0000000000082438
AUTHOR
V. V. Efimov
Structure and Lattice Dynamics in PLZT 8/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam
The comprehensive study of high-current pulsed electron irradiation effect on the structure and lattice dynamics as well as optical properties of PLZT 8/65/35 ceramics have been performed. X-ray powder diffraction studies shown the transformation of the rhombohedral perovskite structure R3m (Z = 1) into orthorhombic Pmmm (Z = 1) for the sample irradiated by one pulse (dose 4 × 1014 electrons/cm2) and, as a consequence, the changes in number of phonon modes position, oscillators strength and damping in IR and Raman spectroscopy data. However neutron powder diffraction measurements of multiple irradiated samples have not been revealed any structural distortions. Dielectric parameters have sho…
Structural, Optical, and Dielectric Investigations of the Relaxor PLZT 9,75/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam
A comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb (1-x )La x )(Zr 0.65 Ti 0.35 ) 1-x/4 O 3 ceramics with x = 9,75 at.% has been performed for the first time. The electron beam had the following parameters: energy E = 250 keV, current density I = 1000 A/cm 2 , pulse duration τ = 300 ns, beam density -10 15 electrons/cm 2 per pulse. Infrared reflectivity spectra in the region of 100 ÷ 2000 cm -1 were obtained in virgin, irradiated by 1500 pulses and annealed up to 500°C ceramics. The reconstruction of perovskite ABO 3 structure in irradiated samples has been studied by combined use of X-ray diffraction…
Neutron diffraction studies of structural and magnetic properties of niobium doped cobaltites.
Neutron powder diffraction studies of the structural and magnetic properties of the La(1-x)Sr(x)Nb(y)Co(1-y)O(3) solid solutions (x = 0.2, 0.5; y = 0, 0.075, 0.1) have been performed. Substitution of Co(2+) by Nb(5+) prevents the formation of Co(4+) and leads to stabilization of the Co(3+) ions in the high- or intermediate-spin state. This is accompanied by the significant change of the Co-O bond length as well as Co-O-Co bond angle in the CoO(6) octahedron. The obtained data are in agreement with the negative sign of the magnetic exchange interactions Co(3+)-O-Co(3+) in a relatively wide range of the Co-O-Co bond angles. Diamagnetic dilution by the niobium ions prevents long-range magnetic…
Short- and long-range order in La1−xSrxCoO3 and La1−xBaxCoO3
Abstract The short- and long-range order correlations of the crystal structure in the distorted perovskites La 1− x Sr x CoO 3 and La 1− x Ba x CoO 3 (0.0⩽ x ⩽0.5) have been studied by the neutron powder diffraction (NPD) and the Co K-edge X-ray absorption spectroscopy (XAS) measurements. The results of XAS and NPD indicate a local distortion around the Co 3+ ions in LaCoO 3 at room temperature. The substitution of the La 3+ ions by the Sr 2+ (Ba 2+ ) ions leads to a gradual increase of the Co–O–Co angle and is accompanied by an increase of the mean square relative displacement (MSRD) of the Co–O bond. These results correlate with an increase of the oxygen amplitude vibration in the directi…
Mechanism of pulsed electron irradiation of the PLZT X/65/35 ceramics
The comprehensive study of high-current pulsed electron irradiation effect on the structure and lattice dynamics as well as Atomic Force (AFM) and Laser Confocal Scanning microscope (LSCM) surface imaginaries of PLZT 8/65/35 ceramics have been performed. X-ray powder diffraction studies show the transformation of the cubic perovskite Pm-3m (Z = 1) into orthorhombic Pmmm (Z = 1) structure for the sample irradiated by one pulse (dose 6 × 1014 electrons/cm2) and into cubic Pm-3m with increased lattice volume and more ordered structure at irradiating by 10 and 100 pulses (dose 6 × 1015 and 6 × 1016 el/cm2). A consequence, the changes of number, intensity and phonon modes position occur in Raman…
Interpretation of the Co K-edge EXAFS in LaCoO3 using molecular dynamics simulations
Abstract Temperature dependent (180–400 K) Co K-edge EXAFS spectra from perovskite-type rhombohedral ( R 3 ¯ c ) LaCoO 3 have been successfully interpreted using a combination of classical NVT molecular dynamics (MD) and ab initio multiple-scattering (MS) theory. The method allowed us to account entirely for thermal disorder and to interpret reliably the contribution from the coordination shells beyond the first one into the total EXAFS spectrum taking into account many-body effects. The best agreement between experimental and configuration-averaged EXAFS spectra was obtained for pure ionic La 3+ and partially ionic Co 1.35+ and O 1.45− charges indicating the mixed ionic-covalent character …
<title>Structual changes of the PLZT ceramics irradiated by high-current pulsed electron beam</title>
First time comprehensive study of high-current pulsed electron irradiation effects on the structural, optical and dielectric properties of relaxor (Pb(1-x)Lax)(Zr0.65Ti0.35)1-x/4O3 ceramics with x = 4 and 9.75 at.% have been provided. The electron beam had the following parameters: energy E = 250 keV, current density I = 1000 A/cm2, pulse duration τ = 300 ns, beam density - 1015 electrons/cm2 per pulse. Infrared reflectivity spectra in the region of 100 ÷ 2000 cm-1 were obtained in virgin, irradiated by 1500 pulses. The reconstruction of perovskite ABO3 structure in irradiated samples has been studied by complex use of X-ray and neutron scattering and IR spectroscopy techniques revealing th…