High pressure synthesis of LnCrs(3) (Ln = La, Ce, Nd, Sm) and LaCr1-xFexS3(x <= 0.2) with NH4CdCl3 structure type

LnCrS(3) (Ln = La, Ce, Nd, Sm) with NH4CdCl3 structure type were prepared i n high pressure synthesis at 4 GPa, 1373 K for 2 h. Their orthorhombic latt ice parameters were a = 0.787(2), b = 0.385(1), c = 1.334(3) nm for LaCrS3; a = 0.776(4), b = 0.379(2), c = 1.316(7) nm for CeCrS3; a = 0.769(2), b = 0.377(1), c = 1.306(4) nm for NdCrS3; and a 0.764(5), b = 0.374(2), c = 1.2 97(8) nm for SmCrS3. The Ln(3+) ions are coordinated with nine S2- ions in CrS6 double chains. The products are antiferromagnetic semiconductors. The paramagnetic temperature Theta varied with a Cr-Cr distance in the CrS6 dou ble chain. They also showed a weak ferromagnetic behavior at low temperatur e below 120 K. Magnetic hysteresis was observed for the ferromagnetism betw een ZFC and FC measurements. LaCr1-xFexS3 solid solution with NH4CdCl3 stru cture type was also obtained in high pressure synthesis at 4 GPa, 1473 K fo r 2 h. The Fe3+ in high spin state substitutes the Cr3+ up to about x = 0.2 . (C) 1999 Elsevier Science Ltd.