Bangladesh Journal of Physics https://www.banglajol.info/index.php/BJPhy <p>Published by the <a href="https://bdphso.org/">Bangladesh Physical Society (BPS)</a>. Full-text articles available.<br><br> <a href="http://creativecommons.org/licenses/by-sa/4.0/" rel="license"><img style="border-width: 0;" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" alt="Creative Commons Licence"></a><br>Articles in the <em>Bangladesh Journal of Physics</em> are Open Access articles published under a <a href="http://creativecommons.org/licenses/by-sa/4.0/" rel="license">Creative Commons Attribution-ShareAlike 4.0 International License</a> (CC BY-SA)</p> Bangladesh Physical Society (BPS) en-US Bangladesh Journal of Physics 1816-1081 Fe Doped MnO<sub>2</sub> Nanostructured Thin Films: Synthesis and Characterization for Biosensor applications https://www.banglajol.info/index.php/BJPhy/article/view/49722 <p>Iron (Fe), a magnetic transition metal, doped manganese oxide (MnO<sub>2</sub>) nanostructured thin films were deposited onto glass substrates by a spray pyrolysis deposition technique at 450<sup>o</sup>C substrate temperature for glucose sensing performance. Fe concentration greatly affects the film surface morphology. The film was found to be more compact and porous for 4 at % Fe doping. The glucose response was measured by electrical four probe method using the pure MnO<sub>2</sub> and 2, 4, 6, 8 at% Fe doped MnO<sub>2</sub> thin films as an active electrode. It was determined that 4 at % Fe: MnO<sub>2</sub> thin film with 20 nm crystallite size has high sensitivity, fast glucose response and recovery time. Optical band gap measurement indicated that the sensitivity increased as the band gap decreased up to 4 at % Fe concentration. The highest glucose sensing response was recorded about 29 % in 5 minutes.</p> <p><em>Bangladesh Journal of Physics, </em><strong><em>27(1)</em></strong><em>, 1</em>-<em>12, June 2</em><em>020</em></p> M Zahan J Podder ##submission.copyrightStatement## http://creativecommons.org/licenses/by-nc-sa/4.0 2020-10-13 2020-10-13 27 1 1 12 10.3329/bjphy.v27i1.49722 Structural Analyses of [Li Salt+Triglyme)] and Ionic Transport in Li-Air Battery Using Molecular Dynamics Simulation https://www.banglajol.info/index.php/BJPhy/article/view/49723 <p>In this work, molecular dynamics (MD) study of triglyme (G3) solution containing lithium bis (trifluoro methyl sulfonyl) amide (Li[TFSA]) were investigated using classical atomistic force fields. G3 is a typical solvent used in non-aqueous Li-air battery. It shows here coordination of Li+ with G3 and [TFSA]- does not significantly change with increasing the concentration of G3 but self-diffusion coefficient of all the ions increases with increasing G3 concentration. The density of [Li(G3)[TFSA] complex decreases with increasing G3 concentration which lead to accelerate diffusivity of ions.</p> <p><em>Bangladesh Journal of Physics, </em><strong><em>27(1)</em></strong><em>, 13</em>-<em>22, June 2</em><em>020</em></p> Md Khorshed Alam Wataru Yamamoto Hiromitsu Takaba ##submission.copyrightStatement## http://creativecommons.org/licenses/by-nc-sa/4.0 2020-10-13 2020-10-13 27 1 13 22 10.3329/bjphy.v27i1.49723 Phase Transition, Dielectric Relaxation and Impedance Spectroscopy of Perovskite xBa<sub>0.95</sub>Sr<sub>0.05</sub>Tio<sub>3</sub>-(1‒X)BiFe<sub>0.9</sub>Sm<sub>0.1</sub>O<sub>3</sub> Ceramics https://www.banglajol.info/index.php/BJPhy/article/view/49724 <p>Polycrystalline xBa<sub>0.95</sub>Sr<sub>0.05</sub>TiO3-(1‒x)BiFe<sub>0.9</sub>Sm<sub>0.1</sub>O<sub>3</sub>[xBST-(1‒x)BFSO] ceramics were synthesized. The structural phase transitions were studied and it was found that structure of the compound transformed from rhombohedral to cubic phase. The compound exhibited a dielectric anomaly in the vicinity of Néel temperature of BiFeO<sub>3</sub> except for x = 0.25. Enhanced dielectric properties were noticed and this might be attributed to the reduction of oxygen vacancies. Studies of electrical conductivity over a wide temperature range showed that the ceramics behaved like a semiconductor with the negative temperature coefficient of resistance. Contribution of grains in conduction mechanism of the materials dominated and the grain resistance was found to be decreased with the increase in temperature. A Non-Debye type relaxation was seen in the material. The impedance data were re-plotted using the modulus formulae to avoid the ambiguity arising out of the presence of grain/grain boundary effect. Activation energy was found to be 0.18 to 0.33 eV in modulus study which was very close to complex impedance observation and it was implied that the charge carrier had the same energy barrier during the relaxation.</p> <p><em>Bangladesh Journal of Physics, </em><strong><em>27(1)</em></strong><em>, 23</em>-<em>42, June 2</em><em>020</em></p> MJ Miah SC Mazumder AKM Akther Hossain ##submission.copyrightStatement## http://creativecommons.org/licenses/by-nc-sa/4.0 2020-10-13 2020-10-13 27 1 23 42 10.3329/bjphy.v27i1.49724 The Density Functional Theory (DFT) And DFT+U Study of the Effect of the on-Site Coulomb Repulsion Parameter U on the Structural and Magnetic Properties of CeO<sub>2</sub> Nanoparticles https://www.banglajol.info/index.php/BJPhy/article/view/49725 <p>a</p> Alamgir Kabir Sadiq Shahriyar Nishat Sumaya Rahman ##submission.copyrightStatement## http://creativecommons.org/licenses/by-nc-sa/4.0 2020-10-13 2020-10-13 27 1 43 58 10.3329/bjphy.v27i1.49725 Impact of Thickness and Substrate on Optical Properties of ZnO Thin Films https://www.banglajol.info/index.php/BJPhy/article/view/49726 <p>During the last decades, ZnO has emerged as the most promising material in optoelectronic and optical applications in the visible region as well as in the infrared and UV region. It is because of the broad direct band gap of 3.37 eV at ambient temperature and high exciton binding energy of 60 meV allowing it to utilize the ultraviolet region. In this investigation, the optical characteristics of ZnO thin film of various thicknesses (300 nm, 600 nm, 900 nm) deposited on Quartz, Fused silica and Sapphire have been studied as a function of wavelength and photon energy. To obtain this, the equations for thin film have been derived, simulated and visualized by Matlab coding language. It is observed that with the increase in the photon energy, the refractive index and extinction coefficient show an increasing tendency. The results represent that among three substrates Fused silica has the lowest refractive index, reflectance and absorbance. In the visible region, the transmission spectra show that the average transmittance of all films is 85%-95%, which is superior for solar continuums. The performance of Fused silica as transparent conducting material is better than other substrates. The present investigation might provide an environment friendly and low cost material for optoelectronic and solar cell devices.</p> <p><em>Bangladesh Journal of Physics, </em><strong><em>27(1)</em></strong><em>, 59</em>-<em>68, June 2</em><em>020</em></p> S Das S Sultana I Akter SC Mazumdar MA Rahman K Kali ##submission.copyrightStatement## http://creativecommons.org/licenses/by-nc-sa/4.0 2020-10-13 2020-10-13 27 1 59 68 10.3329/bjphy.v27i1.49726 Effects of Pump-Pulse Width and Temperature on Experimental Brillouin Gain Spectrum Obtained from Brillouin Optical Time-Domain Analysis Sensors https://www.banglajol.info/index.php/BJPhy/article/view/49727 <p>In this paper, the characteristics of Brillouin gain spectrum (BGS) obtained from a Brillouin optical time-domain analysis (BOTDA) sensor are investigated and analyzed experimentally. The measured BGSs obtained for various pump-pulse widths and temperatures are fitted with different spectrum profiles using nonlinear least-squares curve fitting technique. The fitting performances of used profiles are presented and analyzed. Based on such performances, the proper spectrum profile to be used in the fitting process is determined and used to extract key parameters of the measured BGSs accurately. The variations of such key parameters with pump-pulse widths and temperatures are also investigated and analyzed. The results reveal that pump-pulse widths and temperatures have significant effects on the extracted key parameters of the measured BGSs obtained from BOTDA sensors.</p> <p><em>Bangladesh Journal of Physics, </em><strong><em>27(1)</em></strong><em>, 69</em>-<em>80, June 2</em><em>020</em></p> Abul Kalam Azad ##submission.copyrightStatement## http://creativecommons.org/licenses/by-nc-sa/4.0 2020-10-13 2020-10-13 27 1 69 80 10.3329/bjphy.v27i1.49727