Infrared‐Transparent Y₂O₃–MgO Nanocomposites Fabricated by the Glucose Sol–Gel Combustion and Hot‐Pressing Technique

Abstract

A glucose sol-gel combustion method has been developed to synthesize composite nanopowders with equal volume fractions of Y 2 O 3 and MgO. The synthesis involves the generation of precursor foam containing Y 3+ and Mg 2+ cations via the chemical and thermal degradation of glucose molecules in aqueous solutions. Subsequent calcination of the foam gave the composite nanopowders uniform composition and surface areas of 44-62 m 2 /g depending on the relative amount of glucose. Then the nanopowder with an average particle size of 19 nm was consolidated by the hot-pressing technique with different sintering temperatures. The fabricated nanocomposite is midinfrared transparent as the result of fine grains, narrow grain size distribution, and uniform phase domains. The transmittance increases with increase in the sintering temperature and reaches 83.5% at 3-5 lm mid-infrared wave range once the temperature reaches 1350°C, which is close to the theoretical value of 85%. And it is noteworthy that the cutoff wavelength reaches 9.6 lm, which is superior to those of spinel, AlON, and sapphire. And the Vickers hardness of the sample reaches 10.0 AE 0.1 GPa, which is significantly higher than those of the coarse grained single-phase MgO and Y 2 O 3 . The results indicate that the glucose sol-gel combustion and hot-pressing technique is an effective method to fabricate infrared transparent Y 2 O 3 -MgO nanocomposites.

Fabrication of Gd2O3‐MgO nanocomposite optical ceramics with varied crystallographic modifications of Gd2O3 constituent

“…The hardness values of the samples were 8.4, 10.5, and 14.1 GPa, for sintering temperature 1200, 1250, and 1350°C, respectively. The hardness value for the sample sintered at 1350°C was much higher than that of Y 2 O 3 ‐MgO reported by Xu et al (10.0 GPa) and Ma et al (10.6 GPa) . It is also quite interesting to assess the fracture mechanical performance of this composite to have a better understanding of the behavior of different Gd 2 O 3 polymorphs.…”

“…The hardness value for the sample sintered at 1350°C was much higher than that of Y 2 O 3 -MgO reported by Xu et al (10.0 GPa) and Ma et al (10.6 GPa). 2,3 It is also quite interesting to assess the fracture mechanical performance of this composite to have a better understanding of the behavior of different Gd 2 O 3 polymorphs. It should be noted that the polymorphic transformation of Gd 2 O 3 from its monoclinic to cubic form accompanied by a 10% volume expansion.…”

“…A normally opaque or translucent ceramic can be made transparent if the grains size is reduced to a small fraction of the wavelength of interest. One good example is Y 2 O 3 ‐MgO nanocomposite optical ceramics for mid‐IR window applications . In this two‐phase system, equal volume fractions of Y 2 O 3 and MgO were uniformly mixed such that the grains of each phase pin the boundaries in the other phase.…”

“…Recent advancement in the transparent ceramics fabrication has highlighted the advantages of reducing the ceramic microstructure to the nanometric range in the development of novel optical ceramic materials. 1,2 A normally opaque or translucent ceramic can be made transparent if the grains size is reduced to a small fraction of the wavelength of interest. One good example is Y 2 O 3 -MgO nanocomposite optical ceramics for mid-IR window applications.…”

“…One good example is Y 2 O 3 -MgO nanocomposite optical ceramics for mid-IR window applications. 2,3 In this two-phase system, equal volume fractions of Y 2 O 3 and MgO were uniformly mixed such that the grains of each phase pin the boundaries in the other phase. The obtained nanocomposite was found to exhibit optical and mechanical properties superior to those of any existing single-phase optical ceramics for IR window applications.…”