Identification of structural vacancies in carbides, oxides, and sulfides by Doppler broadening of the gamma-ray line

A method has been developed to identify the sublattices of a crystal structure in which there are atomic vacancies. This method is based on determining the chemical environment of vacancies and is implemented using the method of the positron annihilation by measuring the momentum distribution of core electrons. To determine the characteristic momentum distribution of electrons, a special two-detector spectroscopy is used, which ensures measurements of Doppler broadening of the annihilation gamma-ray line with a high (up to $10^6$) signal-to-noise ratio. To test the method, vacancies in irradiated silicon carbide (6H-SiC), sintered non-stoichiometric titanium carbides (TiC$_y$) and titanium monoxides (TiO$_y$), and chemically deposited lead and cadmium sulfides (PbS and CdS) have been identified. Vacancies in the carbon and silicon sublattices have been identified in silicon carbide after irradiation by low- and high-energy electrons, respectively. Vacancies in the nonmetal sublattice have been identified in TiC$_y$. Vacancies in the metal sublattice have been identified in TiO$_y$, as well as in PbS and CdS.