Dielectric Ceramic Surface Concentration for MLCC
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Solution Overview
Problem
Existing dielectric ceramics with zirconium composition added to barium titanate do not effectively improve the dielectric constant, often resulting in a decrease when the zirconium ratio is increased, failing to stabilize temperature characteristics in multilayer ceramic capacitors.
Innovation Solution
A dielectric ceramic with barium titanate-based crystal grains coated with Mg, Mn, and a rare earth element, where these elements are concentrated higher on the surface than the inside, and 0.04 to 0.2 parts by mass of zirconium oxide are added, forming a composite oxide with improved ferroelectricity and stabilized temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the crystal grains are finely granulated to reduce layer thickness, then the capacitor size is reduced, but the dielectric constant decreases
Solution Approach 1:
The surface concentration of Mg, Mn, and rare earth elements creates a protective surface layer that maintains high dielectric constant even when crystal grains are finely granulated. This local compositional quality at the surface compensates for the size reduction effect, allowing fine grains to be used for thinner layers while preserving dielectric performance
2Stability of the object's composition
If zirconium oxide is added to stabilize temperature characteristics, then temperature stability is improved, but the dielectric constant decreases
Solution Approach 1:
By concentrating functional elements on the surface and controlling zirconium oxide addition to 0.04-0.2 parts by mass, the patent creates a surface-dominated structure where the surface composition controls temperature stability while the bulk composition maintains high dielectric constant, preventing the trade-off between these two properties
Solution Approach 2:
The patent optimizes the zirconium oxide content parameter to a specific range (0.04-0.2 parts by mass) and controls the concentration ratio of surface to interior elements at least 1.5 times, creating optimal conditions where both temperature stability and high dielectric constant are achieved simultaneously
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 approach results in a high dielectric constant and stable temperature characteristics for multilayer ceramic capacitors, enhancing capacitance-temperature performance and reliability, while preventing zirconium diffusion into the crystal grains, thus maintaining high dielectric constant values.
Implementation Method 1
at least one kind of the metal composition of the Mg, the Mn and the rare earth element is present at a higher concentration on the surface side of the primary crystal grains than the inside thereof... preventing zirconium diffusion into the crystal grains
Implementation Method 2
0.04 to 0.2 parts by mass of Zr in terms of oxide to 100 parts by mass of the composite oxide is contained... forming a composite oxide with improved ferroelectricity
Data Source
AI summary
A dielectric ceramic includes primary crystal grains. The primary crystal grains include a composite oxide of Ti and at least one kind of alkaline earth metal element selected from Ca, Sr and Ba. The primary crystal grains contain metal compositions of Mg, Mn and a rare earth element. At least one of the metal composition of the Mg, the Mn and the rare earth element is present at a higher concentration on the surface side of the primary crystal grains than the inside thereof. A 0.04 to 0.2 parts by mass of Zr in terms of oxide to 100 parts by mass of the composite oxide is present. As a result, a high dielectric constant can be imparted even to finely granulated barium titanate based crystal grains.