Giant magnetocaloric effect in a rare-earth-free layered coordination polymer at liquid hydrogen temperatures.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39362871.
- Also identified by DOI 10.1038/s41467-024-52837-x and PMC identifier 11450188.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Magnetic refrigeration, which utilizes the magnetocaloric effect, can provide a viable alternative to the ubiquitous vapor compression or Joule-Thompson expansion methods of refrigeration. For applications such as hydrogen gas liquefaction, the development of magnetocaloric materials that perform well in moderate magnetic fields without using rare-earth elements is highly desirable. Here we present a thorough investigation of the structural and magnetocaloric properties of a novel layered organic-inorganic hybrid coordination polymer Co<sub>4</sub>(OH)<sub>6</sub>(SO<sub>4</sub>)<sub>2</sub>[enH<sub>2</sub>] (enH<sub>2</sub> = ethylenediammonium). Heat capacity, magnetometry and direct adiabatic temperature change measurements using pulsed magnetic fields reveal a field-dependent ferromagnetic second-order phase transition at 10 K < <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>T</mi></mrow> <mrow><mi>C</mi></mrow> </msub> </math> < 15 K. Near the hydrogen liquefaction temperature and in a magnetic field change of 1 T, a large maximum value of the magnetic entropy change, <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>Δ</mi> <msubsup><mrow><mi>S</mi></mrow> <mrow><mi>M</mi></mrow> <mrow><mi>P</mi> <mi>k</mi></mrow> </msubsup> </math> = - 6.31 J kg<sup>-1</sup> K<sup>-1</sup>, and an adiabatic temperature change, <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>Δ</mi> <msub><mrow><mi>T</mi></mrow> <mrow><mi>ad</mi></mrow> </msub> </math> = 1.98 K, are observed. These values are exceptional for rare-earth-free materials and competitive with many rare-earth-containing alloys that have been proposed for magnetic cooling around the hydrogen liquefaction range.