Thermal behavior during the synthesis of spin-ladder compound Sr_(14-x)Ca_xCu_(24)O_(41)

摘要

The thermal behavior of (14-x)SrCO_3-xCaCO_3-24CuO 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 Sr_(14-x)Ca_xCu_(24)O_(41). In the temperature region 900-1000 deg 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 Sr_(14-x)Ca_xCu_(24)O_(41). 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.