In situ observation of the magnetocaloric effect through neutron diffraction in the Tb(DCO₂)₃ and TbODCO₃ frameworks

Abstract

Probing the magnetic structure of magnetocaloric materials in applied fields, can reveal detailed insight into the mechanism of magnetic refrigeration linking the magnetic states that form under applied magnetic fields...

Dy(OH)3: a paramagnetic magnetocaloric material for hydrogen liquefaction

“…We anticipate that this likely stems from the ferromagnetic correlations within the paramagnetic phase of these materials as previously established for the ferromagnetic Ising chains in A(HCO 2 ) 3 (A = Tb and Ho) and BOHCO 3 (B = Tb and Dy) with the higher temperature scale in these hydroxides resulting from the stronger magnetic interactions within them. 14,21,33,47,49,50,54 Future studies of the hydroxides using modern neutron diffractometers to establish if they have magnetic diffuse scattering at these temperatures are needed to conrm this hypothesis.…”

Anomalous evolution of the magnetocaloric effect in dilute triangular Ising antiferromagnets Tb1−xYx(HCO2Falsaperna1, Bulled2, Stenning3 et al. 2022Phys. Rev. MaterialsSelf Cite0000View full textAdd to dashboardCite

“…Consistent with the proposed origin of the magnetocaloric properties of Tb(HCO2)3, neutron diffraction studies have shown that the application of weak magnetic fields helps to stabilise the TIA phase; however, at fields above 0.2 T, the system transforms to a simple ferromagnetic state in which all chains are aligned. 16 It is well-known that diamagnetic impurities readily disrupt low-dimensional magnetic states, [17][18][19][20][21] so the unusual discovery of the TIA state in Tb(HCO2)3 raises the question of how this state responds to the introduction of such impurities, and in turn how diamagnetic impurities affect the magnetocaloric properties observed. In principle, replacing Tb 3+ with diamagnetic Y 3+ should be viable, given that the two cations have similar ionic radii: 1.095 and 1.075 Å for 9-coordinated Tb 3+ and Y 3+ , respectively.…”

Magnetocaloric Ln(HCO2)(C2O4) frameworks: synthesis, structure and magnetic properties

“…This enables the chains to readily align with a magnetic field when it is applied and antiferromagnetic correlations are suppressed, increasing their magnetisation rapidly under low applied fields and thereby enhancing their entropy changes. 26 Geometric frustration has long been identified as a way of improving the MCE performance of materials, including GGG itself, 27 due to it suppressing long-range magnetic order to much lower temperatures, which allows dense magnetic materials to be used leading to a higher ÀDS max m . Coupling this with ferromagnetic chains is, however, a newer concept and it is important to establish if such strong local magnetic order is always associated with enhancing paramagnetic magnetocalorics for high temperature applications.…”