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Calcite crystals; ion-bombardment; optical microscopy; microhardness and planar anisotropy; surface conductivity.

Experimental investigations on the defect sub-structure and surface modifications, brought about by He⁺ ion-bombardment of calcite cleavages (100), have been carried out. Optical and scanning electron microscopic investigations revealed drastic modifications on the surface morphology, local symmetry and defect concentration. Additional structural defects on ion-bombardment of calcite surfaces also have been observed. Changes in shape and form of chemical etch pits are found to be a function of ion-beam energy, as studied by optical microscopy. Radiation damage in calcite has been attributed mainly due to desorption of CO$^{-2}_{3}$ ions from the calcite surfaces, on irradiation. Measurements of surface conductivity on irradiated calcite surfaces have been made employing a four-probe technique. Enhancement of surface conductivity has been considered to be due to an increase in concentration of CO$^{-2}_{3}$ ions formed, on ion irradiation and subsequent thermal stimulation. Planar plastic anisotropy has been studied on irradiated calcite cleavages by measurement of microhardness.

E Venkateshwar Rao¹ M Ramakrishna Murthy¹

1. Department of Physics, University College, Kakatiya University, Warangal 506 009, India

Published

April 2008

Manuscript received

26 July 2007

Manuscript revised

21 December 2007