Piezoelectric Actuator Insulation via Ag Diffusion and Zn2SiO4 Grain Boundaries
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Solution Overview
Problem
Piezoelectric ceramics used in multilayer actuators suffer from deteriorated insulation performance due to the presence of Ag particles at grain boundaries and contamination with Si, leading to fracture and reduced sintering properties when used in environments with electrolytes like ink or water.
Innovation Solution
A multilayer piezoelectric actuator with a PZT phase as the main crystal phase, where Ag is diffused into the crystal particles, and Zn2SiO4 is used at grain boundaries to reduce voids and prevent Pb2SiO4 formation, resulting in improved insulation and reduced fracture, with Ag-Pd alloy electrodes and controlled lattice constants to enhance intergranular fracture and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Ag particles are present at grain boundaries in piezoelectric ceramics, then the piezoelectric actuator can be manufactured with standard processes, but the insulation performance is remarkably deteriorated
Solution Approach 1:
The invention extracts and removes Ag particles from the grain boundaries of the piezoelectric ceramic layer through controlled sintering processes. By adjusting sintering temperature and atmosphere, the Ag particles are selectively eliminated from critical grain boundary regions, preventing insulation deterioration while maintaining manufacturability of the multilayer actuator structure
Solution Approach 2:
The invention changes the sintering parameters (temperature, atmosphere, time) to control the behavior of Ag particles during manufacturing. By optimizing these parameters, Ag particles are prevented from precipitating at grain boundaries or are removed if already present, thereby maintaining both ease of manufacture and high insulation performance
2Ease of manufacture
If Si is contaminated into the raw material during wet grinding, then the manufacturing process can proceed with standard water-based grinding, but the Pb2SiO4 phase forms at grain boundaries causing fracture and insulation deterioration
Solution Approach 1:
The invention converts the harmful effect of Si contamination into a beneficial outcome by controlling the sintering process to prevent Pb2SiO4 phase formation. Through optimized sintering conditions, even when Si is present from wet grinding, the harmful Pb2SiO4 phase is prevented from forming at grain boundaries, thereby eliminating fracture risks while maintaining the simplicity of water-based grinding processes
Solution Approach 2:
The invention changes the sintering parameters to a specific temperature range and atmospheric conditions that prevent the formation of Pb2SiO4 phase at grain boundaries. By controlling these parameters, Si contamination from wet grinding is neutralized, ensuring fracture resistance and insulation performance without complicating the manufacturing process
3Adaptability or versatility
If the piezoelectric actuator is used in environments with electrolytes like ink or water, then the actuator can function in practical applications, but the insulation performance deteriorates due to electrolyte entry through fractured grain boundaries
Solution Approach 1:
The invention applies beforehand cushioning by ensuring the grain boundaries are free from Pb2SiO4 phase and properly sealed through controlled sintering before the actuator is exposed to electrolyte environments. This preventive measure ensures that even when used in inkjet applications with ink or water, the electrolyte cannot penetrate through fractured grain boundaries, maintaining insulation performance throughout the operational life
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 significantly improves insulation performance and reduces piezoelectric performance deterioration, maintaining reliability even in environments with electrolytes, by minimizing Ag precipitation and voids, and applying compressive stress to prevent cracks and ensure uniform characteristics.
Implementation Method 1
oxide ceramics of a perovskite-type crystal structure having an average particle diameter of 1 to 8 μm and exhibiting piezoelectric performance
Implementation Method 2
Ag particles of the internal electrode layer containing Ag-Pd alloy are usually precipitated at grain boundaries
Implementation Method 3
a lattice constant c of c-axis of the PZT phase is 0.4085 nm to 0.4100 nm, and a ratio of the lattice constant c of the c-axis of the PZT phase and a lattice constant a of a-axis, namely, the ratio c/a, is 1.011 or more
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
Amultilayer piezoelectric actuator and a liquid discharge head are provided which are equipped with dense piezoelectric ceramics having improved insulation performance. The multilayer piezoelectric actuator comprises a multilayered body comprising a plurality of piezoelectric ceramic layers containing a PZT phase as a main crystal phase; and an electrode layer containing Ag, which is disposed at least one of on the surface and in the interior of the multilayered body. A lattice constant c of c-axis of the PZT phase is 0.4085 nm to 0.4100 nm, and a ratio of the lattice constant c of the c-axis of the PZT phase and a lattice constant a of a-axis, namely, the ratio c/a, is 1.011 or more. A second phase containing Ag different from the PZT phase is not substantially contained in the piezoelectric ceramic layer. A Zn2SiO4 phase is contained at grain boundaries of the PZT phase, and a Pb2SiO4 phase is not substantially contained at the grain boundaries of the PZT phase.