Valence study of Au in Cs2Au(I)Au(III)Cl6 and Cs2Ag(I)Au(III)X6(X= Cl, Br) by X-ray absorption spectra at the Au L3 edge

Single crystal growth by self-flux method of the mixed valence gold halides Cs2[Au X2][Au X4] (X=Br,I)

“…Although simple charge counting arguments might indicate a single gold valence Au II , and hence a metallic state, the materials are in fact found to be hard insulators, comprising two distinct Au sites with different formal valences Au I and Au III [1][2][3][4][5]. However, hydrostatic pressure can induce a coupled first order structural and valence transition at % 9 GPa for X¼Br and % 5:5 GPa for X¼I, spurring considerable recent interest in the associated changes in the electronic behavior [1,6,7].…”

A New Perspective and Design Principle for Halide Perovskites: Ionic Octahedron Network (ION)

“…In order to further confirm the oxidation states of the Au ions, X-ray absorption near edge structure (XANES) is also measured on the Au L 3 -edge. For transition metals like Au, the L 3 -edge XANES is dominated by a rising-edge Figure e shows exactly the same rising feature for both Cs 8 Au 3.5 In 1.5 Cl 23 and the reference sample CsAu­(III)­Cl 4 in the Au L 3 -edge XANES.…”

“…For transition metals like Au, the L 3 -edge XANES is dominated by a rising-edge. 27 S2. The final crystal structure is determined as a predicted and discussed in Scheme 1.…”