Crystallographic analyses of x-ray and neutron diffraction data have provided a definitive structural representation of {HRh[P(O-i-C(3)H(7))(3)](2)}(2) and {HRh[P(OCH(3))(3)](2)}(3). These polynuclear hydrides are generated from square planar H(2)Rh[P(OR)(3)](2) units by edge (hydrogen atom) sharing and by vertex (hydrogen atom) sharing to form the dimeric and trimeric structures, respectively....

The evolution of the crystal structure and some magnetic properties of the heavy-fermion material CeCu(6-x)Sn(x) (x = 0, 0.25, 0.65, 0.75, 0.85 and 1.0) has been studied by powder neutron diffraction and by specific heat measurements. The substitution of Cu by Sn suppresses the temperature induced orthorhombic to monoclinic transition, known to occur in the pure CeCu(6) phase. No structural pha...

Doping is a primary tool for the modification of the properties of materials. Occlusion of guest molecules in crystals generally reduces their symmetry by the creation of polar domains, which engender polarization and pyroelectricity in the doped crystals. Here we describe a molecular-level determination of the structure of such polar domains, as created by low dopant concentrations (<0.5%). Th...

The superior piezoelectric properties of all polycrystalline ferroelectrics are based on the extent of non-180° domain wall motion under electrical and mechanical poling loads. To distinguish between 180° and non-180° domain wall motion in a soft-doped and a hard-doped lead zirconate titanate (PZT) ceramic, domain texture measurements were performed using x-ray and neutron diffraction after dif...

Molecular segregation in methanol-water mixtures is studied across a wide concentration range as a function of temperature and pressure. Cluster distributions obtained from both neutron diffraction and molecular dynamics simulations point to significantly enhanced segregation as the mixtures are cooled or compressed. This evolution toward greater molecular heterogenity in the mixture accounts f...

The applicability of the molecular-replacement (MR) method, implemented through the AMoRe package [Navaza (1994). Acta Cryst. A50, 157-163], is studied at very low resolution (d > 20 A) and for very large molecular complexes. Due to the nature of the low-resolution data, specific problems appear. In particular, rotation-function peaks are very broad and translation functions based on Patterson ...

Neutron crystallography began to be employed at the Bhabha Atomic Research Centre (BARC), Trombay, Mumbai in the early sixties. At that time, the technique, at BARC as well as elsewhere, was in a nascent state, with emphasis on building of instruments and development of crystallography software. Over the years, the Trombay group kept pace with the advancements in other parts of world and employ...

Neon hydrate was synthesized and studied by in situ neutron diffraction at 480 MPa and temperatures ranging from 260 to 70 K. For the first time to our knowledge, we demonstrate that neon atoms can be enclathrated in water molecules to form ice II-structured hydrates. The guest Ne atoms occupy the centers of D2O channels and have substantial freedom of movement owing to the lack of direct bondi...

W. Ratcliff II,1,* Zahra Yamani,2 V. Anbusathaiah,3,† T. R. Gao,3 P. A. Kienzle,1 H. Cao,4 and I. Takeuchi3 1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA 2Canadian Neutron Beam Centre, National Research Council, Chalk River Laboratories, Chalk River, Ontario, Canada K0J 1J0 3Department of Materials Science and Engineering, U...

In an effort to better understand the structural changes occurring during hydrogen loading of erbium target materials, we have performed in-situ D2 loading of erbium metal (powder) at temperature (450C) with simultaneous neutron diffraction analysis. This experiment tracked the conversion of Er metal to the  erbium deuteride (solid-solution) phase and then on to the  (fluorite) phase. Complet...