WEBINAR "Science for Sustainable Development"

Prof.ssa Cristina Leonelli, Università degli Studi di Modena e Reggio Emilia

Microwave-assisted processing of materials

Dr. Cecilia Mortalò, ICMATE-CNR Padova

Microwave-assisted approach for the preparation of luminescent nanopowders with tuned morphology and optical properties

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Microwave-assisted processing of materials

The use of microwave energy to irradiate pellets of different powders (ceramics,glass,metalsortheirmixtures) typically achieve rapids intering when the process conditions are optimized. In such conditions the particle size and crystalline phase distribution of the starting powders are preserved and higher process sustainability is reached interms of shorter times with respect to conventional heat treatments.

Temperature control and uniformity is the main issue to be overcome by careful design of the experimental setup, sample geometry and choice of microwave frequency. The measure of the dielectric properties allowed obtaining, by means of subsequent numerical simulation, the indirect measure of the temperature distribution in all of the different components of the load, thus helping.

In collaboration with ICMATE the MW-assisted sintering of solid electrolyte membrane has been investigated as well FeCoNiCrAl-family high entropy alloys for targets used in sputtering. The near-net-shape technology starting from powder metallurgy could overcome the limits of current melting technologies (defects formation) or solid state ones (time demanding).

Cristina Leonelli is a full professor in at the Department of Engineering "Enzo Ferrari" (DIEF) of the University of Modena and Reggio Emilia. Since 1996. She has been  active in the field of several innovative preparation techniques and microwave heating applied to materials processing and synthesis and since 2008 is the alkali activation of aluminosilicate materials to obtain cement-like formulations.

Microwave-assisted approach for the preparation of luminescent nanopowders with tuned morphology and optical properties

Luminescent materials are attracting increasing interest for their applications in various fields such as bioimaging, advanced light sources, optoelectronic devices, sensors and optical markers. It is wellknown that the luminescence properties  depend on various factors such as the degree of crystallinity, lattice defects, particle size and morphology. In general, the shape of the particles can influence the distance between the activator ions in the phosphor, which can affect the fluorescence life time or energy transfer. In addition, the presence of some functional groups can be detrimental to the optical properties of these materials. Therefore, in order to improve the luminescence properties, it is important to optimize a synthetic procedure that allows the formation of a proper crystallographic phase and minimizes the concentration of detrimental functional groups.

This talk will focus on the use of a rapid microwave-assisted strategy for the preparation of Eu-doped YPO4 luminescent nano powders, which are also considered as promising materials for anti-counterfeiting applications.

CeciliaMortalò is a researcher at ICMATE-CNR in Padova. Since 2017 her activity is carried out at the Department of Engineering "EnzoFerrari" (DIEF) of the University of Modena and Reggio Emilia, within an agreement between ICMATE and DIEF. At DIEF, she is also involved in the optimization of sustainable synthesis approaches for the preparation of nanomaterials/composites for various applications.