title: Structural phase transitions and magnetic order in SrTcO3.
abstract: The structure of the perovskite SrTcO(3) has been investigated using both synchrotron X-ray and neutron powder diffraction. At room temperature SrTcO(3) is orthorhombic as a consequence of cooperative tilting of the corner sharing TcO(6) octahedra. The tilts are sequentially removed as the sample is heated with the oxide displaying the sequence of structres Pnma→Imma→I4/mcm→Pm ̅3m. Neutron powder diffraction data collected in the temperature range 4-1023 K indicate that SrTcO(3) has G-type antiferromagnetic structure, in which each Tc moment is antiparallel to its six nearest neighbours, below ∼1000 K. The magnetic structure is collinear antiferromagnetic with the technetium moments parallel to c-axis and can be described by the propagation vector k = [0,0,0] and the basis vector (0,0,A(z)). The same magnetic structure is observed in each of the four crystal structures.
authors.affiliation: IME Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai NSW, 2234, Australia.
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Thorogood
authors.forename: Maxim
authors.initials: M
authors.lastname: Avdeev
authors.forename: Melody L
authors.initials: ML
authors.lastname: Carter
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Kennedy
authors.forename: Jimmy
authors.initials: J
authors.lastname: Ting
authors.forename: Kia S
authors.initials: KS
authors.lastname: Wallwork