A comparative study on citrate sol‐gel and combustion synthesis methods of CoAl₂O₄ spinel

Abstract

Aluminates are chemicals made up of ceramic materials based on aluminum oxide as the main constituent. Aluminate materials are widely used in high-technology applications due to their unique properties, for instance, in magnetic materials, ceramic catalysis, absorbent materials, and so forth. 1-4 Spinel is a ceramic oxide with three elements which its general chemical formula is AB 2 O 4 where, in normal spinels, A stands for a bivalent metal cation (A 2+) which occupies a tetrahedral site and B represents a trivalent (B 3+) metal cation which occupies an octahedral site of a cubic lattice. In the same time, in inverse spinels, bivalent cation (A 2+) occupies an octahedral site and a trivalent (B 3+) cation occupies both octahedral and tetrahedral site. 4-6 Nowadays, cobalt aluminate (CoAl 2 O 4) are used as a color pigment in digital ceramic printing, cobalt and gibbsite precursor, catalyst, and color filter. 1-6 Moreover, this kind of spinel is one of the great interests among spinels due to its significant properties such as thermal and chemical stability, 6 optical host matrix, 4 high ability of cation diffusion, 4-7 catalytic application, to name but four. 8-10 Cobalt aluminate conventionally was synthesized by mixing alumina and cobalt oxide, and calcination of the mixture at ~1200°C for an extended period. This type of synthesis requires a long distance diffusion of metal ion that could lead to inhomogeneous and nonstoichiometry spinel. 3 Many novel synthesis methods, like combustion synthesis, 2,11-13 sol-gel, 14,15 low-temperature combustion synthesis (LCS), 3,16 reverse micelle processing, 5 polymeric precursors method, 4 etc. are used to solve these drawbacks. Combustion synthesis (CS) or Self-propagating high-temperature synthesis (SHS) is a potent, and low-cost technique for the synthesis of numerous industrially valuable materials and is used in the fabrication of several ceramic powders for

Biomineralization and mechanical studies of sodium substituted hydroxyapatite by a time‐saving combustion route

“…[12] Because of the highly exothermic reactions during combustion synthesis, an ignited material pellet will exhibit a combustion wave that passes across it in a self-sustaining method. [13] This self-propagating and energy-saving procedure demands no energy to drive this process. [14] In addition, combustion synthesis is characterised by high temperatures, fast heating rates, short reaction times and cost-effectiveness, making this method an ultimate option compared to conventional ceramic synthesis techniques in manufacturing technology.…”

“…Many novel combustion synthesis materials were characterised by highly exothermic reactions (i. e., a reaction that gives off lots of heat) with temperatures ranging typically from 500–3000° [12] . Because of the highly exothermic reactions during combustion synthesis, an ignited material pellet will exhibit a combustion wave that passes across it in a self‐sustaining method [13] . This self‐propagating and energy‐saving procedure demands no energy to drive this process [14] .…”

Facile Synthesis of Nd2Fe14B Hard Magnetic Particles with Microwave-Assisted Hydrothermal Method

“…As depicted in the figure, after the annealing process of the precursors, a composite oxide composed of NdFeO 3 , NdBO 3 and Fe 2 O 3 was generated. To determine the phase transition temperature and confirm the reaction detail during the oxidation process, the isochronal DSC/TG curves of the as-prepared Nd-Fe-B precursor from 100 to 800 • C are provided in Figure S3 (Supplementary Information) [27]. According to Figure S3a, the total weight loss was more than 25% of the whole precursor mass based on the TG curve.…”

Highly stable CuFe1.2Al.8O4 catalyst with low CO selectivity for hydrogen production in HT‐PEMFCs application

“…Due to the relative sliding of tetrahedral and octahedral structures and the deformation and inversion caused by the substitution of central ions (A or B ions), spinel has flexible catalytic performance and good stability. 13,14 It has essential applications in the field of hydrogen production from methanol reforming. 15 Hou et al 16 Cu-Al spinel was modified by adding MgO.…”