Conductive Mayenite Oxide Production via Composition and Temperature Control
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Solution Overview
Problem
Conventional methods for producing conductive mayenite type compounds require expensive equipment, complex reaction condition control, and long reaction times, limiting efficiency and scalability.
Innovation Solution
A method involving heating a mixture of calcium and aluminum compounds within specific molar ratios at 900 to 1,300°C, followed by reduction in an inert gas or vacuum atmosphere at 1,200 to 1,415°C, to produce a calcined powder with an electron concentration of 1×10^18/cm^3 or more, facilitating efficient and cost-effective production of conductive mayenite type compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional heat treatment at 1,300°C for 6 hours is used to produce C12A7 crystal powder, then the crystal structure is formed, but expensive equipment and long reaction time are required
Solution Approach 1:
The invention changes the chemical composition parameters by introducing SrO and BaO into the C12A7 crystal structure, forming solid solutions with compositions (12-x-y)CaO-7Al2O3-xSrO-yBaO. This compositional modification allows the crystal to form at lower temperatures (900-1,300°C) with shorter times (0.5-6 hours), resolving the contradiction between crystal structure formation and production efficiency
Solution Approach 2:
The invention creates a composite crystal structure by incorporating Sr and Ba elements into the C12A7 lattice, forming a multi-element calcium aluminate system. This composite approach modifies the crystal growth kinetics and thermodynamics, enabling faster formation at reduced temperatures while maintaining the characteristic cage structure necessary for conductivity
2Manufacturing precision
If conventional heat treatment at 1,300°C for 6 hours is used to produce C12A7 crystal powder, then the crystal structure is formed, but expensive equipment is required
Solution Approach 1:
By modifying the chemical composition to include SrO and BaO, the invention reduces the required processing temperature from 1,300°C to 900-1,300°C. This temperature reduction eliminates the need for expensive high-temperature furnaces and specialized equipment, while still achieving proper crystal structure formation through the enhanced reactivity of the modified composition
3Reliability
If reduction treatment is performed on C12A7 crystal powder to obtain conductive mayenite, then conductive properties are imparted, but complicated control of reaction conditions is required
Solution Approach 1:
The invention performs preliminary action by incorporating Sr and Ba elements during the initial heating step (900-1,300°C) to form the modified C12A7 crystal structure with enhanced electron trapping capacity. This pre-preparation of the crystal lattice reduces the complexity of subsequent reduction treatment, as the modified structure naturally facilitates electron incorporation at lower temperatures with simpler atmospheric control
Solution Approach 2:
The compositional modification to (12-x-y)CaO-7Al2O3-xSrO-yBaO changes the electronic structure and defect chemistry of the crystal, creating more favorable conditions for electron incorporation during reduction. This parameter change allows reduction to proceed under milder conditions with less stringent control requirements, while maintaining high conductivity
4Reliability
If conventional production method is used to produce conductive mayenite, then the compound is obtained, but long-term reaction time is required
Solution Approach 1:
The invention simultaneously optimizes multiple parameters: compositional ratios (CaO:Al2O3:SrO:BaO), temperature (900-1,300°C), and time (0.5-6 hours). The Sr and Ba incorporation accelerates crystal formation kinetics and enhances electron trapping, achieving reliable conductive mayenite production in significantly shorter times compared to conventional methods
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
This method enables the stable and efficient production of conductive mayenite type compounds with high electron concentration, improving electrical conductivity and secondary electron emission characteristics, while reducing production costs and time, and allowing for large-scale production without specialized equipment.
Implementation Method 1
heating and holding the raw material at 900 to 1,300° C. to produce a calcined powder containing at least one oxide selected from the group consisting of a calcium aluminate, calcium oxide and aluminum oxide
Implementation Method 2
heating and holding the raw material at 900 to 1,300° C. to produce a calcined powder containing at least one oxide selected from the group consisting of a calcium aluminate, calcium oxide and aluminum oxide
Implementation Method 3
heating and holding the calcined powder at 1,200° C. to less than 1,415° C. under a reduction atmosphere in an inert gas atmosphere or a vacuum atmosphere each having an oxygen partial pressure of 1,000 Pa or less
Implementation Method 4
A C12A7 crystal powder or a sintered body thereof is allowed to contain electrons in the cages by conducting a heat treatment in a reduction atmosphere, thereby being able to impart permanent conductive properties at room temperature
Data Source
AI summary
The present invention relates to a method for producing an oxide containing a conductive mayenite type compound and having an electron concentration of 1×1018/cm3 or more, from a raw material which is a combination of a calcium compound and an aluminum compound or is a compound containing calcium and aluminum, each having a molar ratio of calcium oxide and aluminum oxide ranging from 9:10 to 14:5 in terms of the oxides, the method including the steps of: heating and holding the raw material at 900 to 1,300° C. to produce a calcined powder containing at least one oxide selected from the group consisting of a calcium aluminate, calcium oxide and aluminum oxide; and heating and holding the calcined powder at 1,200° C. to less than 1,415° C. under a reduction atmosphere in an inert gas atmosphere or a vacuum atmosphere each having an oxygen partial pressure of 1,000 Pa or less.