Historia del LENIH

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Wellcome!!
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• Outline
• Current research lines.
• Brief history of the Group and the context in
  which it developed.
• Conclusions.

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Who is who in the cake?
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Current lines
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Research group on Zirconia Ceramics
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Study of perovskites and aurivillius oxides.
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Physics of impurities in Condensed Matter
Structural, electronic, and magnetic properties
in doped systems first principles calculations
and nanoscopic experimental techniques
Aims EFG characterization and modeling at
impurity sites in binary oxides.
Structural and electronic properties of doped
semiconductors. Dilute magnetic
semiconductors (DMS) structural, electronic, and
magnetic properties in magnetic- and
nonmagnetic-impurity-doped oxide semiconductors.
Surfaces and clusters in
(pure/defect/doped) oxide semiconductors.
Applications Determination of
nuclear-quadrupole moments (Q).
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Physics of impurities in Condensed Matter
Synchrotron radiation techniques applies to
nanostructured systems.
Catalysis. Fundamental properties of
nanoparticles. Surfaces and
interfaces.
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Laboratory of Applications of the Mössbauer
Effect and Magnetism Department of Physics,
School of Exact Sciences, National University of
La Plata
Promote the academic excellence in the
traditional fields of the School of Exact
Sciences. Encourage interdisciplinary research
activities, scientific extension and services in
the area of the School. Bring up graduates able
to work in trans-disciplinary groups, connected
with the local scientific and technological
necessities.
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RN3M2005
Group of magnetic materials
National Network of Magnetisn and Magnetic
Materials
Magnetic aerogels SiO2/magnetic nanophase
Isolators and transparent Low density magnets
Magnetostriction sensors.
Mössbauer Transmission Spectroscopy at fixed
Doppler energies.
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Nanostructured materials
Aims studies of Nanostructured materials
obtained by mechanical sinthesis. Nanoestructure
d materials appropriated for hydrogen
storage. Complex magnetic structures.
Dr. Luis A. Mendoza Zélis. Dra. Laura
Damonte. Dr. Marcos Meyer. Lic. Lorena Baum.
Ing. Christian Laborde
Techniques MÖSSBAUER SPECTROSCOPY TDPAC
POSITRON ANNIHILATION SPECTROSCOPY(Dra. Laura
Damonte)
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Hyperfine Interactions of impurities in solids
Aims Studies of Magnetism in thin oxide
films, Magnetism in intermetallic
compounds, Hydrogen in
intermetallic compounds,
Hafnium-oxygen system,
Phase transitions in
solids,...
Technique TDPAC
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Perturbed Angular Correlation technique
Perturbed Angular Correlation equipment of four
detectors
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The PAC technique requires a radioactive isotope
(probe)
The isotope 111Cd, appropriated for PAC
determinations, results from the disintegration
of 111In by electron capture.
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The probability of detecting ?2 at an angle ?
from the direction of detection of ?1 is
measured as a function of the time t that the
nucleus is in the intermediate state of the
cascade.
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La Plata, August 1964
Uppsala, 1966
Dr. Othaz brough the electron-gamma spectrograph
gifted for Uppasala University,Sweden.
Prof. Dr Othaz
La Plata, 1966
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"the Night of long knifes."
Beginning of the destruction of the education
at Argentine Universities.
29 de julio de 1966
Anyway the Science was preserved
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Years later, Prof. Sadosky said
We believed that, we were doing transcendental
things that the society valorized, and discovered
our isolation in the worst way.
Seeing what came later, with murders and missing
people, we felt that we had been fortunate that
night. The fact had transcendence because an USA
mathematician (Prof. Warren Ambrose from the
MIT) was among the attacked persons.
This prompted the New York Times to publish a
note on the incident, which gave international
notoriety to the situation.
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Times of the Civil War (1973-1976)
Those were difficult years but nobody could
imagine what will come later.
How to explain to control patrols and police
barriers that such smoke substance was not
explosive.
The probability of overcoming was bigger if you
talk about liquid Nitrogen than liquid air.
The soldiers and policeman were very clever for
discovering great liars.
Most of them did not know what was the normal
physic state of N2 but all know how looks the
air.
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Time of IALE (Isotopes far from stability line)
project.
The magnetic Hyperfine field at 140Ce in nickel.
140Xe was produced by 235U fission
140Ce is obtained via the ?- cascade
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Time of IALE (Isotopes far from stability line)
project.
Will they be on the front cover of the new
TDPAC Herald?
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"something you could show or not, but remember
that somebody could visit you to verify if it is
still in your bookshelf"
1980, flying to the SLAFES at Gramado (Brazil).
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109Ag( ?, 2n)111In
Synchrocyclotron times (1978-1983)
Acknowledgments M. Behar and G. García Bermúdez
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Sincrociclotron times (Indium jailed in silver)
Impurity-defect interactions Impurity
-impurity interactions
Dose-Rate Dependence of the Impurity-Defect
Interaction in Silver. L. Thomé and H. Bernas
. Phys. Rev. Lett. 36, 10551057 (1976)
"TDPAC studies of radiation damage in AgPd and
AgPt alloys"
E. Bozek, K. Królas, B. Wodniecka,
P. Wodniecki,
Hyperfine Interactions 4 (1978) 689. K.
Królas, B. Wodniecka, P. Wodniecki, "Interaction
between impurities in Ag dilute alloys",
Hyperfine Interactions 4 (1978) 605.
Electric field gradients produced by impurity
atoms in a cubic Ag lattice. F. C. Zawislak,
R. P. Livi, L. Amaral, J. Schaf, and
M. Behar.Hyperfine Interactions, 2, 242, (1976).
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Impurity-defect interactions
1979 Prof. Erwin Bodenstedt visits for second
time La Plata.
One month before Bibiloni brings two samples
implanted in Bonn
Au181Hf
Ag181Hf
Radiation damage, e--? PAC
Radiation damage, ?-? PAC
A.F. Pasquevich
F. H. Sánchez
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Times of Internal oxidation.
Beginning with the impurity -impurity interaction
project we accidentaly re-discovered the
interaction between impurities and Oxygen in
Silver.
The important thing was that we were able to
develope an onw research project.
This discovery give us some international
acknowledgement (not much, of course!). But we
were in the herd.
P. Wodniecki, B. Wodniecka, "TDPAC studies of
internal AgIn alloy oxidation", Hyp. Int.12
(1982) 95. W. Bolse, H. Schröder, P. Wodniecki,
M. Uhrmacher, "Innere Oxidation von Silber-Indium
Legierungen", Deutsche Physik. Gesellschaft
Konferenz, Münster 1982.
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Splitting Oxidized and Ionics.
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The oxidized way
After all that, "aftereffects were coming".
The study of PAC spectra of internal oxidized
indium in silver, rise the idea of studying
normal Indium oxide.
Salomón et al.
Bäverstram and Othaz model.
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The ionic way
CsF ( 0,8 ns)
R(t) spectra of 181Ta in K2ZrF6
Martinez, 1981
NaI(Tl) ( 3 ns)
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External War Malvinas War (1982)
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1986, Argentine won the World Cup of football.
Göttingen 1983
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Conclusions The group grew and diversify.
Originated at the Hyperfine field has now many
projections in the Solid State Physics. no nos
fue tan mal!.
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