ICMAB ICMAB INSTITUT DE CINCIA DE INSTITUT DE CINCIA DE MATERIALS - - PowerPoint PPT Presentation
ICMAB ICMAB INSTITUT DE CINCIA DE INSTITUT DE CINCIA DE MATERIALS DE BARCELONA MATERIALS DE BARCELONA Xavier Obradors Director ICMAB CSIC CONSEJO SUPERIOR DE INVESTIGACIONES CIENTFICAS CONSEJO SUPERIOR DE INVESTIGACIONES
INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA
CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS
INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA
CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS
Xavier Obradors Director ICMAB – CSIC
ALBA SYNCHROTRON
Bellaterra campus (Univ. Aut. Barcelona, 20 km)
ICMAB RESEARCH ACTIVITIES
Battery materials
2.0 2.5 3.0 3.5 4.0 4.5 200 150 100 50
E/V (vs Li)
Capacity (mAh/g)
High T batteries
250ºC % O
nitrides
PCT application ES03/00249
ALISTORE ERI
0,5 1 1,5 2 2,5 3 2 4 6 8 10 'x in Li xFe2O3' M M M M M Li2O matrix M M M M M Li2O matrixMxOy amorphous MxOy
MxOy + 2y Li+ -> y Li2O + x M + 2y e-
New materials, alternative mechanisms
9.3 Å
β β-
NiOOH
9.3 Å
β β-
NiOOH
Journal of the American Chemical Society, 129, 5840 (2007) Journal of Materials Chemistry 16, 2925 (2006) β-Ni(OH)2
Correlation microstructure-electrochemical yield
a b
92 Å
a b
92 Å
b
92 Å
c b
14 Å
Nitride materials with photocatalytical activity in the visible range
Advanced Functional Materials, 17, 3348 (2007)
Mesoporous nanostructured thin films
Nx (anatase) 1 2 3 4 5
300 350 400 450 500 550 600
Cut-off wavelength (nm) Rate of CO2 evolution for decomposition of acetaldehyde as a function of irradiation λ
New nitrogen doped ceria (CeO2 ) with photocatalytical activity in the visible range
Chemistry of Materials, 2, 1682 (2008) A.Fuertes, A.B.Jorge. Pat. Esp. 200700482. 23- 02-2007.
N1s XPS as a function of the nitriding temperature in NH3
N bonded to Ti N bonded to Ce
Nitrogen doping of oxides decreases the band gap because of the lower electronegativity of N vs O, shifting the photocatalytical activity from the UV to the visible range
Rate of CO2 evolution (ppm/h.cm2 )
The mesostructure is kept until T=700 oC Solid solution CeO2-x-yNx up to 4.5 mol % N
Hydrogen by Ethanol Reforming
Catalyst grown
cordierite substrate: Nanocomp-
silica aerogel with cobalt nanoparticles (blue
in the idealized inset).
The catalytic device can be simply heated up to the reaction temperature (320-340ºC) under air, and then the ethanol is introduced for the generation of hydrogen. This has a strong potential for fuel cell technology as well as for on-board generation of hydrogen for mobile applications. The catalytic device can be easily operated and doesn’t require special care for shut down cycles, thus allowing interrupted and/or oscillating operation for real practical application. No activation and/or conditioning are required for operation.
Co-SiO2 aerogel-coated catalytic walls for the generation
hydrogen, M.Domínguez, E.Taboada, E.Molins, J.Llorca, Catalysis Today (2008) and CSIC- UPC patent (2007)
Xavier Obradors
Institut de Ciència de Materials de Barcelona, CSIC, 08193 Bellaterra, Spain
Consolider Consolider
T.Puig, A. Pomar, A. Palau, F. Sandiumenge, S. Ricart, N. Mestres,
20 40 60 80 0.01 0.1 1 10 100
B (T) B (T) T (K) T (K)
Magnets
FCL
Cables Transformers
NMR Research Accelerators, etc
Motors generators SMES
MRI
Metallic substrate: RABiTS Ni, SS-IBAD thickness ~ 80 μm Buffer layers : CeO2 , YSZ, STO,… ~ 0.1 μm SC layer : YBCO ~ 1.0 μm Cap layer : Ag thickness ≈ 0.2 - 0.5 μm
growth of nanostructured films and coated conductors:
– A flexible, scalable and controllable bottom-up approach
– Interfacial nanostructured films – Nanocomposites – Ferromagnetic-superconductor nanostructured YBCO films
dependent transport Jc measurements
YBCO Single crystal YBCO Single crystal
Current flow without dissipation Pinning of vortices by material defects FL = Jc x B = Fp → vfl = 0 J NEED of:
Generation
APS
… by nanostructuration
The methodology must be versatile, scalable and low cost We choosed a chemical solution route
… a versatile, scalable and low cost methodology for growth of nanostructured films
For YBCO films …
Low-cost methodology
High production rate
Scalable to large surfaces Versatile: nanostructuration
Spin-coating
Metal-organic TFA solution
Coated conductors
ω
Pirólisis Reacción Oxigenación PO 2, PH 2O Flujo de Gas dT1/dt T 1 T 3, t
T 2, t T(PH
2O)
PO 2, PH 2O
T dT2/dt Pyrolysis Growth Oxygenation PO2 , PH2O T 1 T 3 T 2 Gas Flow PO 2 , PH 2O T
Epitaxial layer
Gas Flow Pirólisis Reacción Oxigenación PO 2, PH 2O Flujo de Gas dT1/dt T 1 T 3, t
T 2, t T(PH
2O)
PO 2, PH 2O
T dT2/dt Pyrolysis Growth Oxygenation PO2 , PH2O T 1 T 3 T 2 Gas Flow PO 2 , PH 2O T
Epitaxial layer
Gas Flow
MOD process
,Y2 Cu2 O5 and CuO embedded in oxyfluorides (OF)
J.Gázquez et al, Chem Mat (2006)
Y long and winding road: TFA-Y / Ba1-x Yx F2 / a-Y2 O3 / Y2 Cu2 O5 / Ba1-x Yx (F,O)2-y / YBa2 Cu3 O7
Film quenched before growth
Multilayers: Epitaxy and cap layer planarity
RHEED IFW-Dresden
RBS channeling χmin = 12 % (CeO2 ) χmin = 46 % (CZO)
400nm
rms: 0.8nm rms: 3 nm
RHEED CZO AFM Ce1-x [Gd(Zr)]x O2-y High energy (00l) facets
25 50 75 100 2 4 6
% Flat CeO2 area Jc(MA/cm
2)
T=77K
nm 5 10 15 20 25 30 1 2 3 4 5 µm µm 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Planarity
96,8 %
Growth of TFAYBCO on MOD CeO2 cap layers
2007 results
Highest critical current
TFAYBCO on MOD-CeO2
cap layers
Jc (77K)= 5.2 MA/cm2
25 50 75 100 2 4 6
% Flat CeO2 area Jc(MA/cm
2)
T=77K 1 2 3 4 5 1 2 3 4 Jc(MA/cm
2)
rms CeO2 (nm) T = 77K
rms rms roughness roughness is is too too rough rough Surface Surface planarity planarity is is more more useful useful
Growth of TFAYBCO on MOD-cap metallic substrates
1 μm
49% YSZ
1 μm
76% CZO
Δφ (YBCO) =5º Δφ (YSZ) =9.5º
4 8 I (a.u.)
φ (deg) Δφ = 5º
YBCO (103)
Jc (77K)= 1.8 MA/cm2 MOD planarization High SC performances
Polycrystalline substrate/epitaxial multilayer
J
Critical current optimization → at high fields (1- 5T) Correlation nanostructure and vortex pinning High quality epitaxial films Jc
sf(77K) ~
4 MA/cm2 Island based nucleation and growth mode → a-b plane defects promotion
dislocations
Pinning defects of specific size and disposition
θ θ Point like defects Linear defects Planar defects
We need to identify and separate different vortex pinning contributions
90 135 180 225 1E-6 1E-5 1E-4 1E-3 0.01 0.1 1
Jc(MA/cm
2)
θ (º)
T= 77K
MOD-YBCO, t ≈ 275 nm
θ θ c a
FL
θ
FL
θ
ANISOTROPIC defect contribution
ISOTROPIC defect contribution
Enable to separate ISOTROPIC and ANISOTROPIC defect pinning contributions
H//ab H//c
/
) (
T T wk c c
e J T J
−
=
2
) / ( 3
) (
+
−
=
T T str c c
e J T J
Nelson et al, Phys. Rew. B 48 (1993) Blatter et al., Rev. Mod. Phys 66 (1994)
J.Gutierrez et al., Appl. Phys. Lett. 90 (2007)
r0 < ξ Weak pinning Strong correlated pinning
PLD-YBCO
Weak-isotropic defects dominate at low T, strong-isotropic
defects at intermediate T and strong-anisotropic defects at high T
275 nm YBCO-TFA films
20 40 60 80 2 4 6 8
0,2 0,4 0,6
20 40 60 80 2 4 6 8
Temperature (K)
μ0H (T)
Janis
c
/Jtotal
c
Hirr
0,8
20 40 60 80 2 4 6 8
0,5 0,5 0,3 0,7 0,3 Temperature (K)
μ0H (T)
Hirr
J
iso-str c
/J
total c
20 40 60 80 2 4 6 8
0.6 0.4 0.2
20 40 60 80 2 4 6 8
Temperature (K)
μ0H (T)
Hirr
J
Iso-wk c
/J
tot c
We have a tool to separate and quantify the three vortex pinning contributions
Iso-wk contribution Iso-str contribution Aniso-str contribution
T.Puig et al., SUST 21, 034008 (2008)
Interfacial nanostructured films: Nanocomposite films:
AIM: Identify and control pinning contributions induced in the different nanostructured YBCO films
YBCO Single crystal YBCO Single crystal Approach:
Metal-organic precursors Spin-coating
Thermal treatment
600oC ≤ T ≤ 1000oC Atm: O2 , Ar-H2
Nanostructures: Chemical Solution Deposition
1x1 μm2 single crystal thermally treated
Tune of the equivalent deposited thickness through concentration
10-3mol/l ~20nm 10-1mol/l ~1nm complete layer
Use of very → dilute solutions
Surface energy Interface energy Elastic relaxation energy
Pentadionates, acetates, propionates in acetic acid, isopropanol and/or propionic acid Self-assembled nanoparticles
5 μm 5 μm
Self-assembled nanostructures grown from chemical methods
0,5 μm
La0.7 Sr0.3 Mn O3 thin film (La,Sr)Ox nanodots
0.2 m μ
Strain induced self-assembled Ce0.9Gd0.1O2-y nanowalls
h ~ 8-10 nm h ~ 50 nm
Spontaneous nucleation of (La,Sr)OX nanoislands on LSMO
Highly anisotropic islands Isotropic islands
0,5 μm
O2
0,5 μm
Ar-H2
Growth atmosphere:
fine selection of interface energy
LAO (011) [1-10] CGO [100] [010] [001]
ξ
~ +5 %
ξ
~ -1 %
LAO (001) [110] CGO [100] [010] [-110]
ξ
~ -1 %
ξ
~ -1 %
(011) (100) (0-11)
(010) (001)
CGO nanowall
LAO
(111)
0,2 0,4 0 ,6 0,8 2 4 6 8
50nm
μm
345 nm
nm
0,1 0,2 0,3 2 4 6
nm
μm
~5 nm ~34 nm
80 100 120 140 160 180 200 220 1E-6 1E-5 1E-4 1E-3 0.01 0.1 1
Standard CGO (La,Sr)Ox dots (La,Sr)Ox pyramids
Jc(MA/cm
2)
θ(º)
T=77K, μ0H=7T
c-axis anisotropic contribution is strongly increased Reduced anisotropic contribution for H//ab
Similar behavior obtained for all the different architectures → defects along the c-axis induced in the YBCO matrix by the interfacial particles
θ
2 4 6 8 1 10 100
CGO (La,Sr)Ox dots (La,Sr)Ox pyramids
Jc
anis nano/Jc anis st
μ0H//c (T)
77K
50μm
4 tracks (20μm*100 μm) defined by lithography:
10μm YBCO/Ce0.9 Gd0.1 O2-y nanowalls
Track 1: full thickness 250nm Track 2: FIB milling down to 175 nm Track 3: FIB milling down to 130nm
90 135 180 225 1
250nm 170nm 130nm
Jc (MA/cm
2)
θ (deg)
μ0 H = 5T, T= 50K
Isotropic defects pinning contribution
90 135 180 225 0.0 0.1 0.2 0.3 0.4 0.5 0.6
250nm 170nm 130nm
Jc
2)
θ (deg)
Enhanced c-axis anisotropic contribution as thickness decreases
100 150 200 250 0.0 0.1 0.2 0.3 0.4
Jc
anis(MA/cm 2)
tickness (nm)
μ0H//c = 5T
T = 50K T = 65K T = 77K
Pinning associated to defects induced by interfacial nano-particles is enhanced by reducing the YBCO thickness → Higher density of defects generated near the nano- structures
STO YBCO BZO
Film thickness= 200 (20) nm
Modification of the (Y,Ba,Cu ) precursor solution by addition of Ba and Zr salts: BaZrO3 nanodots randomly embedded
(006) (005) (004) (003) (002) (110) YBCO BZO 2θ (deg.) 20 25 30 35 40 45 STO (001) (002) 2θ χ
BZO nanodots size : 10-20 nm Two populations of BZO coexist Epitaxial Non epitaxial YBCO
STO YBCO BZO
Film thickness= 200 (20) nm
cube on cube epitaxial relationship with YBCO matrix Interfacial nanodots
YBCO BZO STO
(002)STO (002)BZO
Randomly
(non-coherent with the matrix)
BZO YBCO
(101) (011) (-110) Zone axis [111] BZO
Bulk nanodots Modification of the (Y,Ba,Cu )TFA anhydrous precursor solution by addition of Ba and Zr salts
(112)Y2O3
Y2 O3 YBCO Y2 O3 YBCO LAO Y2 O3 polycrystalline fraction is also present… BUT not identified by TEM
Epitaxial Y2 O3 at the substrate interface and in the bulk
(001)Y2 O3 // (001)YBCO [110]Y2 O3 // [100]YBCO ε=-2.7 %
Need
quantification
non-coherent (or random) fraction
Average size Y2 O3 : 20-25nm
Jc (1T, 77K)=0.5 MA/cm2 for 20 %mol Jc (1T, 77K)=0.3 MA/cm2 for 10 %mol
Can be divided, on the basis of their lattice matching, into three classes
Incoherent
Misfit dislocation
Semi-coherent
Lattice matching with strain relaxation
NO lattice matching NO orientation relationship Disordered structure
Based on an orientation relationship which is specified crystallographically in terms of a pair of planes and directions: { hkl} A / / { hkl} B with < uvw> A / / < uvw> B
Coherent
Perfect lattice matching at the interface plane
Interphase boundary
δ = (dA – dB )/ dA Interfacial energy γ (coherent)= γch Epitaxial interfaces γ (semi-coherent)= γch + γst Very little is known about the detailed structure
High angle grain boundary
Interphase boundary
Interphase boundary
High interfacial energy Nano-structural defects formation
Lattice strain (XRD)
2 4 6 8 5 10 15 20
Fp (GN/m
3)
μ0H (T)
Fp = Jc x B
0,01 0,1 1 10 0,01 0,1 1 10
Jc (MA/cm
2)
μ0H (T)
10 mol.% BZO 7 mol.% BZO 20 mol.% Y2 O3 10 mol.% Y2 O3 Pure YBCO
Maximum pinning force is controlled by random Np
2 4 6 8 4 8 12 16 20
Fp
max
[random Np] mol%
The strained microstructure is very effiective to increase Jc at high magnetic fields (vortex pinning) Isotropic microstrain plays an important role in vortex pinning propeties
5 10 15 20 2 4 6 8 BZO
γ eff
[nanodot] mol. %
Y2O3
Vortex pinning is controlled by isotropic defects
90 135 180 225 1E-4 1E-3 0,01 0,1 1 77K, 5T
Jc(MA/cm
2)
θ(º) 10 mol.% BZO 7 mol.% BZO 20 mol.% Y2 O3 10 mol.% Y2 O3 Pure YBCO
5 10 15 20 2 4 6 8
γ eff
[random nanodot ] mol %
Random nanodots (isotropic microstrain) also control the effective anisotropy (γeff )
0.3 0.2 0.1
20 40 60 80 2 4 6 8
Temperature (K) μ0H (T)
Hirr
Jiso-wk c /Jtot c
10% BZO
20 40 60 80 2 4 6 8
0,1 0,2
20 40 60 80 2 4 6 8
Temperature (K)
μ0H (T)
Hirr
Janis
c
/Jtotal
c 20 40 60 80 2 4 6 8
0,2 0,4 0,6
20 40 60 80 2 4 6 8
Temperature (K)
μ0H (T)
Janis
c
/Jtotal
c
Hirr
20 40 60 80 2 4 6 8
0.7 0.9 0.9 0.7
20 40 60 80 2 4 6 8
0.8 Temperature (K)
μ0H (T)
0.8
J
iso-str c
/J
total c
Hirr
20 40 60 80 2 4 6 8
0,5 0,5 0,3 0,7 0,3 Temperature (K)
μ0H (T)
Hirr
J
iso-str c
/J
total c
20 40 60 80 2 4 6 8
0.6 0.4 0.2
20 40 60 80 2 4 6 8
Temperature (K)
μ0H (T)
Hirr
J
Iso-wk c
/J
tot c
0% BZO
First time, full pinning phase diagram is controlled by strong-isotropic defects
Iso-wk contribution Iso-str contribution Aniso-str contribution
20 40 60 80 2 4 6 8
0.7 0.9 0.9 0.7
20 40 60 80 2 4 6 8
0.8 Temperature (K)
μ0H (T)
0.8
J
iso-str c
/J
total c
Hirr
Chemical solution deposition is a versatile technique to
generate artificial pinning structures.
Complementariry with PLD? The methodology to analyze vortex pinning contributions
can be used for PLD nanocomposites.
I nterfacial nanostructures are successfully grown by CSD
and c-axis anisotropic defects are artificially introduced in YBCO films. Can be combined with PLD?
CSD nanocomposites are very promissing, vortex pinning is
controlled by strain generated by isotropic defects. Strain in
self-organized PLD nanorods? Magnetic nanostructures have been introduced in YBCO
films showing an enhancement of vortex pinning
We need to use the nanoscale imaging methods to
correlate vortex pinning with APC