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Lluís MañosaDepartament ECM. Facultat de Física.
Universitat de [email protected]
Libertas perfundet omnia lucet
Motivation:
Libertas perfundet omnia lucet
Further (latter) motivation:
Libertas perfundet omnia lucet
CALORIMETRY
Best suited technique to determine entropy changes at phase transitions?
Second order phase transitions
Adiabatic,Relaxational, AC calorimetry,....
Cp
First-order phase transitions
Libertas perfundet omnia lucet
CALORIMETRY
Best suited technique to determine entropy changes at phase transitions?
Second order phase transitions
Adiabatic,Relaxational, AC calorimetry,....
Cp
First-order phase transitions
Libertas perfundet omnia lucet
CALORIMETRY
Best suited technique to determine entropy changes at phase transitions?
Second order phase transitions
Adiabatic,Relaxational, AC calorimetry,....
Cp
First-order phase transitions
Differential Scanning Calorimetry (DSC)
Heat flux dQ/dt
Libertas perfundet omnia lucet
Libertas perfundet omnia lucet
PURPOSE-BUILT DSC CALORIMETERS
Peltier cells.
Heat absorbed
Heat Rejected
Ther
mo
elec
tric
coo
ler
Hea
tfl
uxm
eter
Libertas perfundet omnia lucet
A BIT OF HISTORY
Libertas perfundet omnia lucet
THE
ORIGINS
Libertas perfundet omnia lucet
Libertas perfundet omnia lucet
Water freezing
Libertas perfundet omnia lucet
DSCUNDER EXTERNAL FIELDS
MAGNETIC FIELD(Magnetocaloric effect)
ELECTRIC FIELD(Electrocaloric effect)
MECHANICAL FIELD
HYDROSTATIC PRESSURE(Barocaloric effect)
UNIAXIAL STRESS(Elastocaloric effect)
Libertas perfundet omnia lucet
DSC Calorimetry under constant temperature (T), sweeping field ( Y ): DIRECT METHOD
dQ
/dY
H
S
(J K
-1 k
g-1)
T (K)
Computing caloric effects: Field-induced entropy change
285 290 295 300 305
0
200
400
600
800
dQ/d
T (
mW
/K)
T(K)
T0
TdQ
/dT
T
S
(J K
-1 k
g-1)
T (K)T
DSC Calorimetry under constant field ( Y ), sweeping temperature (T) : QUASI-DIRECT METHOD
S
Libertas perfundet omnia lucet
DSC WITH MAGNETIC FIELD v1
1 Cu block2 Sensors (thermobatteries)3 Sample4 Reference5 Carbon-glass resistor (T)
16 mm
Marcos et al., Rev. Sci. Inst. 74, 4768 (2003)
T: 10 – 300 K
B: 0 – 5 T
Libertas perfundet omnia lucet
Gd5(SixGe1-x)4
Casanova et al., Phys. Rev. B. 69, 104416 (2004)
Casanova et al., Appl. Phys. Lett. 86, 262504 (2005)
Gd5(Si0.05Ge0.95)4
Illustrative examples of thermal curves
Isofield, scanning T Isothermal, scanning H
Libertas perfundet omnia lucet
Pt-100 thermometer
Sample
ThermobatteriesHall probe
Libertas perfundet omnia lucet
DSC WITH MAGNETIC FIELD v2
v2.0 v2.1
T: 100 – 400 K
B: 0 – 1 T
T: 100 – 400 K
B: 0 – 6 T
Libertas perfundet omnia lucet
Examples: Reproducibility of ∆S upon field cycling.
Ni51Mn33.4In15.6
Stern-Taulats et al. J. Appl. Phys. 115 (2014) 173907
Stern-Taulats et al. Phys. Rev. B 89 (2014) 214105
Fe49Rh51
H →
0
0 →
H
H →
0
0 →
H
Libertas perfundet omnia lucet
OTHER (PELTIER CELL) DEVICES
Libertas perfundet omnia lucet
OTHER (PELTIER CELL) DEVICES
Libertas perfundet omnia lucet
OTHER DEVICES
Libertas perfundet omnia lucet
DSC WITH ELECTRIC FIELD
ECuBaTiO3
T: 100 – 400 K
V: 0 – 2kV
Illustrative examples of thermograms
PbSc0.5Ta0.5O3
Isofield, scanning T Isothermal, scanning E
Libertas perfundet omnia lucet
Examples
Libertas perfundet omnia lucet
OTHER DSC WITH ELECTRIC FIELD
Libertas perfundet omnia lucet
“DSC” (DTA) WITH HYDROSTATIC PRESSURE
(J.L. Tamarit, Universitat Politècnica de Catalunya)
Cells
O-ring
Capillary
Screw
Metallic O-ring
T: 100 – 500 K
p: 0 – 3kbar (0.3 GPa)
Libertas perfundet omnia lucet
Examples
00.8kbar1kbar1.2kbar1.4kbar1.7kbar2.1kbar
Libertas perfundet omnia lucet
OTHER DTA WITH HYDROSTATIC PRESSURE
Libertas perfundet omnia lucet
DSC WITH UNIAXIAL (TENSILE) STRESS
Libertas perfundet omnia lucet
DSC WITH UNIAXIAL (COMPRESSIVE) STRESS
Libertas perfundet omnia lucet
Libertas perfundet omnia lucet
SUMMARY
DSC calorimetry under field:
Accurate determination of ∆S at caloric effects
Reproducibility of a caloric effect
Future target:
DSC calorimetry under fieldS(more than one applied field)
MULTICALORICEFFECTS
.............
Libertas perfundet omnia lucet
COLLABORATORS
Enric Stern-Taulats, Rubén Millán-Solsona, Antoni PlanesUniversitat de Barcelona.
Pol Lloveras, Maria Barrio, Josep-Lluís TamaritUniversitat Politècnica de Catalunya.
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