MnAs and MnFeP1-xAsx-based magnetic refrigerants: a review

This paper presents a comparative analysis of MnAs and MnFeP1-xAsx family and its alloys from magnetic refrigeration perspective. A thorough literature review was undertaken and to the best of authors knowledge, all samples (similar to 100 samples) with their Curie temperature (T-c) in the range 260-340 K have been reported. For contrastive analysis, samples have been grouped based on their structural and experimental conditions such as magnetic field and sample composition etc. For comparative analysis, all variables of magnetocaloric effect (MCE), e.g., T-c, magnetic entropy change (divide Delta SMdivide delta C-13(ethane)). Through comparing the geochemical characteristics of gases in the southern and northern parts of the gas field, the reasons for the carbon isotopic reversal in the southern Jingbian gas field were determined to be high thermal maturity and mixing action. When thermal maturity reaches a critical value, the carbon isotope value of ethane becomes relatively more depleted with thermal maturity. Although the carbon isotope value of methane increases with thermal maturity, the extent is relatively smaller. Finally, the rare phenomenon of delta C-13(methane) > delta C-13(ethane) occurs. High thermal maturity leads to the secondary thermal cracking of gases. Mixing of the cracked gases and primary gases also leads to carbon isotopic reversal. Both of the above mechanisms share a common premise, which is high thermal maturity.