Incoherent inelastic and quasielastic neutron scattering with simultaneous neutron diffraction control of phase transitions in [Ni(NH3)6](NO3)2

Belushkin, A.; Janik, J. A.; Janik, J.A.; Natkaniec, I.; Nawrocik, W.; Olejarczyk, W.; Otnes, K.; Zaleski, T.

doi:10.1016/0378-4363(83)90084-0

Cited by 10 publications

(7 citation statements)

References 6 publications

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“…The picture of the reorientational dynamics of the ΝΗ 3 groups in the substances under study obtained in this work is in agreement with the information obtained earlier by us and coworkers using the NMR method [3] and the neutron scattering methods [5,6].…”

Section: Resultssupporting

confidence: 92%

“…The hysteresis of phase II-phase III transition in these compounds was discovered using the method of adiabatic calorimetry [2,3] and the neutron scattering methods [3][4][5][6]. Subsequently, its occurrence was confirmed by X-ray diffraction [7], proton magnetic resonance [3] and the temperature analysis of the Raman bands width [8,9] methods.…”

Section: Introductionmentioning

confidence: 99%

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Connection between Reorientational Motions of NH₃Groups and Phase Transitions in [Ni(NH₃)₆](NO₃)₂and [Mg(NH₃)₆](NO₃)₂Compounds

Migdał-Mikuli

Mikuli

1995

Acta Phys. Pol. A

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Quasielastic neutron scattering data for [Νi(ΝH3 ) 6 ](ΝO3 ) 2 and [Mg(ΝH3 )6 ](NO3 )2 were subjected to a new analysis. On the basis of the excess of intensity of elastic component observed in these spectra in comparison to the intensity of this component resulting from the applied reorientational model this analysis determined temperature dependence of the new "R" parameter. This parameter gives us information concerning the number of these NH3 groups which in the [Me(NΗ3 ) 6 ]2+ catioii reorientate with the correlation time of order of 10 -12 s. It has been ascertained that in phases I and II of both substances under study all NH3 groups reorientate fast (R = 6ΝH3 groups), whereas in phases III and IV only part of these groups reorientate fast (R = 3ΝΗ3 groups -in the case of [Νi(ΝΗ3 )

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Connection between Reorientational Motions of NH₃Groups and Phase Transitions in [Ni(NH₃)₆](NO₃)₂and [Mg(NH₃)₆](NO₃)₂Compounds

Migdał-Mikuli

Mikuli

1995

Acta Phys. Pol. A

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“…The large amplitude of the librations, alongside the high scattering cross section of H atoms, strongly suggests that the dominant features, between 20 and 35 meV (Table l), arise from librational modes, as proposed by ref. 9. This assignment is supported by the approximate 1 /~ shift of these peaks and loss of intensity in the spectrum of the deuterated analogue.…”

Section: Rotational Tunnellingmentioning

confidence: 72%

“…Further, a multiplet of peaks has been reported in the librational region of the INS spectrum (9), which has been tentatively assigned to the presence of rather different barriers to rotation for the various NH3 groups. This assignment gained support from the results of QNS spectra, which were interpreted as two of the six NH3 groups on each cation undergoing reorientation on the time scale of this spectroscopy, while the remaining four groups are "stationary" (9). Tunnel splitting varies almost exponentially with the height of the barrier to reorientation, and if the above interpretation were valid, the effects of inequivalent NH3 groups would be more manifest in the tunnelling spectrum.…”

Section: Introductionmentioning

confidence: 82%

“…For Ni(NH3)6(N03)2, the transitions between the phases are usually quoted as (9): Marked thermal hysteresis of the low-temperature transition is now well established for the nitrates, although it may well have been the source of confusion in the past (10) regarding the presence of an "extra" phase transformation at around 80 K. In the present work all temperature changes were made on heating to avoid ambiguity due to hysteresis. The 111-11 transition is usually attributed to disorder of the NH3 ligands (6,7,9), while the onset of NO3-ion disorder is responsible for the 11-1 transformation (7).…”

Section: Introductionmentioning

confidence: 99%

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NH₃ reorientation in phases I, II, and III of Ni(NH₃)₆(NO₃)₂

Kearley¹,

Blank²

1988

Can. J. Chem.

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. 66,692 (1988). The inelastic neutron scattering (INS) spectra of rotational tunnelling and librations of NH3 ligands in phase 111 of Ni(NH3)6(N03)2 are not consistent with a rotational hindrance potential containing only cos ( 3 4 ) terms owing to strong interaction between neighboring cations. This type of interaction, and motion of the whole cation, also influences the classical reorienta$onal motions involving displacement of the H atoms, where the overall radius of rotation is consistently greater than the 0.9 A expected for isolated NH3 rotors. Quasielastic neutron scattering (QNS) suggests that in phase 111 there are two sublattices of cations, one of which becomes completely disordered (with respect to the NH3 rotors) at the 111-11 phase transition.Disorder of the second sublattice marks the 11-1 transformation where only a single type of rotational motion is found. GORDON J. KEARLEY et HERMA BLANK. Can. J. Chem. 66, 692 (1988). Les spectres de diffusion des neutrons inklastiques (DNI) de l'effet tunnel de rotation et des librations des ligands NH3 dans leNi(NH3)6(N03)2 de phase 111 ne sont pas en accord avec un potentiel d'em@chement la rotation ne contenant que des termes cos ( 3~4 ) provenant d'une interaction forte entre les cations voisins. Ce type d'interaction, ainsi que le mouvement du cation dans son ensemble, influencent aussi les mouvements classiques de rkori5ntation impliquant le dkplacement des atomes H dans lesquels le rayon global de la rotation est toujours plus grand que le 0,9 A attendu pour des rotors NH3 isolCs. La diffusion des neutrons quasi-dastiques (DNQ) suggkre que, dans la phase 111, il existe deux sous-rkseaux de cations dont I'un devient completement dCsordonnk (par rapport aux rotors NH3) lors de la transition phase 111 + 11. Le dtsordre du deuxi5me sous-rCseau marque la transformation I1 + I dans laquelle on ne trouve qu'un seul type de mouvement de rotation.[Traduit par la revue] IntroductionThe role played by disorder and reorientations of the ammine ligands in transition-metal hexammine salts has attracted the attention of several groups over the course of a number of years (see ref. 1 and references therein). The overall picture of six ammine groups, which undergo rotational diffusion at high temperature and then freeze into fixed orientations in the lowest-temperature phase transition, is generally accepted, but the details of the NH3 orientations, particularly in the lowtemperature phases, are largely unknown (2-5). In the present study we are concerned with motions not only of the NH3 groups but also of the entire hexammine ion in three phases of nickel hexammine nitrate.The sequence of phase transitions has been studied by ir (6), Raman (7), epr (8), and INS (9) spectroscopies, and by specific heat measurements (10, 1 1). For Ni(NH3)6(N03)2, the transitions between the phases are usually quoted as (9):

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Phase transitions in [Ni(NH3)6](NO3)2

Трыбула¹,

Stankowski²

1988

Physica B: Condensed Matter

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Incoherent inelastic and quasielastic neutron scattering with simultaneous neutron diffraction control of phase transitions in [Ni(NH3)6](NO3)2

Cited by 10 publications

References 6 publications

Connection between Reorientational Motions of NH₃Groups and Phase Transitions in [Ni(NH₃)₆](NO₃)₂and [Mg(NH₃)₆](NO₃)₂Compounds

Connection between Reorientational Motions of NH₃Groups and Phase Transitions in [Ni(NH₃)₆](NO₃)₂and [Mg(NH₃)₆](NO₃)₂Compounds

NH₃ reorientation in phases I, II, and III of Ni(NH₃)₆(NO₃)₂

Phase transitions in [Ni(NH3)6](NO3)2

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Incoherent inelastic and quasielastic neutron scattering with simultaneous neutron diffraction control of phase transitions in [Ni(NH3)6](NO3)2

Cited by 10 publications

References 6 publications

Connection between Reorientational Motions of NH3Groups and Phase Transitions in [Ni(NH3)6](NO3)2and [Mg(NH3)6](NO3)2Compounds

Connection between Reorientational Motions of NH3Groups and Phase Transitions in [Ni(NH3)6](NO3)2and [Mg(NH3)6](NO3)2Compounds

NH3 reorientation in phases I, II, and III of Ni(NH3)6(NO3)2

Phase transitions in [Ni(NH3)6](NO3)2

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Connection between Reorientational Motions of NH₃Groups and Phase Transitions in [Ni(NH₃)₆](NO₃)₂and [Mg(NH₃)₆](NO₃)₂Compounds

Connection between Reorientational Motions of NH₃Groups and Phase Transitions in [Ni(NH₃)₆](NO₃)₂and [Mg(NH₃)₆](NO₃)₂Compounds

NH₃ reorientation in phases I, II, and III of Ni(NH₃)₆(NO₃)₂