Tin Borate Microwave Dielectric Ceramics via Cold Sintering
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Solution Overview
Problem
Existing microwave dielectric ceramics face challenges in achieving a near-zero temperature coefficient and are difficult to produce at low temperatures due to borate decomposition during high-temperature sintering, limiting their application in high-reliability and high-performance microwave frequency bands.
Innovation Solution
A tin borate microwave dielectric ceramic with a chemical formula of (1−x)BaSn(BO3)2−xTiO2 is prepared through a cold sintering process, involving mixing B2O3, SnO2, and BaCO3, followed by pre-sintering, second mixing with TiO2, and annealing, to achieve a near-zero temperature coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid-phase method is used to prepare microwave dielectric ceramics, then high dielectric constant and high quality factor can be achieved, but high sintering temperature causes borate decomposition and makes it difficult to form microwave dielectric ceramics
Solution Approach 1:
The patent changes the sintering temperature parameter from traditional high temperature (900-1100°C) to low temperature (200-400°C) cold sintering process, fundamentally altering the processing conditions to prevent borate decomposition while achieving the desired dielectric properties
Solution Approach 2:
The patent uses composite material formulation combining barium borate, tin borate, and titanium dioxide in specific ratios, creating a multi-component system that enables low-temperature sintering while maintaining high dielectric constant and quality factor through synergistic effects of different materials
2Temperature
If cold sintering process is used to prepare borate microwave dielectric ceramic, then low temperature processing avoids borate decomposition, but the resonant frequency temperature coefficient is negative (−28.62 to −15.98 ppm·° C.−1) and needs optimization
Solution Approach 1:
The patent introduces titanium dioxide as a local modifier with specific positive temperature coefficient characteristics, creating localized compositional adjustment in the ceramic matrix to compensate for the negative temperature coefficient effect and achieve near-zero overall temperature stability
Solution Approach 2:
The patent employs systematic compositional adjustment where titanium dioxide content is varied (x=0.05 to 0.25) to feedback-control the resonant frequency temperature coefficient, optimizing the balance between low-temperature processing benefits and temperature stability requirements
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 ceramic exhibits a resonance frequency temperature coefficient of −7 ppm·° C.−1 to 7 ppm·° C.−1, dielectric constant of 3.97 to 5.48, and quality factor of 10,836 to 13,065, demonstrating superior performance and reduced energy consumption with minimal environmental pollution.
Implementation Method 1
Cold sintering process allows the application of a uniaxial pressure to the material while heating, promoting the flow and mass transfer of the solution in the ceramic powder to achieve rapid densification
Implementation Method 2
subjecting a resulting mixture to cold sintering and annealing in sequence to obtain the tin borate microwave dielectric ceramic with the near-zero temperature coefficient
Data Source
AI summary
Provided are a tin borate microwave dielectric ceramic with a near-zero temperature coefficient and a preparation method thereof. The tin borate microwave dielectric ceramic with the near-zero temperature coefficient has a chemical formula of (1−x)BaSn(BO3)2−xTiO2, x being in a range of 0.05 to 0.25; where a principal crystalline phase of the tin borate microwave dielectric ceramic with the near-zero temperature coefficient has a chemical formula of BaSn(BO3)2.