaniobate ceramics can be avoided
Implementation Method 2
abnormal growth of PbNb2O6 piezoelectric ceramic grains
Implementation Method 3
Piezoelectric ceramic material is one of the most important functional materials for realizing electromechanical energy conversion and coupling
Data Source
AI summary
The present application discloses a dense lead metaniobate piezoelectric ceramic and a preparation method therefor. The chemical composition of the lead metaniobate piezoelectric ceramic is Pb1-xNb2O6, wherein x represents the Pb vacancy concentration of A sites in a tungsten bronze crystal structure, and x is greater than 0.00 and smaller than or equal to 0.20.