Magnetocaloric Properties and Thermal Stability of RTiSi (R = Tb, Dy, Ho, Er) Intermetallic Compounds for Magnetic Refrigeration Applications

Rare-earth intermetallic compounds RTiSi (R = Tb, Dy, Ho, and Er) have attracted considerable attention as metallic functional materials for magnetic refrigeration owing to their tunable magnetic transitions and significant magnetocaloric response. In the present work, a systematic investigation of the thermal stability, microstructure, and magnetocaloric properties of induction-melted RTiSi compounds is reported.

X-ray diffraction confirms the formation of the tetragonal CeFeSi-type structure (space group P4/nmm) for all investigated compounds. Scanning electron microscopy reveals homogeneous and highly crystalline microstructures with well-developed grains, indicating good phase stability and compositional uniformity throughout the series. Differential scanning calorimetry demonstrates the high thermal stability of the intermetallic phases and their systematic variation across the rare-earth series.

Magnetic measurements reveal antiferromagnetic ordering with transition temperatures ranging from approximately 50 K for ErTiSi to 275 K for TbTiSi, enabling magnetocaloric operation over a broad temperature range. The magnetic entropy change under a magnetic field variation of 0–5 T reaches values between 6 and 10 J·kg⁻¹·K⁻¹. The highest values are generally observed for TbTiSi and DyTiSi, while ErTiSi exhibits comparatively lower values, reflecting the variation in rare-earth magnetic moments and exchange interactions.

The total entropy change varies from about 150 to 300 J·kg⁻¹ across the series, while the adiabatic temperature change is estimated to lie between 1.3 and 2.7 K under a 5 T magnetic field change. The enhancement in the magnetocaloric response from ErTiSi to TbTiSi is attributed to the progressive strengthening of magnetic interactions within the rare-earth sublattice.

These results demonstrate that RTiSi compounds are promising metallic materials for magnetic refrigeration, combining structural stability, tunable magnetic ordering temperatures, and appreciable magnetocaloric performance over a wide temperature range.