High-Power Ultrasonic Synthesis and Magnetic-Field-Assisted Arrangement of Nanosized Crystallites of Cobalt-Containing Layered Double Hydroxides

Abstract

High-quality stoichiometric Co2Al–NO3 and Co2Al–CO3 layered double hydroxides (LDHs) have been obtained by precipitation followed by anion exchange, both high-power-sonication assisted. Application of high-power ultrasound has been demonstrated to result in a considerable acceleration of the crystallization process and the anion-exchange reaction. Two independent approaches were used to form bulk and 2-D samples of Co2Al–NO3 with the oriented crystallites, namely uniaxial pressing of deposits from sonicated LDH slurries and magnetic field-assisted arrangement of LDH crystallites precipitating on glass substrates. A convenient way of preparation of semi-transparent compacts with relatively big blocks of oriented crystallites have been demonstrated. Thin dense transparent films of highly-ordered crystallites of Co2Al–NO3 LDH have been produced and characterized.

Magnetic Anisotropy in the CoII-AlIII-nitrate Layered Double Hydroxides with the Co/Al Ratios 2, 3, and 4

“…The red arrows represent magnetic moments of Co II cations. The presence of the directional magnetic anisotropy due to g-factor anisotropy gzz>>gxx,gyy confirms by SEM images (cross section views) of layers of the Co(2)Al-NO3 crystallites deposited on glass substrates without (b) and with (c) application of magnetic field[12]. Magnetic field was applied perpendicular to the substrate surface.…”

“…Directional magnetic anisotropy that suggests a respective short range order in Co(2)Al-NO3 is uncovered under application of static magnetic field during precipitation of dispersed flake-like nanocrystallites of this LDH [12]. It has been shown that the aligning action of magnetic field results in highly oriented dense layers of the Co(2)Al-NO3 nanocrystallites with the flake surfaces perpendicular to the magnetic field (Fig.…”

“…Such a property allows alignment of the crystallites in external magnetic field [11]. We have recently reported a magnetic field assisted formation of dense layers of the Co II Al LDH crystallites [12].…”

A Novel Para-Amino Salicylic Acid Magnesium Layered Hydroxide Nanocomposite Anti-Tuberculosis Drug Delivery System with Enhanced in vitro Therapeutic and Anti-Inflammatory Properties

“…28 Magnesium layered hydroxide (MgLH) is a non-toxic material that has a wide range of applications such as in cosmetic products, serving as a catalyst in flame-retardants and has been used as inorganic absorbents, etc. [29][30][31] MgLH has a layered structure in which the hydroxide ions surround the magnesium ion in an octahedral manner. 30 Infinite layers are formed by these octahedral units by edge-sharing with hydroxide ions in the planes of the layers.…”