Pd–Al interaction at elevated temperatures: a TEM and SAED study

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摘要：

Epitaxially grown Pd particles partly embedded in amorphous Al 2 O 3 were subjected to annealing and reductive treatments in the temperature range 523–873K to induce a possible Pd–Al interaction. The structural, morphological and compositional changes were monitored by transmission electron microscopy and selected area electron diffraction. Formation of Pd 4 Al 3 and PdAl alloys has been observed upon annealing in 1bar He for 1h at T >523K and upon reduction in 1bar H 2 for 1h at T ≥523K, respectively. Both alloys appear to be stable up to 873K, although Pd 4 Al 3 shows beginning decomposition at and above 873K. The stability under oxidative conditions was found to be very similar, a transformation back into metallic Pd sets in for both compounds at around 573–623K. In agreement with previous studies on Pd/SiO 2 , the formation of an amorphous hydride phase and/or a heavily distorted Pd lattice has been detected after reduction in hydrogen at 523K.

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关键词：

Palladium Al2O3 electron microscopy selected area diffraction alloying Pd4Al3 PdAl structural stability reduction annealing treatment