The AuAl2-AuGa2-Au

G.C. Carter

¹

,

I. D. Weisman

²

,

L. H. Bennett

³

et al.

Abstract

The nuclear-magnetic-resonance (NMR) and susceptibility behavior of the intermetallic compound AuGa2 differs anomalously from the isoelectric and isostructural compounds Auln& and AuAlq. In an effort to test and extend the explanation offered by Jaccarino et al. and by Switendick and Narath, spin-lattice relaxation times and Knight shifts have been measured as a function of temperature and composition for the AuAlp-AuGa2, AuA12-AuIn2, and AuGa2-AuIn2 pseudobinary alloy systems. At high temperature, the solute X (Al, In, Ga) resonance properties are dominated by the host. Satellite resonances are observed with temperature dependences differing from the main resonance. The results are partially explainable on the basis of an average-band model and partially on a local atom model. The role of the Au d bands is discussed. Metallurgical results on alloying are obtained using the NMR data.

NMR study of trialuminide intermetallics

“…This is more obvious from the Al 3 V shifts ͑Table II͒: the negative Knight shift for this material cannot be accounted for either by an ordinary s-contact term or by a paramagnetic orbital shift. A negative Knight shift was also found for dilute alloys of Al in V. 18 In that study, the negative term was attributed to core polarization, but the core-polarization term for 3p electrons is now generally agreed to be positive, 19 and too small to account for the shifts observed here. Yokoyama et al noted that direct exchange polarization of s electrons by V-based d states may account for the negative shift.…”

“…Since p and d hyperfine fields are generally an order of magnitude smaller than s hyperfine fields, the main hyperfine field in such alloys arise from contact electrons. With the estimate of H s HF ϳ1.9ϫ10 6 G in Al metal 19 and experimental T 1 T's, the Fermi-level DOS of s electrons can be obtained from Eq. ͑4͒.…”

“…. ͒, the possible crystal structures are Ll 2 , DO 19 , DO 22 , as well as DO 23 . 6 For Al 3 Ti, Al 3 V, Al 3 Nb, and Al 3 Ta, the ground state DO 22 is energetically favored.…”

Metallurgy and processing of coloured gold intermetallics — Part II: Investment casting and related alloy design

“…They all crystallize in the same crystal structure and a former investigation of the corresponding ternary systems revealed some limited mutual miscibility [12]. Hence it was speculated that replacing Al by In or Ga, or vice versa, could probably yield to some colour shifts away from purple or blue toward different hues.…”

Electrical Resistivity, Magnetic Susceptibility and Thermoelectric Power of PtGa2

“…However, the observation that the magnetic susceptibility of AuGa 2 between 4.2 and 300K shows a decreasing diamagnetism with decreasing T is still an unresolved issue. 8 In an angle-resolved photoemission spectroscopy (ARPES) study of AuGa 2 , 9 no peak was observed corresponding to the A 2 band, although such a flat band should yield an extremely high density of initial states to be sampled.…”