In transition metal oxide compounds (Eg.NaNi0.5Mn0.5O2, layered structure), each transition metal is co-ordinated with 6 oxygen atoms (octahedral coordination type ). However i have seen in many papers, while mentioning the ionic radius of the transition metals they use radius value that corresponds to 4-cordinate tetrahedral coordination type. Like for Ni2+ it's mentioned 0.69 angstrom. Can you please share your opinion regarding this concept?
Usually in most of the transition metal oxides the coordination number of the oxide is 6, that is the metal is surrounded with with 6 oxygen ions and the radius of the metal in these cases is considered for 6-coordinate geometry. However, in some mixed oxides, such as ferrites with the general formula of M(II)M(III)2O4, which are composed of one two -valent and two three-valent metals in which the M(II) in tetrahedral and M(III) in octahedral sites ( spinel structures). In such cases the radius for the two-valent metal is related to 4-coordinate configuration. In some of these mixed oxides the two-valent metal occupies the 6-coordinate site and half of the three-valent metals are located in the tetrahedral sites and these oxides are named inverse spinel.
Dear Abdullah
I looked through the file you have recommended but there was nothing relevant to Vivek's question there. What is the use of this elementary information?
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