Extended Data Fig. 6: Average size and distribution of particles.
From: Metastable hexagonal close-packed palladium hydride in liquid cell TEM
a, b, Average size of hcp (a) and fcc (b) PdHx nanoparticles in GLC with respect to EDR and Pd concentration. c, d, Average size of hcp (c) and fcc (d) PdHx nanoparticles in SLC in static or flow mode with respect to EDR at a fixed Pd concentration (3.67 mM). Error bars represent standard deviations. e, Size difference between hcp and fcc particles (ΔDhcp-fcc) formed in conditions where both phases were observed. The average diameter of hcp particles subtracted from that of fcc particles is plotted as a function of Pd concentration, EDR, and liquid cell system. No clear trend was observed, possibly because of the complexity of the radiolysis process. Not only the average particle size and its distribution but also the total number of particles depend strongly on both the Pd and hydrated electron concentrations. These factors, along with other radiolysis-driven conditions, including hydrogen ion/radical concentration and pH, significantly influence the nucleation and growth rate of PdHx nanoparticles, which in turn determines the size distribution of the particles according to classical nucleation theory59. Furthermore, the difference in irradiation time for each EDR condition as well as the limited supply of Pd in GLC could affect the particle size and the total number of nanoparticles. Hence, it is difficult to achieve a comprehensive understanding of the size of the particles produced in the liquid cells. No systematic change was observed in the particle size of either hcp or fcc particles (a, b) or their size difference (e) with respect to Pd concentration and EDR. The number of datasets in the case of SLC (c, d) was not enough to find a reliable trend. f–q, Distribution of Vf.u. and particle diameter of hcp (f–k) and fcc (l–q) PdHx nanoparticles formed in GLC and SLC as a function of Pd solution concentration: 3.67 (f, l), 10 (g, m), 18 (h, n), 36.7 (i, o), and 73 mM (j, p) in GLC and 3.67 mM (k, q) in SLC depending on EDR. Conditions where either of hcp phase or fcc phase particles were barely observed were omitted. Vf.u. and particle diameter show no correlation with any of the three factors, EDR, Pd concentration, and liquid flow.
