Investigation of the impact of Nb doping on the low-temperature refrigeration capacity of magnetoelectric material Co₄Ta₂O₉: phenomenological approach

<ns3:p>The study investigates the influence of niobium (Nb) doping on the low-temperature refrigeration capacity of the magnetoelectric (ME) material Co₄Ta₂O₉ (CTO). The primary aim is to explore the potential enhancements in magnetoelectric coupling and electrocaloric properties due to Nb substitution, using a phenomenological model to predict the magnetic-field-induced electrocaloric effect (MECE).A phenomenological model, rooted in Curie-Weiss-type domain theory, is employed to simulate the temperature dependence of electric polarisation and evaluate the MECE of Nb-doped CTO. Theoretical simulations are corroborated with experimental data, and critical parameters such as entropy change (∆S), maximum entropy change (∆Smax), heat capacity change (∆CP), full width at half maximum (δTFWHM), relative cooling power (RCP) and refrigerant capacity (RC) are calculated to assess refrigeration efficiency.The results demonstrate that Nb doping modifies the magnetoelectric properties by altering the structural and electronic configurations of Co₄Ta₂O₉.The work is limited to theoretical simulations supported by prior experimental data. Further experimental validation of the predicted MECE and long-term stability of Nb-doped compounds under operational conditions is recommended for practical adoption. Future work could also explore different dopant concentrations and combinations to achieve optimised performance.The study suggests that low-polarisation magnetoelectric materials can be effective for magnetic refrigeration applications, offering benefits such as reduced hysteresis loss and broader operational temperature range. The results can inform the design of efficient, sustainable, and cost-effective cooling devices that utilise electrocaloric effects.It is the first study to theoretically predict the MECE in Nb-doped CTO using a phenomenological approach. The novelty lies in identifying and quantifying the impact of Nb doping on electrocaloric performance, offering a new perspective on the use of low-polarisation materials in refrigeration applications.</ns3:p>