Surface compositional changes upon heating cobalt oxalate dihydrate in vacuum

Vacuum ◽  
2021 ◽  
Vol 187 ◽  
pp. 110090
Author(s):  
Sergey P. Chenakin ◽  
Norbert Kruse
Author(s):  
D.C. Dufner

The general goal of this research is to clarify mechanisms of solid state reactions at the atomic level as a step in the rationalization of macroscopic reaction behavior in solids. A study of intermetallic alloy formation resulting from interdiffusion of metals in thin films can be made by HREM. In this work, reactions between Pt and Sn in thin films are studied to elucidate mechanisms for structural and compositional changes during the interdiffusion process.Thin films of Pt and Sn used in this study were prepared by the two-film method introduced by Shiojiri. Few hundred angstroms of Pt were vacuum-deposited onto holey carbon films mounted on TEM grids. Sn films with an average thickness of 200Å were created by evaporation at rates of 15-30 Å/sec onto air-cleaved KBr substrates. The Sn films were wet-stripped and collected on the holey Pt grids. Figure 1 shows a cross-section schematic of a Pt-Sn couple. While this two-film arrangement did not allow observations of the actual reaction interface, microtomy was used to produce cross-sections.


2002 ◽  
Vol 202 (3-4) ◽  
pp. 183-198 ◽  
Author(s):  
C.C Surdu-Bob ◽  
J.L Sullivan ◽  
S.O Saied ◽  
R Layberry ◽  
M Aflori

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. A. Forero-Sossa ◽  
J. D. Salazar-Martínez ◽  
A. L. Giraldo-Betancur ◽  
B. Segura-Giraldo ◽  
E. Restrepo-Parra

AbstractBiogenic hydroxyapatite (BHAp) is a widely used material in the biomedical area due to its similarities with the bone tissue mineral phase. Several works have been spotlighted on the thermal behavior of bone. However, little research has focused on determining the influence of calcination temperature in the physicochemical and bioactive properties of BHAp. In this work, a study of the physicochemical properties’ changes and bioactive response of BHAp produced from porcine femur bones using calcination temperatures between 900 to 1200 °C was conducted. The samples’ structural, morphological, and compositional changes were determined using XRD, SEM, and FTIR techniques. XRD results identified three temperature ranges, in which there are structural changes in BHAp samples and the presence of additional phases. Moreover, FTIR results corroborated that B-type substitution is promoted by increasing the heat treatment temperature. Likewise, samples were immersed in a simulated biological fluid (SBF), following the methodology described by Kokubo and using ISO 23317:2014 standard, for 3 and 7 days. FTIR and SEM results determined that the highest reaction velocity was reached for samples above 1000 °C, due to intensity increasing of phosphate and carbonate bands and bone-like apatite morphologies, compared to other temperatures evaluated.


2021 ◽  
Author(s):  
Venkataramanan Mahalingam ◽  
Sourav Ghosh ◽  
Rajkumar Jana ◽  
Sagar Ganguli ◽  
Harish Reddy Inta ◽  
...  

The quest for developing next-generation non-precious electrocatalyst is getting aroused in recent times. Herein, we have designed and developed a low cost electrocatalyst by ligand-assisted synthetic strategy in aqueous medium....


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