Papers by Author: Aleksandra Kolano-Burian

Abstract: Ni₂MnGa alloy exhibits significant magnetocaloric effect due to structural and magnetic transition, which take place at similar temperature range. In this report we present band structure calculations for Ni₂MnGa doped with Cu performed within KKR-CPA scheme. We also calculated the estimated temperature of the magnetic transition as a function of dopant concentration within Mean-Field-Approach (MFA). Our calculations show that the Curie temperature increases with Cu doping in agreement with recent experimental data.

Abstract: The magnetocaloric effect in La0.6Ca0.4MnO3 manganite has been investigated. The isothermal magnetization versus applied magnetic field at various temperatures in the vicinity of Curie temperature was measured, and the temperature dependence of magnetic entropy change was determined using Maxwell’s relation. This value is comparable to that in Gd. Nevertheless, the relative cooling power of La0.6Ca0.4MnO3 was shown to be considerably lower than that of Gd. The experimental results have been analyzed in frames of a phenomenological statistical model. This model considers explicitly Jahn-Teller interactions and allows prediction of the field dependences of the magnetic entropy change and the relative cooling power.

Abstract: Paper presents a novel application of magnetostrictive delay lines, which give a possibility of real time monitoring of strain in ceramic components. Magnetostrictive delay line was based on highly magnetostrictive Fe-Si-B amorphous alloy ribbon, mounted outside of ceramic component, what is a new solution for increasing sensor’s sensitivity. Developed specially for this sensor, hybrid digital-analog signal processing unit covers the sample-and-hold integrated circuit. The achived sensitivity and repeatability of the sensor confirms, that such solution is suitable for ceramic machine tool monitoring.

Abstract: Structural transformations taking place during annealing of rapidly-quenched soft magnetic ribbons from the Finemet type and Hitperm type alloys were investigated. The X-ray quantitative phase analysis and X-ray diffusion scattering methods were used. It was found that the structural changes in the alloys studied, including crystallisation process and short-range ordering in the amorphous phase, are reflected by the changes in their magnetic properties. These properties, and particularly the magnitude of saturation induction Bs , depend on the content of cobalt and silicon in these alloys and on short-range order in the amorphous phase.