Bulletin of Materials Science

In this study, 5,10,15,20-tetrakis(p-chlorophenyl)porphyrin has been synthesized and used as an ionophore for the preparation of a poly(vinyl chloride) (PVC) membrane sensor for aluminium(III) ions. The optimum composition of the best performing membrane contained ionophore, bis(2-ethylhexyl) adipate, PVC and potassium tetrakis(p-chlorophenyl) borate in the ratio of 4.0:63.0:32.0:1.0 (mg). The prepared PVC membrane morphology has been analysed by scanning electron microscopy. The developed aluminium(III)-selective sensor works in a wide linear concentration range of 1.0 × 10–5 to 1.0 × 10–1 mol l–1 and, the detection limit of this sensor is 2.81 × 10−6 mol l–1. The sensor displays near-Nernstian slope of 25.0 ± 2.7 mV per decade for Al3+ ions. The aluminium(III)-selective sensor has a wide working pH range of 5.0–10.0. The sensor shows good reusability, long-term stability and a fast response time of less than 5 s. In addition, the sensor shows good selectivity for Al3+ ions over different cations. This aluminium(III)-selective sensor was successfully used as an indicator electrode in the potentiometric titration of Al3+ ions with EDTA. The developed sensor was successfully applied to the direct determination of Al3+ in different water samples.

A review of the recent applications of renormalisation group techniques to the calculations of the critical properties of random magnetic systems is presented.

The high temperature ceramic oxide superconductor YBa2Cu3O7-x (1–2–3 compound) is generally synthesized in an oxygen-rich environment. Hence any method for determining its thermodynamic stability should operate at a high oxygen partial pressure. A solid-state cell incorporating CaF2 as the electrolyte and functioning under pure oxygen at a pressure of 1·01 × 105 Pa has been employed for the determination of the Gibbs’ energy of formation of the 1–2–3 compound. The configuration of the galvanic cell can be represented by: Pt, O2, YBa2Cu3O7−x , Y2BaCuO5, CuO, BaF2/CaF2/BaF2, BaZrO3, ZrO2, O2, Pt. Using the values of the standard Gibbs’ energy of formation of the compounds BaZrO3 and Y2BaCuO5 from the literature, the Gibbs’ energy of formation of the 1–2–3 compound from the constituent binary oxides has been computed at different temperatures. The value ofx at each temperature is determined by the oxygen partial pressure. At 1023 K for O content of 6·5 the Gibbs’ energy of formation of the 1–2–3 compound is −261·7 kJ mol−1.

Thin films of amorphous germanium were deposited in an oxygen atmosphere.dc conductivity results are interpreted considering the possibility of the formation of Ge-O bonds. The density of states was determined. Results of conductivity are interpreted using the Davis-Mott model. Change in conductivity in annealed films of V-a-Ge and O-a-Ge is also reported.

Potassium hydrogen phthalate (KHP) single crystals are non-linear optical materials and their transmittance window are remarkably enhanced by an organic dopant such as resorcinol. The present study was mainly focused on the growth and characterization of the single-crystal KHP doped with resorcinol which was synthesized by a slow evaporation solution technique and its dimension was found to be $$8 \times 7 \times 2.75 \hbox { mm}^{3}$$ at ambient temperature. Vibrational assignments of the functional groups confirmed the presence of dopants. The optical behaviour of the grown crystal was explored by ultraviolet–visible–near-infrared studies which result in 99% of the transmittance with the cut-off wavelength of 250 nm. The mechanical property was analysed by the Vickers microhardness test. The apparent microhardness increases with increasing applied indentation load revealing the reverse indentation size effect behaviour. Organic impurity increases the second harmonic generation efficiency of KHP, suggesting that the molecular alignment in the presence of resorcinol results in enhanced non-linearity.

The effects of electromagnetic stirring and Al4C3 grain refiner on the grain refinement of semi-continuously cast AZ31 magnesium alloy were discussed in this investigation. The results indicate that electromagnetic stirring has an effective refining effect on the grain size of AZ31 magnesium alloy under the effect of Al4C3 grain refiner. Electromagnetic stirring can ‘activate’ the Al4C3 particles, resulting in more heterogeneous nucleation sites for the primary α-Mg grains. But, longer holding time can ‘deactivate’ the Al4C3 particles and poison the grain refining effect.

Compositions of polycrystalline Zn x Mg1−x Fe2−y Nd y O4 (x = 0.00, 0.20, 0.40, 0.60, 0.80 and 1.00;y = 0.00, 0.05 and 0.10) ferrites were prepared by standard ceramic method and characterized by X-ray diffraction, scanning electron microscopy and infrared absorption spectroscopy. Far infrared absorption spectra show two significant absorption bands, first at about 600 cm−1 and second at about 425 cm−−1, which were respectively attributed to tetrahedral (A) and octahedral (B) sites of the spinel. The positions of bands are found to be composition dependent. The force constants,K T andK O, were calculated and plotted against zinc concentration. Compositional dependence of force constants is explained on the basis of cation-oxygen bond distances of respective sites and cation distribution.

Matrix assisted laser desorption ionization mass spectroscopy (MALDI MS) is a technique which allows the measurement of molecular mass > 200,000 Daltons by ionization and vapourization without degradation. This technique is useful for the mass analysis of synthetic polymers, which have very low volatility. The basic principles of and its applications for polymer characterization have been discussed in this paper. In addition, the possibilities of combining MALDI MS with chromatographic and other analytical techniques have also been discussed.

To promote flow-induced orientation and reserve the formation of the shish-kebab structure, a modified injection-moulding technology named water-assisted injection moulding (WAIM), was applied to provide twice the shear flow and a rapid cooling rate on high-molecular weight high-density polyethylene (HDPE) melt in a mould cavity. Large-scale distribution of highly oriented shish-kebab was successfully achieved in a WAIM sample with a high-molecular weight. More importantly, the high-orientation degree of lamellae (larger than 0.4) in the thickness direction for a high-molecular weight WAIM sample is >60%, which is much more than a conventional injection-moulded sample (15%). This work provides a new insight to achieve injection-moulded products with enhanced oriented structures.