Neutron diffraction study of (SrTiO3)1-x(BaTiO3)x solid solution structure

Complete text of publication follows. This contribution is devoted to neutron Rietveld analysis of the Sr1-xBaxTiO3 (SBT) structure from 300 K down 1.5 K for x=0.02 and x=0.06. The data were collected an the TOF neutron diffractometer DN-2 (JINR, Dubna) and on the powder diffractometer G4.2 (λ=2.3434) at the LLB (Saclay). The temperature dependence of the (1/2 1/2 1/2) superstructure peak intensity (proportional to the square of the order parameter) is obtained and it is pointed out that the temperature Tc of antiferrodistorsive phase transition (APT) is equal to ∼ 95 K for the SBT with x=0.02. Below Tc the structure is well described by the 14/mcm space group, but at 1.5 K the Debye-Waller factors is greater then for the pure SrTiO3 approximately in 1.5 times. This fact can be consider as indirect evidence of glassy low-temperature state suggested in the paper [1]. In the SBT with x=0.06 we did not observe any traces of the superstructure, i.e. in this compound the APT is completely suppressed by the Ba2+ ions. This research was supported by the State Program 'Neutron Studies of Matter'. (author) [1] M.E. Guzhva, V.V. Lemanov and P.A. Markovin Phys. Solid State 39(a), 1997, pp. 618-624