Phase Transformations in physical mixtures of Pd-Cu nanoparticles

Mukundan, Vineetha; Yin, Jun; Zhong, Chuan‐Jian; Malis, Oana

doi:10.1557/opl.2013.367

Cited by 1 publication

(2 citation statements)

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“…We have previously investigated the thermal evolution of Pd:Cu nanoparticle mixtures dispersed on carbon black and annealed in helium gas [16]. The nanoparticles form the B2 phase after annealing at 300 °C and then undergo an incomplete transformation to a disordered fcc alloy during ramp annealing to 700 °C, as shown in figures 8(a) and (b).…”

Section: Resultsmentioning

confidence: 99%

“…The nanoscale alloying and the time evolution of Pd:Cu nanoparticles mixtures on various surfaces (SiO 2 /Si, carbon, and alumina) are examined in helium and forming gas atmospheres. Recently, we reported the structural evolution of Pd:Cu nanoparticle mixtures dispersed on carbon [16]. The structural evolution of Pd:Cu nanoparticle mixtures dispersed on SiO 2 /Si and carbon annealed in helium and forming gas were qualitatively similar in nature.…”

Section: Introductionmentioning

confidence: 95%

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Nanoalloying and phase transformations during thermal treatment of physical mixtures of Pd and Cu nanoparticles

Mukundan

Yin

Joseph

et al. 2014

Science and Technology of Advanced Materials

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Nanoscale alloying and phase transformations in physical mixtures of Pd and Cu ultrafine nanoparticles are investigated in real time with in situ synchrotron-based x-ray diffraction complemented by ex situ high-resolution transmission electron microscopy. The combination of metal–support interaction and reactive/non-reactive environment was found to determine the thermal evolution and ultimate structure of this binary system. At 300 °C, the nanoparticles supported on silica and carbon black intermix to form a chemically ordered CsCl-type (B2) alloy phase. The B2 phase transforms into a disordered fcc alloy at higher temperature (> 450 °C). The alloy nanoparticles supported on silica and carbon black are homogeneous in volume, but evidence was found of Pd surface enrichment. In sharp contrast, when supported on alumina, the two metals segregated at 300 °C to produce almost pure fcc Cu and Pd phases. Upon further annealing of the mixture on alumina above 600 °C, the two metals interdiffused, forming two distinct disordered alloys of compositions 30% and 90% Pd. The annealing atmosphere also plays a major role in the structural evolution of these bimetallic nanoparticles. The nanoparticles annealed in forming gas are larger than the nanoparticles annealing in helium due to reduction of the surface oxides that promotes coalescence and sintering.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%