Livio Battezzati

University of Turin

Livio Battezzati, University of Torino, Master Mamaself, master materials science, Chemistry, Erasmus Mundus,

E-mail : 

Phone :  + 396707567

  1. Current research and funding
  2. Nanoporous gold for electrocatalysis and SERS
  3. High entropy alloys
  4. Metallic Glasses
  5. Selected Publications

 Prof. Livio Battezzati is a full professor in Science and Technology of Materials at the Chemistry Department of UNITO. He presently chirs the Interdepartmental Centre foe Nanostructured Interfaces and Surfaces (NIS)  of UNITO. He is a member of the Administration Council of INRIM, the Italian Metrology Institute.
 

Current research and funding

Nanoporous gold for electrocatalysis and SERS

De-alloying, i.e. selective dissolution of alloys, is currently studied to produce nanoporous gold items suited for use in catalysis, electrochemical applications, sensors and actuators. Either crystalline or amorphous alloys can be selectively etched. In the former, less noble atoms are removed from surface terraces of grains layer by layer, while noble ones form mounds. These evolve by undercutting and electrolyte percolation to form a ligament network. The mechanism of ligament development by de-alloying amorphous alloys is more complex. In the case of Au40Cu28Ag7Pd5Si20, percolation of the electrolyte through cracks of the native surface oxide initiates the formation of protuberances which are soon undercut.

An interlayer develops, where Au crystals germinate, grow to nanometer size by diffusion and impinge. This is how ligaments start to coarsen. The ligaments are defective polycrystals, as opposed to single crystals obtained from crystalline alloys. The effect of alloy composition, electrolyte, temperature is being studied and applications are sought for methanol electro-oxidation and SERS.
 

High entropy alloys

The itinerant electrons vs valence electron concentration map showing the regions where either bcc or fcc HE solid solutions are obtained.
 
High Entropy Alloys (HEAs) are of multicomponent solid solutions in multinary metallic sys-
tems. Our work is aimed at predicting their occurrence by means of both electronic and thermodynamic criteria. Electronegativity, valence electron concentration (VEC), itinerant electron concentration, are employed together with size mismatch in a scheme akin to Hume-Rothery rules. A thermodynamic approach to the formation of solid solutions in multicomponent systems is used based on the regular solution model and computing the temperature at which the free energy hypersurface changes curvature at spinodal points. Maps are obtained (electronegativity vs size mismatch, VEC vs e/a, critical temperature vs size mismatch) to rank the composition of HEAs according to their phase constitution (solid solutions, solid solution +  intermetallics).
Newly formulated HEAs are studied by diffraction. Application is in the field of wear resistant materials and alloys for high temperatures.
 

 

Metallic Glasses

The group has long standing experience in rapid solidification of alloy to produce glassy alloys. The thermodynamic and kinetic conditions for obtaining such materials have been studied over the years. The alloys are applied for magnetic properties, (Fe-based), mechanical properties (Zr- based), as precursor of catalysts (Au-based).
 
 

Selected Publications

  • Giulia Dalla Fontana, Livio Battezzati
Thermodynamic and dynamic fragility in metallic glass-formers
Acta Materialia 61 (2013) 2260–2267.

 

  • Marco Gabriele Poletti, Livio Battezzati
Electronic and thermodynamic criteria for the occurrence of high entropy alloys in metallic systems
Acta Materialia, 75 (2014) 297–306, DOI information: 10.1016/j.actamat.2014.04.033

 

  • E.M. Paschalidou, F. Celegato, F. Scaglione, P. Rizzi, L. Battezzati, A. Gebert,
S. Oswald, U. Wolff, L. Mihaylov, T. Spassov
The mechanism of generating nanoporous Au by de-alloying amorphous alloys
Acta Materialia 119 (2016) 177-183
http://dx.doi.org/10.1016/j.actamat.2016.08.025