aportes de la difracción de - argentina.gob.ar€¦ · los neutrones sirven para... para...
Post on 02-May-2020
6 Views
Preview:
TRANSCRIPT
Aportes de la difracción de neutrones a diversos problemas en ciencia de materiales
Gabriela AurelioInv. CONICET
Lab. de Resonancias Magnéticas, CAB &Proyecto LAHN
Seminario GIyA - Tandar 26/05/2016
¿Porqué neutrones?Laboratorios de NS en el mundo
Los haces de neutrones son una herramienta cara, pero MUY poderosa. Se aplican a gran cantidad de disciplinas y problemas científicos e industriales.
Seminario GIyA - Tandar 26/05/2016
¿Porqué usar neutrones?
E n qué c as os pueden s er útiles – e inc lus o exc lus ivos – los neutrones ? (en c c ia . de
materia les )Para discriminar elementos vecinos de la Tabla Periódica. CONTRASTE.Para obtener información del bulk y evitar cuestiones superficiales (oxidación, tensiones en la
superficie). Alta penetración, baja absorciónPara localizar elementos livianos en las estructuras (H, O)Para estudiar transiciones de fase (poco problema con entornos de muestra)Para mejorar la resolución de los refinamientos de estructuras (alta intensidad a altos Q)Para estudiar orden magnético
DesventajasLa difracción de neutrones es una técnica muy costosa, y no es una técnica de rutina. Alta
complementariedad con DRX. Concienzuda justificación del experimento. Necesita mucha más cantidad de muestra.
Seminario GIyA - Tandar 26/05/2016
Y porqué?
What causes nuclear scattering? Nuclear forces. Short ranged! Range of the interaction 10-14 – 10-15 m
The range of interaction is much smaller than typical thermal neutron wavelengths
The scattered wave may be described as a spherical wave.
nuclear scattering is isotropicnuclear scattering is isotropic
Seminario GIyA - Tandar 26/05/2016
Interacción neutrón-núcleo
Esquemáticamente, se puede definir el problema como:
z- direction
(incident neutrons)
Vector de scatteringQ
cuando |k|=|k'| (caso elástico)Q y 2q se usan
indistintamente como variables de scattering
blongitud de scattering
Seminario GIyA - Tandar 26/05/2016
The scattering length “b”
The isotropic scattering by a fixed nucleus is described by a single parameter, b, throught Fermi's pseudo-Fermi's pseudo-potentialpotential (Born's approximation)
The interaction potential with a givennucleus N
The position of the nucleus
The neutron'smass
The position of the neutron
The nuclear scattering length
Seminario GIyA - Tandar 26/05/2016
Scattering cross-section: single nucleusB a c k to th e d e te c t o r :
I t tu r n s o u t th a t u s in g th is V (r), th e s c a t t e r in g c r o s s -s e c t io n is
S o th e to t a l n u m b e r o f n e u t r o n s s c a t t e r e d in a l l d i r e c t io n s b y a s in g le n u c le u s is s im p ly
sT O T A L
= 4 p b 2
Seminario GIyA - Tandar 26/05/2016
Some properties of bN
I t is a c o n s ta n t , i t d o e s n o t d e p e n d o n q o r f
I t is a c o m p le x n u m b e r. T h e im a g in a r y p a r t is r e la t e d to r e s o n a n c e p h e n o m e n a b e tw e e n c e r t a in n u c le i a n d th e n e u t r o n (a fe w c a s e s )
W h e n b is p o s i t iv e th e p o te n t ia l V (r) is r e p u ls iv e
I n s o m e c a s e s b is n e g a t iv e : th is a l lo w s fo r c o n t r a s t (e .g . T i-Z r a l lo y s )
T h e r e is n o t a th e o r y o f n u c le a r fo r c e s th a t a l lo w s p r e d ic t in g th e v a lu e o f b
N. I t is ta k e n a s a p h e n o m e n o lo g ic a l
p a r a m e te r a n d d e te rm in e d e x p e r im e n ta l ly fo r e a c h n u c le u s (ta b u la t e d ).
Seminario GIyA - Tandar 26/05/2016
Los neutrones sirven para...
Para discriminar elementos vecinos de la Tabla Periódica. Para localizar elementos livianos en las e s t r u c t u r a s (H , O )
PORQUE LA VARIACIÓN DE b CON EL NÚMERO ATÓMICO ES ERRÁTICA. PORQUE LA VARIACIÓN DE b CON EL NÚMERO ATÓMICO ES ERRÁTICA. PORQUE EL H Y EL O SON BUENOS DISPERSORES DE NEUTRONES Y PORQUE EL H Y EL O SON BUENOS DISPERSORES DE NEUTRONES Y
ADEMÁS PUEDO SUSTITUIR ISÓTOPOS Y MEJORAR CONTRASTES.ADEMÁS PUEDO SUSTITUIR ISÓTOPOS Y MEJORAR CONTRASTES.
Seminario GIyA - Tandar 26/05/2016
Para obtener información del bulk y evitar cuestiones superficiales (oxidación, tensiones en la superficie). Alta penetración, baja absorción
P a r a e s tu d ia r t r a n s ic io n e s d e fa s e PORQUE LA INTERACCIÓN NUCLEAR ES DE PORQUE LA INTERACCIÓN NUCLEAR ES DE MUY CORTO ALCANCE. LA MATERIA ESTÁ MUY CORTO ALCANCE. LA MATERIA ESTÁ PRÁCTICAMENTE PRÁCTICAMENTE VACÍAVACÍA PARA UN PARA UN NEUTRÓN.NEUTRÓN.
Y ta m b ié n p o r e s o , n e c e s i t o m u c h a c a n t id a d d e m u e s t r a
Los neutrones sirven para...
Seminario GIyA - Tandar 26/05/2016
P a r a m e jo r a r la r e s o lu c ió n d e lo s r e f in a m ie n t o s d e e s t r u c t u r a s (a l t a in te n s id a d a a l t o s Q )
PORQUE LA INTERACCIÓN NUCLEAR ES PORQUE LA INTERACCIÓN NUCLEAR ES ISOTRÓPICAISOTRÓPICA Y POR LO Y POR LO TANTO NO DEPENDE DE 2q COMO EN DRX.TANTO NO DEPENDE DE 2q COMO EN DRX.
r ad i ac i ó n C u K α
λ= 1 .91 A
Los neutrones sirven para...
Seminario GIyA - Tandar 26/05/2016
P a r a e s t u d ia r e l m a g n e t is m o d e l m a te r ia l
PORQUE EL NEUTRÓN ES UNA PORQUE EL NEUTRÓN ES UNA PARTÍCULA CON SPIN ½PARTÍCULA CON SPIN ½. POSEE . POSEE UN MOMENTO MAGNÉTICO QUE PUEDE INTERACTUAR CON UN MOMENTO MAGNÉTICO QUE PUEDE INTERACTUAR CON LOS CAMPOS MAGNÉTICOS INTERNOS DEL MATERIAL. LOS CAMPOS MAGNÉTICOS INTERNOS DEL MATERIAL. AÚN AÚN EN AUSENCIA de un campo externo.EN AUSENCIA de un campo externo.
Resulta que la longitud de scattering nuclear (bnuc) y la magnética (bmag) tienen magnitudes comparables. Los picos de difracción magnética son tan intensos como los nucelares.
La interacción magnética neutrón-muestra NO es isotrópica, el scattering decae con Q y por eso sólo se „ven“ picos magnéticos a bajo ángulo.
Los neutrones sirven para...
Seminario GIyA - Tandar 26/05/2016
Pasando del núcleo al cristal
H a s ta a q u í h a b la m o s d e „s c a t t e r in g “ n e u t r ó n -n ú c le o .
To d a s la s „v e n ta ja s “ o p r o p ie d a d e s m e n c io n a d a s v a le n p a r a to d a s la s té c n ic a s : e s p e c t r o m e t r í a s , S A N S , d i f r a c c ió n , r e f le c t o m e t r í a , n e u t r o g r a f í a , e t c .
E l r e s t o d e e s ta c h a r la t r a t a d e i lu s t r a r la m a n e r a d e a p r o v e c h a r e s a s v e n ta ja s a l e m p le a r la té c n ic a d e d i f r a c c ió n d e p o lv o sd i f r a c c ió n d e p o lv o s .
Seminario GIyA - Tandar 26/05/2016
Porqué usar la técnica de difracción de polvos?
Para la ciencia de materiales la cristalografía es una herramienta fundamental→siempre el punto de partida ineludible es el conocimiento de la estructura atómica del material de interés. “Generalmente“ se tiene acceso al material policristalino antes o más fácilmente que al monocristral.
Qué aprendemos de un experimento de difracción de polvo? Hay picos en el difractograma? (cristalinidad)
Qué fases cristalinas puedo identificar? (Id. de fases, bases de datos)
Hay varias fases ? (homogeneidad, impurezas, coexistencia)
Cuánto hay de cada una? (análisis cuantitativo)
Refinamiento de estructuras cristalinas (incluso a veces resolución)
Información de tamaño y tensiones
[Refinamiento (y/o resolución) de ordenamientos magnéticos.]
DRX
Example 1: Metastable phases in Zr-Nb and Ti-V alloys
Example 1: Metastable phases in Zr-Nb and Ti-V alloys
Seminario GIyA - Tandar 26/05/2016
Metastable phases in Zr-Nb and Ti-V alloys
0 5 10 30 35
400
600
800
1000
1200
1400
Ω (hex)
α (hcp)
β (bcc)
Tem
pera
tura
[K]
Pres ió n [GPa]
Pressure [GP]
Tem
pera
ture
[K] Ti
Seminario GIyA - Tandar 26/05/2016
Metastable phases in Zr-Nb and Ti-V alloys
0 5 10 30 35
400
600
800
1000
1200
1400
Ω (hex)
α (hcp)
β (bcc)
Tem
pera
tura
[K]
Pres ió n [GPa]
Pressure [GP]
Tem
pera
ture
[K]
Zr-Nb
Ti-VTi
„chemical“ pressure
alloying
E
P
D
Seminario GIyA - Tandar 26/05/2016
Metastable phases in Zr-Nb and Ti-V alloys
0 5 10 30 35
400
600
800
1000
1200
1400
Ω (hex)
α (hcp)
β (bcc)
Tem
pera
tura
[K]
Pres ió n [GPa]
Pressure [GP]
Tem
pera
ture
[K]
0 2 4 6 8 10 12 14 16 18 20 22 24
300
400
500
600
700
800
900
1000
1100
1200
Msα q
Ω start
α + ββ
α
% at. NbTe
mpe
ratu
re [K
]
q + q
q + q q
METASTABLE PHASE DIAGRAM
The W phase (high pressure form of Ti, Zr and Hf) can be metastably stabilised by alloying and quenching.
Zr-Nb
Seminario GIyA - Tandar 26/05/2016
Why not XRD?
M a in d r a w b a c k s o f X R D fo r s t u d y in g (c e r t a in ) a l lo y s
X rays probe the s urfac e: that's w here oxides may form, s tra ins from mechanic a l treatments , big g ra ins due to long annea ling times , diffic ulty of powder avera g ing , s ma ll amount of s ample means few g ra ins !
Ordered a lloys us ua lly form w ith neig hbouring elements : very s im ila r s c attering fac tors , s ite oc c upancy hard to s tudy
Seminario GIyA - Tandar 26/05/2016
Advantages of ND
Advantages of using ND in our scientific problem: Metastable phases produced by quenching from HT → avoid surface oxidation
and study the bulk We were interested in possible Zr/Nb or Ti/V atomic ordering in the binary Ω
phase. We needed reliable phase fractions to study phase coexistence in the diagram,
not possible at Centro Atómico with a conventional diffractometer in this kind of samples.
We were interested in evolution towards thermodynamic equilibrium → in-situ thermodiffraction.
Seminario GIyA - Tandar 26/05/2016
Design!
Design of the experiments, selection of instruments Systematics of quenched alloys at RT as a function of alloying content –
constitution of the alloys and lattice parameters dependence with composition → don't need too much resolution with these simple phases, no excessive peak overlap, good accuracy in peaks positions is enough → low or medium resolution diffractometer → D1B (λ ≈ 1.5 Å)
Phase fractions and possible order Zr/Nb or Ti/V as a function of composition
In situ aging – kinetics towards equilibrium phases → thermodiffraction → medium/low resolution BUT many many neutrons (fast!) → D1B, D20
G. Aurelio - WNS2016 -- Bariloche, 10-12 Feb 2016
Neutron powder diffraction
Ins trument D20: hig h flux diffrac tometer a t ILL
Array of He3 detectors at D2B (ILL)
Inte
nsity
[sca
ttere
d ne
utro
ns]
2θ [scattering angle]
Seminario GIyA - Tandar 26/05/2016
The samples
P [
What is a powder for a metallurgist ??
In metals, crystallites are hold together by grain boundaries, but they may develop very big grains, so you will find a „texture“ problem...
Some alloys are very brittle → you can easily crash them and get fine powders, you may sieve them and get to a good specimen for powder diffraction
Other alloys (these ones!) are NOT! To improve statistics, we cut the alloy in tiny pieces, or make shavings before the final thermal treatment (to remove strains). The best solution is to emulate a good powder average by spinning the sample holder. It works nicely thanks to high penetration depth but not possible inside furnaces...
Seminario GIyA - Tandar 26/05/2016
The instruments
D1B medium/high intensity diffractometer, guides hall
Vanadium Sample holders
Seminario GIyA - Tandar 26/05/2016
The data
Data from D1A (ex-high resolution diffractometer at ILL)
l= 1.51 Å
From these data we constructed the systematics of cell parameters and constitution of alloys as a function of composition, at room temperature.
Seminario GIyA - Tandar 26/05/2016
Some results
Experiment @ RT in D1B with l = 1.28 Å on a sample Zr-10 at.% Nb previously aged for different periods @ 773 K and quenched
0 5 10 15 20 25 30 35 40700
750
800
850
900
950
1000
1050
1100
1150
α +βNb
Perovic & Weatherly [97Per] Fernández Guillermet [91Gui]
Esta Tesis : Experimento de termodifracción a 900 K Experimento T/R/T - recocido a 773 K
α +ββ
% at. NbTe
mpe
ratu
re [K
]
From these experiments we studied thermal expansion of the b phase and evolution towards equilibrium.
Seminario GIyA - Tandar 26/05/2016
Some results
In-situ thermodiffraction @ D1B l=1.28 Å for an alloy Zr-18.6 at.% Nb aged at 600 K
After 250 min a second phase nucleates (Ω)
Evolution of cell parameters with aging time in the b and W phases
With these experiments we could study the kinetics of nucleation and growth of equilibrium phases.
Example 2: Study of ternary Cu-In-Sn alloys for Pb-free soldering
Seminario GIyA - Tandar 26/05/2016
New solder candidates are emerging
Remove Pb from traditional Pb-Sn solders Search for new solder alloys
to improve performance and to respond for new demands (higher service temperatures)
-aerospace industry-automotive industry
Search for novel bonding methods to assemble
components
alternative Sn-based alloys:- low Tm - good wettability- low-cost!!
New challenges for the electronic industry
Seminario GIyA - Tandar 26/05/2016
A candidate: Cu-Sn-In
There is a lack of information on solder alloys at intermediate and high temperatures.There is very little information on ternary phase diagrams of Cu and Sn alloys: COST Action 531-Atlas of Phase Diagrams for Lead-free Solders
Seminario GIyA - Tandar 26/05/2016
Intermetallic Phases
Fig.1. SEM image of Cu/Sn/Cu TLP interconnection fabricated at 270°C after 30min.
γ-InSn4 + β-In3Sn ???
δ + ζ ???
η (Cu2In / Cu6Sn5) ???
???
γ-InSn4 + β-In3Sn ???
δ + ζ ???
η (Cu2In / Cu6Sn5) ???
???
Cu-Sn-Cu TLPB after 30min @ 270ºC Cu-Sn48In-Cu TLPB after 7days @ 400ºC
Need to know the phase diagrams!
Seminario GIyA - Tandar 26/05/2016
Why is there a need for neutron diffraction?
B in a r y p h a s e d ia g r a m s C u -S n a n d C u -In a r e c o m p le t e b u t s o m e d is c r e p a n c ie s a r e s t i l l f o u n d in t h e c r y s t a l lo g r a p h y o f IP s .
Te r n a r y p h a s e d ia g r a m s a r e u n d e r m a jo r r e v is io n a n d a s s e s s m e n t . C r y s t a l lo g r a p h ic d a ta a r e s c a r c e a n d fu n d a m e n ta l p o r m o d e l l in g w i t h p h e n o m e n o lo g ic a l a p p r o a c h e s s u c h a s C A L P H A D .
X -r a y p o w d e r d i f f r a c t io n h a s b e e n u s e d w i t h d o u b t f u l r e s u l t s : m a jo r p r o b le m s w i t h p r e f e r r e d o r ie n t a t io n , la c k o f p o ly c r is t a l l in i t y , b ig a b s o r p t io n c o e f f ic ie n t fo r C u K a r a d ia t io n
N e e d o f d is t in g u is h in g e le m e n t s a t e a c h p o s i t io n .
I n -s i t u th e rm o d i f f r a c t io n to s tu d y p h a s e t r a n s i t io n s
Seminario GIyA - Tandar 26/05/2016
XRD attempts
X-ray diffraction Cu-Ka radiationSample manually ground2 independent scans
Binary sample Cu 55 at.%--Sn 45 at.% (Cu6Sn5)
Huge grains!
Seminario GIyA - Tandar 26/05/2016
Neutron diffraction experiments
D2B: high-resolution l = 1.59 Å Horiz. Slits 500 mm (more intensity) 6mm and 8mm V sample holders Room temperature measurements
Alloy preparation:Melting of Cu, Sn and In in adequate proportions. Homogenized for 3 weeks @ 300ºC.Quenched from 300ºC to ice-water.
D1B: higher intensity - thermodiffraction l = 2.52 Å 8mm V sample holders 25ºC < T < 450ºC 1.6 º/min heating ramps – 2 min/numor
Seminario GIyA - Tandar 26/05/2016
Models for the Cu-Sn h phase
Cu2In
C u6S n
5 (5 5 a t% C u )
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
As-quenched – 1st heating rampExpt. @ D1B: High-Intensity Powder Diffractometer @ Guide HallSAMPLE: ternary alloy S4: 55 % Cu – 40 % Sn- 5 % In
designrepresentation in the
binary (without In)
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
As-quenched – 1st heating ramp
3 transitions
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
2nd DSC peak
1st DSC peak
2nd DSC peak: melting of segregated Sn!
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
3rd DSC peak η → ε
η → ε transition starts around 445ºC for 5% In
In sample S5 (12%In) the transition is not observed below 500ºC @ D1B nor with
DSC → rapid increase of Tη → ε with In addition!
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
follow-up of the η → ε transition
during the waiting time at 450ºC (step 3) the transition evolves
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
quenching from 450ºC (4) - 2nd heating ramp (5)- dwell @ 300ºC (6)
Seminario GIyA - Tandar 26/05/2016
Phase stability and transformations
2nd heating ramp
melting of Sn-rich h
Seminario GIyA - Tandar 26/05/2016
Some conclusions
The neutron diffraction and thermodiffraction technique has proven to give precise and valuable information on the phase transitions „suggested“ by in-house methods as DSC.
It would have been quite difficult to obtain this information from XRD, even at a synchrotron
High-resolution experiments were crucial for the correct identification of phases, and details of the crystallographic arrangement (some files in databases should be carefully used!!)
Neutron thermodiffraction may become a valuable tool in the current process of evaluation of Pb-free solders phase diagrams!
References:1. Crystal Structure of Cu-Sn-In Alloys Around the η-Phase Field Studied by Neutron DiffractionG. Aurelio; S.A. Sommadossi; G.J. Cuello - Journal of Electronic Materials Vol. 41, Nov 20122. Neutron diffraction study of stability and phase transitions in Cu-Sn-In alloys as alternative Pb-free
soldersG. Aurelio, S. A. Sommadossi, and G. J. Cuello - J. Appl. Phys. 112, 053520 (2012)
Seminario GIyA - Tandar 26/05/2016
YBaCoYBaCo22OO5+δ5+δ
Derivado de la estructura perovskita ABO3
A
BO
CúbicaaP x aP x aP (“111”)
El óxido YBaCo2O5.5
Seminario GIyA - Tandar 26/05/2016
YBaCoYBaCo22OO5.55.5
ABO3
A (Y3+,RE3+)A´ (Ba2+)
B (Co2,3,4+)
O3-x
El óxido YBaCo2O5.5
Seminario GIyA - Tandar 26/05/2016
YBaCoYBaCo22OO5.55.5
Orden de cationes ABO3
A (RE3+)A´ (Ba2+)
B (Co2,3,4+)
O3-x
A’
A
TetragonalaP x aP x 2aP (“112”)
AA'B2O6
El óxido YBaCo2O5.5
Seminario GIyA - Tandar 26/05/2016
YBaCoYBaCo22OO5+δ5+δ
Orden de cationes ABO3
A (RE3+)A´ (Ba2+)
B (Co2,3,4+)
O3-x
A’
A
TetragonalaP x aP x 2aP (“112”)
AA'B2O6YBaCo2O6
YBaCo2O6-δ
No-estequiometríade oxígeno
El óxido YBaCo2O5.5
Seminario GIyA - Tandar 26/05/2016
YBaCoYBaCo22OO6-δ6-δOrden de vacancias
Vacancias desordenadas en el plano [Y-O] Caso δ=0.5
Vacancias ordenadas en el plano [Y-O] Caso δ=0.5
TetragonalaP x aP x 2aP (“112”)
OrtorrómbicaaP x 2aP x 2aP (“122”)
Co+3 Co+3
El óxido YBaCo2O5.5
Seminario GIyA - Tandar 26/05/2016
Y(Ba,Ca)CoY(Ba,Ca)Co22OO5.55.5 Dopaje con Ca2+
xCa
= 0
Magnetización
Seminario GIyA - Tandar 26/05/2016
Y(BaY(Ba1-1-xxCaCaxx)Co)Co22OO5.55.5 Dopaje con Ca2+
xCa
= 0
xCa
= 0.05
Magnetización
Seminario GIyA - Tandar 26/05/2016
Y(BaY(Ba1-1-xxCaCaxx)Co)Co22OO5.55.5 Dopaje con Ca2+
Magnetización
xCa
= 0
xCa
= 0.05
xCa
= 0.1
Est
abili
zaci
ón d
e un
est
ado
ferr
imag
nétic
o
Seminario GIyA - Tandar 26/05/2016
TermodifracciónInstrumento D20: difractómetro de alto flujo y resolución variable
10% Ca
T[K
]
10% Ca10% Ca
T[K
]
Seminario GIyA - Tandar 26/05/2016
Resultados neutronesx = 0.10
O12
2 P
M
O12
2 fe
rri-S
SO
0 50 100 150 200 250 300
10-2
10-1
100
101
102 xCa = 0
ρ [Ωcm
]T [K]
TMI
0 50 100 150 200 250 300
10-2
10-1
100
101
102
xCa = 0.10
ρ [Ωcm
]T [K]
0 50 100 150 200 250 3007.45
7.50
7.65
7.70
7.75
7.80
7.85
b1
2a1
c1
Lattice Param
eters [Å]
T [K]
Con 10% Calcio
SSO: Spin State OrderPirámides y Octaedros con ≠ Spin
Seminario GIyA - Tandar 26/05/2016
Resultados neutrones
Con 5% Calcio
O12
2 fe
rri-S
SO
O12
2 P
M
O12
2 A
FM-G
+
O12
2 fer
ri-S
SO
xCa= 0.05
Seminario GIyA - Tandar 26/05/2016
Resultados neutrones
Con 0% Calcio
O12
2 P
M
O12
2 fe
rri-S
SO
O12
2 A
FM-S
SO
O12
2 A
FM-S
SO
+O
122
AFM
-G
x = 0
Seminario GIyA - Tandar 26/05/2016
Resultados neutrones
Con 0% Calcio
O12
2 P
M
O12
2 fe
rri-S
SO
O12
2 A
FM-S
SO
O12
2 A
FM-S
SO
+O
122
AFM
-G
x = 0
Seminario GIyA - Tandar 26/05/2016
Otro tipo de experimentos empleando crio+horno permitió
E s tu d ia r la e v o lu c ió n d e l o r d e n a m ie n t o d e l o x í g e n o a l c a le n t a r la s m u e s t r a s y la p é r d id a d e o x í g e n o e n v a c í o d in á m ic o
E s tu d io s in -s i t u d e lo s c a m b io s c r is t a lo g r á f ic o s y m a g n é t ic o s a l v a r ia r la n o -e s t e q u io m e t r í a d e o x í g e n o
In t e r p r e t a r c u r v a s d e s u s c e p t ib i l id a d m a g n é t ic a e n
Otros experimentos
Seminario GIyA - Tandar 26/05/2016
The neutron guys
“Novel Magnetic Oxides” group in Bariloche
The synchrotron guys
Gabriel Cuello – ILL, France
Javier Campo – ICMA, Zaragoza, Spain
Michel Kenzelmann -PSI, Switzerland
Fabrizio Bardelli – Italy Rogerio Junqueira-
PradoUFMG, Brazil
Rodolfo SánchezGroup Leader
Javier LohrPhD Student
Ana Laura LarraldePost-doc
Eduardo GranadoUNICAMP, Brazil
Javier CurialeScientist
Gabriela AurelioScientist
Agradecimientos
Seminario GIyA - Tandar 26/05/2016
Lo que se viene
LAH
N
|
LABO
RAT
OR
IO A
RG
EN
TIN
OD
E H
AC
ES
DE
NE
UTR
ON
ES
MUCHAS GRACIAS!
top related