Enhancement of electrical conductivity in MgO due to lithium impurities

Chen, Y.; Kernohan, R. H.; Boldú, J. L.; Abraham, M. M.; Eisenberg, D.J.; Crawford, J. H.

doi:10.1016/0038-1098(80)90439-1

Cited by 32 publications

(11 citation statements)

References 10 publications

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“…[3][4][5] After oxidation at high temperatures, the resulting hole-trapped centers are responsible for the p-type semiconducting properties observed at temperatures not much higher than RT. 5 By analogy, Al 2 O 3 :Mg crystals are expected to serve as a p-type semiconductor.…”

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confidence: 99%

High temperature semiconducting characteristics of magnesium-doped α-Al2O3 single crystals

Tardío

Ramı́rez

González

et al. 2001

Applied Physics Letters

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DC and AC electrical measurements were performed to investigate the electrical conductivity of α − Al 2 O 3 : Mg samples with different concentrations of [Mg] 0 centers (Mg ions each with a trapped hole) in the temperature interval 250-800 K. The concentration of [Mg] 0 centers was monitored by the optical absorption peak at 2.56 eV. These centers were produced by oxidation at temperatures above 1050 K. The formation rate of [Mg] 0 centers depends on the previous thermal history of the sample in either reducing or oxidizing atmosphere.At low electrical fields, DC measurements reveal blocking contacts. At high fields, the I-V characteristic is similar to that of a diode (corresponding to a blocking contact at one side of the sample and an ohmic contact at the other side) connected in series with the bulk resistance of the sample. Steady electroluminescence is emitted at the negative electrode when a current in excess of ≈ 10 µA passes through the sample, indicating that the majority of carriers are holes.Low voltage AC measurements show that the equivalent circuit for the sample is the bulk resistance in series with the junction capacitance (representing the blocking contacts) connected in parallel with a capacitance, which represents the dielectric constant of the sample. The values determined for the bulk resistance in both DC and AC experiments are in good agreement. The electrical conductivity of Al 2 O 3 : Mg crystals increases linearly with the concentration of [Mg] 0 centers, regardless of the amount of other impurities also present in the crystals, and is four times higher in the c ⊥ than in the c || direction. The conductivity is thermally activated with an activation energy of 0.68 eV, which is independent of: 1) the [Mg] 0 content, 2) the crystallographic orientation, and 3) the concentration of other impurities. These results favor the small-polaron-motion mechanism.

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confidence: 99%

High temperature semiconducting characteristics of magnesium-doped α-Al2O3 single crystals

Tardío

Ramı́rez

González

et al. 2001

Applied Physics Letters

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“…At room temperature (RT) their electrical conductivities are 10 −18 and < 10 −20 (Ωcm) −1 , respectively [1,2,3]. Replacing the host cation with an aliovalent impurity should in principle result in either electron or hole conduction, although the presence of other impurities, which act as charge compensators, might hinder this effect.…”

Section: Introductionmentioning

confidence: 99%

“…In both systems hole-trapped centers are formed after oxidation at high temperatures. These centers are responsible for the electrical conductivity enhancement [3,4,5,6].…”

Section: Introductionmentioning

confidence: 99%

p-type semiconducting properties in lithium-doped MgO single crystals

et al. 2002

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The phenomenally large enhancement in conductivity observed when Li-doped MgO crystals are oxidized at elevated temperatures was investigated by dc and ac electrical measurements in the temperature interval 250-673 K. The concentration of [Li] 0 centers (Li + ions each with a trapped hole) resulting from oxidation was monitored by optical absorption measurements.At low electric fields, dc measurements reveal blocking contacts. At high fields, the I − V characteristic is similar to that of a diode connected in series with the bulk resistance of the sample.

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“…The good electrochemical properties of all nanocomposite electrodes were attributed to the following factors: the uniform distribution of active nanocrystallites in the matrix and the buffering effect of the various matrices, such as carbon and ceramics. Among the above matrices, the carbon matrix, having higher electrical conductivity [27][28][29], was better than the ceramic matrix because it facilitated better electrochemical reversibility of cobalt oxide-based electrodes.…”

Section: Resultsmentioning

confidence: 98%

Nanostructured cobalt oxide-based composites for rechargeable Li-ion batteries

Lee

Song

et al. 2012

J Solid State Electrochem

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Cobalt oxide-based nanocomposites are prepared using Co 3 O 4 , various metals (Al, Mg), carbon powders, and a simple high-energy mechanical milling technique. X-ray diffraction, X-ray photoelectron spectroscopy, and highresolution transmission electron microscopy show that the cobalt oxide-based composites are mainly composed of nanostructured CoO/Al 2 O 3 , CoO/MgO, and Co 3 O 4 /C composites, respectively. Based on concepts related to the enhanced electrical conductivity of the Co 3 O 4 /C nanocomposite using conducting carbon matrix and to the resistance of inactive ceramic matrices (Al 2 O 3 , MgO) against active CoO particle growth during cycling, various nanostructured cobalt oxidebased composites are tested for use as anode materials. Among the composites, the Co 3 O 4 /C nanocomposite anode exhibits good electrochemical characteristics, such as highcapacity, good initial Coulombic efficiency, and long cycle behavior for Li-ion batteries.

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Enhancement of electrical conductivity in MgO due to lithium impurities

Cited by 32 publications

References 10 publications

High temperature semiconducting characteristics of magnesium-doped α-Al2O3 single crystals

High temperature semiconducting characteristics of magnesium-doped α-Al2O3 single crystals

p-type semiconducting properties in lithium-doped MgO single crystals

Nanostructured cobalt oxide-based composites for rechargeable Li-ion batteries

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