The Hall mobility of electrons and holes in MnO at high temperature

Gvishi, M.; Tallan, N. M.; Tannhauser, D. S.

doi:10.1016/0038-1098(68)90018-5

Cited by 24 publications

(7 citation statements)

References 3 publications

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“…the Δ H f (V Mn ) line would be shifted further upward. , A possible source of this difference is the temperature and phase of the MnO in our work, although we also suggest that a lack of long-distance exchange coupling may have affected the V Mn calculations, which could possibly be rectified by consideration of a larger QM region. Overall, the presence of a stability window for e′ charge carriers is in agreement with (high temperature) Hall measurements that show the existence of e′ charge carriers with higher mobility than h • at low- p (O 2 ). ,− …”

Section: Bulksupporting

confidence: 85%

Hybrid-DFT Modeling of Lattice and Surface Vacancies in MnO

et al. 2018

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We have investigated the properties of defects in MnO bulk and at (100) surfaces, as used in catalytic applications, using hybrid-level density functional theory (i.e., inclusion of exact exchange within the exchange-correlation evaluation) in a hybrid QM/MM embedded-cluster approach. Initially, we calculate the formation energy for bulk Mn and O vacancies, comparing charged-defect compensation with charge carriers at the Fermi Level (ϵ f ) and through Schottky defect formation. Oxygen vacancies were also investigated at the (100) surface, where the vacancy formation energy is very similar to the bulk. Defect levels associated with the most stable vacancies are calculated using the ΔSCF method: all are positioned mid band gap, with surface environments failing to alter strongly the overall nature of the defect relative to bulk. Chemical activity of the (100) MnO surface was considered through the adsorption of a probe CO 2 molecule, which is considered the initial step in the transformation of CO 2 into hydrocarbons. CO 2 adsorption was strongest over a neutral oxygen vacancy, where the associated trapped electrons of the defect transfer to the adsorbate and thus activate it. However, we have shown with our embedded-cluster approach that the neutral oxygen vacancy is not necessarily the dominant species, which has implications when interpreting results for future catalytic applications.

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Section: Bulksupporting

confidence: 85%

Hybrid-DFT Modeling of Lattice and Surface Vacancies in MnO

et al. 2018

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“…To the best of the authors' knowledge, whiskers of beta-rhombohedral boron prepared by CVD have not been reported in the literature. to purify (5). Prior to attempting whisker growth, rates of deposition of boron on resistively heated Ta strips at various molar ratios (H2/BBr3) and flow rates were determined.…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown that the mobility of the electron is much greater than that for electron holes in MnO (5)(6)(7). This means that the predominant type of nonstoichiometric disorder is metal deficit at the p-to n-type transition and for at least some range of the n-type MnO.…”

Section: 'O(rt) -1 --T ~-20(rt) -1 + 20(rt) -1 [5]mentioning

confidence: 99%

“…Electrical conductance, Seebeck effect, and thermogravimetric measurements on polycrystalline and single-crystal samples over the temperature range 1100~176 have been interpreted on the basis of a predominantly metal deficit compound with the mobility of electrons much greater than that for electron holes. This mobility ratio was later calculated to be approximately 50 at 943~ on the basis of Hall effect measurements on a MnO single crystal (5). DeWit and Crevecoer (6,7) have confirmed that the mobility of electrons is much greater than that for electron holes at elevated temperatures and report a ratio of approximately 1000 at ll00~ for polycrystalline MnO.…”

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confidence: 96%

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Nonstoichiometric Disorder in Single Crystalline MnO

Eror

Wagner²

1971

J. Electrochem. Soc.

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The electrical conductivity of single crystalline manganous oxide was investigated over the temperature range of 900°–1150°C while in thermodynamic equilibrium with oxygen partial pressures of 10−6–10−21 atm. Results indicated that normalMnO may be either p‐ or n‐type. Slopes of 1/6 and −1/6 are obtained from the log σ vs. log PO2 data for the p‐ and n‐type regions, respectively. Thermogravimetric measurements at thermodynamic equilibrium support the evidence of the electron mobility being much greater than that for electron holes in normalMnO . The enthalpies of formation of nonstoichiometric disorder and activated enthalpy of movement of electron holes in p‐type normalMnO were determined to be −18 and 12 kcal/mole, respectively. The bandgap of normalMnO was calculated from the minima of the log σ vs. log PO2 data to be 52.8 kcal/mole (2.3 eV).

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“…This was paper 530 presented at the Montreal Meeting of the Society, Oct. [6][7][8][9][10][11] 1968.…”

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confidence: 99%