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Thermal Vibrations of Beta-Brass and the Order-Disorder Transition; Vibrations Thermiques dans le Laiton Beta et Transformation Ordre-Desordre; Teplovye kolebaniya beta-latuni i perekhod iz uporyadochennogo sostoyaniya v razuporyadochennoe; Vibraciones Termicas del Laton Beta y Transicion Orden-Desorden

Conference:

Abstract

Observations of normal modes of vibration of the ordered alloy of copper and zinc, {beta}-brass, at 296 Degree-Sign K have been made by means of the coherent one-phonon scattering of slow neutrons from single crystal specimens. The triple-axis crystal spectrometer at the NRU reactor has been used to measure the frequencies of modes propagating along the high-symmetry directions [00{zeta}], [{zeta}{zeta}0], [{zeta}{zeta}{zeta}{zeta}] and [ Vulgar-Fraction-One-Half Vulgar-Fraction-One-Half {zeta}]. The dispersion curves resemble those of a simple body-centred cubic crystal such as Na, except that certain degeneracies are lifted, mainly by reason of the difference between the second nearest neighbour Cu-Cu and Zn-Zn forces. For example, we find two distinct modes of wave vector (0.5, 0.5, 0.5) (in reciprocal lattice units), whose frequencies are (4.21 {+-}0.06) and (4.93 {+-} 0.10) x 10{sup 12} c/s respectively. Interatomic force models which provide a satisfactory description of the 296 Degree-Sign K results are briefly mentioned. Several normal modes have been studied at elevated temperatures, particularly in the vicinity of the order-disorder phase transition at about 727 Degree-Sign K. There are no striking changes in the overall structure of the dispersion curves as a result of the vanishing of the long range order at this temperature, although  More>>
Authors:
Dolling, G.; Gilat, G. [1] 
  1. Chalk River Nuclear Laboratories, Chalk River, ON (Canada)
Publication Date:
Apr 15, 1965
Product Type:
Conference
Report Number:
IAEA-SM-58/5
Resource Relation:
Conference: Symposium on Inelastic Scattering of Neutrons, Bombay (India), 15-19 Dec 1964; Other Information: 19 refs., 5 figs., 4 tabs.; Related Information: In: Inelastic Scattering of Neutrons. Vol. I. Proceedings of the Symposium on Inelastic Scattering of Neutrons| 476 p.
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BCC LATTICES; BRASS-BETA; COPPER; INTERATOMIC FORCES; LATTICE VIBRATIONS; MONOCRYSTALS; NRU REACTOR; ORDER-DISORDER TRANSFORMATIONS; PHONONS; SCATTERING; SLOW NEUTRONS; SPECTROMETERS; TRANSITION TEMPERATURE; ZINC
OSTI ID:
22141810
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA13M3376096411
Submitting Site:
INIS
Size:
page(s) 343-360
Announcement Date:
Oct 24, 2013

Conference:

Citation Formats

Dolling, G., and Gilat, G. Thermal Vibrations of Beta-Brass and the Order-Disorder Transition; Vibrations Thermiques dans le Laiton Beta et Transformation Ordre-Desordre; Teplovye kolebaniya beta-latuni i perekhod iz uporyadochennogo sostoyaniya v razuporyadochennoe; Vibraciones Termicas del Laton Beta y Transicion Orden-Desorden. IAEA: N. p., 1965. Web.
Dolling, G., & Gilat, G. Thermal Vibrations of Beta-Brass and the Order-Disorder Transition; Vibrations Thermiques dans le Laiton Beta et Transformation Ordre-Desordre; Teplovye kolebaniya beta-latuni i perekhod iz uporyadochennogo sostoyaniya v razuporyadochennoe; Vibraciones Termicas del Laton Beta y Transicion Orden-Desorden. IAEA.
Dolling, G., and Gilat, G. 1965. "Thermal Vibrations of Beta-Brass and the Order-Disorder Transition; Vibrations Thermiques dans le Laiton Beta et Transformation Ordre-Desordre; Teplovye kolebaniya beta-latuni i perekhod iz uporyadochennogo sostoyaniya v razuporyadochennoe; Vibraciones Termicas del Laton Beta y Transicion Orden-Desorden." IAEA.
@misc{etde_22141810,
title = {Thermal Vibrations of Beta-Brass and the Order-Disorder Transition; Vibrations Thermiques dans le Laiton Beta et Transformation Ordre-Desordre; Teplovye kolebaniya beta-latuni i perekhod iz uporyadochennogo sostoyaniya v razuporyadochennoe; Vibraciones Termicas del Laton Beta y Transicion Orden-Desorden}
author = {Dolling, G., and Gilat, G.}
abstractNote = {Observations of normal modes of vibration of the ordered alloy of copper and zinc, {beta}-brass, at 296 Degree-Sign K have been made by means of the coherent one-phonon scattering of slow neutrons from single crystal specimens. The triple-axis crystal spectrometer at the NRU reactor has been used to measure the frequencies of modes propagating along the high-symmetry directions [00{zeta}], [{zeta}{zeta}0], [{zeta}{zeta}{zeta}{zeta}] and [ Vulgar-Fraction-One-Half Vulgar-Fraction-One-Half {zeta}]. The dispersion curves resemble those of a simple body-centred cubic crystal such as Na, except that certain degeneracies are lifted, mainly by reason of the difference between the second nearest neighbour Cu-Cu and Zn-Zn forces. For example, we find two distinct modes of wave vector (0.5, 0.5, 0.5) (in reciprocal lattice units), whose frequencies are (4.21 {+-}0.06) and (4.93 {+-} 0.10) x 10{sup 12} c/s respectively. Interatomic force models which provide a satisfactory description of the 296 Degree-Sign K results are briefly mentioned. Several normal modes have been studied at elevated temperatures, particularly in the vicinity of the order-disorder phase transition at about 727 Degree-Sign K. There are no striking changes in the overall structure of the dispersion curves as a result of the vanishing of the long range order at this temperature, although the various ''splittings'' observed at 296 Degree-Sign K are blurred out into more or less continuous ''bands'' of frequencies. As the temperature rises, the frequencies generally decrease, and the energy widths increase. These changes take place in a smooth manner, except for two longitudinal optic modes, observed at positions (1.27, 1.27, 0) and (1.2, 1.2, 0.2) in reciprocal space, which display sharp increases in energy width at the transition temperature. No reasonable explanation of these effects has yet been found. (author) [French] On a observe les modes normaux de vibration du laiton beta, alliage ordonne de cuivre et de zinc, a une temperature de 296 Degree-Sign K au moyen de la diffusion coherente de neutrons lents a un phonon par des monocristaux. Le spectrometre triaxial a cristal du reacteur NRU a ete utilise pour mesurer les frequences de modes se propageant le long de directions de haute symetrie 00{zeta}], [{zeta}{zeta}0], [{zeta}{zeta}{zeta}{zeta}] et [ Vulgar-Fraction-One-Half Vulgar-Fraction-One-Half {zeta}]. Les courbes de dispersion ressemblent a celles d'un cristal a reseau cubique centre simple, comme Na, a l'exception pres que certaines degenerescences disparaissent, principalement du fait des differences entre les forces Cu-Cu et Zn-Zn entre un atome et le deuxieme atome le plus proche. C'est ainsi que les auteurs ont trouve deux modes de vecteurs d'onde distincts (0,5, 0,5, 0,5) (en unites de reseau reciproque), dont les frequences sont egales respectivement a (4,21 {+-} 0,06) et (4,93 {+-} 0,10)' 10{sup 12} c/s. Les auteurs mentionnent brievement des modeles de force interatomique qui donnent une description satisfaisante des resultats obtenus a la temperature de 296 Degree-Sign K. Ils ont etudie plusieurs modes normaux a des temperatures elevees, en particulier au voisinage de la transformation ordre- desordre a environ 727 Degree-Sign K. On n'observe pas de difference tres nette dans la structure generale des courbes de dispersion du fait de la disparition de l'ordre a grande distance a cette temperature bien que les diverses 'ramifications' ('splittings') observees a 296 Degree-Sign K se confondent en 'bandes' de frequences plus ou moins continues. L'elevation de la terfiperature s'accompagne de facon generale d'une diminution des frequences et d'une augmentation de la largeur des energies. Ces variations se produisent progressivement, a l'exception de deux modes optiques longitudinaux, observes aux positions (1,27, 1,27, 0) et (1,2, 1,2, 0,2) dans un espace reciproque, qui accusent une augmentation brusque de la largeur des energies a la temperature de transformation. Jusqu'a present, aucune explication logique de ces effets n'a ete donnee. (author) [Spanish] Los autores han estudiado los modos normales de vibracion de la aleacion ordenada de cobre y cinc (laton {beta}) a 296 Degree-Sign K por dispersion monofononica coherente de neutrones lentos en muestras monocristalinas. Utilizan el espectrometro triaxial de cristal del reactor NRU para medir las frecuencias de los modos que se propagan a lo largo de las direcciones de simetria elevada [00{zeta}], [{zeta}{zeta}0], [{zeta}{zeta}{zeta}{zeta}] y [ Vulgar-Fraction-One-Half Vulgar-Fraction-One-Half {zeta}]. Las curvas de dispersion se asemejan a las de un cristal cubico simple centrado en el cuerpo, tal como el Na, con la salvedad de que se eliminan ciertas degeneraciones, principalmente en razon de la diferencia existente entre las fuerzas que actuan entre los segundos atomos vecinos Cu-Cu y Zn-Zn. Por ejemplo, se observan dos modos distintos de vectores de onda (0,5, 0,5, 0,5) (en unidades reticulares reciprocas), cuyas frecuencias son (4,21{+-}0,06) y (4,93{+-}0,10) * 10{sup 12}c/s, respectivamente. Se exponen brevemente modelos de fuerzas interatomicas que explican satisfactoriamente los resultados obtenidos a 296 Degree-Sign K. Se han estudiado varios modos normales a temperaturas elevadas, sobre todo en las proximidades de la transicion de fase orden-desorden, a unos 727 Degree-Sign K. No se observan cambios acusados en la estructura general de las curvas de dispersion como resultado de la desaparicion del orden de largo alcance a esta temperatura, aunque los diferentes 'desdoblamientos'observados a 296 Degree-Sign K se unen confusamente en 'bandas' de frecuencia mas o menos continuas. Las frecuencias suelen disminuir al elevarse la temperatura, en tanto que las anchuras energeticas aumentan. Estas alteraciones tienen lugar gradualmente, excepto en el caso de dos modos opticos longitudinales, observados en las posiciones (1,27, 1,27, 0) y (1,2, 1,2, 0,2) en el espacio reciproco, que presentan acusados aumentos de la anchura energetica a la temperatura de transicion. Estos efectos no se han podido explicar aun de manera logica. (author) [Russian] Nabljudenija za obychnymi formami kolebanija uporjadochennogo splava medi i cinka ({beta}-latun') pri 296 Degree-Sign K provodilis' s pomoshh'ju kogerentnogo odno fononnogo rassejanija medlennyh nejtronov na monokristallicheskih obrazcah. Dlja izmerenija chastot kolebanij, rasprostranjajushhihsja vdol' vysokosimmetrichnyh napravlenij [00{zeta}], [{zeta}{zeta}0], [{zeta}{zeta}{zeta}{zeta}] i [ Vulgar-Fraction-One-Half Vulgar-Fraction-One-Half {zeta}] ispol'zovalsja trehosnyj kristallicheskij spektrometr na reaktore NRU. Krivye dispersii napominajut krivye dispersii prostogo ob{sup e}mno-centrirovannogo kubicheskogo kristalla, naprimer Na, za iskljucheniem togo, chto pojavljajutsja nekotorye vyrozhdenija, v osnovnom vvidu razlichija mezhdu vtorym blizhajshim sosedom Si-Si i silami Zn-Zn. Naprimer, my nahodim dve razlichnye formy volnovogo vektora (0.5, 0.5, 0.5) (v obratnyh edinicah reshetki), chastoty kotoryh sootvetstvenno sostavljajut (4,21 {+-}0,06) i (4,93 10) * 10{sup 12} gerc. Kratko upominajutsja modeli mezhatomnyh sil, kotorye predstavljajut udovletvoritel'noe opisanie rezul'tatov, poluchennyh pri 296 Degree-Sign K. Nekotorye normal'nye formy kolebanij izucheny pri povyshennyh temperaturah, osobenno v oblasti perehoda iz uporjadochennogo sostojanija v neuporjadochennoe pri temperature priblizitel'no 727 Degree-Sign K. V obshhej strukture krivyh dispersij ne otmechaetsja znachitel'nyh izmenenij v rezul'tate ischeznovenija porjadka dal'nego rasstojanija pri jetoj temperature, hotja razlichnye ''rasshheplenija'', nabljudaemye pri 296 Degree-Sign K, rasplyvajutsja v bolee ili menee postojannye ''polosy'' chastot. Pri povyshenii temperatury chastoty v celom umen'shajutsja, a jenergeticheskie shiriny uvelichivajutsja. Jeti izmenenija proishodjat plavno, za iskljucheniem dvuh prodol'nyh opticheskih form, nabljudaemyh v polozhenijah (1,27; 1,27; 0) i (1,2; 1,2; 0,2) v obratnom prostranstve, v kotoryh projavljajutsja rezkie uvelichenija jenergeticheskih shirin pri temperature perehoda. Nikakogo razumnogo ob{sup j}asnenija dlja jetih jeffektov eshhe ne najdeno. (author)}
place = {IAEA}
year = {1965}
month = {Apr}
}