Structural investigation of the oxide-ion electrolyte with SrMO₃(M = Si/Ge) structure

Nature of conductivity in SrSiO3-based fast ion conductors

“…4,5 A neutron powder diffraction study on Na and K-doped samples excluded the presence of interstitial oxygen ions in both the systems and suggested that oxide ion vacancies, consistent with the nominal compositions, are present at r.t. and 400 1C for Sr 0.6 Na 0.4 SiO 2.8 , while a larger oxygen under-stoichiometry is expected at 800 1C. 7 In this work we present a detailed study of the structural and transport properties of the Sr 1Àx Na x SiO 3À0.5x series (x = 0.05, 0.25, 0.45). We propose that the complexity of the SiO 2 -Na 2 O-SrO phase diagram must be taken into consideration, as the actual solubility degree of Na in the SrSiO 3 phase may be significantly lower than expected due to the possibility of formation of secondary, spurious and metastable glassy phases.…”

On Sr1–xNaxSiO3–0.5x New Superior Fast Ion Conductors

“…[1][2][3][4][5] The exceptional transport properties were correlated with neutron diffraction based conclusions that K and Na get stoichiometrically doped into SrSiO 3 , creating large numbers of O 2 vacancies and giving rise to oxide ion conduction. 4 Most recently, excellent performance of the Sr 1−x Na x SiO 3−0.5x (x=0.45) composition in a fuel cell was reported. 6 However, a very recent publication on related K-and Ge-doped SrSiO 3 (which we became aware of during the final preparation of this manuscript), reported a direct investigation of oxide ion diffusivity of a nominal Sr 0.8 K 0.2 Si 0.5 Ge 0.5 O 2.9 composition by Isotope Exchange Depth Profiling (IEDP) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), which found no evidence of O 2 diffusion.…”

Phase Relationship and Ionic Conductivity in Na–SrSiO3 Ionic Conductor

“…It is evident that the majority of samples ( x = 0.1–0.8) can be indexed into a crystal structure of SrSiO 3 (PDF No. 36‐0018, c2/c, space group (15)) as reported by Singh et al . A minor impurity phase β‐Sr 2 SiO 4 (PDF No.…”

“…The best conductivity reported was in the order of 0.01 S/cm at 550°C. Oxygen vacancies were thought to be created by A‐site acceptor doping and located within the Si 3 O 9 units between the Sr and Na layers …”

“…Oxygen vacancies were thought to be created by A-site acceptor doping and located within the Si 3 O 9 units between the Sr and Na layers. 10 Since the first report of this material, numerous studies aiming to understand the ionic conduction mechanisms have been carried out. Xu et al confirmed the local crystalline structure of Sr 0.7 K 0.3 SiO 2.85 with nuclear magnetic resonance spectroscopy and neutron diffraction, 11 while others instead suggested that this material consisted of a mixture of a crystalline and amorphous phase.…”