Thermal expansion of CuInTe2 from 30 to 300 K

Abstract

The thermal expansion coefficients αa and αc of the lattire parameters a and c of CuInTe2, are measured in the temperature range from 30 to 300 K using the X‐ray Bond metohod. Both αa and αc decrease with decreasing tcmperature and become negative at about 38 and 54 K, respectively. The results are discussed in terms of the principal Grüneisen parameters of chalcopyrite structure crystals. It is concluded that there are low‐energy lattice vibrational modes with negative Grüneisen parameters in CuInTe2. A comparison is mde with previous measurements for CuInTe2, and other Cu–III–VI2 compounds as well as with theoretical estimates.

Thermal expansion anisotropy and individual bond expansion coefficients in ternary chalcopyrite compounds

“…This means that the characteristic parameters in the anharnionic part of the interatomic potentials and, therefore, also the thermal expansion coefficients should be very close to each other for both types of bonds which agrees with our result for the model with or, = 0 but not with that for the regular tetrahedron model. In the few AIB1llCZ1 conipounds for which the heat capacity due to lattice anharrnonicity has been studied we have the same situation as in the A1lB1"C; compounds (NEU- MANN 1986 b ;NEUMANN et al 1985) indicating also nearly equal values for orAc and cvliC'. Furthermore, the thermal expansion coefficients of the BilICll semiconductors vary only slightly from compound to compound in the range from 8.3 .…”

“…I n noncubic crystals the Griineisen functions are, in general, anisotropic since they are determined by the anisotropy in the lattice vibration spectrum and the corresponding mode Griineisen parameters. From the few related data for the ternary chalcopyrite compounds it follows that ya > ye ( DEUS et al;NEUMANN 1983;NEUMANN et al 1984). However, even if we have ya = yc an anisotropy can be caused by the influence of the elastic compliances on a, and ac.…”

Anisotropy of the Optical Band Edge Absorption in CuInTe2 Single Crystals

“…The lattice parameters of the compound obtained are in agreement with the literature data [6]. After determination of the crystallographic orientation, (loo), (OlO), and (001) plates measuring 4 x 4 x 1 mm3 were fabricated, whose surface was first mechanically lapped and subsequently polished in an etching agent.…”

“…Fig. 6 a compares the temperature behaviour of the edge optical dichroism of CuInTe, and of the tetragonal extension of CuInTe, derived from [6]. One readily sees that the characteristic minima of both curves (Fig.…”

“…Since the optical anisotropy of other chalcopyrites, I-111-VI, and 11-I\--V,, depends substantially on uniaxial lattice deformation, we consider this relation by analyzing the temperature behaviour of dichroism. The lattice parameters of CuInTe, vary nonlinearly with temperature [6], which results in a complex dependence z(T). Fig.…”