Defects in Calcite.

• Main Author: Kotarski, Anthony J.
• Other Authors: NAVAL ACADEMY ANNAPOLIS MD
• Format: Text
• Language: English
• Published: 1991
• Subjects: Crystallography; *FOURIER TRANSFORMATION; OPTICS; PEAK VALUES; POSITION(LOCATION); LOW TEMPERATURE; FLUORESCENCE; VACUUM; MOTION; ELECTRIC FIELDS; PROTONS; RADIATION ABSORPTION; SAMPLING; CALCITE; RELAXATION; ABSORPTION; INFRARED RADIATION; ATOMIC PROPERTIES; NEUTRON ACTIVATION; X RAY LUMINESCENCE; ICELAND; SPARS; OPTICAL PROPERTIES; *CALCITE; *DIELECTRIC RELAXATION; CRYSTALS; DIELECTRIC LOSS; Iceland
• Online Access: http://www.dtic.mil/docs/citations/ADA245645; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA245645

Audio frequency complex impedance measurements have been carried out in vacuum over the temperature range 5.5-300K on three types of naturally occurring calcite samples. The measurements were made with the electric field perpendicular to the cleavage planes and both parallel and perpendicular to the c axis. All materials exhibit a 1000 Hz relaxation peak parallel to the optic axis with a peak position of about 38K. This relaxation is strongest in the Swakopmund (blue) calcite and appears to be associated with an yttrium-(CO3)-3 ion pair. The Gallatin (yellow) and Iceland Spar (clear) samples show a relaxation at very low temperatures perpendicular to the c axis (7K at about 1000 Hz) which exhibits characteristics of tunnelling phenomenon that is attributed to proton motion. Five other relaxations are observed and their possible origins are discussed. Determinative analysis of the calcites was performed by using the following experimental methods: X-ray fluorescence, atomic absorption, optical absorption, neutron activation analysis, Fourier transform infrared analysis, and radiative bombardment. The theory, techniques, and results of these methods are briefly discussed.