Caloric Effects in Ferroic Materials: New Concepts for Cooling SPP 1599

Transcription

1 Sebastian Fähler, IFW Dresden Caloric Effects in Ferroic Materials: New Concepts for Cooling SPP 1599 Program committee: Jürgen Eckert, IFW Dresden Gunther Eggeler, Ruhr U. Bochum Heike Emmerich, U. Bayreuth Peter Entel, U. Duisburg-Essen Stefan Müller, U. Bonn Eckhard Quandt, CAU Kiel Karsten Albe, TU Darmstadt DFG: Burkhard Jahnen

2 Program today 12:30 Lunch at the cafeteria of the IFW Dresden 13:30 Introduction to SPP 1599, S. Fähler, IFW Dresden Chair 14:00 Talks: B. Jahnen (DFG), O. Gufleisch (IFW Dresden), M. Acet (U Duisburg-Essen), O. Gutfleisch (IFW Dresden), A. Ludwig (Ruhr-U Bochum), A. Nayak/ G. Winterlik/ C. Felser (U Mainz), S. Wurmehl (IFW Dresden), A. Waske/ N. Mattern/ J. Eckert (IFW Dresden), H. Wende (U Duisburg-Essen) Gunther Eggeler 15:45 Coffee Break 16:20 Talks: V. Shvartsman (U. Duisburg-Essen), W. Skrotzki (TU Dresden), A. Böhm (Fraunhofer IWU), E. Quandt (CAU Kiel), G. Eggeler/ O. Kastner (Ruhr-U Bochum), S. Seelecke/ A. Schütze (U des Saarlandes), A. Raatz (TU Braunschweig), P. Entel (U Duisburg-Essen), T. Hickel (MPI Düsseldorf), M. Gruner/ P. Entel (U Duisburg-Essen), U. Rößler (IFW Dresden), L. Kienle (CAU Kiel) Heike Emmerich 3 20:00 Dinner at the Pulverturm at the Frauenkirche

3 Program tomorrow Chair 09:00 Talks: S. Scudino/ U. Kühn/ J. Eckert (IFW Dresden), Y. Luo (U Göttingen), A. Hütten (U Bielefeld), S. Fähler (IFW Dresden), M. Kohl (KIT-IMT), T. Lampke/ T. Halle (TU Chemnitz), M. Wagner (TU Chemnitz), H. Emmerich (U Bayreuth) Eckhard Quandt 10:20 Coffee Break 10:50 Talks: J. McCord (CAU Kiel), C. Melcher (RWTH Aachen), I. Opahle (Ruhr-U Bochum), D. Hägele (Ruhr-U Bochum), K. Albe (TU Darmstadt), L. Eng (TU Dresden), A. Schönecker (Fraunhofer IKTS Dresden), K. Albe (TU Darmstadt), D. Rytz (FEE GmbH Idar-Oberstein) Jürgen Eckert 12:30 Concluding remarks and discussion, S. Fähler, IFW Dresden 13:00 Lunch at the cafeteria of the IFW Dresden 14:00 Internal meeting of the programme committee 4

4 Preliminary timeline SPP /2011 Public call for proposals Deadline for submission of proposals Summer 2012 Evaluation Autumn 2012 Start of project 5

5 Magnetocaloric effect 2 nd order H releases heat apply magnetic field H remove magnetic field absorbs heat 6 Adiabatic removal of field shifts entropy from lattice to magnetic subsystem Second order transition at Curie temperature

6 1 st vs. 2 nd order transformation V. K. Pecharsky, K. A. Gschneidner, Phys. Rev. Lett. 78 (1997) nd order: Broad working temperature 1 st order: Huge entropy change Hysteresis loss 7

7 1 st order releases heat Magnetocaloric effect M>>0 M>>0 apply magnetic field remove magnetic field M=0 M=0 absorbs heat G = U T S H M + σ u + p V + E D 8

8 Elastocaloric Effect releases heat apply stress remove stress absorbs heat G = U T S H M + σ u + p V + E D 9

9 Barocaloric Effect releases heat compression decompression absorbs heat G = U T S H M + σ u + p V + E D 10

10 Electrocaloric Effect releases heat apply electric field remove electric field absorbs heat G = U T S H M + σ u + p V + E D 11

11 Length scales involved cm Å Electronic structure 12 Crystal structure Microstructure Device structure

12 Scale bridging modeling Å cm Electronic structure T-dep. DFT Molecular Dynamics Phase Field Multiphysics finite elements 13

13 Connecting time and length scales fs years Spin-lattice coupling Heat conduction Interface movement Fatigue 14

14 Which material is best? Intrinsic properties Huge latent heat High susceptibility to external fields (large M, V, u, D) T M around room temperature (tunable) Extrinsic properties Low hysteresis Cycle stability Technological issues Cost (Fe-based, FeRh ) Environmentally friendly (Pb, As) 15

15 How to quantify ferroic cooling? Indirect measurements of S by Maxwell relation Not valid for 1. order phase transition Hysteresis requires complex measurement protocol Caron et al. J. Mag. Mag. Mat. 321 (2009) 3559 Can result in spurious giant effects due to reorientation Niemann et al, ArXiv: Use direct measurement of T 16

16 Which approach is most applicable? Magnetocaloric effect N S Elastocaloric effect Multicaloric effects Barocaloric effect Electrocaloric effect Toroidalcaloric effect? Towards a unified description 17

17 Summing up entropy changes of lattice, spin Multicaloric effects Tuning of working temperature e. g. Stress induced martensite stress stress T M < RT T M RT Use of actuation properties to establish heat transfer H=0 H>0 18

18 From ferroic materials towards cooling systems Faster heat exchange Foam Films Reduced conduction losses Freestanding films Chmielus et al. Nat. Mat. 8 (2009) 863 Niemann et al. APL. 97 (2010) Generation of sufficient driving fields Innovative cooling system designs S. J. Lee, et al., J. Appl. Phys. 91, 8894 (2002) 19

19 Collaborations Apply for joint projects (up to 4 partners) Bilateral collaborations Before submission: Send semi-public 1-2 page project description until Will be distributed per to all who submitted description Updates every month 20

20 Dinner 8 p.m. 21 -> An der Frauenkirche 12, Dresden

21 Modern society relies on the possibility to cool below ambient. Ll. Manosa, ICOMAT

22 Summary Which scheme is most efficient for solid state refrigeration? Which length scales are involved? What is the correlation between time and length scales? Which are the best materials? 23