Charge & Spin Ordering: Explained & Bond Lengths

[marie2010]

hi,
Can someone explain to me the difference between charge and spin ordering? How are they different and how are they related? I am very confused.
Also, how are the bond lengths affected if an element is in 4+ as opposed to 5+ (e.g. Te4+ or Te5+ bonded to 6 oxygens). Are they shorter/longer, unequal distribution.
Can someone please comment.
Thanks.

 

[DrDu]

Maybe an example is helpful: E. g. Holmium metal is a helicomagnet. Although the charge density at each Holmium atom is equal, the spin of the electrons at different sites points in different directions. Specifically, when moving along some axis in the crystal the spin rotates tracing out a helix in space. So while charge order is homogeneous, the spin order is quite complex.
To the second question: Typically, the higher the charge of the central atom, the shorter the bonds (due to the increased Coulomb interaction). Whether the bond length become unequal depends on details in the bonding and cannot be answered generally. A common cause for unequal bond length is a Jahn Teller distortion.

 

[aruberi]

how to calculate ground state spins of odd-odd nucleus in the nilsson diagrams

 

[marie2010]

Thank you for replying. Can you please help me understand the following:
How come Nb5+ is d0 and diamagnetic, but Nb4+ is d1. I cannot see it.
Thanks in advance.

 

[DrDu]

Niob is in the fifth secondary group in the periodic system, i.e. it has 5 valence electrons (3 d- electrons and 2 s electrons). In Nb(V) you removed all of them leaving only filled shells, hence it is diamagnetic. In Nb(IV) one d-electron is left. Hence it is paramagnetic.

 

[marie2010]

Thank you. I got it now.