Modified Naples yellow in Renaissance majolica: study of Pb-Sb-Zn and Pb-Sb-Fe ternary pyroantimonates by X-ray absorption spectroscopy

X-Ray absorption spectroscopy investigations combined with ab initio structural simulations of ternary
forms (Pb-Sb-Zn and Pb-Sb-Fe) of the pigment Naples yellow (Pb2Sb2O7) allowed to achieve
a detailed insight into the incorporation route of Zn and Fe ions inside the pigment lattice. The study of
newly synthesised yellow pyroantimonates provided direct evidence that Zn and Fe ions enter the
pyrochlore octahedral sites replacing Sb ions. Experimental results were discussed considering, also, the
information provided by Raman spectroscopy used in this study as a sensitive probe of the pyrochlore
lattice distortions in modified yellow pyroantimonates. Finally, by exploiting the non-invasiveness of
the X-ray absorption spectroscopy technique, the same structural arrangement has been
unambiguously observed for Zn cations in a modified Naples yellow pigment of a Renaissance ceramic
shard.