Caesium phosphide

Caesium phosphide refers to any of several inorganic compounds with the formula CsPx. The most studied member is Cs3P7, which forms yellow crystals of tetragonal structure (P41 group), which turn brown when heated to 300 °C, and colorless when cooled with liquid nitrogen.

Other cesium phosphides
CsP15 is also claimed. Cs4P6 is a layered compound consisting of planar P64- rings.