Crystallization behaviour of Metglas 2826 MB (Fe40Ni38Mo4B18)

Differential scanning calorimetry, x-ray diffraction and transmission electron microscopy have been employed to determine the thermal stability and identify the crystalline phases on devitrification of Metglas 2826 MB. The glass crystallizes intoγ-FeNiMo and fcc (FeNi)23B6 with activation energies of 270 and 375 kJ mol−1 respectively. The reactions are primary and polymorphic in nature. The influence of Mo towards crystallization of Fe40Ni40B20 has been to enhance the formation of the fcc (FeNi)23B6 phase in preference to orthorhombic (FeNi)3B phase and to raise the thermal stability of the amorphous state.

Influence of seeding on crystallization behaviour of BaNaB9O15 glasses

Transparent BaNaB9O15 (BNBO) glasses were fabricated via the conventional melt-quenching technique. X-ray powder diffraction (XRD) followed by differential scanning calorimetric (DSC) studies confirmed the amorphous and glassy nature of the as-quenched samples, respectively. The effect of seeding on the crystallization of BNBO glasses was studied by non-isothermal DSC method and was modeled using the Johnson-Mehl-Avrami and Ozawa equations. The activation energy for seeded glasses decreased with the increase in fraction of crystallization. The values for the onset of crystallization and Avrami exponent were found to be lower for seeded samples which were associated with the heterogeneous nucleation and epitaxial processes.

Crystallization studies on bulk SixTe100-x glasses

Bulk SixTe100-x (10 less-than-or-equals, slant x less-than-or-equals, slant 28) glasses have been prepared by the melt quenching technique. The crystallization of these glasses has been studied by using differential scanning calorimetry. The composition dependence of the glass transition temperature Tg, the recrystallization temperature Tcr and the melting temperature Tm show an unusual behaviour at the composition x congruent with 20. The glasses with 10 less-than-or-equals, slant x less-than-or-equals, slant 20 undergo double glass transition and double stage crystallization phenomena. On the other hand, glasses with 22 less-than-or-equals, slant x less-than-or-equals, slant 28 exhibit eutectic crystallization. The phases at different stages of crystallization have been identified by using X-ray diffraction techniques. The unusual behaviour at x congruent with 20 can be explained on the basis of the changes in the network topologies of IV-VI chalcogenide glasses.

Soil sorption-desorption of phosphorus from piggery effluent compared with inorganic sources

The leaching of phosphorus (P) within soils can be a limiting consideration for the sustainable operation of intensive livestock enterprises. Sorption curves are widely used to assist estimation of P retention, though the effect of effluent constituents on their accuracy is not well understood. We conducted a series of P-sorption-desorption batch experiments with an Oxic Haplustalf (soil 1), Haplusterts (soils 2 and 3), and a Natrustalf (soil 4). Phosphorus sources included effluent, orthophosphate-P in a matrix replicating the effluent's salt constituents (the reference solution), and an orthophosphate-P solution. Treated soils were incubated for up to 193 days before sequential desorption extraction. Effluent constituents, probably the organic or particulate components, temporarily increased the vulnerability of sorbed-P to desorption. The increase in vulnerability was removed by 2-113 days of incubation (25 degrees C). Despite vigorous extraction for 20 consecutive days, some P sorbed as part of the treatments of soils 1 and 2 was not desorbed. The increased vulnerability due to effluent constituents lasted a maximum of about one cropping season and, for all other treatments, adsorption curves overestimated vulnerability to desorption. Therefore, adsorption curves provide a conservative estimate of vulnerability to desorption where effluent is used in continued crop production in these soils.

Electrical transport and crystallization studies of glassy semiconducting Si20Te80 alloy at high pressure

The effect of pressure on the electrical resistivity of bulk Si20Te80 glass is reported. Results of calorimetric, X-ray and transmission electron microscopy investigations at different stages of crystallization of bulk Si20Te80 glass are also presented. A pressure induced glass-to-crystal transition occurs at a pressure of 7 GPa. Pressure and temperature dependence of the electrical resistivity of Si20Te80 glass show the observed transition is a pressure induced glassy semiconductor to crystalline metal transition. The glass also exhibits a double Tg effect and double stage crystallization, under heating. The differences between the temperature induced crystallization (primary crystallization) and pressure induced congruent crystallization are discussed.

Pressure induced polymorphous crystallization in bulk Ge20Te80 glass

The pressure and temperature dependence of the electrical resistivity of bulk glassy Ge20Te80 is reported. The effect of annealing is also studied. The glass undergoes a polymorphous or congruent crystallization under high pressures. The high pressure phase is found to have fcc structure with Image . Under thermal treatment the glass undergoes the double stage crystallization. The sample annealed at the first crystallization temperature shows a pressure induced semiconductor-to-metal transition at 4.0 GPa pressure and the crystalline Ge20Te80 samples show the transition at 7 GPa pressure.

ESR studies of non-silicate inorganic glasses through their glass transformation ranges

ESR spectra of three inorganic glasses doped with Mn2+ and Fe3+ have been studied through their glass transition temperatures (Tg). Spectral features in each case have been discussed with reference to site symmetries. The intensity of the ESR signal has been bound to decrease in the region of Tg. An attempt has been made to explain this interesting feature on the basis of a two-state model.

Nanostructured Peptide Fibrils Formed at the Organic-Aqueous Interface and Their Use as Templates To Prepare Inorganic Nanostructures

Formation of fibril-type nanostructures of the Alzheimer's beta-amyloid diphenylalanine (L-Phe-L-Phe, FF) at the organic-aqueous interface and the factors affecting their structures have been investigated. Such nanostructures are also formed by bovine serum albumin and bovine pancreas insulin. The concentration of the precursor taken in the aqueous layer plays an important role in determining the morphology of the nanostructures, The addition of curcumin to the organic layer changes the structure of the self-assembled one-dimensional aggregates of diphenylalanine. By coating the diphenylalanine dipeptide fibrils with appropriate precursors followed by calcination in air, it has been possible to obtain one-dimensional nanostructures of inorganic materials.

Quasi Crystalline A1-Mn Alloys: Pressure Induced Crystallization and Structural Studies

Irreversible, Pressure induced, quasicrystal-to-crystal transitions are observed for the first time in melt spun alloys at 4.9 GPa for Al 78 Mn22 and 9.3 GPa for Al86 Mn14 by monitoring the electrical resistivities of these alloys as a function of pressure. Electron diffraction and x-ray measurements are used to show that these quasicrystalline phases have icosohedral point group symmetry. The crystalline phases which appear at high pressures are identified as h.c.p. for Al78 Mn22 and orthorhombic for Al86 Mn14.

Metallization and crystallization of semiconducting amorphous Ga20Te80 alloy under high pressure

Pressure and temperature dependence of the electrical resistivity of amorphous Ga20Te80 alloy is reported for the first time. The alloy undergoes a pressure induced amorphous semiconductor-to-crystalline metal phase transition at 6.5 ± 0.5 GPa. The high pressure crystalline phase is a mixture of Te and GaTe3 phases.

Using molasses to control inorganic nitrogen and pH in aquaculture ponds

This article describes research designed to determine the molasses addition rates that can control ammonia and pH in eutrophic aquaculture ponds.