Redetermination of crystal structure of Ag(ii)SO4 and its high-pressure behavior up to 30 GPa

Abstract

Here we redetermine the crystal structure of Ag(II)SO₄, an unusual d⁹ system, at 1 atm from powder X-ray data and we report hydrostatic pressure X-ray diffraction experiments on Ag(II)SO₄ inside the diamond anvil cell. AgSO₄ crystallizes in the monoclinic C2/c cell, with a = 12.8476(2) Å, b = 13.6690(4) Å, c = 9.36678(19) Å, β = 47.5653(13)°, and V = 1214.04(5) ų (Z = 16). AgSO₄ exhibits bulk modulus, B⁰, of 36.9 GPa, and undergoes sluggish decomposition at ∼23 GPa yielding a high-pressure phase of Ag₂S₂O₇ (K₂S₂O₇-type), with the substrate and product coexisting at 30 GPa. Theoretical calculations within Density Functional Theory for the C2/c cell nicely reproduce the observed trend for lattice constants as well as the B⁰ values of AgSO₄, and suggest that the rigidity of the infinite [Ag(SO₄)] chains as well as the Jahn–Teller effect for the Ag(II) cation persist even at 30 GPa.