Magnetocaloric effect in M5XB2 family compounds

The purpose of work presented in this thesis is to investigate whether M5XB2 (M = Fe, Mn,V, Cr and X = Si, P) material system has potential as a room-temperature magnetocaloric application material by studying its crystal and magnetic structure, and magnetocaloric properties.

Magnetocaloric properties of Mn₅(Si,P)B₂ compounds for energy harvesting applications

The magnetocaloric properties of Mn₅Si_1-xP_xB₂ (0 ≤ x ≤ 1) compounds were studied for energy harvesting applications. The crystal structure and the magnetic structure were characterized by powder X-Ray Diffraction and powder Neutron Diffraction. The results indicate that these magnetocaloric...

Magnetocaloric effect in the (Mn,Fe)₂(P,Si) system: From bulk to nano

In the field of nanoscale magnetocaloric materials, novel concepts like micro-refrigerators, thermal switches, microfluidic pumps, energy harvesting devices and biomedical applications have been proposed. However, reports on nanoscale (Mn,Fe)₂(P,Si)-based materials, which are one of the most promising bulk materials for solid-state...

Magnetic phase diagram of the mn_x fe_2−x p_1−y si_y system

The phase diagram of the magnetocaloric Mn_x Fe_2−x P_1−y Si_y quaternary compounds was established by characterising the structure, thermal and magnetic properties in a wide range of compositions (for a Mn fraction of 0.3 ≤ x < 2.0 and a Si fraction of 0.33 ≤ y ≤ 0.60). The highest ferromagnetic...

Nonlinear influence of excess Mn on the magnetoelastic transition in (Mn,Cr)₂Sb

The influence of excess Mn on the magnetoelastic ferromagnetic-to-antiferromagnetic transition T_t in the magnetocaloric compound (Mn,Cr)₂Sb has been studied. With increasing excess Mn the magnetoelastic transition temperature for (Mn,Cr)₂Sb initially increases and then decreases. This trend is accompanied by a...

Landau model evaluation of the magnetic entropy change in magnetocaloric materials

The field exponent for the magnetic entropy change n=dlnΔS/dlnH in a magnetic field was evaluated using the Landau model to provide a classification for the nature of the ferromagnetic-to-paramagnetic transitions at the Curie temperature T_C in magnetocaloric materials. The magnetic phase transition can be classified as a first...

Design of efficient magnetocaloric materials for energy conversion

The magnetocaloric effect (MCE) is a magneto-thermodynamic phenomenon in which a temperature change of a material is caused by exposing the material to a changing magnetic field under adiabatic conditions. There are two main applications based on the MCE. One application is magnetic refrigeration, which can expel heat in a magnetic field cycle....