Characterization of ZnAl2O4 Spinel Obtained by Hydrothermal and Microwave Assisted Combustion Method: A Comparative Study

Abstract

In this work, zinc aluminate spinel was prepared by two methods of directly synthesis (without calcination): microwave assisted combustion and hydrothermal method. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N 2 -adsorption/ desorption isotherms. The XRD patterns confirmed the formation of cubic ZnAl 2 O 4 spinel structure with no secondary phases for both synthesis routes, whereas the hydrothermal method yielded powders with crystallite size 3 times smaller (6.9 nm), as compared to the powders produced by microwave assisted combustion method (25.6 nm). The micrographs revealed agglomerated powders with platelike morphologies for both routes. Nitrogen adsorption/desorption isotherms (BET) revealed higher surface area (183 m 2 .g -1 ) and greater pore volume (0.173 cm 3 .g -1 ) for ZnAl 2 O 4 powders prepared by the hydrothermal method.

Synthesis and investigation of dielectric properties of nanoceramic composite material for microwave applications

“…ZnAl 2 O 4 prepared by hydrothermal approach endorsed the enhanced surface area as compared to the sample synthesised by using the combustion process. The enhanced surface area demonstrated improved catalyst activity [3]. In another work, the sample prepared by co‐precipitation showed the mesoporous morphology with the enhanced thermal stability, which ultimately yielded the high photocatalytic activity [4].…”

Preparation of mesoporous ZnAl2O4 nanoflakes by ion exchange from a Na-dawsonite parent material in the presence of an ionic liquid

“…The abovementioned results are similar to those reported in previous studies. 18,45 The thermal stability of the precursor prepared by ion exchange at 50 C in 10 h was investigated by TGA and DTG. As shown in Fig.…”

“…Zinc aluminate (ZnAl 2 O 4 ) spinel is a well-known wide band gap semiconductor (E g ¼ 3.8 eV) 1 ceramic material with optomechanical property, which has been extensively studied as a catalyst and catalyst support, [2][3][4] transparent conductor, 5 dielectric material, 6 optical material 7 and sensor 8 due to its high thermal stability, low surface acidity and high mechanical resistance. 9 Several methods, for example, the solid statereaction or ceramic method, 10 wet chemical routes, 11,12 the sol-gel method, 13,14 the hydrothermal method, 15 the solvothermal method, 16 the plasma method, 17 combustion in an aqueous solution 18 and molten salt synthesis 19 etc., have been applied for the preparation of ZnAl 2 O 4 spinel. However, to date, it is still a challenge to synthesize 2D or 3D ZnAl 2 O 4 spinel nanostructures via a solution route.…”

Microwave-Assisted Hydrothermal Synthesis of Zinc-Aluminum Spinel ZnAl2O4

“…Zinc-aluminum spinel can be obtained by various methods, such as sol–gel [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ], hydrothermal methods [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], co-precipitation [ 21 , 22 , 23 , 24 , 25 , 26 ], combustion methods [ 27 , 28 , 29 , 30 ] and solvothermal synthesis [ 31 , 32 , 33 ]. Implementation of these methods resulted in splines with a size distribution ranging from 15 to 100 nm.…”