VLADIVOSTOK, Russia, Dec. 27, 2019 — A research team that includes scientists from Russia, Ukraine, and China has developed a Y₂O₃-MgO fine-grained composite ceramic material that transmits over 70% of light in the infrared (IR) range with wavelengths up to 6000 nm. Ceramic nanocomposites are considered promising materials for operations in the IR range and are known for their advanced thermal stability, thermal conductivity, and mechanical stability, the researchers said. The mechanical and optical properties of the Y₂O₃-MgO nanocomposite with uniform distribution of two phases surpass its single-phase commercial analogs, Y₂O₃ and MgO.

The new material has a staggered structure with 1:1 phase volume ratio. Its average grain size is 250 nm, and its microhardness is over 11 GPa.

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FESEM images of the Y₂O₃-MgO composite ceramics spark plasma sintered at 1100 °C (a), 1200 °C (b), 1250 °C (c), and 1300 °C (d). Courtesy of FEFU press office.

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The material was manufactured from Y₂O₃ and MgO nanopowders with controlled particle sizes. The powders were compacted using a fast consolidation method called spark plasma sintering. The procedure took 8 minutes and was carried out at 1300 °C and under a pressure of 60 MPa. This method helped the scientists suppress diffusion mass transfer and prevent the growth of the grains beyond the critical size (about 400 nm).

Denis Kosyanov, the head of the research team at Far Eastern Federal University (FEFU), said that the IR transparency of Y₂O₃-MgO nanocomposites increases when the sintering temperatures increase, and that top values are achieved between 1300 °C and 1350 °C. “This is due to the increase of sample density, grain growth, and the reduction of grain boundary length,” Kosyanov said. “At higher sintering temperatures the balance of the system shifts, the staggered structure of the Y₂O₃ and MgO grains is broken, and the so-called abnormal grain growth takes place.”

The new material could be used in high-tech production processes — for example, to manufacture shielding windows for IR systems in aerospace engineering. It was developed by scientists from Far Eastern Federal University; the Far East Branch of the Russian Academy of Sciences, Institute of Chemistry; the Institute for Single Crystals in Ukraine; and the Shanghai Institute of Ceramics.

The research was published in Ceramics International (www.doi.org/10.1016/j.ceramint.2019.11.137).

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