Eur. Phys. J. D 24, 219-222 (2003)
https://doi.org/10.1140/epjd/e2003-00191-8

Phase transitions in gallium nanodroplets detected by dielectric spectroscopy

¹ INFM, Dipartimento di Fisica “A. Volta", Università di Pavia, Via Bassi 6, 27100 Pavia, Italy
² Saint-Gobin Recherche, 39 quai Lucien Lefranc, B.P. 135, 93303 Aubervilliers Cedex, France and Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa, Italy
³ LAMEL, 40129 Bologna, Italy
⁴ LPMC, Université de Nice Sophia Antipolis, 06108 Nice Cedex 2, France

Corresponding author: ^a parravicini@fisicavolta.unipv.it

Received: 10 September 2002
Published online: 3 July 2003

Abstract

Both theoretical and experimental works give evidence that gallium exhibits solid phases labelled β, γ, δ, ϵ besides the stable α phase strongly dependent both on the size and the confinement conditions. An experimental technique was used based on capacitance and conductance measurements vs. temperature in the audiofrequency range. This technique is particularly sensitive to the conditions of the investigated particle surface that plays a fundamental role in the melting and more generally in the phase transition processes. In particular the strict relation between the derivative of the capacitance with respect to the temperature, , and the entropy of the system is considered. In gallium nanoparticles 20 nm in radius, only the δ phase is shown to occur. Further the transition to liquid phase was detected. The melting process was found to start about 65 K below the full melting temperature value. In the case of particles 10 nm in radius, where different metastable phases may occur, the capacitance vs. temperature curve was found to display abrupt changes of the slope. The singularities are associated to a well defined transition temperature.