In laser cooling of crystals in solid-state physics, it is really important to obtain crystals with a large size at a relatively fast growth rate and high-optical quality that is defect-free. To get that, one of the methods to grow crystals is the Czochralski technique. The Czochralski technique will be presented and, in particular, the furnaces in New Materials for Laser Applications Laboratories of Pisa for this application will be discussed. Afterward the parameters for the growth of crystal fluorides are depicted and it is shown how these parameters lead to build samples suitable for optical cooling. All processes that are necessary to avoid contamination inside crystals like ion and how to avoid reduction of to will be given. Spectroscopy of all samples will be treated in order to obtain the cooling parameters and for each sample. Afterward, an efficiency model will be discussed and the data efficiency of cooling obtained by a sample’s own crystals will be shown.