Lead-Free Binary Ceramic Piezoelectric Material
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Solution Overview
Problem
Conventional piezoelectric materials have limited elongation under electric fields due to low dielectric strength and high lead content, which is harmful to humans and the environment.
Innovation Solution
A binary ceramic material composed of (1−x)(Bi0.5Na0.5TiO3)×(K0.5Na0.5NbO3) with variable proportions of bismuth sodium titanate and potassium sodium niobate, offering high elongation, dielectric strength, and being lead-free, produced through a method involving mixing oxygen-containing compounds, calcination, and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional piezoelectric materials are used to achieve high elongation under electric field, then the dielectric strength is limited, but the lead content becomes high which is harmful to people and environment
Solution Approach 1:
The patent changes the chemical composition parameters by replacing lead-based piezoelectric materials with a binary ceramic system comprising bismuth sodium titanate (BNT) and potassium sodium niobate (KNN) in specific proportions (0.05 ≤ x ≤ 0.15). This parameter change eliminates toxic lead while maintaining high elongation properties through optimized stoichiometric ratios that induce morphotropic phase boundary characteristics.
Solution Approach 2:
The patent creates a composite ceramic material by combining two different ceramic phases - BNT (rhombohedral structure) and KNN (orthorhombic structure) - in a binary system. This composite approach leverages the complementary properties of both materials to achieve high piezoelectric response and elongation without requiring lead, resolving the contradiction between performance and environmental safety.
2Reliability
If the proportion of K0.5Na0.5NbO3 is increased to improve dielectric strength, then the elongation decreases, but the piezoelectric stability improves
Solution Approach 1:
The patent optimizes the compositional parameter x within the range 0.05 ≤ x ≤ 0.15 to achieve a balance between dielectric strength and elongation. Within this optimized parameter range, the material simultaneously exhibits high dielectric strength (improved reliability) and high elongation, resolving the trade-off between these two properties through precise parameter control.
Solution Approach 2:
The patent utilizes phase transition phenomena at the morphotropic phase boundary where rhombohedral and tetragonal crystal structures coexist. By positioning the composition within the MPB region, the material exhibits enhanced piezoelectric response and stability while maintaining high elongation, as the phase boundary region allows for easier domain switching and higher polarizability.
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 material achieves high elongation and electrical/mechanical stability, reducing negative elongation and allowing for phase transitions, resulting in enhanced piezoelectric properties and safer, more environmentally friendly electronic components.
Implementation Method 1
electrically induced phase transition from the antiferroelectric to the ferroelectric phase by mixing potassium sodium niobate and bismuth sodium titanate, which together produce a solid solution
Implementation Method 2
Materials which undergo a change in their spatial extent when exposed to a specific applied electric field, i.e. materials which have piezoelectric properties
Implementation Method 3
The achievable elongation of the materials is limited by their dielectric strength
Data Source
AI summary
The invention relates to a ceramic binary material and to a method for the production thereof. The material has piezoelectric properties and has a composition of the formula (1−x)(Bi0.5Na0.5TiO3)×(K0.5Na0.5NbO3), where 0<x≦0.15. Furthermore, the invention relates to a component comprising said material.