THERMAL PROPERTIES AND HOMOGENITY RANGE OF Bi_24+xCo_2-xO₃₉ CERAMICS

摘要

Samples with different Bi2O3/Co2O3 ratio were prepared by ceramic route. Based on the results of DTA, XRD and SEM – EDXa section of phase diagram of the Bi–Co–O diagram in air atmosphere was calculated using the FactSage software. Thesillenite structure of Bi_(24+x)Co_(2-x)O_(39) was confirmed and described. The Rietveld analysis confirmed SEM – EDX results. Theheat capacity and enthalpy increments of Bi_(24)Co_(2)O_(39) were measured by differential scanning calorimetry (DSC) from 258 Kto 355 K and by the drop calorimetry from 573 K to 973 K. Above room temperature the temperature dependence of the molarheat capacity in the form Cpm = (1467.87 + 0.299410 · T – 15888378 · T~(-2)) J K~(-1) mol~(-1) was derived by least-squares methodfrom the experimental data.