The atomic structure of protons and hydrides in Sm_(1.92)Ca_(0.08)Sn_2O_(7-ζ) pyrochlore from DFT calculations and FTIR spectroscopy

摘要

A combined density functional theory and Fourier transform infrared spectroscopy study of the structure and specific site preference of protons and hydrides in the pyrochlore Sm_(1.92)Ca_(0.08)Sn_2O_(7-ζ) is presented. Two protonic sites of particular high stability are identified, both located on 0(1) oxygen atoms closely associated with a Ca dopant. Further, the unexpected presence of H_o hydride defects in undoped, oxygen deficient Sm_2Sn_2O_7 is reported. Finally, the stretching frequencies and relative intensities for these and other sites are calculated. The main features of the Fourier transform infrared spectra are hereby resolved.