Acetylene diffusion in Na-Y zeolite

Study of diffusivity of acetylene adsorbed in Na-Y zeolite by quasi-elastic neutron scattering (QENS) measurements at temperatures of 300, 325 and 350 K is reported. A model in which the acetylene molecules undergo random-walk diffusion characterized by a Gaussian distribution of jump lengths inside zeolite cages describes the data consistently. The diffusion constant, residence time between jumps and root mean square jump length are determined

Spin fluctuation effects in substituted CeRu<SUB>2</SUB>Si<SUB>2</SUB> and YbPd<SUB>2</SUB>Si<SUB>2</SUB> alloys

Effects of chemical substitution in CeRu2Si2, a well-studied heavy fermion system and YbPd2Si2 have been investigated through magnetic susceptibility and X-ray diffraction in the systems CeRuxSi2, CeRu2&#8722;xOsxSi2, CeRu2Si2&#8722;x Gex and YbPd2Si2&#8722;x Gex. Replacing silicon by germanium generates normal chemical pressure effect, namely, Ce and Yb atoms in CeRu2Si2 and YbPd2Si2 became more and less magnetic respectively. With increasing Ge concentration, CeRu2Si2&#8722;x Gex exhibits larger susceptibility at low temperature, goes to an antiferromagnetic state and finally becomes ferromagnetic. In YbPd2Si2&#8722;xGex , increasing Ge concentration drives Yb atoms to more divalent state. Electronic effects are more pronounced in CeRu2&#8722;xOsx Si2 though CeRu2Si2 and CeOs2Si2 have very nearly the same lattice parameters. It is conjectured that CeRu2Si2&#8722;xGex may be the first Ce-based heavy fermion having a magnetic ground state

A New Low-Expansion Composite in Lead Iron Niobate-Lead Titanate System

A composite prepared between lead titanate (PT) and lead iron niobate (PFN) exhibits low thermal expansion coefficient (α) over the temperature range 300–673K. X-ray, DTA, and dilatometric measurements have been used to identify the optimum sintering condition, retaining the individual constituent identity, to achieve overall low bulk thermal expansion. The composite, PFN0.35PT0.65 sintered at 1223K for 15 min. and at 1253K for 60 min. are sufficiently dense and show an overall α of –0.3 × 10–6/K and –1.2 × 10–6/K, respectively, in the temperature range 300–673K

Formulation of Lamination Conditions and Interface Studies using Acrylic Binder System for LOM 9

A multicomponent binder-plasticiser system based on acrylates was formulated for making flexible tapes of Alumina (58 volume %), to be used for Laminated Object Manufacturing. Optimum lamination parameters were arrived at by viscosity measurement of the binder-plasticiser system and dilatometry of the compounded tapes . Lamination was done at five different temperatures (75, 85, 90, 95 and 110°C) with solvent (toluene-butanol) spray and under three different pressures ( below 50 psi). The interlaminar strength was measured and interface studies were made using SEM .The shrinkage along the Z direction during lamination was in the range of 1.7-3.5%. Highest interlaminar strength and defect free lamination could be achieved at the intermediate temperature of 90o C, due to sufficient reduction of polymer viscosity and presence of solvent.Mechanical Engineerin

Corrected spacegroup for M<SUB>0.5</SUB>Ti<SUB>2</SUB>P<SUB>3</SUB>O<SUB>12</SUB> compounds

The space group of the low thermal expansion phosphates, belonging to NASICON structural family, having divalent cations has been reassigned as R3&#x033F; based on powder X-ray diffraction studies in the system M0.5Ti2P3O12. This implies further ordered distribution of M2+ cations and vacancies along the hexagonal 'c' direction of NASICON structure