The month of October also reaped a good harvest for the Metallurgical Engineers working in frontier areas of structural metallurgy with the announcements from Nobel Committee.

This year’s Chemistry Nobel Prize was given to Professor D Shechtman, Technion, Israel for his pioneering work on Quasicrystals.

There are significant contributions made in this area by the BHU Groups.

Soon after the publication of the work of Professor D. Shechtman et al on rapidly solidified Al-Mn alloys in 1984, where they identified the point group of the phase as 532 and named it as Quasicrystal (Name due to Levine and Steinhardt), for which Dr Shechtman from the Technical University, Haifa, Israel has been awarded this year’s Nobel Prize in Chemistry, Professor P Ramachandra Rao, School of Materials Science & Technology, IT, BHU and Professor GVS Sastry, Department of Metallurgical Engineering, IT, BHU published a highly cited paper on the basis for selection of alloy systems that yield quasicrystals and demonstrated the validity of the basis in Mg-Al-Zn alloy (Pramana - J. Phys., 25 (1985) L 225-L 230).

The same basis was shown to be valid in the case of Mg Cu Al system as well (GVS Sastry, VV Rao, P Ramachandrarao and TR Anantharaman, Scripta Metall, 20 (1986) 191-193). This contribution was noteworthy because efforts prior to this were all aluminum transition metal based.

The year 1985 triggered yet another discovery namely the discovery of decagonal quasicrystal independently but almost simultaneously by Professor K Chattopadhyay et al. and Dr Leo Bendersky (K Chattopadhyay, S Ranganathan, GN Subbanna, N Thangaraj, Scripta Metall,1985,19, 767-771 and K Chattopadhyay, S Lele, S Ranganathan, GN Subbanna, N Thangaraj, Curr. Sci.1985, 54, 895-903).

This phase exhibits quasiperiodicity only in two dimensions unlike the icosahedral quasicrystal discovered by Shechtman. This discovery paved the way to the search for a phase that is quasiperiodic only in one dimension.

Incidentally, Dr GVS Sastry observed some metastable phases during his doctoral work (under the joint supervision of Professors C Suryanarayana and Ramachandra Rao) in rapidly solidified and/or vapor deposited Al-Pd and Al-Cu alloys which exhibited electron diffraction patterns that resemble some of those from decagonal quasicrystals and rational approximants to the one dimensional quasicrystals.

The Banaras group continued to work on quasicrystals and made significant contributions. Professor RK Mandal and Professor S Lele made the grand unification of icosahedrally related structures using six dimensional crystallography in the doctoral work of RK Mandal (under the supervision of Professor S Lele). The most significant outcome of the same is the prediction of digonal quasicrystal (R. K. Mandal, S. Lele, Phys. Rev. Lett. 1989, 62, 2695-2698).

Around the same period, Dr Jyothi Menon and Professor C. Suryanarayana made another significant contribution on polytypism in quasicrystals. Dr Arvind Sinha (under the supervision of Professor P Ramachandra Rao) made yet another path breaking contribution wherein he demonstrated that a perfect Penrose tiling with all the permitted vertex configurations can be generated from a single rhomb by making certain operations on it. (P. Ramachandrarao, G.V.S. Sastry, L. Pandey and A. Sinha, Acta Crystallogr., A47 (1991) 206-210). Some part of the above studies was funded by DST, Govt. of India in the form of two projects.

The effect of e/a ratio on the relative stability of two types of stable decagonal quasicrystals in Al-Cu-Co and Al-Co-Ni alloys was studies by Dr A.K. Pramanick, Professor RK Mandal and Professor GVS Sastry in the doctoral work of the former (A.K. Pramanick, RK Mandal and G.V.S. Sastry, Proc. Int. Conf. Rapidly Quenched Metals, RQ10, held at Bangalore during August 22-27, 1999, eds. K Chattopadhyay and S Ranganathan, as special issue of J Mater Sci.& Engg A (2000)). Very recently the groups working on Quasicrystals at the Dept of Met. Engg, IT, BHU, the Dept. of Physics, BHU and the Dept. of Physics, IIT/Delhi completed an Indo-French project in collaboration with the Nancy School working on Ga substituted Al-Mn-Pd icosahedral quasicrystal. This work was funded by IFCPAR, New Delhi.

Noteworthy contributions were also made by the group at Physics Dept., BHU led by Professor ON Srivastava, the groups at BARC, DMRL and IGCAR, or the most significant and sustained contributions from the IISc group led by Professors S Ranganathan and K Chattopadhyay,