KNbTeO6 transparent ceramics prepared by the combination of pressure-less sintering and pseudo hot isostatic pressing.

KNbTeO 6 transparent ceramics were prepared by combining pressure-less sintering and pseudo-hot isostatic pressing (PHIP) of the synthesized submicron single-phase powder. The PHIP was conducted by wrapping coarse magnesium aluminate powders around the pre-sintered body in the spark plasma sintering (SPS) furnace. With an average grain size of 412 ± 23 nm, the in-line transmittance of transparent KNbTeO 6 ceramics reaches 80.25% at 2677 nm. By contrast, the density of the samples prepared by conventional SPS with the same sintering procedure is only 98.73%, and the highest in-line transmittance 64.25% occurs at 4976 nm. In particular, by investigating the sintering mechanism of PHIP, the improvement of microstructure and optical transmittance could be attributed to the plastic deformation caused by shear stress. The obtained ceramics exhibited excellent mechanical and dielectric properties, which was benefited from the novel sintering technology. • KNbTeO 6 transparent ceramics without significant grain growth were prepared by an innovative sintering route，and the optical, mechanical and dielectric properties of ceramics were synergistically improved. • Common SPS equipment was proved to be suitable for PHIP, and that transparent ceramics could be prepared with much higher transmittance compared to conventional SPS. • The plastic deformation of PHIP could effectively strengthen the densification process and optimize the microstructure. [ABSTRACT FROM AUTHOR]