Theory of the Anomalous Temperature Dependence of C₁₂ in NaCl‐Like Structure Solids Direct Observation of Phonon—Lattice Interactions

Abstract

The basic quantum theory is presented for the temperature dependence of the elastic constants of solids. The phonon-lattice interaction is invoked to explain the anomalous temperature dependence of CI2 in NaC1-like structure alkali halides. The calculated values of dCl,/dT for lithium and sodium halides are negative and dC12/dT for potassium and rubidium halides (except KF) are positive (showing an anomalous temperature dependence of C12). These results are in excellent agreement with available experimental data.On presente un calcul quantique fondamental sur la variation des constantes Blastiques des solides en fonction de la temperature. On attribue la dependence anomale des parametres C12 pour les haloides alcalins du type NaCl it I'interaction phonon-reseau. Les valeurs de dCl,/dT ainsi obtenues sont negatives pour le lithium et le sodium, mais positives (et par consequent anomales) pour les haloi'des ( s a d KF) du potassium et du rubidium. Les resultats obtenus sont en tres bon accord avec les valeurs experimentales que I'on a pu trouver.

Anharmonic properties of rocksalt structure solids

“…Owing to lack of theoretical or experimental data for lithium cyanide, comparison cannot be made. The experimental values of sodium and potassium halides [13,25,34,35] are of the same order and are in well agreement with present results, which shows the validity of the present theory. The Temperature variation of SOECs for NaCN is presented in Fig.…”

“…Some interesting results have been presented by several investigators while studying the anharmonic properties of the substances possessing various crystal structures. Some have studied temperature variation of anharmonic properties of mixed alkali halides and cyanides [11], of a few alkali cyanides, of rare gas materials [12], of alkali halides [10,11,13] using ultrasonic [14,15], theoretical [6] and Brillouin scattering [16] methods.…”

Temperature Dependences of Third‐Order Elastic Constants of CsCl, CsBr, and CsI Crsystals

“…These expressions take into account the effect of three-body interactions as well as the temperature contribution in terms of phononpressure theory [4]. The present approach is better than the one adopted by previous workers [l to 31 as mentioned in the Introduction.…”

Extended temperature dependence of elastic constants in cubic crystals

“…The study of the temperature dependence of elastic constants for crystals was provided in Refs. [1][2][3][4][5][6][7][8][9][10][11][12][13]. In Ref.…”