Ag 1+ x TlO 2 (0.03 ≤ x ≤ 0.18), Novel Adaptations of the Delafossite Structure Type Featuring Subvalent Silver

A family of novel variations of the delafossite type of structure, Ag 1+ x TlO 2 , was synthesized and characterized. For three members the crystal structures were solved and refined on single crystal data: Ag 1+ α TlO 2 [ α = 0.18, P $\bar{3}$ m 1, Z = 1, a = 3.40427(9), c = 6.1296(1) Å, R 1 = 0.033, 126 independent reflections]; Ag 1+ β TlO 2 [ β = 0.09, R $\bar{3}$ m , Z = 6, a = 3.40685(8), c = 37.5953(9) Å, R 1 = 0.039, 214 independent reflections]; Ag 1+ γ TlO 2 [ γ = 0.03, R $\bar{3}$ m , Z = 9, a = 3.403(2), c = 56.67(3) Å, R 1 = 0.038, 397 independent reflections]. Different from the conventional delafossite structure, part of the silver layers accommodate an excess of ca. 0.18 silver atoms per layer, thus generating a subvalent bonding state of silver. In accordance with the structural findings, the new silver oxthallates(III) are metallic conductors, and show reduced binding energies for the silver 3 d 5/2 states, compared to silver(I) oxide.