Preparation and Characterization of Spherical AgPd Alloy Powder through Wet Chemical Reduction Method

Abstract

Spherical AgPd alloy powder was prepared through the reaction of metal nitrate and reducing agent. Natural gum Arabic was used as a dispersant. SEM observation showed that as-prepared particles had spherical morphology with narrow size distribution. Powder X-ray diffraction showed that as-prepared powder was crystallized regardless of molar ratio of Ag and Pd and alloyed. Fluorescent X-ray analysis showed that the atomic ratio of Ag and Pd in as-prepared powder was in good agreement with that of starting solution. The particle size (D 50) of as-prepared powder was decreased with increasing the reaction temperature and the content of gum Arabic. The D 50 increased with increasing starting solution concentration. It was assumed from the change of particle number density that the particle growth was due to the diffusion of Ag and Pd ions from starting solution. The thickness of gum Arabic layer on Ag 90 Pd 10 and Ag 40 Pd 60 alloy particles at gum Arabic content of 2 g/cm 3 was 20 nm and 22 nm, respectively and increased to 34 nm and 31 nm, respectively, with increasing gum Arabic content. The specific resistivity of Ag 90 Pd 10 paste was 6.2 © 10 ¹8 ³•m at 1000°C. The specific resistivity of Ag 50 Pd 50 paste and Ag 40 Pd 60 paste was 2.6 © 10 ¹7 ³•m at 1400°C.