Melting Of Tin Nanoparticles Embedded In Lithium Fluoride

Melting of metallic nanoparticles is of considerable importance in both technical applications and fundamental research. However, unfortunately, available methods of sample preparation have various limitations and hence experimental data are scarce, which prohibited further investigations on this subject.Recently, our research group successfully broke the limitations in sample preparation by embedding metallic nanoparticles in an oxide matrix, SiO2, with which melting behaviour of Fe and Cu nanoparticles were studied. Nevertheless, further studies showed that this method did not work effectively for Sn that has a low melting point.On basis of the above work, in this paper, several different matrixes are explored for Sn nanoparticles:(1) With Al2O3 or SiO2 as the matrix, the ultimate average grain size of Sn particles is greater than 100nm either by direct milling or mechanochemical synthesis;(2) Considering the mutual interaction between the matrix and the sample, when ZnO, that has a lower hardness, is chosen as the matrix, the ultimate average grain size of Sn nanoparticles is about 55nm;(3) Finally, LiF that has an even lower hardness is used as the matrix and the ultimate average grain size of Sn nanoparticles is around 15nm.These results show that under the same milling conditions, the better the hardness of the metal and the isolated phase is matched, the smaller the ultimate average grain size will be.Furthermore, we compared the data about size dependent melting of Sn nanoparticles embedded in LiF with those from literature and found that the influence of different matrix (LiF and Al) on the melting of Sn nanoparticles is not obvious.