Lead-Free Piezoelectric Ceramic Composition with KNN-KNT Composite Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lead-free piezoelectric ceramic compositions face challenges in achieving desirable piezoelectric characteristics, sinterability, and practical applications due to poor performance compared to conventional lead-containing compositions, with abrupt fluctuations near the phase transition point and high production costs.
Innovation Solution
A lead-free piezoelectric ceramic composition is developed, comprising a first crystal phase of alkali niobate/tantalate perovskite oxide with a second crystal phase of titanium-containing compounds, where the second phase is strategically incorporated to enhance sinterability and piezoelectric properties, and additional metals like copper, iron, and zinc are localized in the second phase to further improve characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ANbO3 lead-free piezoelectric ceramic composition is used, then environmental friendliness is improved (lead-free), but sinterability deteriorates
Solution Approach 1:
TiO2 is introduced as an intermediary substance that facilitates sintering. The TiO2 reacts with ANbO3 during heating to form KNT composition (KNbTiO5) as a secondary phase, which acts as a sintering aid and improves the sinterability of the lead-free piezoelectric ceramic composition
Solution Approach 2:
The invention creates a composite material system consisting of KNN material (K, Na, Nb) as the first crystal phase and KNT composition (K, Nb, Ti) as the second crystal phase. This composite structure combines the piezoelectric properties of KNN with the sintering enhancement provided by the KNT secondary phase
2Object-affected harmful factors
If ANbO3 lead-free piezoelectric ceramic composition is used, then environmental friendliness is improved (lead-free), but humidity resistance deteriorates
Solution Approach 1:
The composite structure with KNN as the first crystal phase and KNT as the second crystal phase provides improved humidity resistance. The KNT secondary phase forms a stable structure that protects the KNN matrix from humidity degradation
3Ease of manufacture
If Cu, Li, Ta are added to improve sinterability, then sinterability is improved, but piezoelectric characteristics deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters by specifically adding TiO2 to form KNT composition, rather than using Cu, Li, or Ta. This parameter change maintains sinterability improvement while preserving piezoelectric characteristics
Solution Approach 2:
The KNN-KNT composite structure provides both improved sinterability and maintained piezoelectric characteristics, unlike the Cu/Li/Ta additions that degrade piezoelectric properties
4Reliability
If phase transition point is between -50°C to +150°C, then piezoelectric constant is relatively high, but characteristics fluctuate abruptly near phase transition point
Solution Approach 1:
The invention modifies the composition parameters of the KNN material by incorporating TiO2 to form KNT secondary phase, which shifts or broadens the phase transition region, reducing the abruptness of characteristic fluctuations while maintaining relatively high piezoelectric constant
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 composition exhibits improved piezoelectric characteristics, enhanced sinterability, and stability of temperature characteristics, reducing production costs and increasing durability, making it suitable for applications in ultrasonic processing machines and sensing devices.
Implementation Method 1
a first crystal phase in which a plurality of crystal grains formed of an alkali niobate/tantalate perovskite oxide having piezoelectric characteristics is bound to each other in a deposited state
Implementation Method 2
an alkali niobate/tantalate perovskite oxide having piezoelectric characteristics
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A lead-free piezoelectric ceramic composition mainly includes a first crystal phase (KNN phase) and a second crystal phase (NTK phase). In the first crystal phase (KNN phase), a plurality of crystal grains formed of an alkali niobate/tantalate perovskite oxide having piezoelectric characteristics is bound to each other in a deposited state. The second crystal phase (NTK phase) is formed of a compound containing titanium (Ti) and fills spaces between the crystal grains in the first crystal phase.