Low‐Temperature Anomalies in the CdI²Cd Crystalline System

Abstract

From the measurements of elastic coefficients, piezooptical constants, and dilatometrical lengthening the existence of an improper ferroelastic phase transition of first order in the CdI,-Cd single crystalline system within the temperature range 40 to 60 K is found. Different values of the temperature hysteresis are revealed for the piezooptical and elastic constants. From the data obtained an essential role of electron-phonon interaction in the appearance of the mentioned phase transitions is concluded. The obtained results clearly show that in the Cd1,-Cd single crystalline system at lower temperatures long-range forces appear between the impurity subsystems, which due to the specific electron-phonon interactions tend to the appearance of the phase transitions. The behaviour of the elastic constants and the lengthening indicate the possible ferroelastic nature of these transitions. Simultaneously the existence of the temperature hysteresis reflects the first-order nature of the mentioned transitions.

Cadmium clusters in CdI2layered crystals: the influence on the optical properties

“…The proposed model predicts the changes of some physical parameters of crystals, which were observed experimentally. For example, the c lattice parameter decreases due to the attraction between adjacent sandwiches [16], the nuclear quadruple resonance frequency of I 127 nuclei varies due to the electric field gradient changes caused by addition chemical bonds between Cd i and I atoms [17], and changes of the nonlinear susceptibility are also observed [14,18].…”

Morphology and Optical Properties of Nanostructures Formed in Non-Stoichiometric CdI2 Crystals

“…-I]-Cd-I is also confirmed by changes in the nonlinearoptical properties and the NQR frequencies of 127 I [15][16][17].…”

Optically induced second-harmonic generation in CdI2 Cu layered nanocrystals

“…We will present experimental investigations of the photoinduced SHG versus thickness of the CdI 2 layers and their concentration at different temperatures. It was shown earlier [16,17] that there is the possibility of enhancement of second-order optical constants during cooling.…”