Invited talks of Plenary sessions
Czochralski Award lecture:
Magnetic Refrigeration: A New Challenge for Materials Scientists
Magnetic refrigeration can be viewed as an alternative to the conventional vapor-compression technology. Magnetic refrigeration owes its renewed interest not only to its comparatively high efficiency but also to the fact that it is an environmentally friendly techniques, avoiding ozone-depleting or global-warming gases. This opens new research opportunities that have culminated in a worldwide search for novel magnetocaloric materials. In practice, magnetic refrigeration requires the combination of a magnetic field source of high strength and a material with a sufficiently high magnetocaloric effect (MCE). When looking at domestic applications, the best choice of the field source would be a permanent magnet. However, the field generated by permanent magnets falls typically into the 1-2 Tesla range and the MCE of most magnetic materials is too small for such a low field change to result in sufficient cooling power. Recent research activities have therefore been focused on materials with higher than average MCE value, and the prerequisites for attaining high MCEs will be briefly addressed in this talk. A commercially important aspect is the materials cost. Magnetocaloric materials based on magnetic 3d elements are much less expensive than those based on rare earth elements. In the present talk we will concentrate mainly on the results obtained with the former type of materials.
On the occasion of the 80th anniversary of the discovery of the
"Raman scattering" and the 120th birth anniversary of C.V.
C.V. Raman and the Impact of Raman Effect in Quantum Physics, Condensed Matter, and Materials Science
Raman’s momentous discovery in 1928 that the spectral analysis of
the light scattered by matter, illuminated with monochromatic light
of frequency ω
L, reveals new signatures at (ω
L ± ω
i) , ω
i’s being the internal frequencies of the matter [Nature
121, 501 (1928); Indian Journal of Physics
2, 387 (1928)]. In a cable to Nature [
122, 349 (1928)], R.W. Wood, the renowned American Physicist,
hailed it as a “very beautiful discovery, which resulted from
Ramans’s long and patient study of the phenomenon of light
scattering” and underscored its significance as “one of the most
convincing proofs of the quantum theory of light we have at present
After a brief account of Raman’s extraordinary scientific career, I will recount the profound impact made by Raman effect, which launched a new branch of spectroscopy, with two illustrative examples: (1) Rotational Raman Spectra of homonuclear diatonic gases and Bose-Einstein & Fermi-Dirac Statistics and (2) The parity related rule of mutual exclusion in the Raman vs infrared activity of vibrational modes of centro-symmetric matter.
The dramatic change and the vastly expanded scope of Raman spectroscopy brought about by the invention of the Laser in 1960 will be illustrated with select examples from Condensed Matter Physics and Materials Science. In particular, the focus will be on the collective and localized vibrational, electronic, and magnetic excitations in semiconductors and their nanostructures.
Joint session with 11th European Powder Diffraction Conference (EPDIC)