New DC conductivity spectra of Zn–Al layered double hydroxide (Zn–Al–NO3–LDH) and its calcined product of ZnO phase

,Abdullah Ahmed Ali Ahmed,Mohd Zobir Hussein,Zainal Abidin Talib,Yusra Abdullah Ahmed Al-Magdashi

doi:10.3934/matersci.2017.3.670

Abstract

Zn–Al–NO3–LDH nanostructure was synthesized via the coprecipitation method at molar ratio Zn2+/Al3+ = 4 and pH = 7. The resultant sample was thermally treated at calcined temperatures of 50, 100, 150, 200, 250 and 300 °C. The layered structure of the Zn–Al–NO3–LDH samples was stable below the calcination temperature 200 °C as shown in powder X-ray diffraction (PXRD) patterns of calcined samples. The calcination products showed a collapse of LDH structure and ZnO phase was formed at 200 °C and above. The dielectric spectroscopy of LDH was explained using anomalous low frequency dispersion (ALFD) due to the low mobility of LDH carriers. The conductivity spectra of LDH can be theoretically described according to the effective phase within the calcination products of LDH. In the comparison with previously researches, this study presented higher values of DC conductivity for all studied samples.

Highlights

The kind of layered double hydroxides (LDHs) components are anionic clays and have a flat two-dimensional layered structure
powder X-ray diffraction (PXRD) patterns in Figure 1a exhibits that LDHs structure was not affected when it was calcined at 150 °C and below
The ZnO phase with low intensity was present within LDH samples in this range of calcined temperatures

Summary

Introduction

The kind of layered double hydroxides (LDHs) components are anionic clays and have a flat two-dimensional layered structure. The structures of LDH layers has positively charged brucite [(MII, MIII)(OH)x]-like layers where (MII) and (MIII) are trivalent and divalent cations, respectively. The brucite layers have (MII) and (MIII) cations in their octahedral center (OH−). The interlayer galleries were occupied by An− anions and water molecules to balance the resulting brucite layers. The chemical composition of LDH was described by the formula [MII1−xMIIIx(OH)2]x+·[(An−x/n)·mH2O]x−, where n is the anion charge. The coefficient x is the same amount as the molar ratio [MIII/(MII + MIII)], and m is the number of water molecules presented in the region of interlayer [1]

Methods

Results

Conclusion