X-ray and neutron scattering

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X-ray, optical and dielectric studies of diffused phase transitions in NaNbO3-based solid solution crystals

FERROELECTRICS 298 (2004) 261-265

Authors:

SI Raevskaya, AF Semenchev, KG Abdulvakhidov, IP Raevski, SA Prosandeev, LA Shilkina, VG Smotrakov, VV Eremkin, VA Shuvaeva, AM Glazer

Abstract:

In flux-grown (1-x)NaNbO3 -(x)Gd1/3NbO3 solid solution crystals a diffusion of the dielectric permittivity epsilon maximum grows with x and increases dramatically when x exceeds a threshold value x 0 approximate to 0.1. Optical studies by the rotating-polarizer method show that Gd-doping results in a very small mean size of twins and the distribution of the birefringence image becomes very messy. In the x < x(0) range the changes of lattice parameters and birefringence corresponding to the epsilon(T) anomaly were revealed. The results obtained are in line with the assumption that phase transition diffusion in NaNbO3 is a result of the local strains stemmed from the impurities.
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Ferromagnetic in-plane spin fluctuations in NaxCoO2 observed by neutron inelastic scattering

(2003)

Authors:

AT Boothroyd, R Coldea, DA Tennant, D Prabhakaran, LM Helme, CD Frost
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Magnetic Studies of Polycrystalline and Single-Crystal NaxCoO2

ArXiv cond-mat/0312493 (2003)

Authors:

D Prabhakaran, AT Boothroyd, R Coldea, LM Helme, DA Tennant

Abstract:

We have investigated the preparation and bulk magnetic properties of NaxCoO2 in the range 0.5
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A μ+SR study of the rare earth antiferromagnet PrO2

Journal of Physics Condensed Matter 15:49 (2003) 8407-8415

Authors:

T Lancaster, SJ Blundell, FL Pratt, CH Gardiner, W Hayes, AT Boothroyd

Abstract:

We present zero-field muon spin relaxation (μ+SR) measurements on the rare earth antiferromagnet PrO2. Oscillations in the time dependence of the muon polarization, characteristic of a quasistatic magnetic field at two distinct muon sites, are observed below TN, along with relaxation dominated by the magnitude of the local field. Candidate muon sites in the material are suggested on the strength of dipole field calculations. Relaxation above TN allows a prediction of the quasielastic neutron scattering linewidth, which is discussed in terms of a simple model of magnetoelastic relaxation involving a crystal field state at an energy Δ above the ground level. The obtained value of Δ may be taken as an approximate estimate of the splitting of the Γ8 ground state of Pr4+ in the distorted fluorite structure.
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Spin correlations among the charge carriers in an ordered stripe phase

Physical Review Letters 91 (2003) article 257201 4pp

Authors:

AT Boothroyd, A Hiess, D Prabhakaran, P G Freeman
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