Investigation of 12th century denarii by different analytical techniques
I.Calliaria, F.Grazzib , C.Monticellic , D.Ferrod
a
Dep.of Chemical Engineering processes, University of Padova, Italy
b
Consiglio Nazionale delle Ricerche, Istituto Sistemi Complessi, Sesto Fiorentino (FI), Italy
c
Study Centre on Corrosion and Metallurgy "A. Daccò"- University of Ferrara, Italy
d
ISMN-CNR, Rome , Italy
In the present paper the application of different techniques for silver coins metallurgical and analytical
examination is presented. The investigations have been performed: on cross sections with SEM-EDS
and, in a totally non–destructive way, using XRF and Time of Flight Neutron Diffraction (TOF-ND).
The study is aimed to determine the coin chemical composition, in order to compare the Ag content
in the emissions of different doges , to investigate the depth and morphology of Ag surface layer and
to compare the capabilities of different techniques in examining bulk and surface of the coins. The
XRF data are critically discussed and compared with SEM-EDS, they give useful qualitative
information on the bulk and surface composition. The SEM-EDS investigation confirms that the coins
have an Ag surface enrichment, with different depths (10-100 microns), and a bulk composition in the
range 20-27 % wt of Ag., The Neutron diffraction analysis allows determining the bulk average
quantitative phase composition of alpha and beta phases the relative concentration of Ag and Cu, both
in the alpha and beta phases and the detection of corrosion products. By this technique, an accurate
composition determination of the two phases, as well as the overall composition, can be determined in
a totally non-invasive way.
Keywords: coins, metallurgy, TOF