Piezoelectric Ceramic Composition for Ni Electrode Co-Firing
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Solution Overview
Problem
Piezoelectric ceramic compositions with Ni as internal electrode material suffer from defective polarization and degraded piezoelectric properties due to segregation of M4 elements during co-firing, leading to poor performance in laminated piezoelectric actuators.
Innovation Solution
Incorporating a tetravalent M4' element in excess stoichiometric amounts with Na and adding Mn within specific ranges to prevent segregation, along with substituting part of Nb with Sb and including rare earth elements, to enhance sinterability and maintain favorable piezoelectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Ni is used as internal electrode material for co-firing, then manufacturing cost is reduced and ease of manufacture is improved, but segregation of M4 elements occurs during firing leading to defective polarization and degraded piezoelectric properties
Solution Approach 1:
The patent applies preliminary action by adding MnO2 and M4′ elements to the piezoelectric ceramic composition before co-firing with Ni internal electrodes. These additives pre-establish conditions that prevent M4 element segregation during the subsequent firing process, thereby maintaining manufacturing precision while using cost-effective Ni electrodes
Solution Approach 2:
The patent uses MnO2 and M4′ elements as intermediary substances that mediate between the Ni internal electrodes and the M4 elements in the ceramic matrix. These intermediaries prevent direct harmful interactions and segregation, allowing Ni to be used without compromising manufacturing precision
2Ease of manufacture
If Ni is used as internal electrode material for co-firing, then manufacturing cost is reduced, but piezoelectric properties are degraded due to formation of segregated phases
Solution Approach 1:
The patent performs preliminary action by incorporating MnO2 and M4′ elements into the ceramic composition before co-firing. This pre-preparation prevents the formation of segregated phases during firing, thereby maintaining piezoelectric reliability while using inexpensive Ni internal electrodes
Solution Approach 2:
The patent converts the potentially harmful effect of Ni diffusion into a beneficial outcome by using MnO2 and M4′ elements that transform the segregation mechanism. Instead of allowing harmful M4 segregation, these additives create a stable microstructure that maintains piezoelectric properties while enabling cost-effective Ni electrode usage
3Reliability
If M4 element segregation is prevented by compositional adjustment, then piezoelectric properties are maintained, but composition complexity increases
Solution Approach 1:
The patent applies parameter changes by specifically adjusting the MnO2 content (0.1-10 mol%) and M4′ element content (0.1-5.0 mol%) within defined ranges. These controlled parameter adjustments prevent M4 segregation and maintain piezoelectric properties while keeping the composition relatively simple and manageable
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 solution prevents segregation and maintains high piezoelectric properties without defective polarization, enabling the production of cost-effective, high-performance piezoelectric ceramic electronic components using Ni as internal electrodes.
Implementation Method 1
the Ni which constitutes the internal electrode material will diffuse to the ceramic green sheets during the firing, resulting in the segregation of the M4 element
Implementation Method 2
can be sintered stably in the atmosphere
Implementation Method 3
KNbO3 based piezoelectric ceramic compositions provide relatively high piezoelectric d constants (piezoelectric strain constants)
Data Source
AI summary
A piezoelectric ceramic includes a main constituent represented by the general formula {(1−x) (K1-a-bNaaLib)(Nb1-cTac)O3}−xM2M4O3}, and as accessory constituents, 2α mol of Na, (α+β) mole of an M4′ element, and γ mol of Mn with respect to 100 mol of the main constituent, where 0.1≦α≦β, 1≦α+β≦10, and 0≦γ≦10, M2 is Ca, Ba, and/or Sr, the M4 element and the M4′ element are Zr, Sn, and/or Hf, 0≦x≦0.06, 0≦a≦0.9, 0≦b≦0.1, and 0≦c≦0.3. Even in the case of using Ni as the main constituent in an internal electrode material of a piezoelectric element and carrying out co-firing, favorable piezoelectric properties can be obtained without defective polarization.