Temperature dependence of the crystal structure of α-AgSCN by powder neutron diffraction

Abstract

A structural study of α-AgSCN was carried out using the neutron powder diffractometer HIPPO (high-pressure preferred orientation powder) at ten different temperatures between 25 and 275 K. The structure of α-AgSCN was refined using the Rietveld method and the symmetry elements for the material were found to be: space group No. 15,C2/c,a= 8.7210 (8) Å,b= 7.9318 (8) Å,c= 12.3329 (5) Å, β = 138.750 (3)°, volume = 562.497 (9) Å3andZ= 8. The Ag+cation has tetrahedral coordination and is surrounded by three –SCN thiocyanate ligands and one isothiocyanate –NCS ligand down to 25 K, with no structural changes. The bond lengths at 275 K are Ag—S1 = 2.749 (10), Ag—S2 = 2.995 (11), Ag—S3 = 2.411 (11), Ag—N = 2.150 (5), S—C = 1.783 (11) and C—N = 1.1447 (35) Å. The bond lengths at 25 K are Ag—S1 = 2.782 (5), Ag—S2 = 2.941 (5), Ag—S3 = 2.431 (5), Ag—N = 2.1526 (26), S—C = 1.749 (5) and C—N = 1.140 (2) Å.