scholarly journals First-principles research on the effect of high oxygen vacancy concentration in anatase TiO2 on Mott phase transition， absorption spectrum Einstein shift and life_time of electrons

2008 ◽  
Vol 57 (3) ◽  
pp. 1862
Author(s):  
Hou Qing-Yu ◽  
Zhang Yue ◽  
Zhang Tao
Keyword(s):  
Phase Transition ◽  
Absorption Spectrum ◽  
Oxygen Vacancy ◽  
First Principles ◽  
Vacancy Concentration ◽  
Anatase Tio2 ◽  
High Oxygen ◽  
Oxygen Vacancy Concentration ◽  
Mott Phase ◽  
Transition Absorption

scholarly journals Computationally accelerated discovery of high entropy pyrochlore oxides

2021 ◽  
Author(s):  
Krishna Chaitanya Pitike ◽  
Antonio Macias ◽  
Markus Eisenbach ◽  
Craig Bridges ◽  
Valentino Cooper
Keyword(s):  
Monte Carlo ◽  
Oxygen Vacancy ◽  
First Principles ◽  
Degrees Of Freedom ◽  
Vacancy Concentration ◽  
Oxygen Vacancy Concentration ◽  
High Entropy ◽  
Impurity Phases ◽  
Wide Range ◽  
Pyrochlore Oxides

Abstract High entropy ceramics provide enhanced flexibility for tailoring a wide range of physical properties, emerging from the diverse chemical and configurational degrees of freedom. Expanding upon the endeavors of recently synthesized high entropy ceramics in rock salt, fluorite, spinel and perovskite structures, we explore the relative feasibility of formation of high entropy pyrochlore oxides, A2B2O7, with multi-cation occupancy of the B-site, estimated from first principles based thermodynamic descriptors. Subsequently, we used Monte Carlo simulations to estimate the phase composition, oxygen vacancy concentration and local ionic segregation as a function of temperature and oxygen partial pressure. In parallel, we have investigated the synthesis of several multicomponent oxides with a pyrochlore composition, related to our computational investigations, resulting in several high purity pyrochlore oxides, in some cases with minor impurity phases. Ultimately, our approach allows us to evaluate potential impurity phases, ionic disorder and oxygen vacancy concentration in response to the experimental variables, thereby making realistic predictions that can direct and accelerate experimental synthesis of novel multicomponent ceramics.

scholarly journals Combined iDPC and EELS analyses for quantifying oxygen vacancy concentration in LSMO

2021 ◽  
Vol 27 (S1) ◽  
pp. 1196-1197
Author(s):  
Aubrey Penn ◽  
Sanaz Koohfar ◽  
Divine Kumah ◽  
James LeBeau
Keyword(s):  
Oxygen Vacancy ◽  
Vacancy Concentration ◽  
Oxygen Vacancy Concentration

scholarly journals Effects on Microstructure and Ionic Conductivity of the Co-Doping with Strontium and Samarium of Ceria with Constant Oxygen Vacancy Concentration

Solids ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 341-370
Author(s):  
Toby Sherwood ◽  
Richard T. Baker
Keyword(s):  
Oxygen Vacancy ◽  
Grain Boundary ◽  
Vacancy Concentration ◽  
Synthesis Method ◽  
Ionic Conductivities ◽  
Solubility Limit ◽  
Material Structure ◽  
Oxygen Vacancy Concentration ◽  
Co Doping ◽  
Phase Pure

Partially substituted cerias are attractive materials for use as electrolytes in intermediate-temperature solid oxide fuel cells (SOFCs). Ceria doped with Sm or Gd has been found to have high ionic conductivities. However, there is interest in whether doping with multiple elements could lead to materials with higher ionic conductivities. The present study looks at the effects of co-doping Sr and Sm in ceria. A compositional series, Ce0.8+xSm0.2−2xSrxO2−δ (with x = 0–0.08), designed to have a constant oxygen vacancy concentration, was successfully prepared using the citrate–nitrate complexation method. A solubility limit of ~5 cation% Sr was found to impact material structure and conductivity. For phase-pure materials, with increasing Sr content, sinterability increased slightly and intrinsic conductivity decreased roughly linearly. The grain boundaries of phase-pure materials showed only a very small blocking effect, linked to the high-purity synthesis method employed, while at high %Sr, they became more blocking due to the presence of a SrCeO3 impurity. Grain capacitances were found to be 50–60 pF and grain boundary capacitances, 5–50 nF. The variation in the bulk capacitance with Sr content was small, and the variation in grain boundary capacitance could be explained by the variation in grain size. Slight deviations at high %Sr were attributed to the SrCeO3 impurity. In summary, in the absence of deleterious effects due to poor microstructure or impurities, such as Si, there is no improvement in conductivity on co-doping with Sr and Sm.

Magnetic State of Ba-Doped Manganites Depending on the Oxygen Vacancy Concentration

2002 ◽  
Vol 233 (2) ◽  
pp. 321-330 ◽  
Author(s):  
S.V. Trukhanov ◽  
N.V. Kasper ◽  
I.O. Troyanchuk ◽  
H. Szymczak ◽  
K. B�rner
Keyword(s):  
Oxygen Vacancy ◽  
Magnetic State ◽  
Vacancy Concentration ◽  
Oxygen Vacancy Concentration ◽  
Doped Manganites
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