Can you consider for a moment exactly what will happen when such a compound decomposes? You have said solid form - so you would get two intimately mixed solids powders instead of a combination, Imagine for example potassium iodide: both potassium and iodine are solid at low room temperatures. But what happens if you try to separate them? The only way to do this is in solution. Molybdenum disilicide is another 'ionic' compound of two solids which has the advantage at least it conducts electricity. But pass electricity through it and it just gets hot; it doesn't decompose at all.

Hello Abdullah,

I am not sure this is what you had in mind, but may I suggest the Nernst glower. Briefly, this is a rod made of a mixture of metal oxides, which was used for illumination. The glower is in series with a ballast resistor and the series combination of glower and ballast resistor is in parallel with a coil of, for example, nichrome wire. The nichrome wire heats the Nernst glower to the point at which it conducts enough electrical current to be self-sustaining, after which its negative coefficient of resistance guarantees sufficient current flow, while the ballast resistor prevents the current from getting so large that the glower melts. The Nernst glower was usually powered by AC (Alternating Current) to prevent polarization effects at the two electrode at either end of the rod. According to Walther Nernst, the electrical conduction was ionic, i.e., electrolysis of the solid rod with the decomposition products recombining by the oxygen of the surrounding air and diffusion due to the heating of the rod. I have a document with a good number of citations to source material on my RG web page Research APPENDIX B - Illumination by Incandescent Metal Oxides

Unlike, for example, the sodium azide in an air bag, which is thermally decomposed by a bridge wire in order to produce nitrogen gas, the Nernst glower is thought to decompose due to electrolysis of the solid phase oxide mixture. If the glower is operated in a hydrogen atmosphere with DC, then the decomposition products becomes more apparent and the life of the glower decreases markedly.

Regards,

Tom Cuff

Hello Abdullah,

I don't know why I didn't remember this earlier, but the following book by Seitz spends several page discussing ionic semiconductors:

Frederick Seitz; The Modern Theory of Solids; McGraw-Hill Book Company, Inc.; 1940; pp. 64-75.

Most modern books on semiconductors usually only discuss electronic semiconductors (conducting electricity via electrons and/or holes), not ionic semiconductors (conducting electricity via ions).

Regards,

Tom Cuff

Hello Mr.Cuff,

I am truly thankful for your help, but I guess I didn't yet succeed in getting to the point, I was asking If I can find a solid chemical compound that can be instantaneously decomposed into a solid and a gas if a strong AC current runs through not the conductivity through ions themselves. Hope you got the point well and many thanks for your help again.

Regards,

Abdullah

You are just describing an explosive like lead azide.

Hello Tony,

I thought the same thing until Abdullah clarified matters in his message of four days ago. He is looking for, as I understand it, an ionic solid, which can be electrolytically decomposed into a gas and a solid but only electrolytically. Lead azide and other primer explosives can, of course, be ignited electrically and the resulting ignition can set off the remainder of the primer, but Abdullah does not want that to happen. Instead, he wants the decomposition to only take place electrolytically, i.e., if the electrical current ceases the decomposition stops. In contrast, once the lead azide has been ignited electrically, the decomposition reaction proceeds even if the electrical current ceases.

Of course, even if such a conductive ionic solid existed, it is not clear how the electrodes (anode and cathode) would maintain contact with the solid as gas was being evolved at one of these two electrodes. Or perhaps that is why Abdullah wanted to employ an alternating current (AC) so that the gas evolution alternated between the electrodes, i.e., preventing the polarization that would interrupt the current flow through the solid.

According to the reference book by Samsonov, there are some metal oxides which exhibit very high electrical conductivity at or near room temperature - depending on their morphology and surrounding oxygen content of the atmosphere - such as CdO, ZnO, Cu2O3, etc. But whether these conductivities are high enough for Abdullah's application, I do not know.

G. V. Samsonov (editor); The Oxide Handbook; IFI/Plenum Publishing; 1973; pp. 263-280.

Regards,

Tom Cuff