Gandham Lakshminarayana

RESEARCH INTERESTS

RE-doped glasses; Thin films; Fuel Cells; Nanomaterials; Inorganic Scintillators

Scopus Publications

Self-powered solar-blind ultraviolet detectors based on the amorphous boron nitride films
Cheng Wu, Peiwen Lv, Zhaojie Zhu, Jianfu Li, Chaoyang Tu, Chenlong Chen, G. Lakshminarayana, Hongyan Wang, and Yan Wang
Elsevier BV



Yb³⁺ dopant concentration dependence in Yb:CaGdAlO<inf>4</inf> bulk crystals
Xiaohu Liu, Jianfu Li, Zhaojie Zhu, Chaoyang Tu, G. Lakshminarayana, and Yan Wang
Royal Society of Chemistry (RSC)
A series of high-quality CALGO single crystals with varying Yb3+ doping concentrations were grown and their spectroscopic properties were presented.


Structural, optical, dielectric and electrical characteristics of flexible blended polymers based on PMMA/PVAc/TBAI and milled PANI for energy storage applications and optoelectronic devices
A.M. El-naggar, Nourah Alhaqbani, Mohamed Bakr Mohamed, A.M. Kamal, A.A. Albassam, and G. Lakshminarayana
Elsevier BV



Design of a Low-Cost PMMA/PVAc/PANI Blended Polymers: Structural, Electrical and Dielectric Characteristics
A. M. El-naggar, Nourah Alhaqbani, A. M. Kamal, A. A. Albassam, G. Lakshminarayana, and Mohamed Bakr Mohamed
The Electrochemical Society
Polymethyl methacrylate (PMMA)/polyvinyl acetate (PVAc)/tetra-n-butylammonium iodide (TBAI)/x wt % polyaniline (PANI) blended polymers are fabricated using the casting method to operate in energy storage purposes. The structure and morphology of the created blends were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. XRD analysis displayed that the semicrystalline behavior of the polymer blend is unaffected by doping. At 293 K and 100 Hz, the dielectric constant decreased from 22.7 (undoped) to 14.04–21.7 depended on the amount of PANI in the doped blend. The greatest energy density (U) values were reported in the blend with x = 0.33; U = 0.00469 J m−3 at 293 K and 100 Hz. Increasing the temperature also improves the U values for all blends. The U values of the doped blends with x = 0.11, 0.22, and 0.33 showed an impressive rise relative to the undoped blend. In the low and intermediate frequency ranges, the ac conductivity increased in the blend with x = 0.44. The correlated barrier hopping (CBH) model was used to describe the electric mechanism of all blends. The influence of the quantity of PANI doping and temperature on electrical impedance spectroscopy, electric modulus, and relaxation time was investigated. A doped blend with x = 0.44 exhibited the greatest dc conductivity; at 343 K. the dc conductivity was increased from 2.477 × 10−8 S m−1 (undoped) to 1.086 × 10−5 S m−1 (x = 0.44). The activation energies (E a ) for undoped blends varied between 1.36 eV and 1.01 eV based on the temperature range. The amount of PANI added to the host blend controlled the values of E a in all samples.


Electrical and structural investigations of PVA/CMC/PPy/MWCNTs blended polymer composites for energy storage applications
A.M. El-naggar, Lamya A. Alsulaymani, Mohamed Bakr Mohamed, A.M. Kamal, A.A. Albassam, and G. Lakshminarayana
Elsevier BV



A Comparative Study of the Linear/Nonlinear Optical, and Dielectric Properties of PVA/CMC/(1−x)ZnWO<inf>4−x</inf>PbS Blended Polymers for Optoelectronic Applications
Mohamed Bakr Mohamed, Zein K. Heiba, A. M. El-naggar, A. M. Kamal, and G. Lakshminarayana
The Electrochemical Society
An analysis was conducted on the optical, structural, and dielectric characteristics of PVA/CMC/(1−x)ZnWO4/xPbS blends. The structures of the filler samples, undoped, and doped blends were examined using X-ray diffraction. The crystallite sizes of the various phases in the filler samples are affected by the amount of PbS in the nanocomposite. The morphologies of different blends were explored using scanning electron microscopy. The doped blend exhibited superior absorption of Ultraviolet A (UVA) and Ultraviolet B (UVB) types in addition to the visible spectrum. The optical band gaps were minimized to (5.37, 5.56, 4.11) and (4.76, 3.14, 2.92) eV for direct and indirect optical transitions, respectively, when the PVP/CMC doped with nanocomposite had 10% PbS. The highest refractive index, optical dielectric constant,and nonlinear optical parameter values were achieved when the blend was loaded with ZnWO4 only while the highest optical conductivity was obtained as the blend contained 15% PbS. The highest fluorescence intensity was observed when the fillers did not contain PbS, and it decreased as the concentration of PbS in the filler increased.


Incorporated melanin into PMMA/PVAc/TBAI blend for developing structural, optical, electrical and morphological features: Hybrid composite blended polymers for optoelectronic applications
A.M. El-naggar, Nourah Alhaqbani, A.M. Kamal, A.A. Albassam, G. Lakshminarayana, and Mohamed Bakr Mohamed
Elsevier BV



PVA/PEG/CuCo<inf>2</inf>O<inf>4</inf>/PANi/x wt% MWCNTs blended polymers: Improved the physical properties for energy storage devices and optoelectronic applications
A.M. El-Naggar, Mohamed Bakr Mohamed, A.M. Kamal, G. Lakshminarayana, and Zein K. Heiba
Elsevier BV



Influence of nature melanin on the structural, linear/nonlinear optical properties and electrical conduction mechanism of PVA/CMC/PPy blended polymers for optoelectronic applications
A.M. El-naggar, Lamya A. Alsulaymani, Mohamed Bakr Mohamed, Ahmad A. Alsaleh, A.M. Kamal, A.A. Albassam, A.M. Aldhafiri, and G. Lakshminarayana
Elsevier BV



Polyvinyl alcohol/carboxymethyl cellulose blended polymers doped with PPy/milled MWCNTs filler for Flexible optoelectronic and Energy Storage Applications
A.M. El-naggar, Lamya A. Alsulaymani, A.M. Kamal, A.A. Albassam, G. Lakshminarayana, and Mohamed Bakr Mohamed
Elsevier BV



Influence of ZnMn<inf>2</inf>O<inf>4</inf>/CuCo<inf>2</inf>O<inf>4</inf> nano-fillers on the optical and electrical properties PVA/CMC/PEG blended polymers
Mohamed Bakr Mohamed, Zein K. Heiba, A.M. El-naggar, A.M. Kamal, and G. Lakshminarayana
Elsevier BV



Fabrication and adapting the optical, and dielectric performance of PVC/ MnFe<inf>2</inf>O<inf>4</inf>/ZnMn<inf>2</inf>O<inf>4</inf> nanocomposite films for optoelectronic applications
A.M. El-naggar, Zein K. Heiba, A.M. Kamal, G. Lakshminarayana, and Mohamed Bakr Mohamed
Elsevier BV



The bulk crystal growth and yellow–orange spectral performances of Pr³⁺: BaF<inf>2</inf> and Pr³⁺/RE³⁺(RE³⁺ = Gd³⁺, Y³⁺, Lu³⁺, Ce³⁺): BaF<inf>2</inf> crystals
Xuxing Le, Longxing Zheng, Yan Wang, Zhaojie Zhu, Jianfu Li, Hongyan Wang, G. Lakshminarayana, and Chaoyang Tu
Springer Science and Business Media LLC



The role of co-dopant Ce³⁺ on the spectral properties of Dy³⁺ activated YAG single crystal for yellow green laser application
G. Lakshminarayana, Yan Wang, and Jonghun Yoon
Elsevier BV



Comparative analysis of the optical and electrical properties of PVA/PVP blended polymer with ZnCo<inf>2</inf>O<inf>4</inf>/CdS nanocomposites for optoelectronic and dielectric capacitor applications
Zein K. Heiba, A.M. El-naggar, A.M. Kamal, A.M. Aldhafiri, G. Lakshminarayana, and Mohamed Bakr Mohamed
Elsevier BV



Compilation and deciphering MoS<inf>2</inf>’s physical properties: Accurate benchmark DFT simulations and assessment of advanced quantum methods
Najeh Rekik, Ibrahim Isah, Norah A.M. Alsaif, Muath Alkadi, Shehu Aminu Yamusa, Ibtihal M. Alsalamah, Amiruddin Shaari, G. Lakshminarayana, Saed Salman, Razif Razali,et al.
Elsevier BV



Impact of Bi doping on the structural, optical, and dielectric features of nano ZnMn<inf>2</inf>O<inf>4</inf>
Zein K. Heiba, M.M. Ghannam, Mohamed Bakr Mohamed, M. M.S. Sanad, Mohamed H. Abdel-Kader, A.M. El-naggar, and G. Lakshminarayana
Elsevier BV



Optical and Dielectric Features of PVA/CMC/PVP/ZnMn<inf>2</inf>O<inf>4</inf>/CuCo<inf>2</inf>O<inf>4</inf>/x wt% MWCNTs Blended Polymers for Optoelectronic Applications
Zein K. Heiba, A. M. El-naggar, A. M. Kamal, G. Lakshminarayana, and Mohamed Bakr Mohamed
The Electrochemical Society
This study is devoted to optimizing the optical and dielectric parameters of polyvinyl alcohol (PVA)/ carboxymethyl cellulose (CMC)/ polyvinylpyrrolidone (PVP) blended polymer by adding ZnMn2O4/CuCo2O4 nanocomposite and controlling the amounts of multi-walled carbon nanotubes (MWCNTs) to engage them in flexible optoelectronics and storage energy capacitors. Herein, 0.9ZnMn2O4/0.1CuCo2O4 was synthesized by co-precipitation and hydrothermal methods and loaded with different ratios of MWCNTs into PVA/CMC/PVP blend to produce films by solution casting procedure. The crystallite size of 0.9ZnMn2O4/0.1CuCo2O4 was determined using transmission electron microscopy. The structures of the filler and doped blends were explored via the X-ray diffraction technique. The optical features of undoped and doped blends were explored by diffused reflectance and fluorescence spectrophotometers. The addition of ZnMn2O4/CuCo2O4 to PVA/CMC/PVP caused a decline of direct and indirect optical band gaps from 5.33 and 5.03 eV to 5.19 and 4.66 eV, respectively. By adding different amounts of MWCNTs, the direct/indirect optical band gap reduced irregularly, and they attained their minimum values (5.07, 4.46) eV as it doped with 0.6 Wt% MWCNTs. The highest values of refractive index, extinction coefficient, optical conductivity and nonlinear optical parameters were achieved in the blend containing ZnMn2O4/CuCo2O4/0.6 Wt% MWCNTs. It is also found that the dielectric constant and ac conductivity rose with the insertion of ZnMn2O4/CuCo2O4/0.6 Wt% MWCNTs. The highest energy density value was found in the polymer blend of PVA/CMC/PVP/ZnMn2O4/CuCo2O4/0.8 Wt% MWCNTs blended polymer. Electrical modulus and Nyquist plots for different blends were also examined. The results recommend the doped blends as a good candidate for optoelectronics and energy storage capacitor applications.


Spectroscopic properties of Yb³⁺/Ho³⁺:Lu<inf>1.5</inf>Y<inf>1.5</inf>Al<inf>5</inf>O<inf>12</inf> crystals
Xuhong Li, Jiaxue Yang, Zhaojie Zhu, Jianfu Li, Chaoyang Tu, G. Lakshminarayana, and Yan Wang
Elsevier BV



Modification in the Optical and Dielectric Characteristics of Poly (Vinyl Alcohol)/Carboxymethyl Cellulose Blended Polymers Doped with Two Phases Nanocomposites for Application in Optoelectronic and Energy Storage Devices
Zein K. Heiba, A. M. Kamal, A. M. El-naggar, G. Lakshminarayana, and Mohamed Bakr Mohamed
Informa UK Limited



Optical, Structural, and Dielectric Characteristics of Flexible PVA/PEG/ZnMn<inf>2</inf>O<inf>4</inf>/CuCo<inf>2</inf>O<inf>4</inf>/x wt % Melanin Blended Polymer Composites
Zein K. Heiba, A. M. El-Naggar, A. M. Kamal, G. Lakshminarayana, and Mohamed Bakr Mohamed
Informa UK Limited



Modification of the Optical and Dielectric Characteristics of PVA/CMC/NiMoO<inf>4</inf>/TMAI Blends by Adding Carbon Nanoparticles
Zein K. Heiba, A.M. El-naggar, A.M. Kamal, G. Lakshminarayana, and Mohamed Bakr Mohamed
Informa UK Limited



Novel efficient epoxy resin based shielding materials enhanced with BN powder against nuclear radiation: A new perspective of shielding performance analysis
Mengge Dong, Suying Zhou, Xiangxin Xue, He Yang, M.I. Sayyed, Daria Tishkevich, Alex Trukhanov, and G. Lakshminarayana
Elsevier BV



Er³⁺: B<inf>2</inf>O<inf>3</inf>-TeO<inf>2</inf>-ZnO-PbF<inf>2−</inf>M<inf>2</inf>O/MF (M = Li, Na, and K) glasses: An inspection of structural, thermal, optical, chromatic, and near-infrared luminescence traits for displays and potential C-band amplification
G. Lakshminarayana, A.N. Meza-Rocha, O. Soriano-Romero, U. Caldiño, A. Lira, and Jonghun Yoon
Elsevier BV



Crystal Growth and Structural, Optical, and Visible Fluorescence Traits of Dy³⁺-doped SrGdGa<inf>3</inf>O<inf>7</inf> Crystal
Haidong WANG, Yan WANG, Zhaojie ZHU, Jianfu LI, Gandham LAKSHMINARAYANA, and Chaoyang TU
Shanghai Institute of Ceramics

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