Sintesi di nano materiali funzionali utilizzando ultrasuoni  e relativa caratterizzazione tramite la diffrazione dei  raggi X.

Responsabili di progetto

Dritan Siliqi, Jose Luis Solis Veliz

Accordo

PERÙ - CONCYTEC-expired - Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica

Bando

CNR/CONCYTEC 2012-2014

Dipartimento

Progettazione Molecolare

Area tematica

Scienze chimiche e tecnologie dei materiali

Stato del progetto

Nuovo

Proposta di ricerca

Recently, functional nanomaterials based on metal oxide (MO) has attracted extensive interests due to its novel optical, electronic, magnetic, thermal, bactericidal and mechanical properties and potential application in catalyst, battery electrodes, gas sensors, photocatalysis, textile, etc. In these applications, it is a must to synthesize high-quality and ultra-fine powders with required characteristics in terms of their size, morphology, microstructure, composition purity, etc., which are the most essential factors which eventually determine the microstructure and performance of the final products.
Among the different synthesis approaches developed during the last few years, the sonochemical synthesis of metal oxide nanoparticles is a method with great potential because it is simple, cheap, safe and efficient. The physical phenomenon responsible for the sonochemical process is the acoustic cavitation, that is the creation, growth, and collapse of a bubble that is formed in the liquid. The theory [1] claims that very high temperatures (5000-25,000 K) are obtained upon the collapse of the bubble. Since this collapse occurs in less than a nanosecond [2,3], very high cooling rates, in excess of 1011 K/s, are also obtained. This high cooling rate hinders the organization and crystallization of the products. Herein we are going to develop a novel, simple sonochemical one-step process using metallic salts precursors, and obtaining the corresponding nanosized metal oxides (TiO2, ZnO2, ZnO, SnO2, Fe2O3 and NiO) as products. A method well suited to study nanomaterials is X-Ray Powder Diffraction (XRD). Yet, the analysis of the data is a crucial point and requires special care. Many approaches use common solid state techniques to fit the data, like, e.g., the Rietveld refinement. But due to the fact that only several hundred atoms make up one particle, a traditional crystallographic  analysis ,fails in determining detailed structural characteristics. We will applied the Debye Function Analysis (DFA) to the powder diffraction data from nanocrystalline synthesized materials through the use of sampled inter-atomic distances databases to characterize the microstructural of the nanomaterial in terms of size and size distribution, shape and unit cell deformation [4].
For the structural, microstructural and morphological characterization of nanomaterials the CNR-IC will exploit a new synchrotron-class X-ray micro-source in the forefront at the national and international level, which will allow to perform: i) combined scanning Small Angle X-Ray Scattering (SAXS) and Wide Angle X-Ray Scattering (WAXS); ii) Grazing Incidence SAXS and WAXS for nanomaterials assembled on surfaces.
The CNR-IC also has state of the art instrumentation for (XRPD) data acquisition, as a valid alternative WAXS studies. For polycrystalline nanomaterials, diffraction techniques and Total Scattering methods, such as DFA, are the most effective for characterizing their structure and microstructure, for controlling the structure-properties relationships and for tailoring surface effects turn into broad and unpredictably shaped Bragg peaks and diffuse intensity among them, which make the Rietveld approach less accurate. The Debye Function approach is implemented in a new, Free Source Package, named Debussy, which will be used to characterize the nanomaterials, in terms of crystal structure, size and shape of domains, number or mass phase fractions, starting from XRPD data.
References


K.S. Suslick, S.-B. Choe, A.A. Cichowlas, M.W. Grinstaff, Nature 353 (1991) 414.


R. Hiller, S.J. Putterman, B.P. Barber, Phys. Rev. Lett. 69 (1992) 1182.


B.P. Barber, S.J. Putterman, Nature 352 (1991) 414.


A. Cervellino, C. Giannini and A. Guagliardi, J. Appl. Cryst 43, 1543-1547 (2010); Journal of Computational Chemistry 27, 998 (2006); J. Appl. Cryst 36,1148-1158 (2003).

Obiettivi della ricerca

To develop a novel, simple sonochemical one-step process using metallic salts precursors, and obtaining the corresponding nanosized metal oxides (TiO2, ZnO2, ZnO, SnO2, Fe2O3 and NiO) as products. The study of various proprieties as gas sensing, bactericidal, photocatalytic etc.
The aim of the research activity is to gain access to structural (atomic models), micro-structural (domain size and lattice strain) and morphological (domain shape) information from spatial regions of different extension (from millimetric to micrometric) of new nanostructured materials, whose functionality depends on the aforesaid structural properties. The combined use of such imaging techniques allows to obtain a map of micro/nano-structural characteristics of these spatially heterogeneous systems with the great advantage to provide quantitative structural information in a non-destructive manner.

Ultimo aggiornamento: 08/07/2025