Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.704015
Title: 41 published papers
Author: Verma, Anjit Ram
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1967
Availability of Full Text:
Access from EThOS:
Access from Institution:
Abstract:
In 1949 Frank pointed out the possibility that growth of crystals at low supersaturations, essential for good crystals, could take place because of the formation of dislocations in the crystal so that any real crystal should have a number of dislocations with a screw component, terminating on the face. When growth takes place on these exposed molecular terraces, the edges of these layers develop into spirals centred on the dislocation. Griffin has observed these ‘monomolecular’ layers on the (1010) face of a beryl crystal, and has shown by multiple-beam interferometry that the height of these steps is less than 34 A., that is, less than four unit cells of the crystal. It was inferred that these steps are only one unit cell high. In the present investigation, numerous ‘growth spirals’ have been observed on the faces of carborundum and measured with the aid of phase-contrast microscopy and multiple-beam interferometry. Carborundum occurs in at least eight known types, one of which is cubic, whereas the rest are either hexagonal or rhombohedral and have identical layers but differ in their arrangement and are uniquely distinguished by the number of layers in the unit cell. The crystals studied here are of type I (rhombohedral, fifteen layers, with lattice parameter c = 37.7 A.), and type II (hexagonal, six layers, c = 15-1 A.). These spirals were studied by coating the crystal faces with a thin film of silver of reflectivity nearly 90 per cent, deposited by thermal evaporation, and then examining these faces in reflexion.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.704015  DOI: Not available
Keywords: English Literature
Share: