Sharma, B D and Tiwari, G P and Ray, S P (1969) Diffusion in bcc Transition Metals. In: Symposium on Non-ferrous Metals Technology. Symposium on Non-ferrous Metals Technology, Volume III - Nickel, Lead, Zinc, Rare earth and Nuclear Metals . NML, Jamshedpur, Jamshedpur, pp. 1-16.
THE transition metals are of great importance both from industrial as well as scientific view points. In the periodic table,the transition metals representexpansion of a group of 8 (s'p6 ) electron structures into anoth- er one of 18 (s2p "d10). The ground state of free atoms, as the series progresses , also exhibits a change from 4p 3d 4s to 4p 4s 3d state . Such a transition offers excellent opportunity for sd electron hybridization somewhere in the middle of the series . The possibility of spd hybridization also increases as 4p level moves closer to 4s level. Though the exact role of s p- and d - electronic interactions in determining the physical stab-ility of transition metals is a subject of discussion', it is conceded that the major contribution to binding energy comes from d -electrons . According to Engel " and Brewer''', the s-, p- electrons determine the stru-cture of the lattice . However, the strength of bonds in the lattice increases as the tendency for sd and spd hybridization increases ; the maximum being expected in the middle of a period. The `strengthening of bonds' is reflected in the nearest neighbour distances,the cohesive energy values , the melting points and selfdiffusion activation energy values of the metals as one moves along K-Cr-Cu, Rb-Mo-Ag or Cs-W-Pt series.
|Item Type:||Book or NML Publication|
|Uncontrolled Keywords:||Hybridization, Lattice, Polymorphism, Diffusion|
|Divisions:||Metal Extraction and Forming|
|Deposited By:||Sahu A K|
|Deposited On:||13 Sep 2011 13:36|
|Last Modified:||06 Jan 2012 12:00|
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