The Role of Electronic Subsystem in the Negative Thermal Expansion of Ferroelectric-Semiconductor TlGaSe2

Abstract

Effect of illumination and external electric field on thermal expansion of TlGaSe2 crystals has been investigated. Strong transformation of negative linear expansion coefficient has been observed. It is supposed that two main mechanisms are responsible for observed effects: formation of electret state and reverse piezoelectric effect. The electronic nature of negative linear expansion of TlGaSe2 crystals has been proved for the first time. (C) 2011 The Japan Society of Applied Physics