Perfectly transparent pore-free Nd3+-doped Sr9GdF21 polycrystalline ceramics elaborated from single-crystal ceramization

An Nd3+-doped Sr9GdF21 (SGF) transparent pore-free polycrystalline ceramic is produced by the ceramization of single crystals. The average transmittance (TA) of the Nd3+-doped SGF ceramic (8-mm thick) is about 90.6% in the visible region and more than 92% in the near-IR region. The fracture toughness of the Nd3+-doped SGF ceramic is up to 1.28 MPa m1/2, which is significantly higher than that of similar types of ceramics. Gd3+ ions, acting as both buffer ions and pinning ions, effectively improve the optical and mechanical properties of the SGF ceramic, implying that the sample is a promising candidate for high-power lasers. Moreover, the SGF ceramic shows a high mid- and far-infrared (up to 9 μm) transmittance, low phonon energy, and high density (ρ = 4.8466 g/cm3), which pave the way for a wide range of applications such as infrared windows, mid- and far-infrared lasers, scintillators, and in photonics.