International Conference on Magnetism in Pt-nanoparticles

Roberto D'agosta
2017 Mater Sci Nanotechnol   unpublished
Nanoclusters are today of widespread use in various applications, ranging from nanomedicine to memory storage, nano-optics, plasmonics, and catalysis. Such a broad spectrum of applications is possible because of the delicate interplay between electronic structure and geometrical features in the absence of any translation symmetry, allows their peculiar and novel chemo-physical properties to be tunable by cluster architecture (size, shape, chemical composition and ordering) and by nanoparticles'
more » ... d by nanoparticles' interaction with the surrounding environment. Unraveling the difficult shape-property relationship is indeed at the core of the so-called "bottom-up" approach. In the attempt of clarifying and exploiting the dependence of chemo-physical properties on cluster architecture, atomistic modeling based on density-functional theory offers a very powerful and detailed tool as we can manipulate and control nano-objects at the atomic scale in silico. In this talk, we are going to show how the magnetism arising in nano-sized Pt objects is due to a geometrical effect present in the second coordination shell and it is enhanced in twinned shapes. We also demonstrate how magnetism is affected by the environment in the case of small Pt-nanoclusters embedded in zeolite pores. Among the 50 stable isomers in the gas phase, due to geometrical constraints, only about 1/3 of those clusters can be inserted in the zeolite pores. Severe structural rearrangements occur depending on whether the solid angle at the Pt vertex bound to the super-cage, for example, the icosahedron reconstructs into a lower coordinated morphology. The high magnetic moment of Pt13 in a zeolite, is mainly due to four highly coordinated shapes-truncated bi-pyramid; a triaugmented triangular prism; two incomplete double icosahedra-which represent the 30% of the sample in the hypothesis that all the isomers have the same probability to be inserted in the pore. Figure 1 Total magnetisation and coordination of Pt13 inserted into a zeolite pore. Colours refer to energy stability.