Those that have three phase transitions go through these crystallographic point groups : P2 3 -- P2 -- P1 -- P2 2 2 , .
The single phase change crystals only have P2 3 .
Those that have three phase transitions go through these crystallographic point groups : P2 3 -- P2 -- P1 -- P2 2 2 , whereas the single phase change crystals only have P2 3 .