Structural and textural characterization of a novel spatially coherent crystalline nanocomposite obtained from a melt of KBr, RbCl, RbBr, KI, RbI, and KCl salts

Large crystal bulks, grown by the Czochralski technique from a melt prepared by mixing equal molar fractions of KBr, RbCl, RbBr, KI, RbI, and KCl salts, are characterized by X-ray diffractometry and atomic force microscopy. The bulk material consists of a highly textured aggregation of crystallites of two different face-centeredcubic- solid solutions with unit-cell sizes of 7.247 ± 0.001 and 6.536 ± 0.005 A ° , in molar fractions of 1/3 and 2/3, respectively. These solutions are discussed to be the binary KI(34.4%):RbI(65.6%) and the quaternary KBr(42.7%): RbCl(33.2%):RbBr(8.1%)KCl(16.0%) mixed phases, respectively. Most of the crystallites, no matter the phase they belong to, are spatially coherent to each other. Freshly cleaved {100}-faces show surface domains, surrounded by canyons, and surface steps. These domains are plenty of knolls (1.8 ± 0.1 knolls/lm2) with a corresponding average knoll-profile full-width-at-half-maximum-value of 0.054 ± 0.003 lm, suggesting that the material is formed by a mass of individual nanometric grains. Micrometric particles, showing defined crystallographic habits, are immersed within the growths so that they keep in common with the growth matrix important crystallographic directions. The expected consequences of the observed texture on the physical properties of the material, as well as the structural origin of both the observed surface steps and the whitish visual appearance of the growths, are discussed.