Die Messung der Gitterparameteränderung von Strontiumtitanat am Phasenübergang bei 108 °K

A new method was employed to measure the change of lattice parameters of single crystal SrTiO3 as a function of temperature from 77 to 150 °K. A clear indication of a phase transition at 108 °K was observed. The line splitting below 108 °K is consistent with tetragonal symmetry, the axial ratioc/a of the crystal lattice being 1.0004 at 77 °K. When comparing our results with recently performed measurements of the rotating angleϕ of the TiO6 octahedra, good agreement is obtained by assuming an additional tetragonal deformationc/a′=1.0001 of the oxygen octahedra. There was no indication of a temperature hysteresis of the lattice parameters, formerly observed with x-rays.