Direct Bi³⁺–Bi³⁺ contacts mediated by lone pairs in the HP-BiNiO(PO₄) polymorph

Abstract

A high-pressure polymorph of BiNiPO5 was prepared at 5GPa. In the HP phase, the parent 1D- ͚[BiNiO]3+ trans chains of edge-sharing O(Bi2Ni2) oxo-centered tetrahedra are conserved but reor-ganized into a...

Compressibility of structural modulation waves in the chain compounds BaCoX 2O7 (X = As, P): a powder study

“…We could suggest that inorganic arsenates are less compressible before critical phase transition than phosphates for steric reasons [rP 5+ (IV) = 0.17 A ˚versus rAs 5+ (IV) = 0.34 A ˚]. For instance, it was shown recently that 'ambient pressure' BiCu 2 O 2 (PO 4 ) (Colmont et al, 2018) and BiNiO(PO 4 ) (Colmont et al, 2021) transformed into 'high-pressure' polymorphs at high pressure, these latter being both isomorphs of the 'ambient pressure' arsenates analogs, BiCu 2 O 2 (AsO 4 ) and BiNiO(AsO 4 ). These two cases show the greater compactness of inorganic arsenates in comparison with phosphate equivalent materials, which are more prone to structural transition under pressure.…”