Rare earth trialuminides (RAl₃) exhibit an interesting series of structures changing from 2H to 3C in the bulk form. Many of the rare earth trialuminides have been recently found to exhibit curious structural characteristics such as the occurrence of the modulated phases. A detailed investigation of the formation synthesis and characterization of some binary and ternary alloys of the rare earth-aluminium system has been carried out. High resolution microscopic technique has been employed to study the modulated phases for some alloyse.g. HoAl₃, Er_0·5Gd_0·5Al₃ and Y_0·91Er_0·09Al₃. With the help of lattice imaging technique, several new modulated phases have been investigated. A possible mechanism for the formation of these phases has been suggested. The details of the results obtained by lattice imaging technique are discussed.

Proton transport in potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) is briefly reviewed. The experimental results of Wagner’s polarization measurement, coulometry, infrared spectroscopy, transient ionic current measurement, the variation of electrical conductivity with temperature and electrogravimetric analysis for KDP and ADP are reported. H⁺ and OH^- ions are ascertained as the mobile ionic species. A new mechanism for the proton transport in KDP and ADP is suggested: A three-fold rotation of H₂P₄^- units about any of the axes of PO₄ tetrahedra leads to a configuration like O...H...H...O, the rearrangement of which provides H...O...H bridge that gets electrodissociated on the application of a d.c. electric field.

In the present study, a novel method involving nitrogen plasma annealing has been reported for preparing InN nanoparticle/nanorod structures and for improving the properties of InN nanoparticle layers. Plasma annealed structures have been characterized by X-ray diffraction, atomic force microscopy and photoluminescence spectroscopy techniques. InN nanoparticle layers have been prepared using activated reactive evaporation set up. It has been observed that there is a remarkable improvement in the conductivity and crystallinity of InN nanoparticle layers on annealing in nitrogen plasma. This has been attributed to the increase in the nitrogen content of the samples. Experiments involving plasma annealing of In nanorods deposited oxide template has also been carried out. It was found that on plasma treatment In nanorods get converted to mixed phase InN nanorods with hexagonal and cubic fractions.

In the present study, microwave energy (2.45 GHz) has been used to prepare nickel oxide–yttria stabilized zirconia (NiO–YSZ) composites of composition, 𝑚NiO–(1 – 𝑚) Zr_0.9Y_0.1O_1.95 (𝑚 = 0.2, 0.3, 0.4, 0.5 and 0.6), from a precursor obtained by mixing NiO, Y₂O₃ and monoclinic ZrO₂ in their stoichiometric ratio. The composites have been prepared by conventional processing also to compare the products with those of microwave processed products. During comparison, it was observed that NiO–YSZ composites of each composition obtained by microwave processing had cubic phase of YSZ while in the conventionally prepared composites of compositions, 𝑚 = 0.2 and 0.3, monoclinic, tetragonal and cubic phases of zirconia existed instead of its pure cubic phase. The composites were reduced to yield Ni–YSZ.

In recent years the application of metal nanoparticles is gaining attention in various fields. The present study focuses on the additive effect of `green’ synthesized iron nanoparticles (FeNPs) on dark fermentative hydrogen (H₂) production by a mesophilic soil bacterium Enterobacter cloacae. The FeNPs were synthesized by a rapid green method from FeSO₄ using aqueous leaf extract of Syzygium cumini. The synthesized FeNPs showed a characteristic surface plasmon resonance peak at 267 nm. The transmission electron microscopy images confirm that the formation of FeNPs was mainly porous and irregular in shape, with an average particle size of 20–25 nm. The presence of iron (Fe) in the synthesized FeNPs was confirmed by energy-dispersive X-ray spectroscopy. The comparative effect of FeSO₄ and FeNPs on batch fermentative H₂ production from glucose was investigated. The fermentation experiments reveal that the percentage and yield of H₂ in FeNPs supplementation were increased significantly than the control (no supplementation) and FeSO₄ containing media. The maximum H₂ yield of 1.9 mol mol⁻¹ glucose utilized was observed in 100 mg l⁻¹ FeNPs supplementation, with two-fold increase in glucose conversion efficiency. Thus, the result suggests that FeNPs supplementation in place of FeSO₄ could improve the bioactivity of H₂ producing microbes for enhanced H₂ yield and glucose consumption.