A New Approach to Study Vacancy Defects in High-Temperature Intermetallic Compounds

Gary S. Collins, Praveen Sinha
1994 Materials Research Society Symposium Proceedings  
Perturbed angular correlations of gamma rays (PAC) is being applied to study defects in ordered intermetallic alloys. Vacancies on both Pd and In sublattices in the B2 system PdIn were detected after quenching through quadrupole interactions induced at nearby 111 In probe atoms. Fractions of probe atoms having each type of neighboring defect were observed to increase monotonically with quenching temperature over the range 825-1500 K. For compositions close to 50.15 at.% Pd, nearly equal site
more » ... early equal site fractions were observed for Pd and In vacancies, indicating that the Schottky vacancypair defect is the thermal defect at high temperature. The formation enthalpy of the Schottky defect was determined to be 1.3(2) eV through analysis of quenching data from in the range 825-1200 K. Above 1200 K, however, the vacancy concentration was observed to saturate at a value of 1.4(2) atomic percent, perhaps due to breakdown of the law of mass action for high defect concentrations.
doi:10.1557/proc-364-59 fatcat:7iafeuoy5fhkhei2ldb475gymm