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Synthesis and study of Sr-substituted misfit layer sulfides

Journal Article · · Materials Research Bulletin
 [1];  [2];  [3];  [4];  [3]
  1. Chemical Department, Moscow State University, 119899 Moscow (Russian Federation) and Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-10691 Stockholm (Sweden)
  2. Department of Inorganic Chemistry, Arrhenius Laboratory, Stockholm University, S-10691 Stockholm (Sweden)
  3. Chemical Department, Moscow State University, 119899 Moscow (Russian Federation)
  4. Department of Materials Science, Moscow State University, 119899 Moscow (Russian Federation)
Two series of [(Ln{sub 1/3}Sr{sub 2/3}S){sub 1.5}]{sub 1.15}NbS{sub 2} (1.5Q/1H) and (Ln{sub 1-x}Sr{sub x}S){sub 1+y}NbS{sub 2} (1Q/1H) misfit layer sulfides have been synthesised and studied by X-ray powder and single crystal diffraction, EDX-analysis and magnetic measurements. For the early lanthanides (Ln = La, Ce) only the (Ln{sub 1-x}Sr{sub x}S){sub 1+y}NbS{sub 2} (x < 0.40-0.45, y = 0.15-0.17) compounds were formed whereas for late lanthanides (Ln = Pr, Nd, Sm, Gd-Er, Yb, Lu), and yttrium, both types of phases can be obtained. The crystal structure of (Pr{sub 0.55}Sr{sub 0.45}S){sub 1.15}NbS{sub 2} has been refined on the basis of X-ray single crystal data using the superspace approach. It consists of double layers [Pr{sub 0.55}Sr{sub 0.45}S] of NaCl-type (Q-part: a = 5.799(3) A, b = 5.810(2) A, c = 23.331(9) A, z = 4) and NbS{sub 2}-sandwiches (H-part: a = 3.332(3) A), z = 8, yielding a q-vector q = ({alpha} 0 0), {alpha} = 0.74) alternating along the c-direction. The superspace group pair is Fm2m ({alpha} 0 0):Fm2m ({alpha} 0 0) (No. 42.7). The refinement converged to R{sub w(obs)} = 0.069. According to the structure refinement and EDX-analysis data in the [Pr{sub 0.55}Sr{sub 0.45}S]-slab almost half of the Pr-atoms are randomly replaced by Sr. The minimal formal value of charge transfer from the Q- to the H-part of the structure necessary to stabilise the misfit Nb-based layer sulfides has been estimated as about 0.6 e per Nb atom.
OSTI ID:
20883091
Journal Information:
Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 1 Vol. 40; ISSN MRBUAC; ISSN 0025-5408
Country of Publication:
United States
Language:
English