Tuneable giant magnetocaloric effect in (Mn,Fe)₂(P,Si) materials by Co-B and Ni-B co-doping

The influence of Co (Ni) and B co-doping on the structural, magnetic and magnetocaloric properties of (Mn,Fe)₂(P,Si) compounds is investigated by X-ray diffraction (XRD), differential scanning calorimetry, magnetic and direct temperature change measurements. It is found that Co (Ni) and B co-doping is an effective approach to tune...

On the phase stability of CaCu₅-type compounds

We present a hybrid method to inspect the phase stability of compounds having a CaCu₅-type crystal structure. This is done using 2D stability plots using the Miedema parameters that are based on the work function and electron density of the constituent elements. Stable compounds are separated from unstable binary compounds, with a...

Kinetic-arrest-induced phase coexistence and metastability in (Mn,Fe)2(P,Si)

Neutron diffraction, Mössbauer spectroscopy, magnetometry, and in-field x-ray diffraction are employed to investigate the magnetoelastic phase transition in hexagonal (Mn,Fe)2(P,Si) compounds. (Mn,Fe)2(P,Si) compounds undergo for certain compositions a second-order paramagnetic (PM) to a spin-density-wave (SDW) phase transition before further...

Efficient Room-Temperature Cooling with Magnets

Magnetic cooling is a highly efficient refrigeration technique with the potential to replace the traditional vapor compression cycle. It is based on the magnetocaloric effect, which is associated with the temperature change of a material when placed in a magnetic field. We present experimental evidence for the origin of the giant entropy...

Short-range magnetic correlations and spin dynamics in the paramagnetic regime of (Mn,Fe)2(P,Si)

The spatial and temporal correlations of magnetic moments in the paramagnetic regime of (Mn,Fe)2(P,Si) have been investigated by means of polarized neutron diffraction and muon-spin relaxation techniques. Short-range magnetic correlations are present at temperatures far above the ferromagnetic transition temperature (TC). This leads to...

Spin correlations in (Mn,Fe)2(P,Si) magnetocaloric compounds above Curie temperature

The longitudinal-field muon-spin relaxation (LF-μSR) technique was employed to study the spin correlations in (Mn,Fe)2(P,Si) compounds above the ferromagnetic transition temperature (TC). The (Mn,Fe)2(P,Si) compound under study is found to show itinerant magnetism. The standard deviation of the magnetic field distribution of electronic origin...

Structural and magnetocaloric properties of (Mn,Fe)2(P,Si) materials with added nitrogen

Amongst magnetic materials that exhibit a giant magnetocaloric effect near room temperature, the(Mn,Fe)2(P,Si) system is one of the most promising candidates for magnetic refrigeration. Although the(Mn,Fe)2(P,Si) materials hold many advantages, controlling the magnetic entropy changeDSm, theadiabatic temperature changeDTad, the thermal...

Autonomous filling of grain-boundary cavities during creep loading in Fe-Mo alloys

We have investigated the autonomous repair of creep damage by site-selective precipitation in a binary Fe-Mo alloy (6.2 wt pct Mo) during constant-stress creep tests at temperatures of 813 K, 823 K, and 838 K (540 °C, 550 °C, and 565 °C). Scanning electron microscopy studies on the morphology of the creep-failed samples reveal irregularly...

Effects of Milling Conditions on Nano-scale MnFe(P,Si) Particles by Surfactant-assisted High-energy Ball Milling

The influence of the milling conditions on the nano-scale MnFe(P,Si) particles obtained by surfactant-assisted high-energy ball milling has been investigated by X-ray diffraction (XRD) and magnetic measurements. The presence of surfactant oleic acid prevents the re-welding of crushed particles and enhances the dispersion of nanoparticles in...

Determination of the magnetic domain size in the ferromagnetic superconductor UGe2 by three-dimensional neutron depolarization

Dilatometry study of the ferromagnetic order in single-crystalline URhGe