Iridium-Cerium Sintered Electron Source With Lower Work Function
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Solution Overview
Problem
Sintered bodies composed of iridium and cerium exhibit a large work function, limiting their practical use as electron sources.
Innovation Solution
A method involving heating a sintered body of iridium and cerium at 1400 to 1800°C for 0.5 hours or more in a low oxygen atmosphere (10 -1< Pa or less) to produce a sintered material with a work function of 3.8 eV or less, achieved through crystallization and precipitation of metal iridium on the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sintered body of iridium and cerium is used as an electron source, then the material structure is simple and easy to manufacture, but the work function is large which limits electron emission performance
Solution Approach 1:
The patent applies parameter changes by heating the sintered body at high temperature (1400-1800°C) for extended periods (0.5-100 hours) in controlled oxygen atmospheres. This thermal treatment transforms the material's work function from 4.1-4.3 eV to 3.8 eV or less, significantly improving electron emission while maintaining the sintered body structure
Solution Approach 2:
The patent uses composite materials by combining iridium and cerium in specific ratios (Ir:Ce = 4:1 to 9:1) to create a sintered body with optimized properties. The composite structure allows cerium to lower the work function while iridium provides structural stability, achieving both manufacturability and improved electron emission
2Reliability
If the sintered body is heated at high temperature for extended periods, then the work function decreases to enable practical electron source application, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent optimizes heating parameters (temperature, time, oxygen partial pressure) to achieve the desired work function reduction with controlled process complexity. By establishing specific parameter ranges (1400-1800°C, 0.5-100 hours, controlled oxygen atmosphere), the process becomes reproducible and manageable despite the extended treatment 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 resulting sintered material achieves a sufficiently small work function, enabling high current density under low vacuum conditions, suitable for electron sources in devices like electron microscopes and semiconductor inspection devices.
Implementation Method 1
the sintered body is crystalized by heating to form a crystal body
Implementation Method 2
metal iridium is precipitated on the surface of the crystal body
Implementation Method 3
heating the sintered body at a temperature of 1400 to 1800°C for 0.5 hours or more
Implementation Method 4
the emitter includes an electron source and a heater that heats the electron source, and the heater is energized to heat the electron source, thereby obtaining emission current
Data Source
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AI summary
A method for producing a sintered material, the sintered material being constituted by iridium and cerium, and the method including: a step of preparing a sintered body constituted by iridium and cerium; and a step of heating the sintered body at a temperature of 1400 to 1800°C for 0.5 hours or more in an atmosphere having an oxygen partial pressure of 10-1 Pa or less to obtain the sintered material. A sintered material constituted by iridium and cerium, having a work function of 3.8 eV or less.