The Effects of La Doping on the Crystal Structure and Magnetic Properties of Ni2In-Type MnCoGe1−xLax (x = 0, 0.01, 0.03) Alloys

Abstract

In this experiment, a series of MnCoGe1−xLax (x = 0, 0.01, 0.03) alloy samples were prepared using a vacuum arc melting method. The crystal structure and magnetic properties of alloys were investigated using X-ray diffraction (XRD), Rietveld method, physical property measurement system (PPMS), and vibrating sample magnetometer (VSM) analyses. The results show that all samples were of high-temperature Ni2In-type phases, belonging to space group P63/mmc (194) after 1373 K annealing. The results of Rietveld refinement revealed that the lattice constant and the volume of MnCoGe1−xLax increased along with the values of La constants. The magnetic measurement results show that the Curie temperatures (TC) of the MnCoGe1−xLax series alloys were 294, 281, and 278 K, respectively. The maximum magnetic entropy changes at 1.5T were 1.64, 1.53, and 1.56 J·kg−1·K−1, respectively. The respective refrigeration capacities (RC) were 60.68, 59.28, and 57.72J·kg−1, with a slight decrease along the series. The experimental results show that the doping of La results in decreased TC, basically unchanged magnetic entropy, and slightly decreased RC.

Crystal Structure and Magnetic Properties of HfFe6Ge6-Type ErMn6–xCoxGe6 (x = 0–1.45) Alloys

“…The temperature dependence of magnetization was measured in a 500 Oe magnetic field, as shown in Figure , and magnetic data are gathered in Table . The transition temperatures T C have been taken at the maximum of the first derivate (d M /d T ), and the sharp raised peak on the χ– T curve is the Néel point T N . It can be seen that the alloys show sophisticated distinct magnetic states: the alloys display a Néel point at a high temperature T N (∼500 K), magnetization increases again at T C (∼250 K), and a second peak in the temperature dependence of magnetization at about T t (∼150 K), which is spin reorientation.…”

Effect of Metal-Oxide Phase on the Magnetic and Magnetocaloric Properties of La0.7Ca0.3MnO3-MO (MO=CuO, CoO, and NiO) Composite

“…The published literature shows that the Mn ions in the Ca 2+ substituted LaMnO 3 exhibit double-exchange interaction. Mn ions exist in two different oxidation states, +3 and +4, due to the presence of La 3+ and Ca 2+ cations in the A-site [61][62][63][64][65][66]. The magnetic Mn 3+ and Mn 4+ cations bonded through non-magnetic oxygen anion induce the hopping of electrons between the cations through oxygen to attain the least energy state.…”