Method for producing al-doped gadolinium oxysulfide cold storage medium
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Solution Overview
Problem
Existing cold storage materials, such as rare earth intermetallic compounds, have insufficient heat capacity and durability at ultra-low temperatures, leading to reduced refrigerating capacity and high costs, while conventional metal materials lose heat capacity rapidly below 10 K.
Innovation Solution
A method for producing rare earth oxysulfide-based cold storage materials by adding Al2O3 to rare earth oxides, reacting with sulfur-containing gases, and sintering at high temperatures to form grains with a specific surface area and crystal size that enhances thermal stability and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If rare earth intermetallic compounds are used as cold storage materials, then heat capacity at liquid helium temperature is improved, but durability against thermal shock and mechanical vibration deteriorates
Solution Approach 1:
The patent creates a composite material by doping Al2O3 particles into the Gd2O2S ceramic matrix. This composite structure combines the high heat capacity of the rare earth oxysulfide with the high durability and thermal shock resistance of alumina, resolving the contradiction between heat capacity and durability
Solution Approach 2:
The patent introduces Al2O3 dopants at specific locations within the Gd2O2S crystal structure (substituting at rare earth sites) to locally enhance mechanical strength and thermal shock resistance while preserving the overall high heat capacity of the rare earth oxysulfide matrix
2Ease of manufacture
If conventional metal cold storage materials are used, then manufacturing cost is reduced, but heat capacity at ultra-low temperature deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by doping Al2O3 into Gd2O2S, which modifies the thermal and mechanical properties of the material to achieve high heat capacity at ultra-low temperatures while maintaining manufacturing feasibility through ceramic processing techniques
3Reliability
If Al2O3 is added to Gd2O2S to improve durability, then resistance to thermal shock and mechanical vibration is improved, but heat capacity deteriorates
Solution Approach 1:
The patent uses low concentrations of Al2O3 doping (0.03 to 0.12 weight ratio) to locally enhance durability through substitutional doping at rare earth sites, while preserving the bulk heat capacity properties of the Gd2O2S matrix by avoiding excessive dopant addition
Solution Approach 2:
The patent optimizes the doping concentration parameter of Al2O3 to achieve the right balance between durability enhancement and heat capacity preservation, using precise control of dopant amount to avoid excessive reduction in heat capacity
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 material maintains a heat capacity of 0.3 J/cc·K or higher at 10 K or less, with increased durability against thermal shock and mechanical vibration, extending operational life to 10000 hours without grain breakage, compared to 1500 hours for materials without Al2O3 addition.
Implementation Method 1
adding Al2O3 to rare earth oxides, reacting with sulfur-containing gases
Implementation Method 2
sintering at high temperatures to form grains with a specific surface area and crystal size
Implementation Method 3
maintains a heat capacity of 0.3 J/cc·K or higher at 10 K or less
Data Source
Figure 1
AI summary
Provided is a cold storage material having a large thermal capacity in a ultra-low temperature range of 10 K or less and being highly durable against thermal shock and mechanical vibration. The cold storage material contains a rare earth oxysulfide ceramic represented by the general formula R2O2S (wherein R is one or more kinds of rare earth elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), and Al2O3 having a specific surface area of 0.3 m2/g to 11 m2/g is added to the cold storage material.