Surface Characterization Study of the Thermal Decomposition of Ag₂CO₃

Abstract

The changes in chemical states and composition of the surface region of a Ag2CO3 powder at various stages during thermal decomposition have been examined using X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The near-surface region of the as-received powder consists primarily of Ag2CO3 although some hydrocarbon and alcohol contaminants also are present. A 155 °C anneal results in partial decomposition of Ag2CO3 to Ag metal and oxides and reduces the amounts of the C contaminants. An anneal at 170 °C causes further decomposition of the Ag2CO3 to Ag metal, Ag2O, and AgO. ISS data indicate that at 205 °C oxygen migrates more rapidly to the outermost atomic layer than it desorbs, resulting in an increased oxygen concentration. The AgO species undergoes further decomposition to Ag2O during a 340 °C anneal treatment. Between 340 and 430 °C the Ag2O decomposes, leaving only Ag metal and subsurface oxygen in the near-surface region of the sample. These results are consistent with temperature-programmed reaction (TPR) data which exhibit a CO2 peak at 260 °C and an O2 peak at 420 °C. Both the XPS and TPR data indicate that the thermal decomposition of these species are activated since their decompositions occur at temperatures much higher than predicted by equilibrium thermodynamic calculations.

A comparative study of nanosized IB/ceria catalysts for low-temperature water-gas shift reaction

“…Moreover, structures due to chemisorbed and subsurface O species are observable in the O 1s spectra of fresh silver/ceria catalysts (not shown). The results obtained here are consistent with those reported by other authors [50].…”

Reinforcement of Ag nanoparticle paste with nanowires for low temperature pressureless bonding

“…As such, it would be expected that the particle surface free of PVP is active for low temperature sintering. The amorphous citrate complexes on the surfaces of the Ag NPs will readily vaporise and decompose (at temperatures above 90°C) and should completely disappear during low temperature sintering [20,48,49]. This accounts for the rapid formation and growth of bridges even at temperatures of 100-150°C.…”

Thermally-induced optical property changes of sputtered PdOx films

“…2 shows the normalized transmitted light intensity changes at λ = 405 and 635 nm, which are commonly used wavelengths for optical disk storage systems. Both the intensity curves exhibit a sharp leap at 832°C due to the decomposition of PdO [34,35], which is higher than the decomposition temperature of Ag 2 O (400-500°C) [1][2][3][4][5] and PtO x (500-650°C) [6][7][8][9]. There is a gradual increase in the transmitted intensity around 200-300°C, and the change is relatively larger for λ = 635 nm than for 405 nm.…”

“…Noble metal oxides decompose to metals and oxygen at high temperatures showing the large structural and optical changes [1][2][3][4][5][6][7][8][9][10]. Since the thermal decomposition of noble metal oxides has a specific threshold temperature, an optical disk storage system using the decomposition phenomena of silver oxide (AgO x ) thin films induced by laser heating has been proposed [11,12].…”