Growth from the Melt and Properties Investigation of ScF3 Single Crystals

• Published in: Crystals (Basel) Vol. 9; no. 7; p. 371
• Main Authors: Karimov, Denis, Buchinskaya, Irina, Arkharova, Natalia, Prosekov, Pavel, Grebenev, Vadim, Sorokin, Nikolay, Glushkova, Tatiana, Popov, Pavel
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-07-2019
• Subjects: Bridgman method; Bridgman technique; bulk crystals; Crucibles; crystal characterization; Crystal defects; Crystal growth; Crystal structure; Diamond pyramid hardness; Fluorides; Fluorine; Graphite; growth from the melt; Ion currents; ionic conductivity; Lanthanum fluorides; microhardness; negative thermal expansion; Optical materials; Optical properties; Phase transitions; Physical properties; refractive index; scandium fluoride; Single crystals; Solid solutions; Thermal conductivity; thermomiotic materials; Vaporization
• ISSN: 2073-4352; 2073-4352
• DOI: 10.3390/cryst9070371

ScF3 optical quality bulk crystals of the ReO3 structure type (space group P m 3 ¯ m , a = 4.01401(3) Å) have been grown from the melt by Bridgman technique, in fluorinating atmosphere for the first time. Aiming to substantially reduce vaporization losses during the growth process graphite crucibles were designed. The crystal quality, optical, mechanical, thermal and electrophysical properties were studied. Novel ScF3 crystals refer to the low-refractive-index (nD = 1.400(1)) optical materials with high transparency in the visible and IR spectral region up to 8.7 µm. The Vickers hardness of ScF3 (HV ~ 2.6 GPa) is substantially higher than that of CaF2 and LaF3 crystals. ScF3 crystals possess unique high thermal conductivity (k = 9.6 Wm−1К−1 at 300 K) and low ionic conductivity (σ = 4 × 10−8 Scm−1 at 673 К) cause to the structural defects in the fluorine sublattice.