sentences:  At room temperature, strontium bromide adopts a crystal structure with a tetragonal unit cell and space group "P"4/"n".This structure is referred to as α-SrBr2 and is isostructural with EuBr2 and USe2.Around 920 K (650 °C), α-SrBr2 undergoes a first-order solid-solid phase transition to a much less ordered phase, β-SrBr2, which adopts the cubic fluorite structure.