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Rao, A. Sreenivasa; Andrade, P. da R.; Porto, S. P. S.

doi:10.1103/physrevb.9.1077

Cited by 18 publications

(8 citation statements)

References 13 publications

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“….Na vector coinciding with the C3 axis of the P213 unit One is therefore forced to conclude that evidence from interatomic distances in crystals is not likely to lead to meaningful estimates of the effective radius of a LP, since accidents of packing appear generally to obscure whatever systematic effects may arise from the effective size of the LP. shortest O...Cl distance in ~MSOHS; allowing 0 : 4 A for the 4~h e frequency and temperature dependence of the dielectric size difference between and leaves a residue of 0 '4 A' constant of NaC103 have been interpreted (53) as involving inversion Funher, the shortest 0' ''1 For personal use only. Effective volume.…”

Section: Spatial Extension Of the Lp In Crystalsmentioning

confidence: 99%

The lone electron pair and crystal packing: observations on pyramidal YEL₃^ε species, abinitio calculations, and the crystal structures of Me₃SOI, Et₃SI, (Me₃S)₂SnCl₆, (Me₃SO)₂SnCl₆, and (Et₃S)₂SnCl₆

Knop¹,

Linden²,

Vincent³

et al. 1989

Can. J. Chem.

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The results of a detailed analysis of typical situations in crystals containing trigonal-pyramidal YEL3' species are used to argue that, per se, the lone electron pair (E, LP) on the Y atom determines neither the crystal structure nor the onentation of the Y EL3' units in the crystal. Considered as a space-filling entity, the LP has practically no effective volume of its own. Whatever space-filling or orienting properties may be associated with the presence of the LP, they are not autonomous; they arise from the intrinsic stereochemical involvement of the LP in the geometry of and the charge distribution in the free YEL3' ion or molecule and hence from the consequences of this geometry for crystal packing. Ab initio (6-31G*) calculations show that the electron density in the region of the LP in an ion is only slightly perturbed by the charge on the counter ion at distances observed in crystals. There is considerable similarity in the electron density distribution in the LP region of Y between free anionic (~0~~~ and free cationic (Me3S+) species. The problem of the so-called stereochemical inertness of the LP in the 14-electron octahedral Y E X~~-ions in crystals is examined in detail. It is concluded that the crystallographic Oh symmetry of the ion in cubic crystals is the result of dynamic averaging of possible orientations of the inherently noncubic YX62-octahedron (cf. the ab initio results for S e~l~~-) .Such averaging also appears to be responsible for the stereochemical "activation" or "inactivation" of the LP in thermally induced crystallographic transitions in the AYX3 halide perovskites and related crystals. To provide a firmer basis for the discussion of the LP, the crystal structures of the five title compounds have been determined. The crystal chemistry of these and related compounds is discussed.Key words: ab initio calculations, Me3S+ and SeC162-; group V trihalides; lone electron pair; trialkylsulfonium salts; VSEPR theory.OSVALD KNOP, ANTHONY LINDEN, BEVERLY R. VINCENT, S. C. CHOI, T. STANLEY CAMERON et RUSSELL J. BOYD. Can. J. Chem. 67, 1984Chem. 67, (1989.En se basant sur les rCsultats d'une analyse dCtaillte de situations typiques dans des cristaux contenant des espkces YEL3', on suggkre que la paire dYClectron libre (E, PL) sur l'atome Y ne dCtermine pas per se la structure cristalline ou I'orientation des unit& Y EL3' dans le cristal. ConsidCrte comme une entitC qui occupe du volume, la PL n'a pratiquement pas de volume effectif intrinskque. Quelles que soient les propriCtCs associCes avec la prCsence de la PL, elles ne sont pas autonomes; elles dCcoulent de l'implication stCrCochimique intrinskque de la PL dans la gComCtrie de et de la distribution de charge dans l'ion ou la molCcule YEL$ libre et ainsi des consCquences de cette gComCtrie sur I'empilement cristallin. Des calculs ab initio (6-3 lG*) dCmontrent que, aux distances observkes dans les cristaux, la densite tlectronique dans la rkgion de la PL d'un ion n'est que ICgkrement perturbCe par la charge du contre-ion. I1 existe une gr...

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Section: Spatial Extension Of the Lp In Crystalsmentioning

confidence: 99%

The lone electron pair and crystal packing: observations on pyramidal YEL₃^ε species, abinitio calculations, and the crystal structures of Me₃SOI, Et₃SI, (Me₃S)₂SnCl₆, (Me₃SO)₂SnCl₆, and (Et₃S)₂SnCl₆

Knop¹,

Linden²,

Vincent³

et al. 1989

Can. J. Chem.

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“…This was suggested by Rao et al [4] from an analysis of the low-frequency part of the dielectric constant, which could not be explained by regular phonon contributions alone. The deviation was interpreted in terms of a Debyelike relaxational process, which they speculate might be due to a double-well disordering of C1-atoms.…”

Section: Introductionmentioning

confidence: 78%

“…The dashed line is only a guide to the eye 250 K. Above this temperature they broaden and merge, and the broad peak moves to lower frequencies. However, this behaviour can only qualitatively explain the temperature dependence of the dielectric constant [4]. The present study was undertaken because data for the acoustic phonons for NaC10, have not been reported.…”

Section: Introductionmentioning

confidence: 90%

“…For the external modes also the temperature variation is known [4] and was included. For some of the polar F-modes only the TO frequencies are availabe.…”

Section: Calculated Specific Heatmentioning

confidence: 99%

“…Dawson [6] later extended the measurements to a range of temperatures from 10 to 500 K, and Rao et al [4,7] explored some further details as a function of temperature.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Neutron Spectroscopic Study of Lattice Vibrations in NaClO₃ and Specific Heat

Haugstuen¹,

Grip²,

Fjær³

et al. 1980

Physica Status Solidi (b)

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The acoustic branches and one optic branch of phonons in cubic NaCIO, are studied a t room temperature by inelastic neutron scattering. Sound velocities are deduced, and specific heat versus temperature calculated by incorporating also high energy branches from Raman scattering. Connection between the specific heat and a suggested order-disorder process in NaClO, is discussed.Durch unelastische Streuung thermischer Neutronen werden die akustischen und einige optische Phononenzweige bei Raumtemperatur in NaClO, studied. Die Schallgeschwindigkeiten werden bestimmt, und mit Hilfe Raman-spectroskopischer Daten wird die spezifische W&rme berechnet.Ein moglicher Ordnungs-Unordnungs-Prozel3 in NaCIO, wird durch seinen Beitrag zur spezifischen Wiirme kurz diskutiert.

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Raman spectroscopic studies of the high pressure phase transformation of NaClO₃

Ganguly¹,

Nicol

Ellenson³

1977

Physica Status Solidi (b)

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Raman Spectroscopic Studies of the High P r e s s u r e Phase Transformation of NaClO B.N. GANGULY, M. NICOL3), and W.D. ELLENSON 2) 3 BY 4)Most alkali ABO compounds have several stable solid phases /l/. Trans-3 formations between these phases provide interesting insights concerning the interionic interactions. The strong temperature and pressure dependences of the vibrational properties of these compounds also indicate that ABO compounds are appreciably anharmonic. Consequently, the lattice dynamics of these materials have received considJrable attention / 2 to 7/. However, no information appears to have been reported concerning the nature of the phase transitions or the structures and lattice dynamics of NaClO at high pressures. 3 3 3Bridgman /1/ studied the compressibility of NaClO from 300 to 470 K at pressures t o 50 kbar and reported the phase diagram shown in Fig. 1. In addition t o the phase stable a t atmospheric pressure, three other phases were identified at high pressure and high temperature. The stability regions of two of these phases extend to room temperature, with transition pressures of 16 and 36 kbar, respectively. However, the kinetics of these transitions at room temperature were said to be sluggish. The third high temperature phase has been assigned a s the liquid by Rappaport /8/.In this note, we report on vibrational Raman spectra of NaClO t o 40 kbar at 3 300 K and on some insights these spectra provide about the phase transformations.The Raman spectroscopy provides both a quantitative method for detecting structural changes and, through analysis of factor group splitting of degenerate phonon modes, a method for characterizing the structure of the high pressure phases of NaC103.1) Cpntribution No. 3843.

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Phonon behavior and disorder mechanism in NaClO3

Cited by 18 publications

References 13 publications

The lone electron pair and crystal packing: observations on pyramidal YEL₃^ε species, abinitio calculations, and the crystal structures of Me₃SOI, Et₃SI, (Me₃S)₂SnCl₆, (Me₃SO)₂SnCl₆, and (Et₃S)₂SnCl₆

The lone electron pair and crystal packing: observations on pyramidal YEL₃^ε species, abinitio calculations, and the crystal structures of Me₃SOI, Et₃SI, (Me₃S)₂SnCl₆, (Me₃SO)₂SnCl₆, and (Et₃S)₂SnCl₆

Neutron Spectroscopic Study of Lattice Vibrations in NaClO₃ and Specific Heat

Raman spectroscopic studies of the high pressure phase transformation of NaClO₃

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Phonon behavior and disorder mechanism in NaClO3

Cited by 18 publications

References 13 publications

The lone electron pair and crystal packing: observations on pyramidal YEL3ε species, abinitio calculations, and the crystal structures of Me3SOI, Et3SI, (Me3S)2SnCl6, (Me3SO)2SnCl6, and (Et3S)2SnCl6

The lone electron pair and crystal packing: observations on pyramidal YEL3ε species, abinitio calculations, and the crystal structures of Me3SOI, Et3SI, (Me3S)2SnCl6, (Me3SO)2SnCl6, and (Et3S)2SnCl6

Neutron Spectroscopic Study of Lattice Vibrations in NaClO3 and Specific Heat

Raman spectroscopic studies of the high pressure phase transformation of NaClO3

Contact Info

Product

Resources

About

The lone electron pair and crystal packing: observations on pyramidal YEL₃^ε species, abinitio calculations, and the crystal structures of Me₃SOI, Et₃SI, (Me₃S)₂SnCl₆, (Me₃SO)₂SnCl₆, and (Et₃S)₂SnCl₆

The lone electron pair and crystal packing: observations on pyramidal YEL₃^ε species, abinitio calculations, and the crystal structures of Me₃SOI, Et₃SI, (Me₃S)₂SnCl₆, (Me₃SO)₂SnCl₆, and (Et₃S)₂SnCl₆

Neutron Spectroscopic Study of Lattice Vibrations in NaClO₃ and Specific Heat

Raman spectroscopic studies of the high pressure phase transformation of NaClO₃