Anomalous Reconstructions of the (001) Surfaces of AgBr and NaCl

Abstract

He-atom diffraction indicates unexpected reconstructions of the (001) surfaces of AgBr and NaCl. For AgBr, reconstruction occurs only after an initial thermal activation at 430 K, while for NaCl it occurred spontaneously only once in many cleavages. Both AgBr and NaCl then undergo a reversible transition to a ͑2 3 2͒ phase at temperatures below 260 and 450 K, respectively. Above these temperatures the hopping of lattice defects, which are probably responsible for the transition to the ͑1 3 1͒ phase, sets in. [S0031-9007(99)

Nanoscale periodic modulations on sodium chloride surface revealed by tuning fork atomic force microscopy

“…Based on our results, the modulation pattern can be removed by either of these procedures. Note, a (2 × 2) reconstruction of the NaCl (001) surface was previously observed by Glebov et al [14] once out of their 30 preparations, after a NaCl single crystal was cleaved in vacuum at room temperature and annealed at 227 • C for 12 h. It was conjectured that an occasional redistribution of surface ions led to an ionic re-configuration in the surface region [14]. In comparison, the modulation patterns here are observed on samples without annealing, and they have a much longer period.…”

“…Numerous studies have been performed on this textbook ionic surface as well as other similar alkali halide crystal surfaces [8][9][10][11]. Owing to a strong tendency of water adsorption on NaCl, in these applications, NaCl is often cleaved in ultra-high vacuum (UHV) [12][13][14][15] or an environment with controlled humidity [16], a process which produces a fresh surface along the energetically most favorable cleavage plane (001). However, most ionic crystals exhibit charging on and below the cleaved surface arising from charged defects [2-4, 8, 9, 17-22].…”

Spontaneous magnetization of aluminum nanowires deposited on the NaCl(100) surface

“…This surface is also expected to be stable, as a surface reconstruction occurs only in one of many different cleavages. 18 An Al wire on the unreconstructed NaCl surface is a much simpler system than Ga wires on the hydrogenated reconstructed Si͑100͒. Therefore the present calculations are expected to show clearly the essential physical phenomena for simple metal wires on insulating surfaces.…”

Structured surfaces of wide band gap insulators as templates for overgrowth of adsorbates

“…Helium scattering has been employed to study the structure of many insulating surfaces and adsorbates. Examples are the unexpected reconstruction of alkali halide surfaces [52], the cleaved MgO(100) surface [53], or the surface structure of a ferroelectric oxide [54]. Duan et al have used the method to investigate the homoepitaxial growth of NaCl on a NaCl(100) surface [55].…”