# Structural, Magnetic, and Magnetocaloric Properties of Ce2(Fe, Co)17 Compounds: Tuning Magnetic Transitions and Enhancing Refrigeration Efficiency

## TL;DR

This study investigates how substituting cobalt in Ce2(Fe, Co)17 compounds can tune magnetic transitions and improve refrigeration efficiency near room temperature.

## Contribution

The paper introduces a cost-effective Ce-based material with tunable magnetocaloric properties suitable for room-temperature refrigeration.

## Key findings

- Cobalt substitution shifts the magnetocaloric effect to near room temperature (285 K).
- The compounds show a second-order magnetic phase transition with 85% of Gd's cooling power.
- Cerium's low cost and concentration make the material sustainable and affordable.

## Abstract

This study explores the structural, magnetic, and magnetocaloric properties of Ce2(Fe, Co)17 (x = 0, 0.5, 0.6, and 0.7) compounds synthesized via arc melting under high temperatures exceeding 2300 K. The as-cast ingots are subsequently sealed and subjected to a heat treatment at 1323 K to improve homogeneity and crystallinity. Detailed analyses using X-ray diffraction and magnetometry reveal that cobalt substitution significantly impacts the structural and magnetic behavior, enabling precise tuning of the magnetic transition temperature and magnetic order. The substitution induces an anisotropic increase in cell parameters and shifts the magnetocaloric effect (MCE) from low temperatures (200 K for x = 0) to near room temperature (285 K for x = 0.7), enhancing the operating temperature range. The magnetocaloric effect is studied across different magnetic transitions: a metamagnetic and ferro-antiferromagnetic transition followed by a paramagnetic state in one sample, and a direct ferro-paramagnetic transition in another. The compounds exhibit a second-order magnetic phase transition, ensuring a reversible MCE, with a relative cooling power (RCP) that is approximately 85% of that of pure Gd. Moreover, the use of cerium, the most cost-effective rare-earth element (5 $/kg), combined with its low atomic concentration (10%) in these intermetallics, enhances the sustainability and affordability of these materials. These findings underline the potential of iron-rich Ce-based compounds for next-generation refrigeration and energy-harvesting applications.