Results of ultrasonic studies of the magnetoresistive compound Nd0.5Sr0.5Mn
O3 in a broad temperature range (1.5-180K) are reported. With decreasing te
mperature the pronounced acousticniode hardening was observed at about T-CO
= 145 K. The change of sound velocity around T-CO was explained by a stron
g coupling between the acoustic phonons and the charge-ordered states. (C)
2001 Elsevier Science B.V. All rights reserved.