Effect of Temperature on the Nucleation and Growth of Precious Metal Nanocrystals

Abstract

Understanding the effect of physical parameters (e.g., temperature) on crystallisation dynamics is of paramount importance for the synthesis of nanocrystals of well‐defined sizes and geometries. However, imaging nucleation and growth is an experimental challenge owing to the resolution required and the kinetics involved. Here, by using an aberration‐corrected transmission electron microscope, we report the fabrication of precious metal nanocrystals from nuclei and the identification of the dynamics of their nucleation at three different temperatures (20, 50, and 100 °C). A fast, and apparently linear, acceleration of the growth rate is observed against increasing temperature (78.8, 117.7, and 176.5 pm min−1, respectively). This work appears to be the first direct observation of the effect of temperature on the nucleation and growth of metal nanocrystals.

A New Technique for Calculating Kinetic and Thermodynamic Barriers for Nucleation Rates and Interfacial Energy of CaCO3 Prenucleation Nanoclusters at High Temperature Using TGA Models and In Situ Crystallization

“…[ 63 ] Different studies have suggested a tenfold variation in the nucleation rates due to assumption of constant $${J}_o$$ values at normal temperature points. [ 12–64 ] Consequently, computation of $${J}_o$$ was performed by determining $${A}_{\alpha}\ \mathrm{and}\ {E}_{\alpha}$$, using experimentally generated TGA data. A precise value of apparent activation energy $$( {{E}_\alpha } )$$ of nucleation for CCPN matrix is computed by iterative procedure (Equation (16)) and provided in Table 2 and Table S2 (Supporting Information).…”

“…[ 18 ] The nucleation rate of ultra‐small osmium clusters to ultra‐small crystals was computed by increment of temperature from 20 °C (1.02 nm) to 100 °C (1.31 nm), to be 78.8–176.5 pm min −1 , respectively. [ 19 ] In spite of above findings, there is no engineered technology to compute nucleation rate of ultra‐small clusters at higher temperature (>100 °C). Thus, to make it possible, here we use the TGA technology for computation of nucleation rate $$(\mathrm{nuclei}\ \umu{\mathrm{m}}^{-2}\ {\mathrm{\min}}^{-1})$$ at higher temperature, as a first‐time approach.…”

“…On the contrary, in previous research, using TGA technology, the crystallization of In‐Se in the high‐temperature range (40–550 °C) was investigated by adopting DSC and TGA, and the activation energy of nucleation was computed through the iso‐conversional method. [ 20 ] Despite the analysis of nucleation of calcite crystal at a high temperature (315 °C), [ 20 ] the nucleation rate (pm/min) computation of ultra‐small osmium clusters (<1 nm) from 20 to 100°C [ 19 ] and the computation of the apparent activation energy of nucleation for In‐Se crystals in a high‐temperature range (40 to 550 °C), the accurate computation of nucleation rate ( J ), interfacial energy, and thermodynamic parameters ($$\Delta G,\ \Delta H\ \mathrm{and}\ \Delta S)$$ for ultra‐small clusters at high temperatures (>100 °C) is still missing. Thus, there is an urgent need to calculate kinetic barrier $$( {{J}_o} )$$ accurately with thermodynamic barrier for successful computation of nucleation rate at high temperature.…”

“…However, for the computation of the nucleation rate for ultra‐small osmium clusters [ 19 ] between 20 and 100 °C, an aberration‐corrected transmission electron microscope (TEM) is used, which is a subset of the TEMs and can achieve higher resolution when compared to a standard non‐corrected TEM. [ 21 ] It is typically used for imaging and measuring atoms with high accuracy level in the order of 1 pm.…”

“…This is the main reason that iso‐conversional methods, particularly the Cai and Chen integral iso‐conversional methods, are considered to be more precise than conventional Vyazovkin methods, as well as approximation‐based linear integral iso‐conversional methods like FWO and KAS. [ 16–37,38 ]…”