Thermal expansion of single crystals of the layered compounds TlGaSe2 and TlInS2

Experimental data are reported from studies of the thermal expansion of single crystals of the layered compounds TlGaSe2 and TlInS2 in the plane of the layers and in the direction perpendicular to the layers in the temperature region 20-300 K. Observed features of the thermal expansion are discussed in the light of the available data on the elastic properties of TlGaSe2 and TlInS2. It is found that the differences in the temperature behavior of the thermal expansion coefficients in the plane of the layers alpha (parallel to)(T) in the TlGaSe2 and TlInS2 crystals are due to the different degree of anisotropy of these crystals and to the different value of the "interlayer" elastic constant C-13. (C) 2001 American Institute of Physics.