Thermal behavior during the synthesis of spin-ladder compound Sr14−xCaxCu24O41

The thermal behavior of (14−x)SrCO3-xCaCO3-24CuO system has been investigated using combined differential thermal analysis (DTA) and X-ray diffraction (XRD) measurements to get a better understanding of solid-state chemical changes resulting in the synthesis of spin-ladder compound Sr14−xCaxCu24O41. In the temperature region 900-1000 °C, the DTA curves present one and two endothermic peaks for x≤5.6 and x≥8.4, respectively. XRD measurements demonstrated that for x≤5.6, the solid-state reaction consists of three stages and leads to the formation of the single-phase Sr14−xCaxCu24O41. It is found that both XRD and DTA methods can be employed independently to determine the composition or temperature region in which the pure phase forms.