Phase change of hydromagnesite, Mg₅(CO₃)₄(OH)₂・4H₂O by thermal decomposition

Abstract

In-site high temperature powder XRD was performed to clarify the phase transition behavior of hydromagnesite at high temperature. The measurements were made over a temperature range from 20 ℃ to 320 ℃ in 30 ℃ increments. No significant change in the peak profile was observed up to 170 ℃, but some peaks become weaker from 200 ℃. All peaks finally disappeared at 290 ℃, and peaks corresponding to periclase appeared at 320 ℃. Therefore, hydromagnesite undergoes the following phase change at high temperature around 300 ℃. Mg₅(CO₃)₄(OH)₂・4H₂O -> 5MgO + 4CO₂ + 5H₂O.