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On the bindings in the crystal phases of Mn
Author(s) -
Schubert K.
Publication year - 1985
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170200610
Subject(s) - valence electron , crystallography , tetragonal crystal system , chemistry , valence (chemistry) , atom (system on chip) , metastability , crystal structure , electron , physics , organic chemistry , quantum mechanics , computer science , embedded system
The heterotypism of Mn may be interpreted energetically when a temperature dependent valence electron concentration is supposed which takes on values between 2.2 and 0.6 electrons per atom. The room temperature phase Mn.r (= αMn) belongs to a series of structural types: Cr 3 Si, U.h 1 (= βU), Mn.r, which occur in alloy systems such as MoRe M ( M = undetermined mole number) at certain values of the averaged group number (AGN) of the perodic system of chemical elements (rule of Raub). An interpretation of the series by means of the plural‐correlations model becomes possible when instead of the (Ekmanian) AGN count another (non‐Ekmanian) electron count is used. The phase Mo 3 Re (Cr 3 Si‐type) yields a simple bonding type (binding) which undergoes moderate transformations to form the phases Mo 2 Re 3 (U.h 1 ) and MoRe 3 (Mn.r) and the binding of MoRe 3 may be taken to be valid also for Mn.r; it corresponds to the valence electron concentration N ′ A b = 2.16. For the high temperature phases Mn.h 1 (= βMn) and Mn.h 2 (= γMn) the values N ′ A b = 1.6 and 1.0 are probable and allow the brass‐like structures Mn.h 1 (C20) and Cu(Fl). The binding of Mn.h 2 , incidentally, explains the occurrence of the tetragonal metastable phase Mn.m. finally Mn.h 3 (= δMn) crystallizing in the W‐type is isodesmic to Fe.h 2 (= δFe), i.e. of the same binding.