  Metal-insulator transitions strongly coupled with lattice were found in
Bi1-xLaxNiO3. Synchrotron X-ray powder diffraction revealed that pressure (P ~
3 GPa, T = 300 K), temperature (T ~ 340 K, x = 0.05), and La-substitution (x ~
0.075, T = 300 K) caused the similar structural change from a triclinic
(insulating) to an orthorhombic (metallic) symmetry, suggesting melting of the
A-site charge disproportionation. Comparing crystal structure and physical
properties with the other ANiO3 series, an electronic state of the metallic
phase can be described as [A3+Ld, Ni2+L1-d], where a ligand-hole L contributes
to a conductivity. We depicted a schematic P-T phase diagram of BiNiO3
including a critical point (3 GPa, 300 K) and an inhomogeneous region, which
implies universality of ligand-hole dynamics in ANiO3 (A = Bi, Pr, Nd,...).
