Magnetocaloric Effect Panhellenic Patra
1
Magnetocaloric Effect in Pseudobinary Ce – La – Ni compounds of LaNi 5 type intermetallics. An experimental study of the major parameters. E.I Gkanas 1,2 *, S.S Makridis 1,2* , D. Gounidis 1 , K. Efthimiadis 3 and A. K Stubos 2 1 Department of Mechanical Engineering, University of Western Macedonia, Bakola & Sialvera Street, Kozani, 50100, Greece 2 .Environmental laboratory, Institute of Nuclear technology and Radiation protection, NCSR “Demokritos” Agia Paraskevi, Athens 15310, Grecee 3. Aristotle University of Thessaloniki, Department of Physics Thessaloniki GR54124, Greece. *[email protected] , [email protected] The magnetocaloric effect is the heating or cooling of magnetic materials, when subjected to magnetic field variation. It is characterized by temperature change (ΔΤ ad ) in an adiabatic process and by the entropy change (ΔS iso ) in an isothermal process. In the present work, three different Ce-La-Ni type samples used in order to experimentally study their magnetocaloric effect. The experimental work can summarized: Sample Preparation (Arc Melting, Ball Milling, Thermal Annealing), Sample Characterization (XRD, SEM, VSM Measurements) and ΔS calculation according the isothermal curves. XRD Analysis Figure 1. XRD Pattern for Sample Before Hydrogenation Figure 2. XRD Pattern After Hydrogenation SEM Analysis Figure 3. SEM micrograph for the first sample. Figure 4. SEM spectrum for the first sample VSM Analysis Introduction Figure 5. Hysteresis loops for different temperatures (up and left), temperature hysteresis of structural and magnetic transition is shown up and right, and left is shown the magnetic isotherms for Ce 0.4 La 0.6 Ni 5. According to the magnetic isotherms, by using the Maxwell equation m ax min ( ) H m H dM S dH dT ΔS = - 2.67 J/kgK at 25 0 C, for H=0 to 2 (T) Conclusions. 1) Addition of Ce decreases the lattice constant 2) Ce 0.4 La 0.6 Ni 5 has ferromagnetic properties, while Ce 0.6 La 0.4 Ni 5 and Ce 0.9 La 0.1 Ni 5 have paramagnetic properties 3) Ms increase with the incerase of the Ce, due to the presence of secondary phases. 4) ΔS found - 2.67 J/kgK at 25 0 C, for H=0 to 2 (T). For Gd alloys the ΔS is almost 10 J/kgK for the same conditions. References 1] Karl G. Sandeman, “Magnetocaloric materials: the search of the new systems”, Scripta Materialia (2012) [2] N.A. de Oliveira, P.J von Ranke, “Theoritical aspects of the magnetocaloric effect”, Physics Reports 489 (2010) 89-159 [3] E.P. Nobrega, N.A. de Oliveira, P.J. von Ranke, A. Troper, “Magnetocaloric effect in rare earth based compounds: A Monte Carlo study”, Physica B 378-380 (2006) 716-717 [4] Andrej Kitanovski, Peter W. Egolf, “Innovative ideas for future research on magnetocaloric technologies”, International journal of refrigeration 33 (2010) 449-464 Environmental Technology Laboratory, Group http://h2matters.weebly.com/ Materials for Energy Applications Group. http://h2matters.weebly. com/ [email protected]
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Transcript of Magnetocaloric Effect Panhellenic Patra
Magnetocaloric Effect in Pseudobinary Ce – La – Ni compounds of LaNi5 type intermetallics. An experimental
study of the major parameters.
E.I Gkanas1,2*, S.S Makridis1,2*, D. Gounidis1, K. Efthimiadis3 and A. K Stubos2
1Department of Mechanical Engineering, University of Western Macedonia, Bakola & Sialvera Street, Kozani, 50100, Greece
2.Environmental laboratory, Institute of Nuclear technology and Radiation protection, NCSR “Demokritos” Agia Paraskevi, Athens 15310, Grecee
3. Aristotle University of Thessaloniki, Department of Physics Thessaloniki GR54124, Greece.
*[email protected] , [email protected]
The magnetocaloric effect is the heating or cooling of magnetic materials, when subjected to magnetic field variation. It is characterized by temperature change (ΔΤad) in an adiabatic process and by the entropy change (ΔSiso) in an isothermal process. In the present work, three different Ce-La-Ni type samples used in order to experimentally study their magnetocaloric effect. The experimental work can summarized: Sample Preparation (Arc Melting, Ball Milling, Thermal Annealing), Sample Characterization (XRD, SEM, VSM Measurements) and ΔS calculation according the isothermal curves.
XRD Analysis
Figure 1. XRD Pattern for Sample Before Hydrogenation
Figure 2. XRD Pattern After Hydrogenation
SEM Analysis
Figure 3. SEM micrograph for the first sample.
Figure 4. SEM spectrum for the first sample
VSM AnalysisIntroduction
Figure 5. Hysteresis loops for different temperatures (up and left), temperature hysteresis of structural and magnetic transition is shown up and right, and left is shown the magnetic
isotherms for Ce0.4La0.6Ni5.
According to the magnetic isotherms, by using the Maxwell
equation max
min
( )H
m
H
dMS dH
dT
ΔS = - 2.67 J/kgK at 25 0C, for H=0 to 2 (T)
Conclusions.1) Addition of Ce decreases the lattice constant
2) Ce0.4La0.6Ni5 has ferromagnetic properties, while Ce0.6La0.4Ni5 and Ce0.9La0.1Ni5 have paramagnetic properties
3) Ms increase with the incerase of the Ce, due to the presence of secondary phases.
4) ΔS found - 2.67 J/kgK at 25 0C, for H=0 to 2 (T). For Gd alloys the ΔS is almost 10 J/kgK for the same conditions.
References
1] Karl G. Sandeman, “Magnetocaloric materials: the search of the new systems”, Scripta Materialia (2012)
[2] N.A. de Oliveira, P.J von Ranke, “Theoritical aspects of the magnetocaloric effect”, Physics Reports 489 (2010) 89-159
[3] E.P. Nobrega, N.A. de Oliveira, P.J. von Ranke, A. Troper, “Magnetocaloric effect in rare earth based compounds: A Monte Carlo study”, Physica B 378-380 (2006) 716-717
[4] Andrej Kitanovski, Peter W. Egolf, “Innovative ideas for future research on magnetocaloric technologies”, International journal of refrigeration 33 (2010) 449-464Environmental Technology Laboratory, Group http://h2matters.weebly.com/
Materials for Energy Applications Group.
http://h2matters.weebly.com/[email protected]
