A(3)B intermetallics: Defect chemistry and nonstoichiometry

作者：Ipser Herbert^*

来源：Pure and Applied Chemistry, 2007, 79(10): 1675-1689.

DOI：10.1351/pac200779101675

• intermetallics
• A(3)B intermetallics
• Wagner-Schottky
• configurational defects
• thermal defects
• nonstoichiometry

The defect chemistry of different ordered intermetallic compounds with the A(3)B stoichiometry was investigated. Three groups were distinguished according to their crystal structure: Ll(2) compounds (Ni3Al, Ni3Ga, Pt3Ga, Pt3In), D0 (19) compounds (Ti3Al), and D0(3) compounds (Fe3Al, Ni3Sb). Statistical-thermodynamic models were derived based on a Wagner-Schottky approach, and the calculated activity curves (thermodynamic activity vs. composition) were compared with experimental activity data. In this way, we attempted to obtain at least estimated values for the energies of formation of the different types of point defects present in the corresponding compound, both as configurational defects (which are responsible for nonstoichiometry) and as thermal defects. In the majority of cases, thermodynamic activities had to be determined experimentally in the present study, using either an emf method with a solid electrolyte (Ni3Ga, Pt3Ga, Pt3In, Fe3Al) or a Knudsen cell-mass spectrometric method (Ni3Sb).

• 出版日期2007-10