THERMAL PROPERTIES AND HOMOGENITY RANGE OF Bi24+xCo2-xO39 CERAMICS

• Main Authors: O. JANKOVSKY, D. SEDMIDUBSKY, Z. SOFER, J. CAPEK, K. RUZICKA
• Format: Article
• Language: English
• Published: University of Chemistry and Technology, Prague 2013-07-01
• Series: Ceramics-Silikáty
• Subjects: Cobalt sillenite; Thermal properties; Heat capacity
• Online Access: http://www.ceramics-silikaty.cz/2013/pdf/2013_02_83.pdf
• ISSN: 0862-5468; 1804-5847

Samples with different Bi2O3/Co2O3 ratio were prepared by ceramic route. Based on the results of DTA, XRD and SEM – EDX a section of phase diagram of the Bi–Co–O diagram in air atmosphere was calculated using the FactSage software. The sillenite structure of Bi24+xCo2-xO39 was confirmed and described. The Rietveld analysis confirmed SEM – EDX results. The heat capacity and enthalpy increments of Bi24Co2O39 were measured by differential scanning calorimetry (DSC) from 258 K to 355 K and by the drop calorimetry from 573 K to 973 K. Above room temperature the temperature dependence of the molar heat capacity in the form Cpm = (1467.87 + 0.299410 · T – 15888378 · T-2) J K-1 mol-1 was derived by least-squares method from the experimental data.