Combined Dilatometer‐Mass Spectrometer Analysis of the Sintering of Barium Titanate

Evolved gas analysis during sintering of barium titanate

“…13 Although no swelling of the sample was observed in the dilatometer trace at the heating rate of 14°C/min used here, temporary excess expansion was observed at 1100°C for a heating rate of 20°C/min. 16 Finally, we note that the gas evolution from BaTiO 3 has a number of similarities to the gases evolved from SrTiO 3 . 6 For both perovskites, CO 2 evolution preceded that of SO 2 and in greater amount.…”

“…The CDMS apparatus, described in detail elsewhere, 6,16 consists of a furnace housing a pushrod dilatometer unit, a gas flow system and a MS. A mullite combustion tube separates the sample environment from the heating elements of the furnace. Prior to each experiment, the combustion tube is evacuated twice to 0.06 mbar and backfilled with high purity helium (99.999%) to 1 bar, and then a gas flow rate is set at 135 cm 3 /min.…”

“…At temperatures above 500°C in the presence of carbon, reaction 8 dominates over reaction 9, resulting in an increased CO signal and cracked species ( 12 C, 16 O) relative to CO 2 . The source of the carbon may come from trace impurities in the raw materials or from the carbonate synthesis route (see reaction 2).…”

“…Another source for the family of traces in Fig. 4 is the presence of SO 2 (m/z = 64), and its corresponding cracked species of 32 S 16 O (m/z = 48), 32 S (m/z = 32) and 16 O (m/z = 16). These species may arise from the oxidation of trace sulphur or from the decomposition of barium sulphate, respectively, as:…”

“…This design was used for studying the background gas chemistry in graphite furnaces 14 as well as the sintering and decomposition of calcium carbonate, 15 an important candidate material for flue gas amelioration. A more recent configuration 6,16 has utilised a silica capillary for transporting the evolved gases to the MS; this design has been shown to yield high signal intensity, high mass-to-charge resolution, excellent temperature resolution and can be used semi-quantitatively.…”