"The existence of definite hydrides of nickel and platinum is in doubt".[2] This observation does not preclude the existence of nonstoichiometric hydrides. Indeed, nickel is a widely used hydrogenationcatalyst. Experimental studies on nickel hydrides are rare and principally theoretical.
Hydrogen hardens nickel (as it does most metals), inhibiting dislocations in the nickel atom crystal lattice from sliding past one another. Varying the amount of alloying hydrogen and the form of its presence in the nickel hydride (precipitated phase) controls qualities such as the hardness, ductility, and tensile strength of the resulting nickel hydride. Nickel hydride with increased hydrogen content can be made harder and stronger than nickel, but such nickel hydride is also less ductile than nickel. Loss of ductility occurs due to cracks maintaining sharp points due to suppression of elastic deformation by the hydrogen, and voids forming under tension due to decomposition of the hydride.[3] Hydrogen embrittlement can be a problem in nickel in use in turbines at high temperatures.[4]
In the narrow range of stoichiometries adopted by nickel hydride, distinct structures are claimed. At room temperature, the most stable form of nickel is the face-centred cubic (FCC) structure α-nickel. It is a relatively soft metallic material that can dissolve only a very small concentration of hydrogen, no more than 0.002 wt% at 1,455 °C (2,651 °F), and only 0.00005% at 25 °C (77 °F). The solid solution phase with dissolved hydrogen, that maintains the same structure as the original nickel is termed the α-phase. At 25 °C 6 kbar of hydrogen pressure is needed to dissolve in β-nickel, but the hydrogen desorbs at pressures below 3.4 kbar.[5]
Surfaceedit
Hydrogen dissociates on nickel surfaces. The dissociation energies on Ni(111), Ni(100), and Ni(11O) crystal faces are respectively 46, 52, and 36 kJ/mol. The H2 dissociates from each of these surfaces at distinct temperatures: 320–380, 220–360, and 230–430 K.[5]
High pressure phasesedit
Crystallographically distinct phases of nickel hydride are produced with high pressure hydrogen gas at 600 MPa.[5] Alternatively it can be produced electrolytically.[6] The crystal form is face-centred cubic or β-nickel hydride. Hydrogen to nickel atomic ratios are up to one, with hydrogen occupying an octahedral site.[7] The density of the β-hydride is 7.74 g/cm3. It is coloured grey.[7] At a current density of 1 Amp per square decimeter, in 0.5 mol/liter of sulfuric acid and thiourea a surface layer of nickel will be converted to nickel hydride. This surface is replete with cracks up to millimeters long. The direction of cracking is in the {001} plane of the original nickel crystals. The lattice constant of nickel hydride is 3.731 Å, which is 5.7% more than that of nickel.[6]
The near-stoichiometric NiH is unstable and loses hydrogen at pressures below 340 MPa.[5]
Molecular nickel hydridesedit
A large number of nickel hydride complexes are known. Illustrative is the complex trans-NiH(Cl)(P(C6H11)3)2.[8]
Referencesedit
^Stanislaw M. Filipek, Izabella Grzegory, Janusz Lipkowski, Stanislaw Sieniutycz. "In Memoriam: Professor Bogdan Baranowski". researchgate.net. Retrieved 8 November 2023.{{cite web}}: CS1 maint: multiple names: authors list (link)
^Xu, Xuejun; Mao Wen; Zhong Hu; Seiji Fukuyama; Kiyoshi Yokogawa (2002). "Atomistic process on hydrogen embrittlement of a single crystal of nickel by the embedded atom method". Computational Materials Science. Elsevier. 23 (1–4): 131–138. doi:10.1016/s0927-0256(01)00217-8.
^Xu, Xuejen; Mao Wen; Seiji Fukuyama; Kioshi Yokogawa (2001). "Simulation of Hydrogen Embrittlement at Crack Tip in Nickel Single Crystal by Embedded Atom Method" (PDF). Materials Transactions. 42 (11): 2283–2289. doi:10.2320/matertrans.42.2283. ISSN 1345-9678.
^ abcdShan, Junjun (11 November 2009). On the formation and decomposition of a thin NiHx layer on Ni(111)(PDF). Leiden: Universiteit Leiden. p. 94. ISBN9789085704171. Retrieved 11 February 2013. {{cite book}}: |work= ignored (help)
^ abTakano, Noriyuki; Shinichirou Kaida (2012). "Crack Initiation by Cathodic Hydrogen Charging in Nickel Single Crystal". ISIJ International. 52 (2): 263–266. doi:10.2355/isijinternational.52.263.
^ abTravares, S. S. M.; A. Lafuente; S. Miraglia; D. Fruchart; S. Pairis (2003). "SEM Characterization of Hydrogenated Nickel". Acta Microscopia. 12 (1).
^Eberhardt, N. A.; Guan, H. (2016). "Nickel Hydride Complexes". Chemical Reviews. 116 (15): 8373–8426. doi:10.1021/acs.chemrev.6b00259. PMID 27437790.
nickel, hydride, nickel, hydride, battery, nickel, hydrogen, battery, either, inorganic, compound, formula, nihx, variety, coordination, complexes, discovered, polish, chemist, bogdan, baranowski, 1958, contents, binary, nickel, hydrides, related, materials, s. For Nickel hydride battery see Nickel hydrogen battery Nickel hydride is either an inorganic compound of the formula NiHx or any of a variety of coordination complexes It was discovered by Polish chemist Bogdan Baranowski in 1958 1 Contents 1 Binary nickel hydrides and related materials 1 1 Surface 1 2 High pressure phases 2 Molecular nickel hydrides 3 References 4 See alsoBinary nickel hydrides and related materials edit The existence of definite hydrides of nickel and platinum is in doubt 2 This observation does not preclude the existence of nonstoichiometric hydrides Indeed nickel is a widely used hydrogenation catalyst Experimental studies on nickel hydrides are rare and principally theoretical Hydrogen hardens nickel as it does most metals inhibiting dislocations in the nickel atom crystal lattice from sliding past one another Varying the amount of alloying hydrogen and the form of its presence in the nickel hydride precipitated phase controls qualities such as the hardness ductility and tensile strength of the resulting nickel hydride Nickel hydride with increased hydrogen content can be made harder and stronger than nickel but such nickel hydride is also less ductile than nickel Loss of ductility occurs due to cracks maintaining sharp points due to suppression of elastic deformation by the hydrogen and voids forming under tension due to decomposition of the hydride 3 Hydrogen embrittlement can be a problem in nickel in use in turbines at high temperatures 4 In the narrow range of stoichiometries adopted by nickel hydride distinct structures are claimed At room temperature the most stable form of nickel is the face centred cubic FCC structure a nickel It is a relatively soft metallic material that can dissolve only a very small concentration of hydrogen no more than 0 002 wt at 1 455 C 2 651 F and only 0 00005 at 25 C 77 F The solid solution phase with dissolved hydrogen that maintains the same structure as the original nickel is termed the a phase At 25 C 6 kbar of hydrogen pressure is needed to dissolve in b nickel but the hydrogen desorbs at pressures below 3 4 kbar 5 Surface edit Hydrogen dissociates on nickel surfaces The dissociation energies on Ni 111 Ni 100 and Ni 11O crystal faces are respectively 46 52 and 36 kJ mol The H2 dissociates from each of these surfaces at distinct temperatures 320 380 220 360 and 230 430 K 5 High pressure phases edit Crystallographically distinct phases of nickel hydride are produced with high pressure hydrogen gas at 600 MPa 5 Alternatively it can be produced electrolytically 6 The crystal form is face centred cubic or b nickel hydride Hydrogen to nickel atomic ratios are up to one with hydrogen occupying an octahedral site 7 The density of the b hydride is 7 74 g cm3 It is coloured grey 7 At a current density of 1 Amp per square decimeter in 0 5 mol liter of sulfuric acid and thiourea a surface layer of nickel will be converted to nickel hydride This surface is replete with cracks up to millimeters long The direction of cracking is in the 001 plane of the original nickel crystals The lattice constant of nickel hydride is 3 731 A which is 5 7 more than that of nickel 6 The near stoichiometric NiH is unstable and loses hydrogen at pressures below 340 MPa 5 Molecular nickel hydrides editA large number of nickel hydride complexes are known Illustrative is the complex trans NiH Cl P C6H11 3 2 8 References edit Stanislaw M Filipek Izabella Grzegory Janusz Lipkowski Stanislaw Sieniutycz In Memoriam Professor Bogdan Baranowski researchgate net Retrieved 8 November 2023 a href Template Cite web html title Template Cite web cite web a CS1 maint multiple names authors list link Greenwood Norman N Earnshaw Alan 1997 Chemistry of the Elements 2nd ed Butterworth Heinemann ISBN 978 0 08 037941 8 Xu Xuejun Mao Wen Zhong Hu Seiji Fukuyama Kiyoshi Yokogawa 2002 Atomistic process on hydrogen embrittlement of a single crystal of nickel by the embedded atom method Computational Materials Science Elsevier 23 1 4 131 138 doi 10 1016 s0927 0256 01 00217 8 Xu Xuejen Mao Wen Seiji Fukuyama Kioshi Yokogawa 2001 Simulation of Hydrogen Embrittlement at Crack Tip in Nickel Single Crystal by Embedded Atom Method PDF Materials Transactions 42 11 2283 2289 doi 10 2320 matertrans 42 2283 ISSN 1345 9678 a b c d Shan Junjun 11 November 2009 On the formation and decomposition of a thin NiHx layer on Ni 111 PDF Leiden Universiteit Leiden p 94 ISBN 9789085704171 Retrieved 11 February 2013 a href Template Cite book html title Template Cite book cite book a work ignored help a b Takano Noriyuki Shinichirou Kaida 2012 Crack Initiation by Cathodic Hydrogen Charging in Nickel Single Crystal ISIJ International 52 2 263 266 doi 10 2355 isijinternational 52 263 a b Travares S S M A Lafuente S Miraglia D Fruchart S Pairis 2003 SEM Characterization of Hydrogenated Nickel Acta Microscopia 12 1 Eberhardt N A Guan H 2016 Nickel Hydride Complexes Chemical Reviews 116 15 8373 8426 doi 10 1021 acs chemrev 6b00259 PMID 27437790 See also editSolid solution Lattice energy Retrieved from https en wikipedia org w index php title Nickel hydride amp oldid 1184124150, wikipedia, wiki, book, books, library,
