Melting of iron nanoparticles embedded in silica prepared by mechanical milling

• Melting of metallic nanoparticles was studied for some eight elements.
• This slim range of materials is successfully expanded to iron.
• A mechanical-milled iron–silica composite is employed.
• For iron particles of 15 nm in diameter, the melting point depression is 30 K.
• The measured data is in agreement with our theoretical calculations.

For decades, experimental studies on the size-dependent melting of metals are regretfully limited to some eight archetypal examples. In this work, to expand this slim range of materials, the melting behavior of Fe nanoparticles embedded in SiO2 prepared by using mechanical milling are investigated. Effects of factors in sample preparation on the size, isolation and thermal stability of Fe nanoparticles are systematically studied. On this basis, the size-dependent melting of Fe is successfully traced: for Fe nanoparticles with a diameter of about 15 nm, the melting point depression is 30 °C in comparison with bulk Fe, in accordance with our recent theoretical prediction.