Fluorocarbonate
The salts are usually insoluble in water, and can have more than one kind of metal cation to make more complex compounds.
Other artificial compounds are under investigation as non-linear optical materials and for transparency in the ultraviolet, with effects over a dozen times greater than Potassium dideuterium phosphate.
Compounds where fluorine connects to carbon making acids are unstable, fluoroformic acid decomposes to carbon dioxide and hydrogen fluoride, and trifluoromethyl alcohol also breaks up at room temperature.
Trifluoromethoxide compounds exist but react with water to yield carbonyl fluoride.
[4] Carbonate fluoride compounds can be formed by a variety of related methods involving heating the precursor ingredients with or without water.
The high pressure is needed to keep the water liquid and the carbon dioxide under control, otherwise it would escape.
[2] Bastnäsite along with lukechangite (and petersenite) can be precipitated from a mixed solution of CeCl3, NaF, and NaOH with carbon dioxide.
[6] Pb2(CO3)F2 can be made by boiling a water solution of lead nitrate, sodium fluoride and potassium carbonate in a 2:2:1 molar ratio.
[4] The visible spectrum of the rare-earth fluorocarbonates is almost entirely due to narrow absorption bands from neodymium.
The aim is to separate out the rare-earth elements from calcium, aluminium, iron and thorium.
When heated in air or oxygen at over 500 °C, bastnäsite oxidises and loses volatiles to form ceria (CeO2).
[5] When other rare-earth carbonate fluorides are heated, they lose carbon dioxide and form an oxyfluoride: In some rare-earth extraction processes, the roasted ore is then extracted with hydrochloric acid to dissolve rare earths apart from cerium.
[10] KCdCO3F when heated yields cadmium oxide (CdO) and potassium fluoride (KF).
When lanthanum carbonate fluoride is heated at 1000 °C with alumina, lanthanum aluminate is produced:[13] Within the hot part of the Earth's crust, rare-earth fluorocarbonates should react with apatite to form monazite.
