Abstract:
The aim of the present work is to study the influence of a partial substitution of Mn by Pd on structure, thermomagnetic properties and phase transitions in half-Heusler MnCoGe alloys. The XRD studies revealed a coexistence of the orthorhombic TiNiSi-type and hexagonal Ni2In- type phases. Deep analysis of the XRD pattern supported by the Rietveld analysis showed that the changes in lattice constants and content of recognized phases depended on the Pd addition. An increase of palladium in alloy composition at the expense of manganese induced a rise of the Curie temperature. The values of ΔSM measured for the change of external magnetic field ~5T equaled 8.88, 23.99, 15.63 and 11.09 for Mn0.97Pd0.03CoGe, Mn0.95Pd0.05CoGe, Mn0.93Pd0.07CoGe and Mn0.9Pd0.1CoGe alloy, respectively. The highest magnetic entropy change ΔSM was observed for sample with Pd content x=0.05 induced by magnetostructural phase transition. The analysis of the n vs. T curves allowed to confirm XRD and DSC results of an occurrence of magnetostructural transition in Mn0.95Pd0.05CoGe and Mn0.93Pd0.07CoGe alloys samples.
Biography:
Piotr Gebara graduated in 2008 from the Faculty of Process Engineering, Materials Science and Applied Physics (currently the Faculty of Production Engineering and Materials Technology) at the Czestochowa University of Technology, majoring in Technical Physics with a specialization in Computational Physics. During the 2007/2008 academic year, he was awarded a scholarship by the Minister of Science and Higher Education for his academic achievements. That same year, he began doctoral studies at his home faculty and later defended his doctoral thesis in physics at the Jan Długosz University in Czestochowa. In October 2012, he was employed at the Institute of Physics (now the Department of Physics) of the Czestochowa University of Technology, initially as an assistant and later, from February 2013, as an assistant professor. In 2015, he received a scholarship from the Minister of Science and Higher Education for outstanding young scientists. In 2016, he was awarded a scholarship from the Slovak Academic Information Agency, through which he completed a postdoctoral fellowship at the Institute of Experimental Physics of the Slovak Academy of Sciences in Košice under the supervision of RNDr. Ivan Skorvanek, CSc. He also completed internships at the Institute of Molecular Physics of the Polish Academy of Sciences in Poznan in 2017 under Prof. Zbigniew Sniadecki, and at the Department of Solid State Physics at the University of Seville in 2018 under Prof. Victorino Franco. In 2019, he obtained his habilitation degree in physics at the Institute of Physics of the University of Silesia. From October 2019 to August 2024, he served as deputy head of the Department of Physics at PCz, and since September 2024, he has been serving as Vice-Dean for Teaching at the Faculty of Production Engineering and Materials Technology. His research interests focus on the magnetic properties of rare-earth and transition metal alloys, particularly the magnetocaloric effect in La(Fe,Si)13 alloys, gadolinium-based alloys, and MnCoGe alloys. He also conducts magnetic studies on high-entropy alloys and magnetite nanoparticles for hyperthermia applications. Over the past five years, he has led three research teams, including two interdisciplinary teams. He has authored 112 papers indexed in the Philadelphia List, which have received 1,182 citations, and he has a Hirsch index of 21.
