MnNiSi Multicaloric Alloy Phase Transition Tuning
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Solution Overview
Problem
Current materials for magnetic refrigeration lack giant magnetocaloric effects near room temperature, sensitivity to hydrostatic pressure, and low hysteresis, which are essential for efficient refrigeration devices.
Innovation Solution
The development of MnNiSi-based multicaloric systems through isostructural alloying of compounds with different magnetic and structural properties, such as (MnNiSi)1-x(FeGe)x or (MnNiSi)1-x(CoFeGe)x, which exhibit extraordinary magnetocaloric and barocaloric properties and acute sensitivity to applied hydrostatic pressure, shifting the phase transition temperature and maintaining a large isothermal entropy change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional magnetocaloric materials are used, then magnetic refrigeration can be achieved, but giant magnetocaloric effects near room temperature are not obtained
Solution Approach 1:
The patent applies parameter changes by systematically varying the compositional parameters (x, y, z) in the MnNiSi-based alloy system to tune the magnetostructural transition temperature to near room temperature (below 400K). By changing the stoichiometric ratios and substituting elements, the transition temperature and magnetocaloric effect intensity are optimized simultaneously, resolving the contradiction between achieving room-temperature operation and maintaining giant MCE.
Solution Approach 2:
The patent employs composite materials by creating MnNiSi-based multicaloric alloys that combine multiple elements (Mn, Ni, Si, Fe, Co, Ge) with different magnetic and structural properties. This composite approach enables the material to exhibit both giant magnetocaloric effects and barocaloric effects, while tuning the transition temperature to the desired range for efficient room-temperature magnetic refrigeration.
2Loss of energy
If materials with strong magnetic-structural coupling are used to achieve giant MCE, then magnetocaloric effect is enhanced, but sensitivity to hydrostatic pressure is not obtained
Solution Approach 1:
The patent achieves multi-functionality by developing MnNiSi-based multicaloric materials that simultaneously exhibit giant magnetocaloric effects, giant barocaloric effects, and high pressure sensitivity. The strong coupling between magnetic and structural degrees of freedom in these alloys enables them to respond to multiple external stimuli (magnetic field, hydrostatic pressure, electric field), making the material adaptable for various refrigeration applications and resolving the contradiction between enhancing MCE and achieving pressure sensitivity.
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
These systems achieve a significant enhancement of magnetocaloric effects with minimal hysteresis, allowing for efficient temperature tuning over a broad range, thereby improving the relative cooling power and efficiency of magnetic refrigeration devices.
Implementation Method 1
Giant MCE occurs when a large entropy change arises with a magnetic field-induced first order magnetostructural transition
Implementation Method 2
extraordinary magnetocaloric and barocaloric properties and an acute sensitivity to applied hydrostatic pressure
Implementation Method 3
The effects are associated with a strong coupling of magnetic and structural degrees of freedom that result in a giant MCE in the vicinity of the magnetostructural transition (MST), accompanied by changes in crystal symmetry or volume
Data Source
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AI summary
A multicaloric alloy material combines two isostructural compounds, the first compound being MnNiSi and the second compound being either MnFeGe or CoFeGe, each such compound having extremely different magnetic and thermo-structural properties. The resulting alloy material (MnNiSi)l_x(MnFeGe)x or (MnNiSi)l_x (CoFeGe)x possesses extraordinary magnetocaloric and/or barocaloric properties with an acute sensitivity to applied pressure and no appreciable magnetic hysteresis losses.