Browsing by Author "Dr. Junaid Amjad"

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A Molecular Dynamics Study Of Oxide Based Glasses For Potential Applications As Nuclear Waste Host
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Neha; CIIT/FA23-RPH-051/LHR; Dr. Junaid Amjad; LHR TP 9869
The immobilization of high-level radioactive waste (HLW) is a critical challenge in the nuclear fuel cycle, necessitating the development of structurally durable and chemically stable waste forms. In this study, molecular dynamics (MD) simulations were employed to investigate the structural, dynamic, and radiation-tolerant properties of a complex borosilicate glass matrix composed of SiO₂, B₂O₃, Na₂O, BaO, ZrO₂, and UO₂. The objective was to assess its suitability as a potential host for the safe containment of actinide-rich nuclear waste. A melt-quench protocol was applied to generate an amorphous glass structure, followed by equilibrium and radiation-damage simulations using the LAMMPS simulation package. Structural analysis through radial distribution functions (RDFs), coordination number calculations, and Voronoi volume analysis revealed the presence of stable tetrahedra units, and ZrO₆ octahedra—suggesting a well-connected, radiation-tolerant glass network. Uranium ions were observed to be immobilized within the cage-like structure formed by Zr and O polyhedra, which effectively limited their mobility even under thermal and irradiation conditions. Displacement cascade simulations, initiated by imparting kinetic energy to uranium atoms (1–5 keV), demonstrated localized structural damage without long-range atomic diffusion, confirming the glass’s inherent resistance to radiation-induced destabilization. Mean squared displacement (MSD) analyses further confirmed negligible mobility of heavy ions like U, while lighter species such as Na⁺ reflecting the role of network modifiers in accommodating dynamic rearrangements. Post-radiation thermal annealing simulations suggested partial self-healing capabilities of the glass network, with RDF peaks and coordination distributions largely recovering to pre-damage states. Overall, the simulation results highlight the resonable structural integrity, uranium retention potential, and self-repair behaviour of the proposed borosilicate glass under radiation. These findings support its viability as a long-term nuclear waste host, contributing to the broader goal of safe and sustainable radioactive waste management.
Composition-Structure-Property Correlations in Lanthanide Doped Oxide Glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Tayyaba Akram; CIIT/SP20-RPH-018/LHR; Dr. Junaid Amjad; LHR TP 7712
Rare earth pyrophosphate-based glass materials show promise for optical, photonic, and biomedical uses. In this study, Dy3+ ions and TiO2 were co-doped in pyrophosphate glass, and new glass with varied characteristics was created using the melt-quenching approach. The intensities of rare earth 4f intrabank transitions changed when metallic titanium nanoparticles (NPs) were added. Ti plasmonic nanoparticles impact photoluminescence spectroscopy of pyrophosphate glass co- doped with Dy3+ ions. Advanced techniques, such as Raman, PL (photoluminescence), and FTIR, are used to study the optical characteristics of these glasses. The results demonstrate absorption and luminescence spectroscopy, as well as the excited state lifetime, which influences the optical characteristics of the glass
Comprehensive Study on Network Former Mixing Effect in Heavy Metal Based Oxide Glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Manawal Shuja; CIIT/FA19-RPH-027/LHR; Dr. Junaid Amjad; LHR TP 7260
Phospho-Tellurite glass with Ytterbium Yb+3 was prepared which is a rare earth to study the network former mixing effect in the prepared glass. The glass was prepared by melt quench technique in an electrical furnace at a temperature of 1100 °C. Glass were made in palettes of 2mm in size. The prepared glass was then characterized by using Raman, FTIR and UV-VIS (Reflectance) Spectroscopy. The Raman Spectra reveled that phospho-tellurite are suitable for Raman broadband Amplifiers. FTIR revealed the functional groups of glass and verified the presence of non-bridging oxygen atoms. Whereas UV-VIS (Reflectance) Spectra was used to calculate the band gap of prepared glass sample. The band increases from 2.7 eV to 3.25 eV which shows change in structure of tellurite from TeO4 to PO4 units by increasing amount of network former P2O5 gradually.
Copper mediated optical properties of rare earth doped amorphous materials
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) RABIA KHALID; CIIT/FA19-RPH-025/LHR; Dr. Junaid Amjad; LHR TP 7274
Borophosphate based glass materials having rare earth, shows promising optical photonic and biomedical applications. Here in the current report, Dy3+ ions and CuO is co-doped in Borophosphate glass and new hybrid glasses with different properties were prepared by using melt-quenching method. The intensities of 4f intrabands transitions of rare earth ions changed by the addition of metallic Cu nanopartciles (NPs). Photoluminescence spectroscopy of Borophosphate glass co-doped with Dy3+ ions and Cu nanoparticles revealed the dynamic decay of Dy3+ ions due to the influence of Cu plasmonic nanoparticles. The optical properties of these glasses were characterized by different methods as UV-Vis, Raman, PL (photoluminescence), FTIR and XRD. The results show the absorption and luminescence spectroscopy also the excited state lifetime that gives the optical properties of the glass.
Development of Strontium Oxide and Natural Fiber-based Paper Electrodes for Water Splitting Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Maria Fiaz; CIIT/FA19-RPH-030/LHR; Dr. Junaid Amjad; LHR TP 7273
In literature, several conversion devices for the purpose to convert green energy into useful hydrogen production are reported e.g., two-electrode electrolysis of water, splitting of water, solar cell, thermoelectrical device, and nanogenerators. However, harvesting green energy for the splitting of water can decrease the expenditure of external energy. Natural fiber-based paper electrodes are employed for water splitting application due to the characteristics of the highly porous structure to enhance the kinetics of water molecules to reach active sites in the electrode. The incorporation of natural fibers as binders with metal oxide nanoparticles is highly feasible to fabricate the porous, lightweight, and environmentally safe paper electrode for water splitting application. Among metal oxide, strontium oxide is suitable to employ as an electrode for water splitting applications. Strontium oxide is more stable than other metals like Zn/ZnO and Fe/FeO. due to its high efficiency and good performance, we use it for water splitting. A microwave-assisted method will be employed for the fabrication of Strontium oxide nanoparticles. For the synthesis of the strontium oxide, strontium acetylacetonate solution will be added to benzyl alcohol. Subsequently, the mixture will place in the microwave oven for different treatment of input power, time, and concentrations. The resulted sample will be centrifuged and the precipitate will be washed with acetone. The selection of microwave method is advantageous due to template free, facile to synthesis, cheaper, and relatively quicker than methods. Natural fibers extracted from Monochorea Vaginalis will disperse in water and mix with fabricated Strontium oxide nanoparticles in different ratios for the development of Strontium oxide-based porous and flexible paper sheets. For increasing the efficiency and stability of the photoactive material, the sample will be tested for photocatalytic water splitting to produce hydrogen. For better photocatalytic performance, the bandgap of the sample will be checked. Different characterization techniques like Cyclic voltammetry (CV), X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM), etc. of the prepared sample will be done to check its different properties.
DFT Study of Diffusion Rate in Solid Electrolytes for Safe Design of Solid State Batteries
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Atiqa Razzaq; CIIT/FA19-RPH-005/LHR; Dr. Junaid Amjad; LHR TP 7704
Lithium ion batteries(LIBs) are in high demand as energy storage media because of their high energy density, outstanding power density, and main feature is deliberate self- discharge rates. In point of fact, LIBs are leading the market of portable devices since their launch in the 1990. However, high emergent demand for large battery packs, especially those to be equipped on electric vehicles, requires severe safety concerns because of incapable electrolytes being more toxic and flammable. Solid state batteries are encouraging substitutions to LIBs and eventual key solution to the safety issues because of non-flammability of solid electrolytes which is the leading feature of solid electrolyte. The compatible potential between SEs and Lithium metal anodes and with high voltage cathode also lead to solid state batteries with higher energy density compared with conventional lithium ion batteries. So, solid-state batteries have been appealing wide attention for next generation energy storage devices due to the probability to realize higher energy density and superior safety performance compared with the state of art the art lithium ion batteries. However, the currently available SSBs have low performance due to slow ionic transport between SE and electrodes which leads to poor cycling stability. There are still many issues to be addressed to meet the industrially scalable solid state batteries. In the present thesis, the main focus is on the calculation of diffusion rate through solid electrolytes in order to get contribution in the research of finding the parameters which are involved in ionic diffusivity through solid electrolytes. Lithium argyrodite superionic conductor of the form Li7GeS5Br has shown great promise as a sulfide based solid state electrolytes due to high energy density and high diffusivity rate. In the present work simulation method is used to calculate the Li ions diffusion coefficient through solid electrolytes. Molecular Dynamics simulation is a powerful tool to study the diffusion coefficient through solid electrolytes. In this project, MD simulation is used to calculate the diffusion coefficient through Li7GeS5Br. With the help of MSD versus time plot the diffusion coefficient is calculated. Firstly, the structure of Li7GeS5Br is optimized. The optimized supercell was used as a benchmark model for subsequent calculations. During simulation process different trajectories of ionic movement have been collected in which lithium ions intra cage and inter cage jumps have been visualized. These detailed diffusion pathways and properties offer a throughout understanding of the diffusion process in solids and provide improved road map to design solid state batteries.
Effect of Silver Species on Luminescence of Lanthanide Ions incorporated with an Amorphous host material
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Muhammad Yasir Ilyas; CIIT/FA18-RPH-038/LHR; Dr. Junaid Amjad; LHR TP 6344
We studied the photonic characteristics of rare earth (RE) lanthanide samarium ions Sm3+ mixed with boro-phosphate glass. We prepared samples having composition69.9% [P2O5]—5% [B2O3]—25% [Na2O3]—0.1% [Sm2O3] by varying amount of AgCl. These Sm3+ mixed phosphate glasses was prepared by highly recommended melt-quenching method. Their physical, conductive,structural,chemical and photonic characteristics are recorded. The effect of Sm3+ doping on emission spectra (up-conversion or down-conversion) and lifetimes (over all behavior) was investigated .Samples were polished, passed through finishing process and crushed into powder for characterization i.e. UV visible, XRD, Raman spectroscopy photoluminescence spectrum PL & FTIR spectroscopy. The optical band gap energy (Eopt) direct and indirect allowed transitions. Density was measured by Archimedes method, which directly correlated SPR and LSPR. The irregular shapes of atoms of the glass samples were recorded from the X-ray diffraction pattern. The emission spectrum and other optical properties were recorded using photoluminescence characterization. The fluorescence spectra of Sm3+ ions exhibit emission transition of 4G5/2→6H13/2, &4G5/2→6H5/2 under514 nm excitation wavelengths by giving emission of green and red lights. When material is excited with 514nm light source it gives rise to down conversion from green light (514nm) to yellowish green (~530nm)&red light (~650nm).Down conversion of Green visible into both yellowish green &Red visible radiation could use in no of sundry applications in such as solid state lasers, LED/LCD displays, optical fibers, and fast optoelectronic devices The electronic/conducting properties of material were studied and calculated band gap using UV visible technique.
Effect of TiO2 on the Structural, Mechanical and Optical Properties of Bioactive Glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Muhammad Zahid; CIIT/FA18-RPH-002/LHR; Dr. Junaid Amjad; LHR TP 6076
The aim of the study presented in this thesis is to prepare bioactive sodium base borophosphate system with varying titanium content and fixed ratio of calcium oxide.This study aims to provide the structural, mechanical and optical analysis of such glasses to have a proper insight in the glass structure for better understanding of structure property correlation. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. Understanding the novel application of bioactives borophosphate glass system in bone tissue engineering to be used as bone graft material. It is worth important to fabricate material with enhanced chemical durability, mechanical strength, sufficient thermal expension coefficient and bioactivity to further develop these biomedical devices. Present study provides the effect of structural, mechanical and optical properties of borophosphate glasses. Five Boro-phosphate samples with composition 70 B2O3 – 25 Na2O3 – 5 P2O5 – 1 CaO – x TiO2 where x=0 %, 0.1%, 0.3%, 0.5% and 1, weight % were prepared using melt quenching method. From the results of X-ray Diffraction (XRD), it was confirmed that the structure of the samples was amorphous and Na2O2 played an important role in assisting the glass formation. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. From the results, direct and indirect energy band gaps were calculated. Direct energy band gaps were in the range 3.59 eV - 4.18 eV. Indirect band gaps were in the range 2.92 eV - 3.95 eV. Refractive index was also calculated which was in the range 2.19 - 2.42.
Effect of TiO2 on the Structural, Mechanical and Optical Properties of Bioactive Glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Muhammad Zahid; CIIT/FA18-RPH-002/LHR; Dr. Junaid Amjad; LHR TP 7696
The aim of the study presented in this thesis is to prepare bioactive sodium base borophosphate system with varying titanium content and fixed ratio of calcium oxide.This study aims to provide the structural, mechanical and optical analysis of such glasses to have a proper insight in the glass structure for better understanding of structure property correlation. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. Understanding the novel application of bioactives borophosphate glass system in bone tissue engineering to be used as bone graft material. It is worth important to fabricate material with enhanced chemical durability, mechanical strength, sufficient thermal expension coefficient and bioactivity to further develop these biomedical devices. Present study provides the effect of structural, mechanical and optical properties of borophosphate glasses. Five Boro-phosphate samples with composition 70 B2O3 – 25 Na2O3 – 5 P2O5 – 1 CaO – x TiO2 where x=0 %, 0.1%, 0.3%, 0.5% and 1, weight % were prepared using melt quenching method. From the results of X-ray Diffraction (XRD), it was confirmed that the structure of the samples was amorphous and Na2O2 played an important role in assisting the glass formation. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. From the results, direct and indirect energy band gaps were calculated. Direct energy band gaps were in the range 3.59 eV - 4.18 eV. Indirect band gaps were in the range 2.92 eV - 3.95 eV. Refractive index was also calculated which was in the range 2.19 - 2.42.
Mixed Former Effect on the Photo Physical Properties of Phospho Tellurite Based Glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Tayyaba Yousaf; CIIT/FA20-RPH-005/LHR; Dr. Junaid Amjad; LHR TP 7970
Phospho-Tellurite glass was prepared earth to study the network former mixing effect in the prepared glass. The glass was prepared by melt quench technique in an electrical furnace at a temperature of 1100 °C. Glass were made in palettes of 2mm in size. The prepared glass was then characterized by using Raman, FTIR and UV- VIS (Reflectance) Spectroscopy. Raman Spectra revealed that phospho-tellurite are suitable for Raman broadband Amplifiers. FTIR revealed the functional groups of glass and verified the presence of non-bridging oxygen atoms. Whereas UV-VIS (Reflectance) Spectra was used to calculate the band gap of prepared glass sample. When UV-Vis spectrum will be examined via various wavelength it will show the absorbance of one or more sample component. The crystalline phase available in material will be recognized by XRD technique and it also discloses the chemical structure. Absorption data will assist the calculation of band gap. To compute the spectroscopic and electronic properties we also aspire to achieve the computational simulation that will yield further awareness.
Plasmon Assisted Quantum Cutting in Rare Earth Doped Glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Ahmad Wadood; CIIT/SP22-RPH-016/LHR; Dr. Junaid Amjad; LHR TP 8780
Borophosphate based glass materials having rare earth, shows promising optical photonic and biomedical applications. Here in the current report, Ce3+ ions and AgCl are co-doped in Borophosphate glass and new hybrid glasses with different properties were prepared by using melt-quenching method. The intensities of 4f intrabands transitions of rare earth ions changed by the addition of metallic Ag nanopartciles (NPs). Photoluminescence spectroscopy of Borophosphate glass co doped with Ce3+ ions and Ag nanoparticles revealed the dynamic decay of Ce3+ ions due to the influence of Ag plasmonic nanoparticles. The optical properties of these glasses were characterized by different methods such as UV-Vis, Raman, PL (photoluminescence), FTIR and XRD. The results show the absorption and luminescence spectroscopy and the excited state lifetime that gives the optical properties of the glass.
Plasmonic Effect on the Liminescence Properties of Rare Earth Doped Nanoparticles
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Noor ul Ain Ahmed; CIIT/FA19-RPH-021/LHR; Dr. Junaid Amjad; LHR TP 7271
Photovoltaic conversion efficiency of solar cells can be enhanced using up conversion (UC)down conversion (DC) emission. With a lot of scientific data available on metal enhanced up-conversion emission, only few studies are found focusing on metal enhanced down-conversion emission. Here we studied the mechanisms of Quenching of the upconversion luminescence for NayF4: Yb3+, Er3+ co-doped nanoparticles spin-coated on the substrate with prefabricated gold thin film of 200nm along with the SAMs of 1-Octane thiol (OT), 1,8-Octane dithiol (ODT), Benzyl Mercaptan (BMT), 1-Do decanethiol (DDT) with an aim of having enhanced down-conversion emission. Based on the PL spectra, we have observed the quenching of the upconversion photoluminescence (PL) of the prepared geometry as compared to the bare upconverting nanophosphors (UCNPs) of NaYF4: Er3+, Yb3+. This includes the emission from energy states of dopants in NaYF4:Yb3+, Er3+ UCNPs by measuring the PL intensity between 525 and 585 and 650 nm upon 514-nm excitation source. The luminescence intensities and decays were measured from both bare and the nanoparticles treated with prepared gold substrates, the quenching of the upconversion photoluminescence intensity of all the coated samples is observed. The main mechanism of quenching was found to be the effect of separation distance between gold and UCNPs. The separation distance of ≈ 2nm lead to the fluorescence quenching. Raman and FTIR was also done for a better understanding of the pathways that are responsible for the non-radiative decay which led to fluorescence quenching in prepared samples.
Plasmonic interactions of silver nanoparticles with quantum dots embedded in borophosphate amorphous matrix: A photoluminescence study
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Muhammad Zeshan Haider; CIIT/FA18-RPH-013/LHR; Dr. Junaid Amjad; LHR TP 6358
We studied the photonic characteristics of Cadmium sulfide (CdS) with boro-phosphate glass. We prepared samples having composition 5% [P2O5]—70% [B2O3]—25% [Na2O2] 1% [CdS] by varying amount of AgCl. We mixed CdS with phosphate to prepare glasses by highly recommended melt-quenching method. Their physical, conductive, structural, chemical and photonic characteristics are recorded. The effect of CdS doping on emission spectra (up-conversion or down-conversion) and lifetimes (over all behavior) was investigated. Samples were polished, passed through finishing process and crushed into powder for characterization i.e., UV visible, XRD, Raman spectroscopy photoluminescence spectrum PL& FTIR spectroscopy. The optical band gap energy direct and indirect allowed transitions. Density was measured by Archimedes method, which directly correlated SPR and LSPR. The irregular shapes of atoms of the glass samples were recorded from the X-ray diffraction pattern. The emission spectrum and other optical properties were recorded using photoluminescence characterization. The fluorescence spectra of CdS exhibit emission transition of excitation wavelengths by giving emission of green and red lights. When material is excited with 514nm light source it gives rise to down conversion from green light (514nm) to yellowish green (~530nm) &red light (~650nm). Down conversion of Green visible into both yellowish green &Red visible radiation could use in no of sundry applications in such as solid-state lasers, LED/LCD displays, optical fibers, and fast
Preparation and Characterization of Solid-State Electrolyte Material for Energy Storage Applications
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) Muhammad Shahzad; CIIT/FA17-RPH-012/LHR; Dr. Junaid Amjad; LHR TP 5713
Seven Boro-phosphate samples with composition (70 - x) B2O3 – 30 Na2O3 – xP2O5 where x=0.5%, 1%, 1.5%, 2% and 3, 5, 10 mole% and 0.02 g Er2O3 in extra were prepared using melt quenching method. From the results of X-ray Diffraction (XRD), it was confirmed that the structure of the samples was amorphous. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. The spectroscopy was performed with wavelength ranging from 400 nm to 1600 nm to obtain the absorption peaks of the samples. Five absorption peaks were observed because of the transition from the ground state 4I15/2 to the different excited states. From the results, direct and indirect energy band gaps were calculated. Direct energy band gaps were in the range 3.59 eV - 4.18 eV. Indirect band gaps were in the range 2.92 eV - 3.95 eV. Refractive index was also calculated which was in the range 2.19 - 2.42. Photoluminescence was performed between 200 nm to 800 nm to observe the emission peaks of the samples. Two broad peaks were observed centred at 540 nm to 565 nm. These peaks were due to the transition from 2H11/2 → 4S3/2 and 4S3/2 → 4I15/2 respectively. Then Raman spectroscopy was performed on the samples between 200 cm-1 to 1600 cm-1. Under an excitation wavelength of 488 nm, characteristic Raman peaks of borate and phosphate were observed. Shifts and appearance of new bands were due to the replacement of borate with phosphate contents.
Study on Metal Ions Mediated Structural Properties of Bio-Glass Matrix
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Saira Saif; CIIT/SP20-RPH-019/LHR; Dr. Junaid Amjad; LHR TP 7713
Study on Metal Ions Mediated Structural Properties of Bio-Glass Matrix Rare earth Bioglass materials show promise for biomedical uses. In this study, Yb3+ ions and CuO were co-doped in borophosphate glass, and new glass with varied characteristics was created using the melt-quenching approach. The intensities of rare earth 4f intraband transitions changed when metallic Cu nanoparticles (NPs) were added. Advanced techniques, such as Raman and UV are used to study the optical characteristics of these glasses. The results demonstrate absorption and luminescence spectroscopy, as well as the excited state lifetime, which influences the optical characteristics of the glass.