On the critical exponent of order parameter in Sn2P2S6 and Sn2P2(Se0.28S0.72)6 crystals

Abstract

Abstract. We have determined critical exponents of the order parameter in ferroelectric Sn 2 P 2 S 6 and Sn 2 P 2 (Se 0.28 S 0.72 ) 6 crystals at the atmospheric pressure. They are equal to 0.29 0.02  for Sn 2 P 2 S 6 and 0.24 0.02  for Sn 2 P 2 (Se 0.28 S 0.72 ) 6 . These value suggest that, with changing selenium concentration from x = 0 up to x = 0.28, the solid solutions Sn 2 P 2 (Se x S 1-x ) 6 approach the conditions of tricritical point, which is realised in the vicinity of x = 0.28. The conclusion agrees well with the results of our recent works derived with the other techniques.