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Journal ArticleDOI

Electrical conduction in Na3H (SO4)2 and (NH4)3 H(SO4)2 crystals

01 Jul 1981-Journal of Materials Science (Kluwer Academic Publishers)-Vol. 16, Iss: 7, pp 2011-2016
About: This article is published in Journal of Materials Science.The article was published on 1981-07-01. It has received 14 citations till now. The article focuses on the topics: Solid mechanics.
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Journal ArticleDOI
TL;DR: In this article, the angular dependence of EPR spectra of K3H(SO4)2 with VO2+ or Mn2+ was found to be time-dependent and indicate anomalously slow kinetics of the paraelastic/ferroelastic phase transition which takes place far below the temperature proposed by Baranov et al. (TII =463 K).

4 citations

Journal ArticleDOI
TL;DR: In this paper, a new iron fluorophosphate compound, Fe(H2PO4)2F, was synthesized by a solventless method at low temperatures and its structure was determined from single crystal X-ray diffraction.
Journal ArticleDOI
TL;DR: In this article , single crystals of [K1-x(NH4)x]3H(SO4)2 (x ≤ 0.57) were grown in the K3H 2 O water-salt system and the atomic structure including H atoms were determined at room temperature using X-ray structural analysis.
Abstract: Single crystals of [K1-x(NH4)x]3H(SO4)2 (x ≥ 0.57) grown in the K3H(SO4)2-(NH4)3H(SO4)2-H2O water-salt system are studied. The atomic structure including H atoms was determined at room temperature using X-ray structural analysis. [K1-x(NH4)x]3H(SO4)2 (x ≥ 0.57) crystals have trigonal symmetry and disordered hydrogen-bond networks at ambient conditions similar to the high-temperature phases of K3H(SO4)2, (NH4)3H(SO4)2 and other superprotonic compounds M3H(AO4)2. Impedance measurements performed on single crystals show high values of conductivity characteristic for superprotonic phases. Using the methods of impedance spectroscopy and atomic force microscopy, a significant anisotropy of the conductivity of crystals has been detected. It was also shown that there is a qualitative correlation of bulk and local conductivity measured for samples of the same composition and orientation at room temperature, which is due to the peculiarities of their crystal structure.
Journal ArticleDOI
TL;DR: In this article, the spin Hamiltonian parameters of Fe 3+ centers in Na 3 H(SO 4 ) 2, crystals were fitted to the most general spin Hamiltonians by the method of least squares.
References
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Journal ArticleDOI
TL;DR: In this article, the electrical conductivity of pure and sulphate-doped KH2PO4 samples is analyzed in terms of defects likely to occur in KH 2PO4.

104 citations

Journal ArticleDOI
TL;DR: In this paper, phase transitions in triammonium hydrogen disulfate (NH4)3H(SO4)2 were studied by means of dielectric measurements and differential thermal analysis.
Abstract: Phase transitions in triammonium hydrogen disulfate (NH4)3H(SO4)2 were studied by means of dielectric measurements and differential thermal analysis. Below room temperature three phase transitions were observed at −8, −132, and −140°C. The dielectric constant along the c*-direction shows breaks at the −8 and −132°C transitions, while it shows a discontinuous change accompanied with a thermal hysteresis at the −140°C transition. In addition to the above-mentioned transitions, a broad maximum of the dielectric constant was found at about −28°C along the c*-direction. However, no thermal anomalies were observed around −28°C. Mit Hilfe dielektrischer Messungen und differentieller Thermoanalyse wurden die Phasenubergange in Triammoniumhydrogendisulfat (NH4)3H(SO4)2 untersucht. Unterhalb der Raumtemperatur wurden drei Phasenubergange bei −8, −132 und −140°C gefunden. Die entlang der c*-Richtung gemessene Dielektrizitatskonstante zeigt bei den −8 und −132°C-Ubergangen stufenformige Anderungen, beim −140°C-Ubergang andert sie sich, begleitet von thermischen Hystereseerscheinungen, diskontinuierlich. Zusatzlich zu den o. g. Ubergangen wurden bei Messung in c*-Richtung ein breites Maximum der Dielektrizitatskonstanten bei etwa −28°C, aber keine thermischen Anomalien gefunden.

85 citations

Journal ArticleDOI
TL;DR: In this article, the enthalpy of defect migration in KDP and ADP was shown to be 0.53 eV and 0.46 eV, respectively, in both cases.
Abstract: Experiment, plus critical discussion of previous work, suggests the following. Conductivity is primarily due to the migration of L defects (proton vacancies), the enthalpy for L‐defect mobility being 0.53 eV in KDP and 0.46 eV in ADP. Such L defects are produced by impurities, but there is an additional tendency towards incipient decomposition in both crystals. This leads to a high‐temperature conductivity which, in KDP, is associated with the formation of water molecules and the thermal generation of L defects and, in ADP, with the formation of ammonia molecules and the thermal generation of proton vacancies in the ammonium lattice (A defects). The enthalpy of L‐defect formation in KDP is 0.46 eV; that for A‐defect formation in ADP is 0.19 eV. Previously reported overheating effects are spurious. The conductivity is independent of field.

83 citations