High purity, optical grade single crystals of sodium chloride (NaCl) MSDS, potassium bromide (KBr) and potassium chloride (KCl) form excellent substrates to grow epitaxial films. The orientation of the vacuum coated thin films is directly related to the orientation of the single crystal substrate thereby creating single crystal films. Ideal for thin film research, education and studies of properties of single crystal films. Impurities are less than 1%.