Accession Number : AD0008948


Title :   INHOMOGENEITY OF THALLIUM HALIDE MIXED CRYSTALS AND ITS ELIMINATION


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH


Personal Author(s) : Smakula, A ; Kalnajs, J ; Sils, V


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/008948.pdf


Report Date : Mar 1953


Pagination or Media Count : 25


Abstract : A study was made of the optical inhomogeneity of prisms used in IR spectroscopy, which are cut from mixed crystals of thallium halides. The cause of the defect was determined to be the use of incorrect minimum melting points of the compositions from which the crystals were grown. The freezing points of thallium halides and the minimum freezing points of the binary systems (TlCl with TlBr and TlBr with TlI were determined by cooling the melted samples and measuring the temperature with an Fe-Constantan thermocouple. The freezing points were higher than those of Moenkemeyer (Neves Jahrb. Mineral. Geol. Pal. 22, Beilage-Band, 1906). Crystals of binary systems were grown on the basis of the new data, and the greatest deviation of the lattice constant along the crystal length was determined to be no more than 5 x 10 to the minus 5th power. These results show that the optical inhomogeneity was caused by the incorrect composition of the melt. The refractive index variation in the new crystals was less than 1 x 10 to the minus 5th power.


Descriptors :   *THALLIUM COMPOUNDS , *INFRARED OPTICAL MATERIALS , REFRACTIVE INDEX , CRYSTALS , COOLING , VARIATIONS , LENGTH , CONSTANTS , HALIDES , HETEROGENEITY , MIXING , MELTING POINT , MINERALS , PRISMS(OPTICS) , CRYSTAL LATTICES , OPTICAL PROPERTIES , SPECTROSCOPY


Subject Categories : Infrared Detection and Detectors


Distribution Statement : APPROVED FOR PUBLIC RELEASE