posted on 2023-11-04, 13:04authored byNiels Kubitza, Pedram Babaei, Ulf Wiedwald, Christina S. Birkel
Magnetocaloric materials
form highly promising candidates to fundamentally
change the current vapor compression-based refrigeration technology,
with the benefits of bypassing the use of greenhouse gas emissions
and improving the energy efficiency. One member within this group
of materials is the antiperovskite phase Mn3GaC. However,
despite the big potential that lies in its materials properties, the
synthesis of this phase and antiperovskites in general is still mainly
achieved by conventional energy-consuming solid-state methods, resulting
in long reaction times (>7 days) and challenges in influencing
the
microstructure or morphology. Here, we report a rapid sol–gel
approach using citric acid as a gelling agent, which allows us to
obtain a highly phase-pure, crystalline Mn3GaC phase after
only 5 h of annealing. Ex situ X-ray powder diffraction
data, combined with DSC/TGA measurements, elucidate the reaction mechanism,
which involves carbothermal reduction of intermediate oxides. Vibrating
sample magnetometry of the annealed products demonstrates the ability
to alternate the magnetic properties of Mn3GaC simply based
on the variation of the gelling agent amount in the reaction mixture.
Overall, this offers a facile alternative and energy- and time-efficient
approach for the synthesis of antiperovskite carbide phases with the
power to specifically influence materials properties by only slight
adjustments of parameters within this wet chemical-based synthesis
procedure.