The growth of Nd: YAG single crystals

Y3Al5O12 doped with 0.8%wt.Nd (Nd:YAG) single crystals were grown by the Czochralski technique under an argon atmosphere. The conditions for growing the Nd:YAG single crystals were calculated by using a combination of Reynolds and Grashof numbers. The critical crystal diameter and the critical rate of rotation were calculated from the hydrodynamics of the melt. The crystal diameter Dc=1.5 cm remained constant during the crystal growth while the critical rate of rotation changed from ?c=38 rpm after necking to ?c=13 rpm at the end of the crystal. The value of the rate of crystal growth was experimentally found to be 0.8?1.0 mm/h. According to our previous experiments, it was confirmed that 20 min exposure to conc. H3PO4 at 603 K was suitable for chemical polishing. Also, one-hour exposure to conc. H3PO4 at 493 K was found to be suitable for etching. The lattice parameter a=1.201 (1) nm was determined by X-ray powder diffraction. The obtained results are discussed and compared with published data. Monokristali Y3Al5O12 dopirani sa 0,8% tez. Nd (Nd:YAG) rasli su u argonu tehnikom rasta kristala po Cohralskom. Uslovi rasta monokristala Nd:YAG su izracunati koriscenjem kombinacije Rejnoldsovog i Grashofovog broja. Vrednosti kriticnog precnika i kriticne brzine rotacije su odredjene pomocu jednacina dinamike fluida. Precnik kistala Dc=1,5 cm je drzan konstantnim za vreme procesa rasta kristala, dok se vrednost kriticne brzine rotacije menjala od ?c=38 o/min posle sirenja i postizanja zeljenog precnika ("obaranja krune") do ?c=13 o/min pri kraju kristala. Brzina izvlacenja kristala je odredjena eksperimentalno i kretala se od 0,8?1,0 mm/h. Saglasno nasim ranijim eksperimentima, kao sredstvo za hemijsko poliranje je potvrdjena konc. H3PO4 na 603 K pri izlaganju od 20 minuta. Konc. H3PO4 na 493K pri izlaganju od 1 sata se pokazala kao pogodno sredstvo za nagrizanje. Odredjen je parametar resetke a=1,201 (1) nm pomocu rendgenske difrakcione analize praha. Dobijeni rezultati su diskutovani i uporedjeni sa literaturnim podacima.