Grinding and particle size selection as a procedure to enhance the magnetocaloric response of La(Fe,Si)13 bulk samples

The magnetocaloric effect of La(Fe,Si)13 samples deteriorates with the presence of secondary phases. However, it is highly challenging to produce single phase samples by conventional procedures and purification requires long annealing time. We propose grinding and particle size selection of non-optimal starting samples as procedure to enhance the magnetocaloric response. In this study a starting multiphase LaFe11.8Si1.2 ingot was grinded and sieved to select three different particle size ranges. X-ray diffraction and Mössbauer spectrometry reveal that all samples mainly contain fcc-La(Fe,Si)13 and bcc-Fe(Si) phases. Microstructural and magnetic results show that the fcc-La(Fe,Si)13 phase fraction increases for samples with the smallest average particle size, increasing their magnetocaloric response in a factor larger than three with respect to that of the bulk sample.