Bangladesh Journal of Physics

Crystal Structure Refinement, Magnetic and Mössbauer Analysis of LaFeO3 Perovskite Synthesized by SOL-GEL method

2022-01-19T10:50:43+00:00

In this present study, LaFeO3 nanoparticles have been successfully synthesized by sol-gel method and annealed the produced sample at 600 °C, 800 °C, 1000 °C, 1200 °C. The influence of annealing temperature on the structural, morphological and magnetic properties of the developed nanoparticles has been investigated systematically. The XRD patterns confirmed the absence of impurity or secondary phase in the spectra. Orthorhombic crystal system of pbnm space group was successfully determined by Rietveld refinement. Scherrer method was used to calculate crystallite size. An increasing trend in crystallite size and improving crystallinity were obtained with increasing annealing temperature. Scanning Electron Microscopy (SEM) images showed a homogeneous distribution of increasing average particle sizes ranging from 35 nm to 450 nm. Magnetic hysteresis (M-H) loop was recorded at room temperature revealed weak ferromagnetism in nanocrystalline lanthanum ferrite. The maximum magnetization was found to be 1.82 emu/g at 600 °C, and it was sharply decreased to 0.33 emu/g at 1200 °C annealing temperature. Interactions between the antiferromagnetic and ferromagnetic exchange coupling are influenced by the uncompensated spin canting causes to accomplish the ordering of weak ferromagnetism in LaFeO3. Moreover, the bond length of Fe-O and the bond angle of Fe-O-Fe were decreased with decreasing annealing temperature. As a result, Fe ions, come closer to each other, enhancing the ferromagnetic exchange interaction between iron ions via oxygen ions made significant contributions to the magnetic properties of LaFeO3 nanoparticles. Mössbauer spectroscopy was used to find the nature of interactions for the observed magnetic behavior depending on different site environments with varying annealing temperatures.

Bangladesh Journal of Physics, 27(2), 27-37, December 2020

The Effect of Na-Based Salts on Critical Aggregation Concentration of Aqueous Peg-Sds Mixtures

2022-01-19T10:50:44+00:00

Critical aggregation concentration (CAC) is a well-known parameter used to study the interactions between constituents in an aqueous mixture containing surfactant molecules. In this study, we have studied the effect of Na-based salts on CAC of aqueous binary mixture of neutral polymer, polyethylene glycol (PEG) and anionic surfactant, sodium dodecyl sulfate (SDS) using viscometric method. To estimate CAC, we have applied Jiang model to the measured viscosity data. From the estimated results, we observe that the value of CAC decreases with the increase of salt molecules in the mixtures. This behavior confirms that the presence of salt molecules favors the binding of SDS molecule to the PEG chain.

Bangladesh Journal of Physics, 27(2), 39-48, December 2020

A Study on the Mechanical, Optical and Electrical Properties of Nylon-Mesh/Epoxy Composite

2022-01-19T10:50:44+00:00

We fabricated the nylon-mesh reinforced epoxy composite by using the hand lay-up method. In this composite, nylon mesh act as the reinforcing material whereas epoxy resin is the matrix material. Comparisons have been made between blank epoxy sheet and the composite. We observed improved mechanical properties such as tensile strength, strain, hardness, and flexural strength from the composited rather than blank epoxy sheet. However, Young’s modulus was not found promising. In case of optical observations, Light absorbance increases, and optical band gap decreases slightly. Considering the Electrical properties, we observed better electrical insulation properties from our fabricated composite than the blank epoxy sheet. In addition, the water absorption properties have also been discussed in this research article. These observations of different properties will contribute to open the new wings of many new applications and help to further improve the quality of the composites.

Bangladesh Journal of Physics, 27(2), 49-57, December 2020

Design and Modelling of Cell Irradiation with Laser-Driven Protons

2022-01-19T10:50:53+00:00

The biological effectiveness of laser driven protons on cells in a single exposure has been studied. In this experiment, V79 cell lines were irradiated with laser driven protons whereas comparison with the effectiveness of X-ray exposures was studied. Here design of the experiment and irradiation setup are explained in details as it is a first and foremost experiment in this field.

Bangladesh Journal of Physics, 27(2), 59-70, December 2020

Microscopic Origin of Immiscibility and Segregation in Liquid Metallic Binary Alloys

2022-01-19T10:50:43+00:00

Microscopic description in the study of immiscibility and segregating properties of liquid metallic binary alloys has gained a renewed scientific and technological interests during the last eight years for the physicists, metallurgists and chemists. Especially, in understanding the basic mechanisms, from the point of interionic interaction, and how and why segregation in some metallic alloys takes place at and under certain thermodynamic state specified by temperature and pressure. An overview of the theoretical and experimental works done by different authors or groups in the area of segregation combining electronic theory of metals, statistical mechanics and the perturbative approach is presented in this review. Main attention in this review is focused on the static effects such as the effects of energy of mixing, enthalpy of mixing, entropy of mixing and understanding the critical behavior of segregation of alloys from the microscopic theoretical approach. Investigation of segregating properties from the dynamic effects such as from the effects of shear viscosity and diffusion coefficient is just becoming available. However, we have restricted this review only on static effects and their variation of impacts on different alloys.

Bangladesh Journal of Physics, 27(2), 1-25, December 2020