As distinguished from the mobility of atoms/molecules, which is unequivocally correlates with temperature (by its definition), reactivity of solids, in particular with gases, can be in different relations to temperature parameter; although the reactivity is also increasing with temperature growth commonly. Nevertheless, in some temperature ranges for certain solid chemical compounds the effect of temperature on the reactivity of solids is quite different and it declines with temperature growth because of the specific structures of reaction products formed on the surface of solid reagents. Up to date I am aware of the following issues: (a) oxidation of titanium and zirconium carbides; (b) chlorination of niobium carbide; (c) hydrogenation of lithium nitride, but hope on your kind assistance to widen this specific list (for some details please see also my publications and presentations on ridge effect phenomenon at my ResearchGate account/page).
Thanks, but sorry... All these topics are not connected with solids reactivity (their capability to any chemical reactions)... I am looking for examples, when this capability becomes lower with temperature increase... Higher temperatures - but more chemically inert solids become!
Igor,
In my masters thesis, University of Tennessee, Knoxville, I showed that different chemical species exist in a gaseous mix at different temperatures. In particular, some chemical species only existed over a specific range of temperatures. Thus, as temperature was increased some species concentrations increased from 0 to maximum and with continued temperature increase, returned to 0 again. I'm not sure if this is the effect you are describing, but, it sounds related as those temperature dependent concentrations could have reactions with solids in contact with the gasses. Our measurements were made with a TOF MS sampling gasses over a growth surface in CVD thin film diamond growth. We worked with a methane / hydrogen atmosphere as a basis and then added chlorine via the chlorinated-methanes.
James
Hi James,
Many thanks to you for your comments. However, could you explain more detailed what the interaction is going between solids and gases in the case you have described. In common CVD processes there is only the deposition of solids, but - no interaction between gas atmosphere and solid surface...
Regards,
Igor
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