Epitaxy of Anthraquinone on (100) NaCl: A Quantitative Approach

Abstract

A growth cell suitable for microscopic in situ observation of well-controlled crystal growth from the vapor phase is used to study the heteroepitaxial growth of anthraquinone crystals on a (100) NaCl substrate. In this, the morphology, orientation, nucleation, and growth rate of the crystals is studied as a function of driving force, Δμ/kT. At the lowest Δμ/kT, the crystals are block-shaped and show no preferential orientation with respect to the substrate. Increasing the driving force leads to the growth of oriented block- and needle-shaped crystals, which nucleate from macrosteps on the substrate. At the highest Δμ/kT, crystals nucleate on the flat surface areas or at monatomic steps on the substrate, resulting in a dramatic increase in epitaxial needle density. Growth rate measurements show an exponential behavior as a function of Δμ/kT. In all cases, the supply of growth units proceeds via surface diffusion over the NaCl substrate surface toward the anthraquinone crystals. At the lowest Δμ/kT, growth is partly limited by integration of the growth units at the crystal surfaces. At intermediate driving force, kinetic roughening sets in, leading to rounded needle tips. At the highest supersaturation, growth is completely governed by the supply of growth units via surface diffusion, leading to tip splitting as a consequence of morphological instability.

Analysis of the Ordering Effects in Anthraquinone Thin Films and Its Potential Application for Sodium Ion Batteries

“…A Δ E P A–A′ of 0.24 V and Δ E P B–B′ of 0.13 V is measured for the AQ thin-film electrodes, compared to a Δ E P A–A′ of 0.63 V and Δ E P B–B′ of 0.82 V for the AQ powder electrodes. In the thin-film configuration, the stacked AQ molecules, like pigment molecules in general, are expected to adopt tight π–π stacking along one crystallographic direction of the carrier substrate. , This aligned orientation of the AQ molecules in the film is beneficial to obtain a good charge transport in the electrode film. The electric field, induced by the respective polarized electrodes, allows for the delocalization of charges through the already established π–π network, resulting in faster charge-transfer kinetics compared to the inordinate AQ molecules in the powder-based AQ electrodes.…”

Additive induced pseudo-homoepitaxy of nanoneedles on NaCl crystals

“…A considerable amount of literature exists on 3D epitaxial needle growth on top of crystalline substrates [21][22][23][24][25][26][27][28][29][30][31][32]. However, these cases all involve heteroepitaxial growth (guest ≠ host) and the needle morphology is largely determined by the guest's anisotropic crystal structure.…”

Biocompatible Polymers for the Synthesis of Nanosalts via Supramolecular Ion–Dipole Interaction

“…A number of strategies have been attempted to fabricate micro- or nanoscale NaCl, − including grinding, − laser ablation, , vapor drying, − nanospray drying, electrospray techniques, and a cryochemical method . In addition, different morphologies of NaCl crystals with uniform microscale sizes have been synthesized by controlled precipitation of NaCl in organic solvents. , However, the NaCl particles produced through these methods would be difficult to store due to the caking property of NaCl as a result of the lack of surface ligand protection, which limited its further application.…”