Phase change in calcination process for BaTi2O5 and proposal of a new temperature profile

• Rutile-type TiO2 is available as a raw material for BaTi2O5 (BT2) calcination.
• Slow heating is effective to obtain BT2 phase.
• Two narrow temperature ranges exist in which slow heating is effective to obtain BT2 phase.
• The slow heating between 800 and 850 °C probably prevents the formation of BaTiO3 single particles.
• Use of powder compacts is effective to obtain BT2 phase compared with powder form.

The mixture of BaCO3 and rutile-type TiO2 powders mixed with wet ball-milling was calcined in air and the phase change in calcination process was investigated in detail. The slow heating in the temperature range from 800 to 850 °C was effective to change BaTiO3 to BaTi2O5 in the following heating process. The influence of two factors in calcination for the synthesis of BaTi2O5, which are temperature profile with slow heating and packing state of the mixture, was investigated. The slow heating in two temperature ranges, 800–850 °C and 1100–1160 °C, was effective for the synthesis of BaTi2O5. The production amount of BaTi2O5 was increased by using powder compacts rather than powder form. By calcining powder compacts at 1160 °C for 2 h, the powder of BaTi2O5 having an αs value of 0.93, which is semi-quantitatively corresponding to BaTi2O5 production ratio, was obtained.

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