U. Peuchert et al., K2NIWO2(PO4)(2) - A NEW STRUCTURE TYPE RELATED TO KTIOPO4 (KTP), Acta crystallographica. Section C, Crystal structure communications, 51, 1995, pp. 1719-1721
Substitution of the two symmetrically unrelated Ti4+ ions in the struc
ture of the well known non-linear optical crystal KTiOPO4 (potassium t
itanyl phosphate, KTP, space group Pna2(1)) by Ni2+ and W6+ (2Ti(4+) -
-> Ni2+ + W6+) leads to the new compound K2NiWO2(PO4)(2) [dipotassium
nickel bis(monophosphato)tungstate, KNiWP], which forms a new structur
e type. The main structural characteristic of tetragonal KNiWP (space
group P4(1,3)2(1)2))is helical chains of corner-linked alternate [WO6]
and [NiO6] octahedra along [001] connected via phosphate groups. Stru
ctural and metric relationships exist between the KNiWP and KTP struct
ure types.