Layered Metal Hydroxides Containing Calcium and Their Structural Analysis

Abstract

Layered metal hydroxides (LMHs) containing calcium were synthesized by coprecipitation in solution having two different trivalent metal ions, iron and aluminum. Two mixed metal solutions (Ca 2+ /Al3+ and Ca 2+/Fe 3+ = 2/1) were added to sodium hydroxide solution and the final pH was adjusted to ~11.5 and ~13 for CaAl-and CaFe-LMHs. Powder X-ray diffraction (XRD) for the two LMH samples showed well developed (00l) diffractions indicating 2-dimensional crystal structure of the synthesized LMHs. Rietveld refinement of the Xray diffraction pattern, the local structure analysis through X-ray absorption spectroscopy, and thermal analysis also confirmed that the synthesized precipitates show typical structure of LMHs. The chemical formulae, Ca2.04Al1(OH)6(NO3)·5.25H2O and Ca2.01Fe1(OH)6(NO3)·4.75H2O were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Particle morphology and thermal behavior for the synthesized LMHs were examined by field emission scanning electron microscopy and thermogravimetricdifferential scanning calorimetry.

Interlayer Structure of Bioactive Molecule, 2‐Aminoethanesulfonate, Intercalated into Calcium‐Containing Layered Double Hydroxides

“…Figure 1 shows the X-ray diffraction patterns for the CaM-LDHs and their taurine intercalates. The diffraction patterns for the pristine LDHs corresponded well with previously reported results (Figure 1) [21,26]. After intercalation, the (00l) peaks shift to the lower 2-theta region, revealing lattice expansion from ∼8.…”

“…In a previous study [26], we reported that the bond distance between calcium and the seventh coordinated nitrate is approximately 2.3Å. The molecular dimensions along the z-axis for taurine (distance from outermost sulfate oxygen to amine hydrogen) and water are approximately 4.6 and 0.6Å, respectively.…”

Polymer Coated CaAl-Layered Double Hydroxide Nanomaterials for Potential Calcium Supplement

“…LDH consisted of calcium and aluminum (CaAl-LDH) was prepared through coprecipitation method, as previously reported [ 38 ]. Typically, NaOH solution (1.26 M) was added dropwise to the mixed metal chloride solution (0.315 M and 0.1575 M for CaCl 2 ·2H 2 O and AlCl 3 ·6H 2 O, respectively) until the pH reached to around 11.5.…”

Carbon nanotube-layered double hydroxide nanocomposites

“…These octahedra are connected to each other by edge sharing to form an infinite sheet. When the divalent ion is Ca(II), the structure is somewhat different; it is the hydrocalumite type structure (Evans & Slade, 2006;Taylor, 1969;Rousselot et al, 2002;Vieille et al, 2004;Kim et al, 2012). Its parent structure is that of portlandite.…”