研究目的
To refine the symmetry, structural features, and point defects in Czochralski-grown single crystals with the initial compositions CeSc3(BO3)4 and Nd1.25Sc2.75(BO3)4 using the full-profile Rietveld method on synchrotron X-ray powder data.
研究成果
The Rietveld refinement reveals the crystallization of Czochralski-grown powdered single crystals with the initial charge compositions CeSc3(BO3)4 and Nd1.25Sc2.75(BO3)4 in the space group P321. The real crystal compositions are found to be CeSc3(BO3)4 and [Nd0.455(1)Sc0.045(39)(1)]Nd0.500(2)Sc3(BO3)4 with antisite defect, Sc in Nd1 trigonal-prismatic site. X-ray diffraction studies exclude the crystallization of these compounds in the space group R32.
研究不足
The study's limitations include the difficulty of revealing the space group P321 due to the almost complete similarity of theoretical diffraction patterns for the space groups R32 and P321, except for the redistribution of the intensities of a number of reflections.
1：Experimental Design and Method Selection
The study employed the full-profile Rietveld method on synchrotron X-ray powder data to analyze the symmetry, structural features, and point defects in the crystals.
2：Sample Selection and Data Sources
Single crystals with the initial compositions CeSc3(BO3)4 (CSB-1.0) and Nd1.25Sc2.75(BO3)4 (NSB-1.25) were grown by the Czochralski technique. Microprobe samples were taken from powdered crystals and investigated by X-ray powder diffraction.
3：List of Experimental Equipment and Materials
The X-ray powder diffraction was performed at the X-ray structural analysis beamline of the Kurchatov Synchrotron Radiation Source using the Rayonix SX 165 two-dimensional detector.
4：Experimental Procedures and Operational Workflow
The 'transmission' scheme with the registration of the spatial pattern at the wavelength λ = 0.78972 ? was applied. The 2D diffraction patterns obtained on the detector were integrated to the standard form of the dependence of the intensity on the scattering angle I(2θ) using Dionis software.
5：Data Analysis Methods
The crystal structure was refined using Rietveld profile refinement principles with the Jana2006 software. The refinement included unit cell parameters, coordinates of atoms, the atomic displacement parameters, and the occupancies of RE, Sc, B, and O crystallographic sites.
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