Investigation of the metal ions effect on the growth of KDP crystal with emphasize on Al3+ ions effect

Effect of Al3+ ions on the optical quality، growth rate، shape، and structure of potassium dihydrogen phosphate (KDP) crystal was investigated. Growth method was based on the “point seed” method in a solution with optimum concentration، following spontaneous growth at room temperature. FTIR spectrum showed neutralization of O-H group in KDP crystal by Al3+ ions. UV-Visible spectrum of the crystal containing Al3+ displayed an undesirable increase of the optical absorption in the 200-300 nm region with a maximum at 270 nm. It seems that the absorption in the 200-300 nm region is due to substitution of phosphorus by Al ions. In fact، (AlO4) 2- ions are present in the KDP crystals and give rise to ultraviolet absorption.