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Control of the Growth Optimum in Producing High‐Quality CaF 2 Crystals by an Improved Bridgman‐Stockbarger Technique
Author(s) -
Mouchovski J. T.,
Penev V. Tz.,
Kuneva R. B.
Publication year - 1996
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170310603
Subject(s) - crucible (geodemography) , molybdenum , temperature gradient , diaphragm (acoustics) , materials science , analytical chemistry (journal) , metallurgy , chemistry , mineralogy , electrical engineering , computational chemistry , physics , chromatography , quantum mechanics , loudspeaker , engineering
The axial temperature distribution in an empty crucible and the determination of quenched interface within fixed crucible were investigated to find the relationships governing the growing process of CaF 2 by Bridgman‐Stockbarger methods. A system of additional molybdenum reflective sheaths was placed into the furnace unit and its effect on the temperature field was estimated in order to achieve the growth optimum. A long liner into the diaphragm bore of the furnace and a number of thin rings slipped on the crucible stem were found capable to provide a reproducible optimum on each stage of growing in single and multicamera crucibles at a relatively low level of power supply. Single and in‐group growth experiments were carried out using high density quenched ingots purified from oxygen contaminants through high temperature treatment of fluorspar. The properties of the grown crystals were found to depend on the degree of the fluorspar purification and on the improvement of the thermal conditions yielding either competitor or laser‐grade CaF 2 . In multicamera crucibles the crystals grown in the central compartment are of better characteristics than those in the peripheral ones.