Transformation of the Chromium Coordination Environment in LaCrAsO Induced by Hydride Doping: Formation of LaCrAsOH.

We report the synthesis of LaCrAsOH (0.1 < y < 1.6) oxyhydride solid solutions using a solid-state reaction under high pressure with a solid-state hydrogen source and exhibit an example of how H doping can also promote structural changes: H doping in LaCrAsO results in the formation of LaCrAsOH with the LaFeSeO-type layered structure.

Large-moment antiferromagnetic order in overdoped high- superconductor SmFeAsO D .

In iron-based superconductors, high critical temperature () superconductivity over 50 K has only been accomplished in electron-doped FeAsO ( is heavy rare earth () element). Although FeAsO has the highest bulk (58 K), progress in understanding its physical properties has been relatively slow due to difficulties in achieving high-concentration electron doping and carrying out neutron experiments. Here, we present a systematic neutron powder diffraction study of SmFeAsO D , and the discovery of a long-range antiferromagnetic ordering with ≥ 0.

Ferrimagnetic Cage Framework in CaFeSiOCl.

The positively charged cage framework of the natural mineral mayenite, which enables various species with negative charge to be stabilized, is one of the key structures to provide the new functionalities exploited in applications. Here we report the structural and magnetic properties of recently found eltyubyuite, CaFeSiOCl, which is the first compound bearing a transition metal oxide as a main constituent in the mayenite-type structure. From neutron powder diffraction measurements at T = 20 K and the low temperature Mössbauer measurement, we determined the magnetic structure of eltyubyuite to be a ferrimagnet with oppositely aligned magnetic moments of +3.

New LaMAsH(x) (M = Co, Ni, or Cu) arsenides with covalent M-H chains.

A new series of tetragonal LaPtSi-type mixed-anion arsenides, LaMAsH(x) (M = Co, Ni, or Cu), has been synthesized using high-temperature and high-pressure techniques. The crystal structure of these intermetallic compounds determined via powder neutron diffraction is composed of a 3D framework of three connected planes with the La ions filling the cavities in the structure. Each late transition-metal ion M, all of which have relatively large electronegativities, behaves like a main group element and forms a planar coordination configuration with three As ions.

An anti CuO2-type metal hydride square net structure in Ln2M2As2H(x) (Ln=La or Sm, M=Ti, V, Cr, or Mn).

Using a high pressure technique and the strong donating nature of H(-), a new series of tetragonal La2Fe2Se2O3-type layered mixed-anion arsenides, Ln2M2As2H(x), was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x≈3). In these compounds, an unusual M2H square net, which has anti CuO2 square net structures accompanying two As(3-) ions, is sandwiched by (LaH)2 fluorite layers. Notably, strong metal-metal bonding with a distance of 2.

Hydrogen ordering and new polymorph of layered perovskite oxyhydrides: Sr₂VO(4-x)H(x).

Compositionally tunable vanadium oxyhydrides Sr2VO(4-x)H(x) (0 ≤ x ≤ 1.01) without considerable anion vacancy were synthesized by high-pressure solid-state reaction. The crystal structures and their properties were characterized by powder neutron diffraction, synchrotron X-ray diffraction, thermal desorption spectroscopy, and first-principles density functional theory (DFT) calculations.