Synthesis, structural characterization, and magnetic properties of NaRE9(GeO4)(6)O-2 (RE=Nd, Pr)

Abstract

The new compounds NaRE9(GeO4)(6)O-2 (RE = Nd, Pr) have been synthesized at 500 and 524 degreesC, respectively, via the hydrothermal method. The compounds crystallize with an oxyapatite structure in the hexagonal space group P6(3)/m with one formula unit in a cell of dimensions a = 9.782(1) Angstrom, c = 7.083(1) Angstrom (T = 293 K), V = 587.0(2) Angstrom(3) for RE = Nd and a = 9.802(1) Angstrom, c = 7.116(1) Angstrom (T = 293 K), V = 592.1(2) Angstrom(3) for RE = Pr. Each structure is composed of REO7 and REO9 polyhedra as well as GeO4 tetrahedra. The magnetic susceptibility data indicates paramagnetic behavior for both compounds at temperatures between 60-300 K for Nd and 2-300 K for Pr with a Weiss constant of theta = 44.8 and 33.5 K for Nd and Pr, respectively. (C) 2003 Elsevier B.V. All rights reserved.