Alloy formation in the Co/Pd{111} system — A study with medium energy ion scattering and scanning tunnelling microscopy

Murdoch, A.; Trant, Aoife G.; Gustafson, Johan; Jones, T.E.; Noakes, T.C.Q.; Bailey, Paul; Baddeley, Christopher J.

doi:10.1016/j.susc.2012.10.009

Cited by 8 publications

(14 citation statements)

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“…[19] In this study we used reflection absorption infrared spectroscopy (RAIRS) and medium energy ion scattering (MEIS) to probe the effect of CO adsorption on the surface composition of bimetallic CoPd surfaces as a function of initial Pd composition. We recently reported a MEIS study of the growth and alloying behaviour of Co thin films on Pd{111} at 300 K. [20] …”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…sample and the approximate surface composition (prior to CO exposure) derived from MEIS data reported in our earlier study. [20] Figure 1b shows the RAIR spectra after evacuation of CO from the vacuum system. During exposure to 1000 L CO (10 -7 mbar CO for 10000 s) at 300 K two absorption bands are observed at 2015 and 2061 cm -1 .…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…Under these conditions, the amount of cobalt in the near surface region has fallen to a few atomic percent (Figures 4a-b) as significant dissolution of cobalt into the bulk has occurred. [20] At room temperature, adsorbate induced segregation is likely to be kinetically limited to atoms in the top few layers, so any segregation would have a minor effect on the surface composition. In catalytic terms, it would be interesting to investigate how CO/H 2 mixtures influence the surface composition of the PdCo surface.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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The influence of CO adsorption on the surface composition of cobalt/palladium alloys

et al. 2016

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Segregation induced by the adsorption of gas phase species can strongly influence the composition of bimetallic surfaces and can therefore play an important role in influencing heterogeneous catalytic reactions. The addition of palladium to cobalt catalysts has been shown to promote Fischer Tropsch catalysis. We investigate the adsorption of CO onto bimetallic CoPd surfaces on Pd{111} using a combination of reflection absorption infrared spectroscopy and medium energy ion scattering. The vibrational frequency of adsorbed CO provides crucial information on the adsorption sites adopted by CO and medium energy ion scattering probes the surface composition before and after CO exposure. We show that cobalt segregation is induced by CO adsorption and rationalise these observations in terms of the strength of adsorption of CO in various surface adsorption sites.

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted M Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

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The influence of CO adsorption on the surface composition of cobalt/palladium alloys

et al. 2016

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“…According to the phase equilib rium diagram, in the Co-Pd system, there is only a disordered Co x Pd 1 -x solid solution with a lattice con stant that varies depending on the composition from a = 0.3826 nm for Pd to a = 0.3544 nm for β Co. However, the metastable ordered phases L1 0 CoPd and L1 2 CoPd 3 with the order-disorder transition tem peratures of ~830°C were revealed in Co x Pd 1 -x alloy thin films prepared by vacuum deposition [10,15].…”

Section: Introductionmentioning

confidence: 97%

“…However, annealing at temperatures higher than 400°C leads to a degradation of the perpendicular magnetic anisot ropy, and the easy magnetization direction becomes aligned with the sample plane. This is interpreted by assuming that the heating is responsible for the mixing and alloying at the initially sharp Pd/Co interface [6][7][8][9][10]. The chemical mixing at the Co/Pd interface is observed upon ion implantation [11] and intense laser irradiation, which lead to a decrease in the perpendic ular magnetic anisotropy [12,13].…”

Section: Introductionmentioning

confidence: 99%

Solid-state synthesis, structural and magnetic properties of CoPd films

et al. 2015

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The results of the investigation of the structural and magnetic properties of CoPd films with equi atomic composition have been presented. The films have been synthesized by vacuum annealing of polycrys talline Pd/Co and epitaxial Pd/α Co(110) and Pd/β Co(001) bilayer samples. It has been shown that, for all samples, the annealing to 400°C does not lead to the mixing of layers and the formation of compounds. A fur ther increase in the annealing temperature results in the formation of a disordered CoPd phase at the Pd/Co interface, which is fully completed after annealing at 650°C. The epitaxial relationships between the disor dered CoPd phase and the MgO (001) substrate are determined as follows: CoPd(110)〈 〉 || MgO(001)〈100〉 and CoPd(001)[100] || MgO (001)[100], which are formed in the Pd/α Co(110) and Pd/β Co(001) films, respectively. According to the calculations, the first magnetocrystalline anisotropy constants of the disordered CoPd phase for Pd/α Co(110) and Pd/β Co(001) samples have close values:= -(1.6 ± 0.4) × 10 5 erg/cm 3 . A possible mechanism of the solid state synthesis of the CoPd alloy is proposed.

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