Indium Oxide Tablet Density Control for Electron Beam Stability
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Solution Overview
Problem
Indium oxide sintered body tablets with cerium as a dopant are prone to breakage when irradiated with high-power electron beams, and existing methods struggle to produce tablets with a relative density of 50% to 80% that maintain structural integrity and produce high-refractive-index transparent conductive films.
Innovation Solution
A method involving a calcined indium oxide powder heat-treated between 1300°C and 1550°C, mixed with uncalcined cerium oxide powder, followed by granulation and sintering at a temperature 200°C lower than the calcination temperature, results in an ICO sintered body tablet with a relative density of 50% to 80% and a crystal grain distribution where the most frequent crystal grain percentage is 20% or less, preventing breakage during electron beam irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a tablet with low density is used for vapor deposition, then the tablet shrinks and breaks under electron beam irradiation, but if a tablet with high density is used, then thermal shock causes breakage due to temperature difference between surface and inside
Solution Approach 1:
The patent applies parameter changes by precisely controlling the relative density of the tablet within the range of 30% to 70% (particularly 35%-65%), and by controlling the crystal grain size distribution where the maximum crystal grain diameter is 0.5 mm or less. These parameter optimizations resolve the contradiction by creating a density that is neither too low (causing shrinkage breakage) nor too high (causing thermal shock breakage), while the fine crystal grain distribution ensures uniform heat distribution during electron beam irradiation.
2Stability of the object's composition
If the tablet density is too low, then rapid sintering occurs during electron beam irradiation causing tablet breakage, but if the tablet density is too high, then thermal shock causes breakage
Solution Approach 1:
The patent optimizes the density parameter to a specific range (30%-70%, particularly 35%-65%) that balances stability and strength. This intermediate density value prevents both rapid sintering (which occurs at low density) and thermal shock (which occurs at high density), thereby resolving the contradiction between composition stability and mechanical strength.
Solution Approach 2:
The patent performs preliminary sintering to create a tablet with controlled density and crystal grain distribution before actual vapor deposition. This preliminary structuring ensures that the tablet has the appropriate density stability and mechanical strength to withstand electron beam irradiation without breakage during the deposition process.
3Illumination intensity
If a high-refractive-index material like cerium oxide or titanium oxide is used, then the refractive index increases, but the electrical conductivity deteriorates
Solution Approach 1:
The patent uses composite materials by combining indium oxide (which provides electrical conductivity) with cerium oxide (which provides high refractive index). This composite approach allows the vapor deposition target to simultaneously achieve both high refractive index (2.0-2.2) and adequate electrical conductivity, resolving the contradiction between optical and electrical properties.
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 method produces ICO sintered body tablets that are resistant to high-power electron beams and enables the formation of high-refractive-index transparent conductive films with a refractive index of 2.0 to 2.2, maintaining film quality and continuity during deposition.
Implementation Method 1
when a tablet having a too-low density is irradiated with electron beams, the sintering of the tablet occurs rapidly, simultaneously with the evaporation of the material from the surface
Implementation Method 2
a material for vapor deposition made of an oxide sintered body for use in producing a low-resistance transparent conductive film by a vacuum vapor deposition method
Implementation Method 3
an ITO sintered body having a relative density of 90% or more is crushed, and the obtained granules having grain diameters of 0.5 mm or less is sintered again
Data Source
AI summary
A tablet for vapor deposition characterized in that on a fracture surface of an indium oxide sintered body, the percentage of crystal grains having a grain diameter corresponding to a highest peak is 20% or less. The tablet is produced by: mixing indium oxide powder and cerium oxide powder, and subjecting the mixture to a heat treatment at 1300° C. to 1550° C. to calcine; mixing an uncalcined indium oxide powder and/or an uncalcined cerium oxide powder with the obtained calcined powder such that the ratio of the calcined powder is 50% to 80% by mass, followed by granulation; and molding the obtained granulated powder, thereby forming a molded body, and then sintering the molded body at a temperature which is 1100° C. to 1350° C., and which is lower than the temperature of the heat treatment on the calcined powder in the first step by 20° C. or more.