Nomenclature hazard warning:- Ian, Thankyou for drawing attention to the nomenclature school:- Partial occupancy disorder Which I prefer to refer to as Partial occupancy order.
Outside our MX field static disorder refers to what we call split occupancy order. I like the latter and dislike the former. Ie where there is disorder surely such a chemical moiety would be invisible, let alone allowing us to be able to determine its occupancy from Bragg intensities. I once tried to propose an amendment to the IUCr Nomenclature Committee to replace static disorder terminology with split occupancy order terminology. The forces to which you refer were too strong. Static disorder remains the term in approved use. Prof John R Helliwell DSc On 20 Nov 2012, at 15:49, Ian Tickle <[email protected]> wrote: > PS: Partial occupancy is not the same as disorder. You can have well-ordered > different occupancies that manifest themselves then in superstructure > patterns. Common in small molecule/materials. > > > Hello Bernhard > > Agree with everything you said up till this point, but I think the owners of > the "site occupancy disorder" websites below would disagree that partial > occupancy is not the same as disorder! > > http://www.ucl.ac.uk/~uccargr/sod.htm > > http://www.tcm.phy.cam.ac.uk/castep/documentation/WebHelp/Html/thCastepDisorder.htm > > There are also many research papers on partial occupancy disorder of > superlattice materials in the solid state, eg: > > http://www.researchgate.net/publication/226559734_Order-disorder_behavior_in_KNbO3_and_KNbO3KTaO3_solid_solutions_and_superlattices_by_molecular-dynamics_simulation > > Cheers > > -- Ian > > >
