Temperature distribution in growing semi‐transparent crystals (I). Theory

1978

Cryst Res and Technol

Self Cite

Temperature Distribution in Growing Semi-Transparent Crystals (II). Comparison of Theory with ExperimentsCalculated temperature difference between the liquid/solld interface and bulk of the melt was compared with the wide-angle scattering (celluae density) of A1 0 and YAG crystals. Celluae free coloured crystals were grown using higher e$e& losses from the upper part of the crystal and the melt. Colourless crystals were successfully grown under opposite conditions. The results a r e in accordance with the calculated temperature differences which a r e proportionaldo the actual temperature gradient at the interface. ze von nach Czochralskl gezuchteten A1 03und YAG-Kristallen wurde mit dem Grad ihrer Lichtstreuung verglichen. V e r f d t e Kristalle lassen sich bei hoheren Energieverlusten aus dem oberen Teil des Kristalls und der Schmelze zlichten, w2hrend die Bedingungen fiir die Zuchtung von perfekten farblosen Kristallen umgekehrt sind. Dies e Ergebnisse sind in f2berelnstimmung mit den berechneten Temperaturunterschieden.Der berechnete Temperaturunterschied zwischen der Phasengrenze und der Schmel-

Section: Introductionmentioning

confidence: 99%

Temperature distribution in growing semi‐transparent crystals (II). Comparison of theory with experiments

Kubelka

1978

Cryst Res and Technol

Self Cite

Growth of sapphire by the kyropoulus method

Stránský

1979

Cryst Res and Technol

Single crystals of leuko-sapphire (a-AbO,) are grown from the melt by an improved Kyropoulos technique using Mo or W crucibles. The influence of the temperature field on the structural and optical quality has been studied. Best results were obtained when heat losses from crystal and melt are minimized.Einkristalle von farblosem Saphir (a-A40,) wurden aus der Schmelze nach der Kyropoulos-Methode aus Mobzw. W-Tiegeln gezogen. Der EinfluS des Temperaturfeldes auf die strukturellen und optischen Eigenschaften wurde studiert. Die besten Ergebnisse wurden unter Bedingungen erhalten, bei denen die WIrmeverluste von Kristall und Schmelze am geringsten gehalten werden.

Temperature distribution in growing semi‐transparent crystals (III). Conical liquid/solid interface

Kubelka

1983

Cryst. Res. Technol.

Temperature distribution in A1,0, and YAG crystals grown by Czochralski method and in tho melt layer adjacent to the liquid/solid int,erfacc of the conical shape was computed. The results were compared with the quality of t h e crystals. Using a highly absorbing material, trinperature differericc near the deeply submerged sharp intorface decreases from tho edge t o tho centre of a crystal and it is relatively great and unalterable in t,hc case of a shallowly submerged blunt interface. Sharp interface show the cryst,als grown from tho melt of the same composition (Al,O, or accurately "stoichiometric" YAG), whrroas tho blunt one is typical of YAG grown from the melt of the "non-stoichiometric" composition, bccause its solidifying point is below t>he molting point of YAG phase.