Showing papers by "Sergey Vakhrushev published in 2001"
TL;DR: In this paper, the structural evolution of PMN/PT10% and PMN (PbMg 0. 3 Nb 0. 6 Ti 0. 1 O 3 ) was studied and compared using high-resolution x-ray and neutron diffraction.
Abstract: Structural evolutions of PMN/PT10% (PbMg 0 . 3 Nb 0 . 6 Ti 0 . 1 O 3 ) and PMN (PbMg 1 / 3 Nb 2 / 3 O 3 ) are studied and compared using high-resolution x-ray and neutron diffraction. At high temperature, PMN-like diffuse scattering, associated with local disordered shifts, is evidenced by PMN/PT10%. A part of this intensity condenses at T c =285 K when PMN/PT10% exhibits a structural phase transition toward a long-range rhombohedral phase, whereas in PMN the polar order remains short ranged. In the ferroelectric phase of PMN/PT10% local [100] displacements of lead are evidenced, and are connected to the observation of diffuse scattering far below T c . The local symmetry in which oxygen and Ti/Mg/Nb cations are shifted along the [111] direction, but in which the lead atoms are shifted along one of the tetragonal [100] directions is monoclinic. This short-range polar order reconstructs on average a polar rhombohedral symmetry. A global picture for the structural evolution in the PMN/PT compounds is proposed. It is based on competition between rhombohedral and tetragonal polar order, which connects the relaxation properties of PMN and the high piezoelectric response of morphotropic monoclinic PMN/PT with a high concentration of PT.
180 citations
TL;DR: The results of a neutron diffraction study of the antiferromagnet MnO embedded in a porous glass show the size of the magnetic region is smaller than the average size ofThe nanoparticles, and the reasons for this behavior are discussed.
Abstract: We present the results of a neutron diffraction study of the antiferromagnet MnO embedded in a porous glass. The type of magnetic ordering and the structural distortion are similar to those of the bulk, but the ordered magnetic moment of 3.84(4){mu}{sub B}/ion is strongly reduced and the Neel temperature is enhanced. The magnetic transition is second order, in contrast to the first order transition of the bulk. The size of the magnetic region is smaller than the average size of the nanoparticles. The reasons for this behavior are discussed.
69 citations