Fabrication of Y2Ti2O7 Transparent Ceramic by Spark Plasma Sintering

Y2Ti2O7 transparent ceramic was fabricated by reactive sintering using spark plasma sintering at 1673 K for 2.7 ks. The sintered body exhibited a cubic pyrochlore structure and uniform microstructure with an average grain size of 2.9 μm. The transmittance reached 73% at a wavelength of 2000 nm after annealing at 1023 K for 21.6 ks.

Low-reflective wire-grid polariser sheet in the visible region fabricated by a nanoprinting process

For the construction of next-generation optical products and systems, the evolution of polariser sheets is a necessary requirement. To this end, a low-reflective wire-grid polariser (WGP) sheet for the visible light region is demonstrated, the nanowires of which consist of a sintered body of silver nanoparticle ink. The nanowires are formed by a nanoprinting process using a thermal nanoimprint method and ink filling. This process makes it easier to achieve multiple wafer-scale productions without using sophisticated equipment compared to conventional WGP nanofabrication techniques, which typically employ lithography and elaborate etching processes. The optical characteristics are controlled by the shape of the printed nanowires. A WGP sheet with a luminous degree of polarisation of 99.0%, a total luminous transmittance of 13.6%, and a luminous reflectance of 3.6% is produced. Its low reflectance is achieved through the uneven surface derived from the sintered body of the nanoparticle ink, and the shape of the bottom of the nanowire is derived from the tip shape of the mould structure. Furthermore, the printed WGP sheet has the durability required for the manufacturing of curved products, including sunglasses. The optical structures made of nanoparticle ink using this nanoprinting process have the potential to significantly contribute to the development of fine-structured optical elements with unprecedented functionality.