Ionic conductivity in three crystalline phases of LiBH<sub>4</sub>under pressure

Sundqvist, Bertil; Yao, Mingguang; Andersson, Ove

doi:10.1080/08957959.2012.762913

Cited by 4 publications

(13 citation statements)

References 24 publications

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“…This behavior is probably due to parasitic capacitances and inductances in the measurement circuit. No minima in Z″, such as those observed in our previous study on LiBH 4 [14], were found in this work. However, the results clearly show that the low-frequency data (f < 100 Hz) give reliable values for R.…”

Section: C 60contrasting

confidence: 67%

“…If both the resistance and the capacitance of the 'electrode' part are much larger than those of the sample the two arcs will be well defined and R dc can be found from the osculation point. In our earlier study on LiBH 4 [14] the continuous development from single-to double-arc plots during the transformation from the insulating to the superionic phase was very clear and we refer the reader to that work for details.…”

Section: Experimental and Analytic Methodsmentioning

confidence: 94%

“…Expressions for the real and imaginary parts of Z are easily found from circuit theory [16]. As in the case of LiBH 4 [14] we plotted Z″ as a function of Z′ (Cole-Cole plots [16]) and for large values of R the results usually fell on a semicircle (or, in practice, often a semiellipse) with one end, corresponding to infinite frequency, at the origin and the other end defining the dc value of R, R dc . Although measurements over a limited frequency range define only part of this arc a reasonably accurate value for R dc can still be extracted by this procedure from a simple extrapolation or curve fit.…”

Section: Experimental and Analytic Methodsmentioning

confidence: 99%

“…The pressure cells were identical to those used in our recent studies [14] of the superionic conductor LiBH 4 , except that no internal heaters were used. Weighted powder samples were sandwiched between two cylindrical stainless steel electrodes, 6 mm in diameter.…”

Section: Equipmentmentioning

confidence: 99%

“…The ac impedance was measured using electronic bridges. For the experiment on K 4 C 60 and the first two experiments on Li 4 C 60 we used an Agilent E4980A precision LCR meter, while for the experiments on Na 4 C 60 and the remaining experiments on Li 4 C 60 we used the same Solartron SI 1260A impedance/gain-phase analyzer as in our recent study on LiBH 4 [14]. No differences were observed between results obtained with different bridges.…”

Section: Equipmentmentioning

confidence: 99%

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Ac impedance of A₄C₆₀fullerides under pressure

et al. 2015

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Three A 4 C 60 compounds, with A = Li, Na and K, have been studied by impedance spectroscopy between 100 and 293 K at pressures up to 2 GPa. The results are in very good agreement with earlier dc resistance studies and with data from the literature. For all three materials the measured conductivity can be fitted by a sum of at least two Arrhenius terms. The band gaps derived from the resistance data, 0.3 eV for Na 4 C 60 and 0.5 eV for K 4 C 60 , are in excellent agreement with data measured by other methods. For Li 4 C 60 , our results disagree with a recent suggestion that the conductivity is dominated by ionic conduction. Although a certain ionic component probably exists we suggest that electronic transport dominates in our samples at and below room temperature because the derived 'activation energy' decreases under pressure, the derived 'activation volume' is negative, and we observe neither a significant electrode blocking capacitance nor any significant metal transport under dc conditions. changes in conductivity magnitude might be due to changes in the sample geometry there remained possibilities that the results were modified by deintercalation due to heating, ionic electrotransport, or both.We present here new data for the resistivity of A 4 C 60 under pressure for A = Li, Na and K, measured by ac impedance spectroscopy. Using an ac method in a mechanically very stable experimental set-up proved to yield very stable and repeatable results, and the derived transport parameters (excitation energies and/or band gaps) were very similar to those found earlier. This confirms that the large changes in magnitude observed earlier were experimental artifacts caused mainly by deformation of the samples. To investigate ionic transport in Li 4 C 60 further we also carried out a simple dc experiment, driving a small dc current through a sample sandwiched between lithium electrodes. After 50 h, no change was detected in the relative weights of the electrodes, showing that most of the current was carried by electrons rather than Li + ions.

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Section: C 60contrasting

confidence: 67%

Section: Experimental and Analytic Methodsmentioning

confidence: 94%

Section: Experimental and Analytic Methodsmentioning

confidence: 99%

Section: Equipmentmentioning

confidence: 99%

Section: Equipmentmentioning

confidence: 99%

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Ac impedance of A₄C₆₀fullerides under pressure

et al. 2015

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Phase boundaries and molar volumes of high-temperature and high-pressure phase V of LiBH4

Yamawaki

Fujihisa

Gotoh

et al. 2015

Journal of Physics and Chemistry of Solids

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Li-Ion Conductivity and Phase Stability of Ca-Doped LiBH₄ under High Pressure

Mezaki

Kuronuma²,

Oikawa

et al. 2016

Inorg. Chem.

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The effect of Ca doping on the Li-ion conductivity and phase stability of the rock-salt-type LiBH phase emerging under high pressures in the range of gigapascals has been investigated. In situ electrochemical measurements under high pressure were performed using a cubic-anvil-type apparatus. Ca doping drastically enhanced the ionic conductivity of the rock-salt-type phase: the ionic conductivity of undoped and 5 mol %Ca-doped LiBH was 2.2 × 10 and 1.4 × 10 S·cm under 4.0 GPa at 220 °C, respectively. The activation volume of LiBH-5 mol %Ca(BH), at 3.2 cm·mol, was comparable to that of other fast ionic conductors, such as lithium titanate and NASICONs. Moreover, Ca-doped LiBH showed lithium plating-stripping behavior in a cyclic voltammogram. These results indicate that the conductivity enhancement by Ca doping can be attributed to the formation of a LiBH-Ca(BH) solid solution; however, the solid solution decomposed into the orthorhombic LiBH phase and the orthorhombic Ca(BH) phase after unloading the high pressure.

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Ionic conductivity in three crystalline phases of LiBH₄under pressure

Cited by 4 publications

References 24 publications

Ac impedance of A₄C₆₀fullerides under pressure

Ac impedance of A₄C₆₀fullerides under pressure

Phase boundaries and molar volumes of high-temperature and high-pressure phase V of LiBH4

Li-Ion Conductivity and Phase Stability of Ca-Doped LiBH₄ under High Pressure

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Ionic conductivity in three crystalline phases of LiBH4under pressure

Cited by 4 publications

References 24 publications

Ac impedance of A4C60fullerides under pressure

Ac impedance of A4C60fullerides under pressure

Phase boundaries and molar volumes of high-temperature and high-pressure phase V of LiBH4

Li-Ion Conductivity and Phase Stability of Ca-Doped LiBH4 under High Pressure

Contact Info

Product

Resources

About

Ionic conductivity in three crystalline phases of LiBH₄under pressure

Ac impedance of A₄C₆₀fullerides under pressure

Ac impedance of A₄C₆₀fullerides under pressure

Li-Ion Conductivity and Phase Stability of Ca-Doped LiBH₄ under High Pressure