The growth and perfection of phenanthrene single crystals: 1. Purification and single crystal growth

Abstract

A study has been made of the purification of phenanthrene, and the growth of large crystals from the melt by the Bridgman technique and their perfection. Of eight major impurities in the starting material four have segregation coefficients, k < 0.6 and segregate efficiently during zone refining. The remaining four which were identified as anthracene ( k = 1.6), flourene ( k = 0.95), dibenzothiophene ( k = 0.8) and dihydrophenanthrene ( k = 0.8) are inefficiently removed. When these are removed chemically, subsequent zone refining yields material in the centre part of the refined ingot of total impurity content ⪡ 1 ppm. When this material is used for crystal growth by the Bridgman technique, crystals of excellent quality can be produced. The influence of impurities on the growth process is outlined.