Competition between Order and Phase Separation in Au-Ni

Abstract

We have measured and theoretically analyzed the diffuse scattering in the binary alloy system Au-Ni, which has been proposed as a testing ground for theories of alloy phase stability. We found strong evidence that in the alloys Au3Ni and Au3Ni2, fluctuations of both ordering- and clustering-type are competing with each other. Our results resolve a long-standing controversy on the balance of relaxation and mixing energies in this alloy system and explain recent findings of ordering in thin Au-Ni films.

Alumina‐Supported Ni–Au: Surface Synergistic Effects in Catalytic Hydrodechlorination

“…However, the miscibility gap for bulk Au and Ni is such that bulk alloy formation is not possible at the temperatures employed in our study. [63] Molenbroek et al [36] have reported surface Ni-Au alloy formation on silica at a reduction temperature of 823 K. Our STEM-EDX results demonstrate a close proximity of Au and Ni on the Al 2 O 3 carrier and a possible consequence of surface Ni-Au interaction may be the depleted H 2 uptake capacity ( Table 2). The HDC of 2,4-DCP generated 2-chlorophenol (2-CP) as the partially dechlorinated product and phenol as the ultimate dechlorination product.…”

Gas Phase Hydrogenation of m-Dinitrobenzene over Alumina Supported Au and Au–Ni Alloy

“…The passivated sample was contacted with HAuCl 4 , posttreatment as above. After preparation, the sample (sieved into a batch of 75 lm average diameter) was activated in 60 cm 3 min -1 H 2 at 2 K min -1 to 603 ± 1 K, cooled to room temperature in a He flow and subsequently subjected to a temperature controlled treatment in 65 cm 3 min -1 N 2 at 50 K min -1 to 1273 ± 1 K. The latter step was necessary to generate the supported alloy as the Au-Ni miscibility gap is such that bulk alloy formation is not possible at temperatures below 1083 K [23]. The Au/Al 2 O 3 sample underwent the same annealing treatment to facilitate a direct comparison of catalytic performance with that of the alloy.…”

Growth and characterization of Au, Ni and Au–Ni nanoclusters on 6H-SiC(0001) carbon nanomesh

“…However, there are many fewer studies dealing with the catalytic applications of Au-Ni catalysts [15,16]. One of the primary reasons lies in the fact that the bulk binary phase diagram of Au-Ni has a large miscibility gap and thus alloy formation becomes difficult at temperatures below 800°C [17,18]. On the other hand, atomic resolution scanning tunneling microscopy (STM) studies revealed that when Au is deposited onto Ni(110) or Ni(111) surfaces, Au replaces Ni in the first atomic layer to form a surface alloy [19,20].…”