Electric and electrochemical properties of solid LiH2PO4

Šušić, M.V.; Minić, Duško

doi:10.1016/0167-2738(81)90032-1

Cited by 15 publications

(7 citation statements)

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“…All atoms have the same coordinates of the Wyckoff site, 4a, and general position of site symmetry, 1ÀC 1 . The extraordinarily high electrical conductivity of LDP may be attributed to the long hydrogen bond lengths and the favorable crystallographic features [26e28, 38,39]. While no anomaly characteristic of a phase transition has been seen in LDP between 12 and 300 K [35,40e42], the dielectric constant and the electrical conductivity showed anomalies at 178 C (T p1 ) and 196 C (T p2 ) on heating [39,43].…”

Section: Introductionmentioning

confidence: 98%

Crystal growth and morphology of LiH2PO4

Lee

Kweon

et al. 2012

Materials Chemistry and Physics

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Section: Introductionmentioning

confidence: 98%

Crystal growth and morphology of LiH2PO4

Lee

Kweon

et al. 2012

Materials Chemistry and Physics

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“…In the so-called superprotonic phase transition at 230 °C, an increase of protonic conductivity by up to 4 orders of magnitude has been observed for CDP, resulting from rapid dynamic motion between two different H-bonding environments and fast rotation of the phosphate ions . On the other hand, LiH 2 PO 4 (LDP) exhibits an exceptionally high protonic conductivity (i.e., 10 –3 –10 –5 Ω –1 cm –1 ) even at RT, − but the underlying conduction mechanism has not been fully understood, thus suggesting an attractive research area.…”

Section: Introductionmentioning

confidence: 99%

High Field MAS NMR and Conductivity Study of the Superionic Conductor LiH₂PO₄: Critical Role of Physisorbed Water in Its Protonic Conductivity

Kweon

Steven

et al. 2014

J. Phys. Chem. C

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LiH2PO4 (LDP) is a favored candidate for hydrogen fuel cells, but the mechanism of its high protonic conductivity remains unclear. A complicating factor has been the lack of resolution in the reported proton NMR spectra. We now report multinuclear magic angle spinning NMR in LDP at magnetic fields up to 21.2 T. Well-resolved 1H NMR spectra are observed that are assignable to protons in the short and long O–H···O hydrogen bonds and a peak to physisorbed H2O. The position and intensity for the H2O peak depend on the H 2 O content, implying fast exchange between the adsorbed H2O and the O–H···O protons. 31P and 7Li NMR spectra and spin–lattice relaxation measurements showed that the proton hopping/exchange processes involve concerted hindered rotational fluctuations of the phosphate groups. Conductivity data from adsorbed H2O-controlled samples clearly suggest that the mechanism of LDP’s protonic conductivity is dominantly the exchange (and hopping) of the adsorbed H2O protons with the short O–H···O hydrogen bonds, in contrast to an earlier model that ascribed it to intermolecular hopping of O–H···O protons. The new findings enable us to modulate LDP’s protonic conductivity by several orders of magnitude via controlling physisorbed water.

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“…The narrow signal at 10.5 ppm in Figure 4 is attributed to the 31 P chemical shift in aqueous LiH 2 PO 4 solution, which is formed over time by the hygroscopic LDP powder with residual moisture in the MAS rotor. (θ, ϕ) in the orthorhombic abc crystal (CRY) frame and refer to the atom closest to the origin, i.e., P (1). Error values are derived from the fit residuals.…”

Section: P Nmr Of Ldpmentioning

confidence: 99%

“…Here, n 0 is the Larmor frequency which solely scales with the magnetic field strength, and n CS 8 is the contribution of the chemical shift (CS). The interaction between the non-symmetric charge 9 distribution of the nucleus and its electronic surroundings further shifts the resonance frequencies 10 by n (1) m,m+1 (k) and n (2) m,m+1 (k), corresponding to the quadrupolar interaction to first and second order, These tensors are conveniently determined from the separations ('splittings') of the satellite transitions (ST's) with k = ±1 for 7 Li, since these are not affected by either the second-order quadrupolar interaction or the chemical shift. Thus, the difference ∆ν(k) of the resonance frequencies depends on the relative orientation of the Q CRY tensor to the external magnetic field vector b 0 (ϕ):…”

Section: LI Nmr Of Ldpmentioning

confidence: 99%

“…Lithium dihydrogen phosphate (LDP), LiH 2 PO 4 , exhibits a conductivity of the order of 10 −4 Ω −1 cm −1 , which is exceptionally high for a solid at room temperature. This conductivity is predominantly attributed to fast proton movements in the crystal lattice of LDP [1]. This, and the fact that LDP is widely available, makes it a promising material for fuel cell or rechargeable battery applications and hence precise structural and electronic characterization of this material is of great interest.…”

Section: Introductionmentioning

confidence: 99%

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Single-Crystal 31P and 7Li NMR of the Ionic Conductor LiH2PO4

Zeman

Kainz²,

Bräuniger

2020

Crystals

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The electronic surroundings of phosphorus and lithium atoms in the ionic conductor lithium dihydrogen phosphate (LDP) have been studied by single-crystal nuclear magnetic resonance (NMR) spectroscopy at room temperature. From orientation-dependent NMR spectra of a large homegrown LDP single crystal, the full 31 P chemical shift (CS) and 7 Li quadrupole coupling (QC) tensor was determined, using a global fit over three rotation patterns. The resulting CS tensor is characterized by its three eigenvalues: δ PAS 11 = (67.0 ± 0.6) ppm, δ PAS 22 = (13.9 ± 1.5) ppm, and δ PAS 33 = (−78.7 ± 0.9) ppm. All eigenvalues have also been verified by magic-angle spinning NMR on a polycrystalline sample, using Herzfeld-Berger analysis of the rotational side band pattern. The resulting 7 Li QC tensor is characterized by its quadrupolar coupling constant χ = Q PAS 33 = (−71 ± 1) kHz and the two eigenvalues Q PAS 11 = (22.3 ± 0.9) kHz, and Q PAS 22 = (48.4 ± 0.8) kHz. The initially unknown orientation of the mounted crystal, expressed by the orientation of the rotation axis in the orthorhombic crystal frame, was included in the global data fit as well, thus obtaining it from NMR data only.Crystals 2020, 10, 302 2 of 12 with four formula units per unit cell [6]. The PO 4 tetrahedra build a three-dimensional framework connected by two different types of hydrogen bonds. The LiO 4 coordination tetrahedra are linked by their vertices forming [100] isolated chains and share each edge with the PO 4 units. All atoms in the unit cell are located at Wyckoff position 4a with the general site symmetry 1 − C 1 [7]. As a result, no symmetry constraints affect the algebraic form of the NMR interaction tensors, as will be explained in the following.Abstract: Last thing to be done...

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Electric and electrochemical properties of solid LiH2PO4

Cited by 15 publications

References 3 publications

Crystal growth and morphology of LiH2PO4

Crystal growth and morphology of LiH2PO4

High Field MAS NMR and Conductivity Study of the Superionic Conductor LiH₂PO₄: Critical Role of Physisorbed Water in Its Protonic Conductivity

Single-Crystal 31P and 7Li NMR of the Ionic Conductor LiH2PO4

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Electric and electrochemical properties of solid LiH2PO4

Cited by 15 publications

References 3 publications

Crystal growth and morphology of LiH2PO4

Crystal growth and morphology of LiH2PO4

High Field MAS NMR and Conductivity Study of the Superionic Conductor LiH2PO4: Critical Role of Physisorbed Water in Its Protonic Conductivity

Single-Crystal 31P and 7Li NMR of the Ionic Conductor LiH2PO4

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High Field MAS NMR and Conductivity Study of the Superionic Conductor LiH₂PO₄: Critical Role of Physisorbed Water in Its Protonic Conductivity