Strontium orthosilicate
exists in two crystallographic modifications, viz. a0
-Sr2SiO4
(orthorhombic) and b-Sr2SiO4 (monoclinic) [19]. The transition
between the b-phase and the high temperature a0
-phase occurs
at 358 K involves the rearrangement of SiO4 tetrahedra without
disconnection of bonds [20–22