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Journal ArticleDOI

Direct current conduction in ammonium and potassium dihydrogen phosphate

15 May 1973-Journal of Chemical Physics (American Institute of Physics)-Vol. 58, Iss: 10, pp 4550-4557
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.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors show that L-arginine addition leads to reduction of electrical parameters of KDP and ADP single crystals which can be attributed mainly to the decrease of L-defects due to creation of additional hydrogen bonds by the impurity in random directions.
Abstract: Potassium dihydrogen orthophosphate (KDP) and ammonium dihydrogen orthophosphate (ADP) single crystals added with L-arginine have been grown by the solution methods. DC and AC electrical measurements were carried out at various temperatures along both a- and c- directions. Results indicate an increase of the electrical parameters with the increase of temperature which can be attributed mainly to the increase of thermally generated hydrogen bond vacancies (L. defects). Also, the present study indicates that L-arginine addition leads to reduction of electrical parameters of KDP and ADP single crystals which can be attributed mainly to the decrease of L-defects due to creation of additional hydrogen bonds by the impurity in random directions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

132 citations

Journal ArticleDOI
Kwang-Sei Lee1
TL;DR: In this article, it is suggested that the nomenclature high-temperature phase transition (HTPT) around T p should be replaced by that onset of partial polymerization at reaction sites distributed on the surface of solids.

131 citations

Journal ArticleDOI
TL;DR: In this article, the activation energy of migration is 1.02 eV in the temperature range between 150 and 179 eV and 2.94 eV at temperatures above 186 eV.

89 citations

Journal ArticleDOI
TL;DR: In this paper, X-ray diffraction, TGA, differential scanning calorimetric (DSC), and impedance analysis were used to study the reported high-temperature phase transitions at 107, 149, 230, and 256 °C in crystals of cesium dihydrogen phosphate, CsH2PO4 (CDP).
Abstract: X-ray diffraction, thermogravimetric (TGA), differential scanning calorimetric (DSC), and impedance analysis were used to study the reported high-temperature phase transitions at 107, 149, 230, and 256 °C in crystals of cesium dihydrogen phosphate, CsH2PO4 (CDP). Our results show strong evidence that at all these temperatures, the observed DSC or differential thermal analysis (DTA) endothermic effects appear only as a consequence of a dehydration process starting on the surface of the crystal. Our results thus show that the reported transition at 230 °C is not a polymorphic transition. This means that the monoclinic symmetry, stable at room temperature, with space group P21/m–C2k2, is maintained up to the final decomposition. Moreover, since we have not found any evidence for the existence of a superprotonic high-temperature phase above 230 °C, the high conductivity above 230 °C is thus only a consequence of the dehydration of the crystal surface.

58 citations

Journal ArticleDOI
TL;DR: In this article, X-ray diffraction and thermogravimetric analysis were used to study the kinetic process of dehydration and the high-temperature phase transition (HTPT) at Tp = 453 ± 10 K in KH2PO4.

54 citations

References
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Book
01 Jan 1973

1,907 citations

Journal ArticleDOI
TL;DR: Piezoelectric crystals and their application to ultrasonics were discussed in this paper, where the authors proposed a method for the extraction of the ultrasonic properties of these crystals.
Abstract: Piezoelectric crystals and their application to ultrasonics , Piezoelectric crystals and their application to ultrasonics , دانشگاه تهران

1,057 citations

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754 citations

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274 citations