Uniaxial internal stress in CdS nanoparticles by zinc blende-wurtzite transition. 1LO phonon softening of CdS in plane-substrate by cubic-hexagonal transition. CdS lattice compressed along of (111) zinc blende and (002) wurtzite phases. Very sharp zinc blende-wurtzite phase transition of CdS nanoparticles at T∼94 °C.