The double-peak phenomenon of the phase transition of Rb substituting K in LiKSO₄, competition between Rb sub-lattice and smearing the phase transition

Abstract

The influence of Rb in the triple sulfate LiK(1−x)RbxSO4 (0 ≤ x ≤ 0.2) compound on the structural and thermal properties of the bulk material is discussed. Samples were prepared by fusing the sulfates in stoichiometric ratios in a platinum crucible at 1273 K for 30 min. The x-ray powder diffraction measurements were performed at ambient temperature. The crystal structure parameters were refined by the Rietveld method using the FullProf program. The analysis indicated a single-phase having a hexagonal symmetry with space group P63 regardless of the Rb content. Thermal analysis by differential scanning calorimetry shows a considerable shift of the phase transition point towards lower temperatures with increasing Rb content. A pretransitional effect is observed by differential thermal analysis of the sample without Rb contribution while for the sample with 20% Rb the transition is represented by double endothermic peaks. The energy of transition has been estimated using the Kissinger method for samples with different concentrations of Rb

Microstructural study and numerical simulation of phase decomposition of heat treated Co–Cu alloys

“…However, due to significant overlapping of Bragg reflections for Co-Cu alloys, the possibility of texture effect becomes more dominant and accuracy of phase quantification diminishes. An alternative method for structure refinement is the Rietveld method (RM) [17][18][19][20][21][22]. RM eliminates peaks overlapping by explicitly including all lines for each phase in the refinement.…”

Crystallography and Computer Simulation of Heat Treated Co- 10 at. Pct. Cu Alloys

“…Phase compositions are quantified by x-ray diffraction (XRD) technique. An alternative method for structure refinement is the Rietveld method (RM) [17][18][19][20]. It has been established that phase decomposition in multiphase alloy is controlled by the change in free energy of the system.…”