Magnetocaloric and magnetovolume effects in Fe-based alloys                                                Pablo Alvarez A...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Magnetocaloric effectOrigin     P. Alvarez (University of Oviedo)   MCE and magnetovolume effects in Fe-based alloys   04/...
Magnetocaloric EffectDefinition and Theory Total Entropy of Metallic Gd under Two Applied Magnetic Fields.     P. Alvarez (...
Magnetocaloric EffectDefinition and Theory Total Entropy of                        Adiabatic Temperature Metallic Gd under ...
Magnetocaloric EffectDefinition and Theory Total Entropy of                        Adiabatic Temperature                   ...
Magnetocaloric EffectDefinition and Theory Total Entropy of                        Adiabatic Temperature                   ...
Magnetocaloric EffectMagnetic Refrigeration: Principles and Applications     P. Alvarez (University of Oviedo)     MCE and...
Magnetocaloric EffectMagnetic Refrigeration: Principles and Applications                                                  ...
Magnetocaloric EffectRelative Cooling Power                                                                 Estimation of ...
Magnetocaloric EffectRelative Cooling Power                                                                 Estimation of ...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Magnetovolume Anomalies  Lattice Parameters a and  c, and the cell volume V  vs T for Sm2 Fe14 B  P. Alvarez (University o...
Magnetovolume Anomalies  Lattice Parameters a and  c, and the cell volume V                                               ...
Magnetovolume Anomalies  Lattice Parameters a and  c, and the cell volume V                                               ...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group)                                              ...
R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group)                                              ...
R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group)                                              ...
R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group)                                              ...
R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group)                                              ...
R2 Fe17 alloysMagnetovolume Anomalies and Magnetocaloric Effect in R2 Fe17 alloysMagnetovolume Anomalies: Causes          ...
R2 Fe17 alloysMagnetovolume Anomalies and Magnetocaloric Effect in R2 Fe17 alloysMagnetovolume Anomalies: Causes          ...
R2 Fe17 alloysMagnetovolume Anomalies and Magnetocaloric Effect in R2 Fe17 alloysMagnetovolume Anomalies: Causes          ...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
FeZrBCu amorphous alloys                                                                          Fe-content variation of ...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Fabrication                          Arc Furnace                                         Melt Spinner                     ...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
CharacterizationStructure and MicrostructureElectronic Microscopies (University of Oviedo)                  Scanning (JEOL...
CharacterizationMagnetic CharacterizationVSM                                      PPMS                                    ...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic StructureXRPD patterns for      ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic StructureXRPD patterns for      ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic StructureXRPD patterns for      ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic Structure     NPD pattern for th...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic Structure                       ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic Structure                       ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies                  VCell (T ) f...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume AnomaliesLinear and Volume Magnetostric...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume AnomaliesLinear and Volume Magnetostric...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume AnomaliesLinear and Volume Magnetostric...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies       Lattice Parameters a an...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies       Lattice Parameters a an...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies       Lattice Parameters a an...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies M vs T under Pressure for Pr2...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies M vs T under Pressure for Pr2...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect   M vs (T , H)     P. Alvarez (...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect                                ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect  Heat Capacity and Total Entrop...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect                                ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsEffect of Ball-Milling  NPD patterns for Bulk and BM ...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds                      SEM images forEffect of Ball-Mi...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds                      SEM images forEffect of Ball-Mi...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsEffect of Ball-Milling  M vs T for Bulk and 10h-BM  P...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds                 ∆S (T ) for Nd FeEffect of Ball-Mill...
Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds                 ∆S (T ) for Nd FeEffect of Ball-Mill...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMagnetic PropertiesAx B2 -x Fe17 alloys Synthesized   Y1.2 Ce0.8...
Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMagnetocaloric Effect                                         ∆S...
Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMagnetocaloric Effect                                         ∆S...
Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMaster Curve Master Curve: Theory                               ...
Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMaster Curve Master Curve: Theory            ∆SM (T ) → ∆SM (T )...
Outline1   Introduction       Magnetocaloric Effect       Magnetovolume Anomalies       R2 Fe17 alloys       FeZrBCu amorp...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetic PropertiesFeZrBCu Amorphous Alloys Produ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetic PropertiesFeZrBCu Amorphous Alloys Produ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect         A general view of ∆...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect         A general view of ∆...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect                            ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect                            ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMaster Curve   Master Curve for Fe86 Zr7 B6 Cu1  ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMaster Curve   Master Curve for Fe86 Zr7 B6 Cu1  ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysFlattening of the ∆SM (T ) Curve                 ...
Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysFlattening of the ∆SM (T ) Curve                 ...
Conclusions   The R2 Fe17 alloys cell volume decreases when the temperature is increased in the   magnetically oredered st...
´                 GRACIAS POR VUESTRA ATENCIONP. Alvarez (University of Oviedo)   MCE and magnetovolume effects in Fe-base...
Perspectives   Synthesize Y2 Fe17 in both rhombohedral and hexagonal crystal structures, and   Gd2 Fe17 , Tb2 Fe17 and Dy2...
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Magnetocaloric and magnetovolume effects in Fe-based alloys

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Magnetocaloric and magnetovolume effects in Fe-based alloys

  1. 1. Magnetocaloric and magnetovolume effects in Fe-based alloys Pablo Alvarez Alonso Department of Material Science and Metallurgic Engineering University of Oviedo 4 July 2011P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 1 / 48
  2. 2. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 2 / 48
  3. 3. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 2 / 48
  4. 4. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 2 / 48
  5. 5. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 2 / 48
  6. 6. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 3 / 48
  7. 7. Magnetocaloric effectOrigin P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 4 / 48
  8. 8. Magnetocaloric EffectDefinition and Theory Total Entropy of Metallic Gd under Two Applied Magnetic Fields. P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 5 / 48
  9. 9. Magnetocaloric EffectDefinition and Theory Total Entropy of Adiabatic Temperature Metallic Gd under Change (∆Tadi ) of Gd Two Applied Magnetic Fields. P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 5 / 48
  10. 10. Magnetocaloric EffectDefinition and Theory Total Entropy of Adiabatic Temperature Magnetic Entropy Metallic Gd under Change (∆Tadi ) of Gd Change for GdAl2 Two Applied Magnetic Fields. P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 5 / 48
  11. 11. Magnetocaloric EffectDefinition and Theory Total Entropy of Adiabatic Temperature Magnetic Entropy Metallic Gd under Change (∆Tadi ) of Gd Change for GdAl2 Two Applied Magnetic Fields. Maxwell Relation Isothermal Magnetic Entropy Change H2 ∂M ∆SM (T , H2 )P,∆H = dH H1 ∂T P,H P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 5 / 48
  12. 12. Magnetocaloric EffectMagnetic Refrigeration: Principles and Applications P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 6 / 48
  13. 13. Magnetocaloric EffectMagnetic Refrigeration: Principles and Applications Applications Consumer Electronics Air conditioning Active cooling of Dehumidifiers electronic circuits Refrigerators Motor refrigerators Medicine Magnetic resonance Commercial imaging Vending machines Portable coolers Cooling drinks Cold store Science Exhibitors & Gas liquefaction Showcases Cryogenics Adventages Low maintenance Less energy costs consumption Large durability and High cooling efficiency stability Environmental friendly No mechanical vibrations P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 6 / 48
  14. 14. Magnetocaloric EffectRelative Cooling Power Estimation of RCP Relative Cooling Power RCP1 (H) = |∆SM Peak (H) | × δTFWHM (RCP) RCP2 (H) = TH |∆SM (T , H)| dT . TC RCP3 (H) = max ∆Smag (T1 , H) × (T2 − T1 ) Peak Combination of δTFWHM and ∆SM Broad ∆SM → Large RCP RCP (5 T) for Metallic Gd RCP1 = 687 Jkg−1 RCP2 = 503 Jkg−1 RCP3 = 402 Jkg−1 P.Gorria et al., J. Phys D: Appl. Phys., 41 (2008) 192003 (5pp) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 7 / 48
  15. 15. Magnetocaloric EffectRelative Cooling Power Estimation of RCP Relative Cooling Power RCP1 (H) = |∆SM Peak (H) | × δTFWHM (RCP) RCP2 (H) = TH |∆SM (T , H)| dT . TC RCP3 (H) = max ∆Smag (T1 , H) × (T2 − T1 ) Peak Combination of δTFWHM and ∆SM Broad ∆SM → Large RCP RCP (5 T) for Metallic Gd RCP1 = 687 Jkg−1 RCP2 = 503 Jkg−1 RCP3 = 402 Jkg−1 P.Gorria et al., J. Phys D: Appl. Phys., 41 (2008) 192003 (5pp) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 7 / 48
  16. 16. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 8 / 48
  17. 17. Magnetovolume Anomalies Lattice Parameters a and c, and the cell volume V vs T for Sm2 Fe14 B P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 9 / 48
  18. 18. Magnetovolume Anomalies Lattice Parameters a and c, and the cell volume V Magnetovolume anomalies: Coupling between vs T for Sm2 Fe14 B the crystal lattice and the magnetism Extrapolation from the Non-Ordered State Gruneisen relation ¨ κΓCp (T ) αnm (T ) = 3V P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 9 / 48
  19. 19. Magnetovolume Anomalies Lattice Parameters a and c, and the cell volume V Magnetovolume anomalies: Coupling between vs T for Sm2 Fe14 B the crystal lattice and the magnetism Extrapolation from the Non-Ordered State Gruneisen relation ¨ κΓCp (T ) αnm (T ) = 3V Magnetostriction λa = (a − a0 )/a0 λc = (c − c0 )/c0 ωS = (V − V0 )/V0 P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 9 / 48
  20. 20. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 10 / 48
  21. 21. R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group) Y Ce Pr Nd Sm Gd Tb Dy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 11 / 48
  22. 22. R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group) Y Ce Pr Nd Sm Gd Tb DyHexagonal Th2 Ni17 -type (P63 /mmc space group) Gd Tb Dy Ho Er Tm Yb Lu Y P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 11 / 48
  23. 23. R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group) Y Ce Pr Nd Sm Gd Tb DyHexagonal Th2 Ni17 -type (P63 /mmc space group) Gd Tb Dy Ho Er Tm Yb Lu Y P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 11 / 48
  24. 24. R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group) Y Ce Pr Nd Sm Gd Tb DyHexagonal Th2 Ni17 -type (P63 /mmc space group) Gd Tb Dy Ho Er Tm Yb Lu Y P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 11 / 48
  25. 25. R2 Fe17 alloysCrystal StructureRhombohedral Th2 Zn17 -type (R3m space group) Y Ce Pr Nd Fe1(6c): <<Dumm-bell site>> Sm Oriented along the c-axis Gd Tb DyHexagonal Th2 Ni17 -type (P63 /mmc space group) Gd Tb Dy Ho Fe1(4f): <<Dumm-bell site>> Er Oriented along the c-axis Tm Yb Lu Y P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 11 / 48
  26. 26. R2 Fe17 alloysMagnetovolume Anomalies and Magnetocaloric Effect in R2 Fe17 alloysMagnetovolume Anomalies: Causes DFe−Fe ˚ 2.45 A → Negative exchange Interactions Dumb-bell sites ˚ DFe−Fe ≥ 2.45 A → Positive exchange Interactions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 12 / 48
  27. 27. R2 Fe17 alloysMagnetovolume Anomalies and Magnetocaloric Effect in R2 Fe17 alloysMagnetovolume Anomalies: Causes DFe−Fe ˚ 2.45 A → Negative exchange Interactions Dumb-bell sites ˚ DFe−Fe ≥ 2.45 A → Positive exchange InteractionsMagnetovolume Anomalies: Effects Anomalous thermal expansion Magnetovolume Anomalies Negative pressure dependence of TC P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 12 / 48
  28. 28. R2 Fe17 alloysMagnetovolume Anomalies and Magnetocaloric Effect in R2 Fe17 alloysMagnetovolume Anomalies: Causes DFe−Fe ˚ 2.45 A → Negative exchange Interactions Dumb-bell sites ˚ DFe−Fe ≥ 2.45 A → Positive exchange InteractionsMagnetovolume Anomalies: Effects Anomalous thermal expansion Magnetovolume Anomalies Negative pressure dependence of TC Magnetocaloric Effect in R2 Fe17 alloys Magnetic Properties R2 Fe17 alloys exhibit SOPT TC arround RT H. Chen et al., JM 3 320 (2008) 1382-1384 Large MS P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 12 / 48
  29. 29. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 13 / 48
  30. 30. FeZrBCu amorphous alloys Fe-content variation of TC for Nanoperm alloys ∆SM (T ) for Nanoperm alloys V. Franco et al., J. Appl. Phys. 100 (2006) 064307 P. Alvarez et al., Intermetallics 18 (2010) 2464-2467 Magnetic and Magnetocaloric Properties Broad Second Order Magnetic Phase Transition Tunnable Curie Temperatures in the RT Regime Moderate values of MS P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 14 / 48
  31. 31. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 15 / 48
  32. 32. Fabrication Arc Furnace Melt Spinner Furnace Ball-Mill P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 16 / 48
  33. 33. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 17 / 48
  34. 34. CharacterizationStructure and MicrostructureElectronic Microscopies (University of Oviedo) Scanning (JEOL JSM-6100) Transmission (JEOL 2000 EX-II)Diffraction X-ray (University of Oviedo) Synchrotron (ESRF: ID27) Neutron (ILL: D1A, D1B, D2B, D4) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 18 / 48
  35. 35. CharacterizationMagnetic CharacterizationVSM PPMS SQUIDUniversity of Sevilla University of Oviedo University of Cantabria University of Cantabria Slovak Academy of Science IPICYT P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 19 / 48
  36. 36. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 20 / 48
  37. 37. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic StructureXRPD patterns for NPD pattern below and overRhombohedral and TCHexagonal R2 Fe17alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 21 / 48
  38. 38. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic StructureXRPD patterns for NPD pattern below and overRhombohedral and TCHexagonal R2 Fe17alloysMagnetic Structure Pr2 Fe17 , Nd2 Fe17 and Y2 Fe17 → Collinear Ferromagnetic Gd2 Fe17 , Tb2 Fe17 , Dy2 Fe17 , Ho2 Fe17 , Er2 Fe17 and Tm2 Fe17 → Collinear Ferrimagnetic (Tm2 Fe17 Spin Reorientation at 100 K) Ce2 Fe17 and Lu2 Fe17 → Complex Magnetic Behavior P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 21 / 48
  39. 39. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic StructureXRPD patterns for NPD pattern below and over FerrimagneticRhombohedral and TC StructureHexagonal R2 Fe17alloysMagnetic Structure Pr2 Fe17 , Nd2 Fe17 and Y2 Fe17 → Collinear Ferromagnetic Gd2 Fe17 , Tb2 Fe17 , Dy2 Fe17 , Ho2 Fe17 , Er2 Fe17 and Tm2 Fe17 → Collinear Ferrimagnetic (Tm2 Fe17 Spin Reorientation at 100 K) Ce2 Fe17 and Lu2 Fe17 → Complex Magnetic Behavior P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 21 / 48
  40. 40. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic Structure NPD pattern for the Dy2 Fe17 alloy Rhombohedral Dy2 Fe17 Ferrimagnetic (TC = 363 K) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 22 / 48
  41. 41. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic Structure Thermo-Diffraction experiments P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 23 / 48
  42. 42. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsCrystal and Magnetic Structure Thermo-Diffraction experiments Er2 Fe17 Magnetic Moments Tb2 Fe17 Magnetic Moments P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 23 / 48
  43. 43. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies VCell (T ) for Rhombohedral and Hexagonal R2 Fe17 alloys Extrapolation V(T) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 24 / 48
  44. 44. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume AnomaliesLinear and Volume Magnetostriction λa = (a − a0 )/a0 λc = (c − c0 )/c0 ωS = (V − V0 )/V0 P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 25 / 48
  45. 45. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume AnomaliesLinear and Volume Magnetostriction λa = (a − a0 )/a0 λc = (c − c0 )/c0 ωS = (V − V0 )/V0 P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 25 / 48
  46. 46. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume AnomaliesLinear and Volume Magnetostriction λa = (a − a0 )/a0 λc = (c − c0 )/c0 ωS = (V − V0 )/V0Comparation between ωS and MFe P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 25 / 48
  47. 47. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies Lattice Parameters a and c vs Pressure for Dy2 Fe17 and Er2 Fe17 alloys- RT P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 26 / 48
  48. 48. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies Lattice Parameters a and c vs Pressure for Dy2 Fe17 and First-Order Birch-Murnaghan Er2 Fe17 alloys- RT Equation of State −7/3 −5/3 3 V V P= B0 − 2 V0 V0 P(V ) curve for the Gd2 Fe17 alloy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 26 / 48
  49. 49. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies Lattice Parameters a and c vs Pressure for Dy2 Fe17 and First-Order Birch-Murnaghan Er2 Fe17 alloys- RT Equation of State −7/3 −5/3 3 V V P= B0 − 2 V0 V0 P(V ) curve for the Gd2 Fe17 alloy V vs T for Er2 Fe17 alloy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 26 / 48
  50. 50. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies M vs T under Pressure for Pr2 Fe17 compound dTC dP ≈ −4 K/kBar P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 27 / 48
  51. 51. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetovolume Anomalies M vs T under Pressure for Pr2 Fe17 M vs T under Pressure for Tm2 Fe17 compound compound dTC dTC dP ≈ −4 K/kBar dP ≈ −10 K/kBar P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 27 / 48
  52. 52. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect M vs (T , H) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 28 / 48
  53. 53. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect ∆SM (T ) for Rhombohedral and Hexagonal R2 Fe17 alloys (µ0 H = 0 − 5 T) M vs (T , H) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 28 / 48
  54. 54. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect Heat Capacity and Total Entropy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 29 / 48
  55. 55. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsMagnetocaloric Effect Temperature dependence of Adiabatic Temperature Change Heat Capacity and Total Entropy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 29 / 48
  56. 56. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsEffect of Ball-Milling NPD patterns for Bulk and BM Pr2 Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 30 / 48
  57. 57. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds SEM images forEffect of Ball-Milling BM Nd2 Fe17 alloys NPD patterns for Bulk and BM Pr2 Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 30 / 48
  58. 58. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds SEM images forEffect of Ball-Milling BM Nd2 Fe17 alloys TEM images NPD patterns for Bulk and BM for 20h-BM Pr2 Fe17 alloys Nd2 Fe17 alloy Hystogram for 20h-BM Nd2 Fe17 alloy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 30 / 48
  59. 59. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compoundsEffect of Ball-Milling M vs T for Bulk and 10h-BM Pr2 Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 31 / 48
  60. 60. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds ∆S (T ) for Nd FeEffect of Ball-Milling M 2 17 alloys M vs T for Bulk and 10h-BM Pr2 Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 31 / 48
  61. 61. Magnetovolume Anomalies and Magnetocaloric Effect of R2 Fe17compounds ∆S (T ) for Nd FeEffect of Ball-Milling M 2 17 alloys RCP values for Nd2 Fe17 alloys M vs T for Bulk and 10h-BM Pr2 Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 31 / 48
  62. 62. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 32 / 48
  63. 63. Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMagnetic PropertiesAx B2 -x Fe17 alloys Synthesized Y1.2 Ce0.8 Fe17 (253 K) - Pr1.5 Ce0.5 Fe17 (264 K) - Dy1.15 Ce0.85 Fe17 (273 K) - YPrFe17 (290 K)XRD Pattern for M VS T for YPrFe17 MS VS T for Ax B2 -x Fe17Dy1.15 Ce0.85 Fe17 pseudobinary alloy alloyspseudobinary alloy Rhombohedral Crystal Structure TC ≈ RT P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 33 / 48
  64. 64. Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMagnetocaloric Effect ∆SM (T , H) for Ce-based M(T , H) curves for Ax B2 -x Fe17 alloys Ce-based Ax B2 -x Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 34 / 48
  65. 65. Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMagnetocaloric Effect ∆SM (T , H) for Ce-based M(T , H) curves for Ax B2 -x Fe17 alloys Ce-based Ax B2 -x Fe17 alloys RCP for Ax B2 -x Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 34 / 48
  66. 66. Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMaster Curve Master Curve: Theory Peak ∆SM (T ) → ∆SM (T )/∆SM  θ = (T − TC )/(Tr1 − TC )  T → (T − TC )/(Tr1 − TC ) T ≤ TC θ = (T − TC )(Tr2 − TC ) T > TC  Master Curve for Ce-based Ax B2 -x Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 35 / 48
  67. 67. Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloysMaster Curve Master Curve: Theory ∆SM (T ) → ∆SM (T )/∆SM Peak Master Curve for Ce-based  Ax B2 -x Fe17 alloys θ = (T − TC )/(Tr1 − TC )  T → (T − TC )/(Tr1 − TC ) T ≤ TC θ = (T − TC )(Tr2 − TC ) T > TC  Master Curve for Ce-based Ax B2 -x Fe17 alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 35 / 48
  68. 68. Outline1 Introduction Magnetocaloric Effect Magnetovolume Anomalies R2 Fe17 alloys FeZrBCu amorphous alloys2 Experimental Techniques Fabrication Structural and Magnetic Characterization3 Results Magnetovolume Anomalies and Magnetocaloric effect of R2 Fe17 compounds Magnetocaloric Effect in Pseudobinary Ax B2 -x Fe17 alloys Magnetic Properties and Magnetocaloric Effect of Fe-based amorphous alloys4 Conclusions P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 36 / 48
  69. 69. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetic PropertiesFeZrBCu Amorphous Alloys Produced Fe90 Zr10 (230 K) - Fe90 Zr9 B1 (209 K) - Fe91 Zr7 B2 (240 K) - Fe90 Zr8 B2 (280 K) Fe88 Zr8 B4 (301 K) - Fe86 Zr7 B6 Cu1 (321 K) - Fe87 Zr6 B6 Cu1 (230 K) M(T ) for the FeZrBCu amorphous Magnetization Isotherms for the ribbons Nanoperm alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 37 / 48
  70. 70. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetic PropertiesFeZrBCu Amorphous Alloys Produced Fe90 Zr10 (230 K) - Fe90 Zr9 B1 (209 K) - Fe91 Zr7 B2 (240 K) - Fe90 Zr8 B2 (280 K) Fe88 Zr8 B4 (301 K) - Fe86 Zr7 B6 Cu1 (321 K) - Fe87 Zr6 B6 Cu1 (230 K) M(T ) for the FeZrBCu amorphous Magnetization Isotherms for the ribbons Nanoperm alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 37 / 48
  71. 71. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect A general view of ∆SM (T ) curves for Nanoperm alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 38 / 48
  72. 72. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect A general view of ∆SM (T ) curves for Nanoperm alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 38 / 48
  73. 73. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect Metallic Gd (µ0 H = 5 T) RCP1 = 687 Jkg−1 RCP1 (H) for FeZrBCu amorphous RCP2 = 503 Jkg−1 alloys RCP3 = 402 Jkg−1 P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 39 / 48
  74. 74. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMagnetocaloric Effect Metallic Gd (µ0 H = 5 T) RCP1 = 687 Jkg−1 RCP1 (H) for FeZrBCu amorphous RCP2 = 503 Jkg−1 alloys RCP3 = 402 Jkg−1 Width of the ∆SM (T ) Curves P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 39 / 48
  75. 75. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMaster Curve Master Curve for Fe86 Zr7 B6 Cu1 amorphous alloy P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 40 / 48
  76. 76. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysMaster Curve Master Curve for Fe86 Zr7 B6 Cu1 Comparation of the Master amorphous alloy Curves for the FeZrBCu amorphous alloys P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 40 / 48
  77. 77. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve the RCP Via the ∆SM (T ) Broadening P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 41 / 48
  78. 78. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve the RCP Via the ∆SM (T ) Broadening Past: Low Temperature Magnetic Composites T. Hashimoto et al., J. Appl. Phys. 62 (9) (1987) 3873-3878 P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 41 / 48
  79. 79. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve the RCP Via the ∆SM (T ) Broadening Past: Low Temperature Recent: RCP Improvement around Magnetic Composites RT by Using Magnetic Composites T. Hashimoto et al., J. Appl. Phys. 62 (9) (1987) 3873-3878 R. Caballero-Flores et al., Appl. Phys. Lett. 98 (2011) 102505 P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 41 / 48
  80. 80. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysComposite Compounds: an Effective way to Improve the RCP Via the ∆SM (T ) Broadening Past: Low Temperature Recent: RCP Improvement around Magnetic Composites RT by Using Magnetic Composites T. Hashimoto et al., J. Appl. Phys. 62 (9) (1987) 3873-3878 R. Caballero-Flores et al., Appl. Phys. Lett. 98 (2011) 102505Further Comments RCP Optimization for a Two-Phase Magnetic Composite The Maximum Refrigeration Efficiency is attained with Constant Magnetic Entropy Shape of ∆SM (T ) Change curves. δTC A.M. Tishin and Y.I. Spichkin. Magnetocaloric Effect Weight Fraction of Both Phases and Its Applications. Series in Condensed Matter Physics, 1 edition (2003). Applied Magnetic Field P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 41 / 48
  81. 81. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 1 ∆SM (T ) curves of Component ∆SM (T ) curves of the Composite A (Fe90 Zr9 B1 ) and B (Fe87 Zr6 B6 Cu1 ) System 0.4 A + 0.6 B P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 42 / 48
  82. 82. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 2 ∆SM (T ) for the two-ribbon system 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 43 / 48
  83. 83. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 2 Increase of δTFWHM for the Two-Phase System 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) ∆SM (T ) for the two-ribbon system 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 43 / 48
  84. 84. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysA Concrete Two-Phase Composite based on amorphous FeZrCuB ribbons: EXAMPLE 2 Increase of δTFWHM for the Two-Phase System 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) ∆SM (T ) for the two-ribbon system 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) Resulting RCP for the Two-Phase System 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) RCP ≈ 95% of Metallic Gd P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 43 / 48
  85. 85. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysFlattening of the ∆SM (T ) Curve Flattening of ∆SM (T ) for the system 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 44 / 48
  86. 86. Magnetic Properties and Magnetocaloric Effect of Fe-based amorphousalloysFlattening of the ∆SM (T ) Curve Flattening of ∆SM (T ) for the system 0.5 A (Fe87 Zr6 B6 Cu1 ) + 0.5 B (Fe90 Zr8 B2 ) P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 45 / 48
  87. 87. Conclusions The R2 Fe17 alloys cell volume decreases when the temperature is increased in the magnetically oredered state, with a minimum located around TC . The magnetostriction is correlated with the total Fe-magnetic moments. The MCE depends on the magnetic structure: Ferromagnetic → single-peak magnetic entropy change; Ferrimagnetic → double-peak with opposite sign; Ce2 Fe17 → double-peak with the same sign. dTC The Curie temperature is largely decreased with pressure ( dP ≈ −10 K/kBar for Tm2 Fe17 alloy). The microstructure is modified by ball-milling without changes in either the magnetic nor crystal structures. Grain breaking (nanosized scale) → Curie temperature distribution and wider |∆SM |(T ) curves. Ax B2 -x Fe17 alloys have been synthesized in the rhombohedral phase. The Curie temperatures, RCP and ∆SM are tuned combining different rare-earths. Temperature of the maximum magnetic entropy change of FeZrBCu amorphous alloys is tuned by changes in the %Fe. Spreading of the |∆SM |(T ) curve as wider as 230 K. Optimizing the selection of both, the δTC of the two Nanoperm alloys which form a two-phase composite system and their relative weight fraction → enhancement of the Relative Cooling Power due to the increase of δTFWHM of the ∆SM and flattening of the ∆SM (T ) curves (up to 100 K for µ0 ∆H = 5 T). P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 46 / 48
  88. 88. ´ GRACIAS POR VUESTRA ATENCIONP. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 47 / 48
  89. 89. Perspectives Synthesize Y2 Fe17 in both rhombohedral and hexagonal crystal structures, and Gd2 Fe17 , Tb2 Fe17 and Dy2 Fe17 in hexagonal crystal structure. Y2 Fe17 , Pr2 Fe17 and Nd2 Fe17 alloys exhibit the largest magnetic entropy change values → combination of these alloys or synthesis of PrNdFe17 pseudobinaries to optimize the MCE properties. Due to the change of the Tm2 Fe17 Curie temperature with pressure, and that Tm2 Fe17 exhibits magnetovolume anomalies, it would exhibit a large magneto-barocaloric effect. Ball-milling provokes a broadening of the magnetic transitions → The Tm2 Fe17 spin-reorientation would not occur over a critical pressure → Study the MCE when the magnetic anisotropy is along the uniaxial direction. Measure the temperature dependence of the heat capacity in FeZrBCu alloys to determine the adiabatic temperature change. Optimize the total entropy of combined two-ribbons systems to enhance the adiabatic temperature change. P. Alvarez (University of Oviedo) MCE and magnetovolume effects in Fe-based alloys 04/07/11 48 / 48

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