Effect of high heating rates on the melting behavior of embedded In nanoparticles

Melting and Structural Dynamics of Indium Nanoparticles Embedded in Aluminum

“…An ensemble of Bi NPs with size in the range of 20–150 nm, grown on a carbon film, showed superheating by at least 5 K, as detected by the change in the NP shape from platelets to compact polyhedrons . In time-resolved RHEED studies of surfaces heated by ∼120 ps laser pulses (heating rates ∼10 11 K/s), superheating by ∼120, ∼90, and 73 ± 9 K of the Pb(111), Bi(0001), and In(111) surfaces, respectively, were observed. ,, NPs embedded in a crystal, or coated with an immiscible low-energy coherent interface, can be superheated above its T m to a temperature that is dependent on the interface and the heating rate. − …”

“…It is now well understood that the superheating of the solid phase depends on factors that include the material properties, , the surface orientation, , the surface interface, , and the rate of heating. ,,, Higher heating rates can achieve higher superheating of a crystal due to limits on the rate of nucleation and growth of the melt. The maximum superheating temperature is, generally, assumed to be a fundamental limit of material properties, as stated in Born’s mechanical instability. ,, Realization and observation of high degrees of superheated solids are difficult due to the limitations on the heating rate and the difficulty in observing the material structure with high time resolution.…”

Structural Phase Transformations in Nanoscale Systems

“…Recently, the melting temperature onset of Pb nanoparticles embedded in an Al matrix was investigated as function of the applied heating rate using fast scanning chip calorimetry. [ 98 ] This new technique allows applying controlled rates up to several 10 5 K s −1 , i.e., more than four orders of magnitude higher rates as previously possible. While Pb nanoparticles with faceted interfaces showed a clear dependence of the melting onset on the applied heating rate, larger particles situated at the grain boundaries of the Al matrix present in the same sample presented the onset of melting at a fixed value, i.e., at the bulk melting temperature T m,0 .…”

“…[ 75 ] A different case is presented by the results of fast scanning chip calorimetry, where the system showed a shift of the melting temperature due to the size confinement, but in addition it showed the kinetic effect of superheating of the melting transformation at strongly increased heating rates of the order of few thousand degrees per second. [ 98 ] It is thus recommended to carefully analyze the specific conditions of the specific nanosystem under study, especially concerning the atomic structure of the interfaces of the nanosystem with its environment, to assess whether kinetic superheating or size‐dependent thermodynamics govern the melting transformation. While complex systems such as ice might show a completely different behavior, [ 100 ] recent studies on homogeneous melting close to the limit of superheating might need to take special care to evaluate the respective contributions due to thermodynamics and kinetics to the observed shift of the transformation temperature.…”

Observation of Bismuth Nanoparticle Premelting by Slow and Ultrafast Laser Heating

“…The degree of superheating depends on the properties of the material and the heating rate. In slow heating, superheating of solids was observed when surface melting was suppressed. , The degree of superheating is limited by the rate of nucleation and growth of the melt. ,− Superheating of solids was reported for micro- and nanosized materials under slow heating. ,,, For example, Bi thin platelets with extensive {0001} surfaces (in hexagonal notation), which are {111} (in rhombohedral notation), and Pb particles (which are of the fcc structure) with {111} surfaces were superheated at slow heating rates up to 7 and 2 K for Bi and Pb, respectively. , In another study, Bi crystallites with diameters more than ∼100 μm were observed to superheat by ∼8 K . Superheating was also observed in small particles that were coated or embedded in another material with a higher T m , forming a low-energy interface. − In such cases, the degree of superheating depends on the interface quality, heating rate, and properties of the embedded and surrounding materials.…”