Articles written in Proceedings – Section A
Volume 66 Issue 2 August 1967 pp 107-111
The 122 Shubnikov groups are derived directly starting from the 11 pure rotation groups and simultaneously introducing two anti-identity operations.
Volume 67 Issue 2 February 1968 pp 109-114
Group theoretical methods have been used for obtaining the relaxation modes and relaxation times for the case of two vacancies simultaneously occurring when a crystal with CsCl structure has a trivalent impurity like Pr3+ introduced substitutionally.
Volume 69 Issue 4 April 1969 pp 182-188
The phenomenon of piezoelectric relaxation in crystals has been dealt with briefly by applying group theoretical methods. Three typical crystal classes which are capable of exhibiting piezoelectricity are considered in some detail and a study is presented of the possible piezoelectric relaxation when different defect complexes are introduced in the crystals. The concept of an anisotropy in piezoelectric relaxation has been brought out in a crystal class belonging to the orthorhombic system.
Volume 75 Issue 3 March 1972 pp 132-137
Pure undamaged NaClO3 and KClO3 crystals show four Raman lines arising from the internal oscillations in the ClO3 ion, besides a few other Raman lines due to lattice oscillations. On radiation damage by X-rays or γ-rays some new lines are observed in each crystal. In particular, two lines at ∼ 680 and ∼ 930 are assigned to the ozonide ion (O3−) in these lattices. It is postulated that by radiation damage a certain number of ClO3 ions, which initially have a pyramidal structure, loose the chlorine atom leaving the three oxygen atoms at the corners of an equilateral tri-angle. Since an equilateral triangular structure should exhibit two normal oscillations, both of which are Raman active, such a postulate satisfactorily explains experimental results.