KNN Sputtering Target Densification by Hot Press Sintering
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Solution Overview
Problem
The challenge is to develop a high-density potassium sodium niobate sputtering target with superior piezoelectric properties to replace lead-based PZT, as existing methods struggle to produce targets with sufficient density and stability for industrial use due to sintering resistance and low density issues.
Innovation Solution
A method involving the mixing of Nb2O5, K2CO3, and Na2CO3 powders, followed by pulverization and hot press sintering in an inert gas or vacuum atmosphere at specific temperatures and pressures, along with optional heat treatment, to achieve a potassium sodium niobate sputtering target with a relative density of 95% or higher, ensuring stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional sintering methods are used to produce potassium sodium niobate sputtering targets, then production cost and process simplicity are maintained, but the targets achieve insufficient density (below 95% relative density) and exhibit sintering resistance
Solution Approach 1:
The invention changes the sintering parameters by applying high pressure (150-400 kgf/cm²) combined with controlled temperature (900-1150°C) in a hot press sintering process. This parameter combination overcomes the sintering resistance of potassium sodium niobate powder while achieving high density (95% or higher relative density), resolving the contradiction between improving density and maintaining ease of manufacture
Solution Approach 2:
The invention introduces an intermediary binder material mixed with the potassium sodium niobate powder before sintering. This binder acts as a mediator that facilitates densification during the hot press sintering process by filling voids and promoting particle bonding, thereby achieving high density while maintaining reasonable manufacturing ease
2Reliability
If lead-based PZT is used as piezoelectric material, then superior piezoelectric properties are achieved, but environmental burden increases due to lead content
Solution Approach 1:
The invention changes the material composition by substituting lead-based PZT with potassium sodium niobate (KNN) having specific compositional ratios (0.96 ≤ x ≤ 1.04). This compositional parameter change maintains piezoelectric properties close to PZT while eliminating lead content, thereby resolving the contradiction between reliability and environmental burden
Solution Approach 2:
The invention uses composite material design by combining potassium carbonate, sodium carbonate, and niobium oxide in specific proportions to create a lead-free piezoelectric ceramic with KNN structure. This composite approach achieves PZT-like piezoelectric performance without harmful lead content, resolving the environmental burden issue while maintaining reliability
3Force
If hot press sintering is performed at higher temperatures to increase density, then relative density improves, but crystal grain size increases and flexural strength decreases
Solution Approach 1:
The invention optimizes the sintering temperature parameter to a specific range (900-1150°C) rather than using excessively high temperatures. Combined with high pressure (150-400 kgf/cm²), this moderate temperature parameter achieves high density (95% or higher) while limiting crystal grain growth to 1-20 μm, thereby maintaining flexural strength of 50 MPa or more and resolving the contradiction between density and strength
4Productivity
If pulverization is performed to reduce grain size for better sintering, then sintering efficiency improves, but production time and energy consumption increase
Solution Approach 1:
The invention performs preliminary pulverization of the starting materials (potassium carbonate, sodium carbonate, and niobium oxide) to achieve a grain size of 100 μm or less before mixing and sintering. This preliminary size reduction facilitates subsequent sintering by improving particle packing and reactivity, thereby enhancing sintering efficiency while keeping the pulverization time and energy consumption at reasonable levels
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 resulting high-density sputtering target exhibits improved strength, reduced particle generation, and controlled deposition rates, enabling stable and efficient film deposition while maintaining environmental sustainability by using a lead-free material.
Implementation Method 1
performing hot press sintering to the obtained pulverized powder in an inert gas or vacuum atmosphere under conditions of a temperature of 900° C. or higher and less than 1150° C.
Implementation Method 2
performing, after hot press sintering, vacuum heat treatment at 600° C. or higher and 900° C. or less
Implementation Method 3
performing HIP treatment at 800° C. or higher and 1150° C. or less
Data Source
AI summary
A potassium sodium niobate sputtering target having a relative density of 95% or higher. A method of producing a potassium sodium niobate sputtering target, including the steps of mixing a Nb2O5 powder, a K2Co3 powder, and a Na2Co3 powder, pulverizing the mixed powder to achieve a grain size d50 of 100 μm or less, and performing hot press sintering to the obtained pulverized powder in an inert gas or vacuum atmosphere under conditions of a temperature of 900° C. or higher and less than 1150° C., and a load of 150 to 400 kgf/cm2. A high density potassium sodium niobate sputtering target capable of industrially depositing potassium sodium niobate films via the sputtering method is provided.