Dear Joseph,

Ammonium uranyl carbonatedecomposes between 165-185 C.

https://www.google.ps/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjwqbLhm8bKAhXJzRQKHQc7CvgQIAgmMAE&url=https%3A%2F%2Fwebcache.googleusercontent.com%2Fsearch%3Fq%3Dcache%3ANpoiIz6_APkJ%3Ahttps%3A%2F%2Fen.wikipedia.org%2Fwiki%2FAmmonium_uranyl_carbonate%2B%26cd%3D2%26hl%3Den%26ct%3Dclnk%26gl%3Dps&usg=AFQjCNELl3EPs64zRc77k-LLBptTno26QQ&sig2=YnRF8ZUa3wIXBNk145mQww

This is the only carbonate derivative that its decomposition point was reported.

Rafik

Hi Joseph,

Herewith thermochemical studies on liebigite, studtite, andersonite, cejkaite and bayleyite.

Frost, Ray L., Matt L. Weier, and W. Martens. "Thermal decomposition of liebigite." Journal of thermal analysis and calorimetry 82.2 (2005): 373-381.

Rey, A., et al. "Effect of temperature on studtite stability: Thermogravimetry and differential scanning calorimetry investigations." Journal of Nuclear Materials 385.2 (2009): 467-473.

Čejka, J., and Z. Urbanec. "Thermal and infrared spectrum analyses of natural and synthetic andersonites." Journal of thermal analysis 33.2 (1988): 389-394

Ondrus, Petr, et al. "ˇCejkaite, the triclinic polymorph of Na4 (UO2)(CO3) 3—a new mineral from Jáchymov, Czech Republic." American Mineralogist 88.4 (2003): 686-693.

Mayer, H., and K. Mereiter. "Synthetic bayleyite, Mg2 [UO2 (CO3) 3]· 18H2O: thermochemistry, crystallography and crystal structure." Tschermaks mineralogische und petrographische Mitteilungen 35.2 (1986): 133-146.

Hope this helps

Best Regards,

Graham