Crystal growth and characterisation of rare earth phosphates

Full text: Rare earth phosphates find extensive applications in a variety of laser devices owing to their special crystal chemical characteristics. The laser beams were first obtained in a crystal of NdP5O14 during 1973, and since then a lot of work has been done on rare earth phosphates. However, the interest in these compounds rejuvenated recently after the discovery of non-stoichiometric compounds like (La, Nd)P5O14(La, Eu)P5O14,K(La, Nd)P4O12 and so on with relatively smaller concentration of Nd showing unusual properties laser properties. In the present work, the authors have carried out the crystal growth of these above listed rare earth phosphates from phosphoric acid solutions within a temperature range of 350 to 500 deg C. The concentration of Nd in all these compounds was maintained in the range of 5 to 20%, and the crystals obtained were used in laser applications. A systematic study of the concentration of the solution, its pH, growth temperature and so on was carried out on the quality of the crystals obtained. The size of the crystals obtained varied from 2 to 5 mm. The morphology of the crystals obtained has been studied in great detail with reference to the growth conditions. Such studies help in the in situ fabrication of the crystals for ready use as solid state laser hosts without further cutting or polishing or processing, or just one step to obtain the functional products. Also the preliminary study of luminescent properties has been carried out