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Influence of hard rock dust on the physical and microstructural properties of red ceramic materials
Ahmed Aninda Nafis,Sultana Mst. Shanjida,Zaman Mohammad Nazim,Rahman Md. Aminur 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.1
Rock dust disposal is a concern in a hard rock mining site which results from blasting operation during mining. Signifi cant amount of rock dust is generated during mining which causes dusting problem as well. In this work, Rock dust was used with red clay to produce ceramic tiles. XRF analysis revealed the existence of more than 60 wt.% SiO 2 in red clay and more than 50 wt.% SiO 2 in rock dust. Pressed ceramic bodies having diff erent amount (10–30 wt.%) of rock dust were sintered at 1050 °C, 1100 °C and 1150 °C. Diff erent properties were measured for ceramics samples such as water absorption, porosity, mechanical strength, linear shrinkage and bulk density. Lowering of porosity (1.88–10.17%) and water absorption (1.1–6.03%) were found with 10–30 wt.% rock dust addition. Above 50 MPa of compressive strength was found, which is satisfactory for producing ceramic tiles. Microstructures of ceramics samples studied by FESEM provided eff ective information on structure-property relationships. Maximum quantities of rock dust waste were utilized, in reducing environmental pollution and establishing it as a raw material for ceramics industries.
Transonic Speed Mobility Support Techniques for 6G-Non Terrestrial Networks
Chaitali J. Pawase,Nafis Ahmed,KyungHi Chang 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.6
Non-Terrestrial Network (NTN) connectivity is expected to be used in sixth Generation (6G) telecommunication systems to support transonic speed mobility applications. NTN systems can provide wide-area coverage for applications that require high mobility. Third Generation Partnership Project (3GPP) is investigating a study on New Radio (NR) and solutions for NR to support NTN in Release-15 and Release-16 respectively. In this paper, we provide an overview of use cases, requirements and architecture of a non-terrestrial network and explain high mobility such as transonic speed mobility challenges and potential solutions to be resolved in 6G-NTN. In addition, we also describe the existing open research opportunities for non-terrestrial network implementation based on 5G-NR in order to encourage extensive research in 6G technology.
K. Ganesh Kumar,P. Balaji Bhargav,Nafis Ahmed,C. Balaji 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6
In the present study, pure and Tin (Sn) doped ZnO (Sn–ZnO) nanostructures are grown using hydrothermal method. The effect of Sn doping on the physical properties of ZnO is extensively studied. Till 4 mol% of Sn doping, the dopant is completely dissolved in the host matrix and no secondary phases are formed as evident from XRD studies. The presence of the constituent elements of the host matrix (Zn,O) and dopant (Sn) is confi rmed using Energy Dispersive X-ray Spectroscopy (EDX). From FESEM images, it is evident that the morphology of the grown structures changes from rods to flowers and flakes with doping. The microstructural analysis is carried out using HRTEM analysis. Various polar and non-polar optical modes present in the samples are analysed using Raman spectra. Two dominant emission bands around ~391 nm, ~470 nm are noticed from photoluminescence (PL) spectra. The potential of the Sn doped ZnO nanostructures in photocatalytic degradation of Rhodamine B is investigated and found that 1 mol% Sn doped ZnO exhibits superior photo catalytic performance.
Kossar Shahnaz,Amiruddin R.,Rasool Asif,Kumar M.C. Santhosh,Katragadda Nagamalleswari,Mandal Pranab,Ahmed Nafis 한국물리학회 2022 Current Applied Physics Vol.39 No.-
The present work reports on resistive switching (RS) characteristics of Neodymium (Nd)-doped bismuth ferrite (BFO) layers. The Nd (2–10 at%) doped BFO thin film layers were deposited using a spray pyrolysis method. The structural analysis reveals that a higher Nd doping concentration in BFO leads to significant distortion of the prepared Nd:BFO thin films from rhombohedral to tetragonal characteristics. The morphological analysis shows that all the deposited Nd:BFO thin films have regularly arranged grains. The X-ray photoelectron spectroscopy (XPS) analysis reveals that the prepared Nd:BFO thin films have a higher Fe 3+/Fe 2+ratio and less oxygen vacancy (VO) defects which enriches the ferroelectric characteristics in Nd:BFO layers. The polarization-electric field (P-E) and RS characteristics of the fabricated Nd:BFO-based RS device were examined. It was observed that the Nd (7 at%) doped BFO RS device shows large remnant polarization (P r) of 0.21 μC/cm2 and stable RS characteristics.