Journal of the Physical Society of Japan · 1987 · 49 citations · 9 references
Natural SciencesMaterials SciencePhysicsCondensed Matter PhysicsCrystal StructureSolid State PhysicsCrystal ChemistryCrystal LatticeCrystallographyPhase TransitionsX-ray CrystallographyX-ray DiffractionAntiferroelectric TransitionsCommensurate TransitionsCommensurate-incommensurate TransitionsCrystallographic Phase TransitionsCrystallographic Symmetry AnalysisDifference Fourier MapsSpatial OccupationX-ray Diffraction Analysis
The crystal structures of LiRbSO 4 are analyzed in the disordered phase (250, 220 and 210°C), the antiferroelectric phase (190°C), the ferroelectric phase (170°C) and the paraelectric phase (160 and -100°C) from X-ray diffraction data. In the disordered phase, it is concluded that the SO 4 tetrahedron is in disorder by using of the split atom method as well as the difference Fourier maps. Following the incommensurate-commensurate transition, the tetrahedra occupy one of two configurations alternately. The modulation period 2 c 0 at 190°C is elongated to 5 c 0 in the ferroelectric phase, where c 0 is the basic cell dimension in the disordered phase. The structural transformation is characterized by the change of the occupation pattern of the SO 4 tetrahedron correlated to the displacement of its center of mass and positions of Li and Rb atoms.
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Significance tests on the crystallographic <i>R</i> factor
Walter C. Hamilton · Acta Crystallographica · 1965 · 1.9K citations
Natural Sciences, Chemistry, Physics +11