Abstract
End member and solid-solution single crystals of alkali halides were prepared by Bridgman method, using sodium chloride (NaCl), potassium chloride (KCl), sodium bromide (NaBr) and potassium bromide (KBr). Transparent and crack-free specimen was obtained in each end member single crystal. As a result of X-ray diffraction experiment in solid-solution single crystals, it was found that maximum content is 20 to 25mass%. Lattice parameter in each solid-solution single crystal was satisfied with Vegard's law. The solid-solution single crystals without cracks also were obtained in wider solid-solution region in anion (Cl- or Br-)-replacement type than in cation (Na+ or K+)-replacement type. This result in cation-replacement appears to be attributed to difference between two cationic radii. Single crystal in KBr-KCl system indicated increment of Vickers hardness with adding the alkali halide. On the other hand, in NaBr-NaCl system, adding NaBr to NaCl caused solid-solution hardening, while adding NaCl to NaBr caused solid-solution softening. Curves of density and refractive index versus the content had a downward convex shape. This result corresponds to Lorentz-Lorenz relationships, which connects density with refractive index.
