The structure of two orthorhombic nitroprussides:Cd[Fe(CN)5NO]·2H2O and Zn[Fe(CN)5NO]·2H2O

When zinc and cadmium nitroprussides, obtained as powders or single-crystals samples, are aged in air they lose crystallization water and change their crystalline structure. In the stable form these two complexes are orthorhombic dihydrates with four molecules in the unit cell. In the aging process the crystals become brittle producing a polycrystalline material. The crystalline structure of these two complexes (orthorhombic dihydrates) was refined from their XRD powder patterns using the Rietveld method. As the starting model in the refining process the reported orthorhombic structure of copper nitroprusside (dihydrate) was used. The main changes in the dehydration process associated with the structural transformation take place in the coordination sphere of the outer cation (Cd or Zn). © 2001 Elsevier Science B.V. All rights reserved

Highly stable cooperative distortion in a weak Jahn-Teller d 2 cation: Perovskite-type ScVO 3 obtained by high-pressure and high-temperature transformation from bixbyite

A novel ScVO 3 perovskite phase has been synthesized at 8 GPa and 1073 K from the cation-disordered bixbyite-type ScVO 3. The new perovskite has orthorhombic symmetry at room temperature, space group Pnma, and lattice parameters a = 5.4006(2) \uc5, b = 7.5011(2) \uc5, and c = 5.0706(1) \uc5 with Sc 3+ and V 3+ ions fully ordered on the A and B sites of the perovskite cell. The vanadium oxygen octahedra [V-O 6] display cooperative Jahn-Teller (JT) type distortions, with predominance of the tetragonal Q 3 over the orthorhombic Q 2 JT modes. The orthorhombic perovskite shows Arrhenius-type electrical conductivity and undergoes a transition to triclinic symmetry space group P-1 close to 90 K. Below 60 K, the magnetic moments of the 4 nonequivalent vanadium ions undergo magnetic long-range ordering, resulting in a magnetic superstructure of the perovskite cell with propagation vector (0.5, 0, 0.5). The magnetic moments are confined to the xz plane and establish a close to zigzag antiferromagnetic mode. \ua9 2011 American Chemical Society.Peer reviewed: YesNRC publication: Ye

Neutron diffraction and 119Sn Moessbauer study of Sm3Ag4Sn4

The magnetic properties of Sm3Ag4Sn4 have been investigated using bulk magnetization, Sn-119 Mossbauer spectroscopy and neutron diffraction. We find that the Neel temperature (T-N) is 26.0( 5) K, well above the value of similar to 9 K previously determined using magnetic susceptibility measurements. Neutron diffraction data indicate that the Sm moments most likely adopt either the I(P)mm' m or I(P)mmm' magnetic space groups, neither of which allows order at the 2d site, in marked contrast to the vast majority of other compounds in the R3T4X4 family. Transferred hyperfine field models suggest that the I(P)mmm is the only group that is consistent with the 119Sn Mossbauer results. We derive a samarium moment of 0.47 +/- 0.10 mu(B) on the Sm 4e site at 3 K. 119Sn Mossbauer spectroscopy shows that the system undergoes a spin reorientation transition at 8.3(3) K, where the moments rotate towards the a-axis