A Sucrose‐Mediated Sol–Gel Technique for the Synthesis of MgO–Y₂O₃ Nanocomposites

Abstract

A sucrose‐mediated aqueous sol–gel procedure was developed to synthesize MgO–Y2O3 nanocomposite ceramics for potential optical applications. The synthesis involves the generation of a precursor foam containing Mg2+ and Y3+ cations via the chemical and thermal degradation of sucrose molecules in aqueous solution. Subsequent calcination and crushing of the foam gave MgO–Y2O3 nanocomposites in the form of thin mesoporous flake‐like powder particles with uniform composition and surface areas of 27–85 m2 g−1, depending on calcination conditions. The flakes exhibited a homogeneous microstructure comprising intimately mixed nanoscale grains of the cubic MgO and Y2O3 phases. This microstructure was resistant to grain coarsening with average grain sizes of less than 100 nm for calcination temperatures of up to 1200°C. The results indicate that the sucrose‐mediated sol–gel process is a simple effective method for making nanoscale mixed oxides.

Hot Pressing of Infrared‐Transparent Y2O3–MgO Nanocomposites Using Sol–Gel Combustion Synthesized Powders

“…It is clear the distribution between Y 2 O 3 and MgO grains are not uniform as seen in Figs. (b), (d) and (f), because of the existence of the cluster Y 2 O 3 or MgO aggregates in the synthesized composite nanopowder …”

“…8(b), (d) and (f), because of the existence of the cluster Y 2 O 3 or MgO aggregates in the synthesized composite nanopowder. 18 The distributions of pore size and Y 2 O 3 and MgO grain size are shown in Fig. 9.…”

“…The transmittance of sintered nanocomposite ceramics at 3.25 lm decrease slightly due to the stretching vibration of hydroxyl groups (O-H), because the synthesized composite nanopowder has a very high specific surface area (45.9 m 2 /g), large amount of the moisture in the air can be absorbed during handing especially for MgO component. 18 The absorption peak at about 7 lm are ascribed to asymmetrical and symmetrical stretching vibrations of the carboxylate group (O-C=O), which was formed during the combustion process and was not released after calcination process. 19 In addition, the contamination from the graphite die also contribute to the existence of carboxylate group.…”

“…The main drawback of this method is that a 24 h low temperature (400°C) was required before postcalcination heat treatment. In addition, direct high‐temperature calcinations of the organic foam leaded to coarser and less homogenous microstructures in the composites …”

“…In addition, direct high-temperature calcinations of the organic foam leaded to coarser and less homogenous microstructures in the composites. 18 To get excellent mechanical, optical, and thermal properties, the nanocomposite ceramics should be of fine grains and uniform microstructures. Consequently, the composite nanopowders should be sintered at a relative low temperature to inhibit the grain growth.…”