Temperature-Dependent Vibrational Modes in Sodium Nitrite

Barnoski, M. K.; Ballantyne, J. M.

doi:10.1103/physrev.174.946

Cited by 70 publications

(12 citation statements)

References 16 publications

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“…The strength of the wl, w3, and TO lattice niodes increases with temperature and is of the same order of magnitude (Fig. 4), while that of o2 and w5 TO lattice modes is much weaker and nearly temperature independent [4,5]. This behavior c m confirm the assignment of w,, 03, and ~4 to translational lattice modes, o2 and o6 to librational ones as proposed by several authors [G, 71.…”

Section: -12 Osriflator Strewgflrssupporting

confidence: 87%

“…2). The five modes continue to be active in the paraelectric phase, in violation of the group theoretical selection rules, as observed previously by infrared [4,5] and Raman spectroscopy [7, 91. The U, reflectivity spectra show two distinct reflectivity maxima at every temperature, contrarily in the B, reflectivity spectra the two maxima distinct a t low temperature, overlap as the phase transition is approached [5, 7, 01, but the B, reflectivity spectrum a t 460 I< is better fitted with two modcs than with only one as we tried to do it.…”

Section: Ih*eqttezcciessupporting

confidence: 52%

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Lattice Mode Anharmonicity in Sodium Nitrite

Bréhat¹,

Wyncke²,

Shérif³

1982

Physica Status Solidi (b)

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The snharmonicity of the infrared active lattice modes of sodium nitrite is studied from measurements of the infrared reflectivity from 60 to 400 cm-l, in the temperature range 80 to 460 K. The infrared reflectivity spectra are analysed with the four-parameter dispersion model based on the factorized form of the dielectric fnnction. The comparison between the results of the quantum theory and the dependence observed of damping shows that cubic anharmonicity drives the lattice dynamics of sodium nitrite when the crystal structure is ordered, and that disorder occurs below the phase transition temperature. The results confirm the breakdown of the selection rules in the paraelectric phase and suggest the existence of dielectric dispersion in the low frequency region.Sous avons Btudib I'anharmonicit8 des modes de rBseaux actifs en infrarouge dans le nitrite de sodium, .?t partir de l'evolution du facteur de reflexion de 60 B 400 cm-' pour des temperatures comprises entre SO et 460 K. La comparaison entre les rksultnts de la th6orie quantique e t l'bvolution de 1' 1 fonction amortissement avcc la temperature montre que l'anharmonicite cubique regit la dynamiqiie dii r6seeu du nitrite de sodium quand la structure cristalline est ordonnhe, e t que le dbsordre apparait dans le cristal en dessous de la temperature de transition de phase. Lesr6sultats confirrnent In d6faillnnce des r&gles de sblection dans la phase parablectrique et sugghrent l'existence de dispersion diblectriqne dam les basses frbquenccs.

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Section: -12 Osriflator Strewgflrssupporting

confidence: 87%

Section: Ih*eqttezcciessupporting

confidence: 52%

Lattice Mode Anharmonicity in Sodium Nitrite

Bréhat¹,

Wyncke²,

Shérif³

1982

Physica Status Solidi (b)

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“…In this connection we have undertaken an independent investigation of far IR reflectivity spectra of NaNO, to obtain the full dielectric response of the system in this range. The results obtained are close to those of [15].…”

Section: Experimental Results and Their Discussionsupporting

confidence: 86%

Low‐Frequency Lattice Dynamics of NaNO₂ Crystals

Козлов¹,

Kryukova²,

Wyncke

et al. 1985

Physica Status Solidi (b)

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Submillimeter monochromatic BWT spectroscopy (3 to 33 cm-I) and far infrared reflection spectroscopy (40 to 600 cm-l) are used to investigate the low-frequency dynamics of the classical ferroelectric NaNO, of the order-disorder type in the temperature interval 20 to 210 "C in the ferro-and paraelectric phase. I n the submillimeter dielectric spectra e*(v, T) of the NaNO, crystal, together with the previously observed radiofrequency mode and the optical phonon 180 cm-1, low-frequency anharmonic excitation subsidiary to the soft mode is recorded a t the intermediate frequency 33 cm-1. Analysing the temperature behaviour of the parameters of this apparently relaxation excitation it is possible to assume that it is directly associated with the process of ferroactive crystal subsystem disordering a t the ferroelectric phase transition. MeTOnaMElCy6MElJIjI&iMeTpOBOf MOHOXpOMaTM ¶eCKOm floB-cneKTpocKonmi (3 a0 33 Cm-l) M n&llbHef I?K CIIeKTpOCKOIIElEl (40 a0 600 Cm-' ) H3yqeHa HEl3K09aCTOTHaH HEl HaMMKa paTyp 20 no 210 "c. B Cy6MElJIJIElMeTpOBbIX CneHTpax &*(V, T) KpHCTajIma, Hapflny C Ha6~110naBIJlliMHCfl paHee panElO4aCTOTHOf PejIaKCaUHOHHOf MOnOfi El OnTElrIeCKHM @OHOHOM 9aCTOTbI 180 CII1-l, 3aperElCTpIlpOBaHO aOlIOJIHkiTeJIbHOe K M H r K O n MOD@ HI13KO-gaCTOTHOe aHrapMOHHgeCHOe BO36ylrcneHHe nPOMeHEYTO9HOfi 9aCTOTbI (=33 Cm-l). A~a n~a 6ylrcneHIlrl HaeT OCHOBaHEltI IIpeAIIOJlOwElTb, 9 T O OH0 3JieKTPM9eCKOM @830BOM IIepeXOne. KnaccwecKoro C~~H~T O~J I~K T P E~K~ Tnna nopxno~-6ecnop~no~ NaNO, B o6nac~&i TeMne-TeMnepaTypHoro nosenenm napaMeTpoB ~T O~O , no-BlizpMoMy, p e n a~c a~u o~~o r o ~0 3 -UeccaMki pa3ynop~nore~ufl CerHeToaHTkimoB noacucTeMbr KpmcTanna npa ceraeTo-HeIIOCpenCTBeHHO CBH3aHO C np0-1)

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“…Both the lattice parameters and the phonon frequencies in the r-point agree reasonably well with experiment. It should be noted that the phonon frequencies exhibit some temperature dependence [ 15, 40,41] while the harmonic lattice dynamics calculations assume zero temperature. Also the calculated phonon dispersion curves agree well with the data obtained from neutron scattering [23].…”

Section: Discussionmentioning

confidence: 99%