Abstract. The lattice parameters of tetragonal strontium titanate are determined to about 1 part in 10⁶ with penetrating X-rays. While no peculiarity is detected in a bulk sample, a distinct anomaly at 37 K is observed in an optically polished thin platelet derived from the same single crystal. This suggests that the anomaly is related to a high density of dislocations. A possible mechanism is that dislocations stabilize transverse antiphase boundaries which undergo a ferroelectric transition near 37 K. If so, this transition stresses the boundaries which then strain the bulk leading to the observed anomaly.

PACS numbers: 61.50.Ks, 77.84.Dy, 61.10.-i

Print publication: Issue 5 (March 2003)
Received 5 August 2002, in final form and accepted for publication 16 December 2002