Polymorphism in Benzene, Naphthalene, and Anthracene at High Pressure

Science  07 Aug 1970:
Vol. 169, Issue 3945, pp. 586-587
DOI: 10.1126/science.169.3945.586


Optical observations, in which a microscope was used with the diamond-anvil pressure cell, were carried out on benzene, naphthalene, and anthracene up to temperatures of about 600°C and pressures of approximately 40 kilobars. New high-pressure phases of benzene (benzene III) and anthracene (anthracene II) were observed, and the existence of the high-pressure polymorph, naphthalene II, was verified. All three materials decompose initially to a reddish-orange liquid, and ultimately to amorphous carbon. The decomposition temperatures decrease with increasing molecular size.