Research output: Contribution to journal › Article › peer-review
2D diffusion of oxygen in Ln10Mo2O21 (Ln = Nd, Ho) oxides. / Sadykov, Vladislav; Shlyakhtina, Anna; Sadovskaya, Ekaterina et al.
In: Solid State Ionics, Vol. 346, 115229, 03.2020.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - 2D diffusion of oxygen in Ln10Mo2O21 (Ln = Nd, Ho) oxides
AU - Sadykov, Vladislav
AU - Shlyakhtina, Anna
AU - Sadovskaya, Ekaterina
AU - Eremeev, Nikita
AU - Skazka, Valeriy
AU - Goncharov, Vladimir
PY - 2020/3
Y1 - 2020/3
N2 - Ln molybdates are promising materials for hydrogen/oxygen separation membranes. This work aims at elucidating features of oxygen transport in Ln10Mo2O21 (Ln = Nd, Ho) oxides using novel 2D diffusion models. Nd10Mo2O21 and Ho10Mo2O21 were synthesized by the mechanical activation followed by sintering in the 1600–1650 °C temperature range and characterized by XRD as a complex rhombohedral phase and fluorite one, respectively. Oxygen transport features were studied by the oxygen isotope heteroexchange with C18O2 in a flow reactor using temperature-programmed and isothermal modes. According to numerical analysis, isotope exchange in Ln10Mo2O21 cannot be described by a single diffusion coefficient, which is explained by nonuniformity of the oxygen diffusion pathways. The mathematical model including equations for a faster diffusion along grain boundaries and a slower diffusion within grain bulk (2D diffusion model) gives the best fit. The same accuracy was achieved using the model including 2D diffusion and exchange between grain bulk oxygen forms with different M-O bonds strength. The values of oxygen tracer diffusion coefficient are ~10−7–10−6 cm2/s and ~10−11–10−8 cm2/s at 700 °C along grain boundaries and within grain bulk, respectively. Hence, new 2D models were developed to describe oxygen diffusion in polycrystalline oxides. A fast oxygen diffusion demonstrated for Ln10Mo2O21 oxides makes them promising for design of hydrogen/oxygen separation membranes.
AB - Ln molybdates are promising materials for hydrogen/oxygen separation membranes. This work aims at elucidating features of oxygen transport in Ln10Mo2O21 (Ln = Nd, Ho) oxides using novel 2D diffusion models. Nd10Mo2O21 and Ho10Mo2O21 were synthesized by the mechanical activation followed by sintering in the 1600–1650 °C temperature range and characterized by XRD as a complex rhombohedral phase and fluorite one, respectively. Oxygen transport features were studied by the oxygen isotope heteroexchange with C18O2 in a flow reactor using temperature-programmed and isothermal modes. According to numerical analysis, isotope exchange in Ln10Mo2O21 cannot be described by a single diffusion coefficient, which is explained by nonuniformity of the oxygen diffusion pathways. The mathematical model including equations for a faster diffusion along grain boundaries and a slower diffusion within grain bulk (2D diffusion model) gives the best fit. The same accuracy was achieved using the model including 2D diffusion and exchange between grain bulk oxygen forms with different M-O bonds strength. The values of oxygen tracer diffusion coefficient are ~10−7–10−6 cm2/s and ~10−11–10−8 cm2/s at 700 °C along grain boundaries and within grain bulk, respectively. Hence, new 2D models were developed to describe oxygen diffusion in polycrystalline oxides. A fast oxygen diffusion demonstrated for Ln10Mo2O21 oxides makes them promising for design of hydrogen/oxygen separation membranes.
KW - 2D diffusion
KW - 6170N
KW - 6610M
KW - 6630D
KW - 8220P
KW - 8220W
KW - 8610B
KW - Isotope exchange of oxygen
KW - Ln molybdates
KW - Mathematical modeling
KW - Oxygen diffusion
KW - TRANSPORT-PROPERTIES
KW - ANOMALOUS TRANSPORT
KW - ION
KW - MODEL
KW - NONSTOICHIOMETRIC PEROVSKITES
KW - GRAIN-BOUNDARY
KW - MICROSTRUCTURE
UR - http://www.scopus.com/inward/record.url?scp=85078570565&partnerID=8YFLogxK
U2 - 10.1016/j.ssi.2020.115229
DO - 10.1016/j.ssi.2020.115229
M3 - Article
AN - SCOPUS:85078570565
VL - 346
JO - Solid State Ionics
JF - Solid State Ionics
SN - 0167-2738
M1 - 115229
ER -
ID: 23263913