NaCl-assisted growth of micrometer-wide long single crystalline fluoride fibres

We describe a method for preparing millimetre- to centimetre-long LiF and MgF2:Co single crystal fibres (SCF), with diameters of the order of the visible and infrared light wavelength, by using halite eutectics as the precursor. In this method, a large eutectic ingot composed of an ordered array of fibres embedded in a NaCl matrix is directionally solidified by using the Bridgman method. Then the matrix is dissolved into water leaving bundles of fibres. The size of the fibres is related to the eutectic growth rate and can be varied in the 1.5-5 μm diameter range. The quality of the fibres was studied by transmission electron and optical microscopy. The single crystal character and growth direction has been established by electron diffraction experiments.