Surface texture of strontium carbonate

Two batches of strontium carbonate (SrCO3) prepared at temperatures <=333 Kd(A) and 373 K (B) were investigated using differential thermal analysis (DTA), thermogravimetric (TG), X-ray diffraction (XRD) and N2 adsorption techniques. Heat treatment up to 1073 K causes no material decomposition of the carbonate and DTA and TG results indicate impurity action. XRD patterns of both samples though slightly different at low temperatures, are identical with orthorhombic SrCO3 above 773 K. The N2 specific surface area of sample B is about three times that of sample A. Thermal treatment of batch A shows two regions of area development resulting from two different types of entrapped water whereas batch B shows only one region and contains only one type of entrapped water. Both samples and their decomposition products are predominantly lyophobic towards cyclohexane adsorption. With sample A the parent material was mesoporous. These pores widen at 423 K due to growth in grain size, but narrowing commences with the evolution of area at 573 K. At temperatures >= 773 K the pores widen again. Sample B contains both micro-and meso-pores with the latter dominating at higher temperatures where sintering operates. (author)