From Layered Double Hydroxide to Spinel Nanostructures:  Facile Synthesis and Characterization of Nanoplatelets and Nanorods

Abstract

Mg-Al spinel (MgAl2O4) nanorods and nanoplatelets transformed from Mg-Al layered double hydroxide (Mg-Al-LDHs) were synthesized via a combined hydrothermal method and calcination route using Al(NO3).9H2O and Mg(NO3)2.6H2O as raw materials. The nanorods and nanoplatelets were characterized by means of physical techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microcopy (HRTEM), selected-area electron diffraction (SAED), Fourier transform infrared spectra (FT-IR), thermogravimetric (TG), and nitrogen adsorption-desorption isotherms. XRD patterns reveal that the Mg-Al-LDHs nanostructures were obtained under a hydrothermal reaction temperature of 200 degrees C and Mg-Al spinel nanostructures were fabricated via calcination of the Mg-Al-LDHs nanostructures at 750 degrees C. It can be seen from TEM that the sizes of the Mg-Al-LDHs nanoplatelets were about 20-40 nm and the diameters of the MgAl2O4 nanorods were ca. 6 nm. The HRTEM images indicate that the crystal lattice spaces of the MgAl2O4 nanorods and nanoplatelets are 0.282 and 0.287 nm, respectively.

Effect of temperature on the transformation from Zn–Ga layered double hydroxides into (GaN)1−x(ZnO)x solid solution

“…The structure of the Zn/Ga/CO 3 LDH can be described as a layered zinc hydroxide where a fraction of the divalent Zn 2þ coordinated octahedrally by hydroxyl groups have been isomorphously replaced by Ga 3þ , at relatively low temperature (below 500 C), H 2 O and CO 2À 3 were lost as vapor and CO 2 , the Zn(OH) 6 and Ga(OH) 6 octahedron dehydration and transformed to hexahedron immediately. Usually, calcination of LDHs in air is known to give oxides of the divalent metal uniformly mixed spinels [34,35], but in NH 3 atmospheres, there is not spinel phase appearing as XRD pattern shown, the precursors were prior to reaction with NH 3 and part of O atoms were substituted by N atoms, formation a pure hexagonal wurtzite structure. More and more N atoms enter the lattice with the temperature increasing.…”

Effect of different ionic layered compounds decorated with zinc hydroxystannate on flame retardancy and smoke performance of epoxy resin

“…By the hydrothermal method according to reference, Mg‐Al‐LDH was prepared . ZHS@ Mg‐Al‐LDH was prepared by coprecipitation; 2.0 g Mg‐Al‐LDH was dissolved in 100‐mL deionized water.…”

Electrophoretic deposition of organically modified gibbsite nanocomposites with liquid crystalline character

“…However, the examples of alumina nanoplatelets [66] are limited, and the conversion of gibbsite to alumina is typically accompanied by gross morphological changes [67]. Some work [68,69] suggests that spinel nanoplatelets may be templated on LDH precursors, but as yet there is no evidence that these materials can be reliably produced with narrow size distributions and in single-crystalline form. The current activities in oxide nanoplatelet and nanosheet development suggest a bright future for discontinuous-phase nanocomposites.…”