Evidence for two new crystalline forms of sodium peroxide

Theoretical predictions for low-temperature phases, softening of phonons and elastic stiffnesses, and electronic properties of sodium peroxide under high pressure

“…Moreover, the AIRSS results at ambient pressure revealed that the simulated XRD patterns of the structures look like the XRD patterns calculated from the experimental results of Tallman et al 8 One is the I4/mmm structure which is approximate to the Na 2 O 2 -II at 550 C ( Fig. S3, ESI †), and the other structures (C2/m, Pmmm, and Immm) are close to the Na 2 O 2 -Q at room temperature ( Fig.…”

“…In addition, Tallman et al 8 reported evidence for two new phases of Na 2 O 2 that were observed over the range of 25-550 C. One was found at 512 C, and the other was found at room temperature and was prepared by pouring liquid Na 2 O 2 into liquid air. 8,9 They suggested that the quenched Na 2 O 2 may be stable in the temperature range of 596-675 C or at low temperature. 8 However, the crystal structures of the two phases have not been identied.…”

“…8,9 They suggested that the quenched Na 2 O 2 may be stable in the temperature range of 596-675 C or at low temperature. 8 However, the crystal structures of the two phases have not been identied. Therefore, the determination of new phase structures of Na 2 O 2 at room and high temperature needs guidance from theoretical prediction.…”

Recent results in solid state chemistry of ionic ozonides, hyperoxides, and peroxides

“…The existence of two additional high-temperature modifications of this compounds, as quoted by Tallman et al [212], explaining the thermal anomalies described by Föppel [196], has never been proved.…”

Unveiling the charge migration mechanism in Na2O2: implications for sodium–air batteries

“…Na 2 O 2 crystallises in a P62m hexagonal space group with the peroxides lying parallel to the c axis, one in each corner of the structure and two more inside. [27][28][29] Each peroxide is surrounded basically by 9 sodium ions. Tallman 28 reported a melting point value of 675 1C for Na 2 O 2 with a structural transition occurring at 512 1C and another possible transition around 596 1C.…”