Ramadevudu Gokarakonda
@vce.ac.in
Assistant Professr (Sr), Department of Physics
Vasavi College of Engineering
EDUCATION
M.Sc., Ph.D
RESEARCH INTERESTS
Glasses, Glass Ceramics, Thin films, EPR
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Bodige Narsimha, K. Chandra Sekhar, Md. Shareefuddin, M. Narasimha Chary, and Gokarakonda Ramadevudu
Springer Science and Business Media LLC
M. M. Ahmed Mahmoodi, Shaik Kareem Ahmmad, G. Ramadevudu, Y. S. Rammah, and J. Laxman Naik
Springer Science and Business Media LLC
Chandrasekhar Maalegoundla, Abdul Hameed, G. Ramadevudu, and Md. Shareefuddin
AIP Publishing
G. Sangeetha, Abdul Hameed, G. Ramadevudu, and Md. Shareefuddin
AIP Publishing
Sarap Krishnaprasad, Md. Shareefuddin, M. Lakshmipathi Rao, and G. Ramadevudu
The Electrochemical Society
Alkali tetraborate glasses 10RO-30ZnO-xLi2B4O7-(60-x) K2B4O7 (R = Mg, Ca) with x varying from 0 mole% to 60 mole% were synthesized by melt quenching approach at around 1150 °C. Broad and peak less X-ray diffraction spectra confirmed the amorphous nature of synthesized glass samples. Physical and optical properties namely density, molar volume, refractive index, optical band gaps, molar refractivity and Urbach energy values have been reported. The density of the present glass samples improved with increasing x mole% except at the presence of equal amounts of alkali oxides in the glass system. The molar volume decreased continuously with x mole%. Oxygen packing density (OPD) increased with increasing x mole%. The optical energy band gap Eopt values with increasing lithium tetraborate in the glass composition have shown a downward trend, where are refractive index values shown upward. FTIR and Raman studies revealed the variation of BO3 and BO4 units in the glasses with composition is marginal. EPR spectra of copper ions confirmed the existence of Cu2+ ions in the ground state dx 2–y 2 orbital (2B1g). The observed non-linear variations of various properties are attributed to the structural changes caused by mixed alkali effect.
B. Ashok, K. Chandra Sekhar, B. Srikantha Chary, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Springer Science and Business Media LLC
G. Sangeetha, K. Chandra Sekhar, Abdul Hameed, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Elsevier BV
S. Vedavyas, K. Chandra Sekhar, Sheik Ahammed, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Springer Science and Business Media LLC
Prabhu Kiran Martha*, , K. Kishore, Gokarakonda. Ramadevudu*, , and
Blue Eyes Intelligence Engineering and Sciences Engineering and Sciences Publication - BEIESP
The small and medium scale industry in drilling and cutting sector widely use cutting tools made by High Speed Steel (HSS). The improvement of lifetime of HSS drill bits helps these establishments to achieve product economy. The improvement in the performance and service lifetime of high-speed steel (HSS) twisted drill bits are studied by depositing Titanium dioxide (TiO2) nano-coatings using reactive dc magnetron sputtering Method. Pure titanium (99.99%) metal is used as target material for making nano-coatings in oxygen atmosphere. X-ray diffraction studies indicated change of phase of annealed samples compared to as-deposited coatings. X-ray reflection (XRR) measurements estimated nanocoating thickness on the HSS drill bit around 100nm. The lifetime of TiO2 nano-coated, and cryogenically treated nano-coated tools significantly improved compared to uncoated (bare) HSS drill bit. The tool life has been enhanced by about 16% when TiO2 nano-coatings were made on HSS drill bits. Further lifetime enhancement of 10% was observed when the nanocoated drill bit is given cryogenic treatment in liquid nitrogen. SEM images and EDS profiles are reported. The minimum surface roughness measured as 7.296x10-6m for TiO2 coated and cryo-treated HSS drill tool.
B. Srinivas, Abdul Hameed, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Elsevier BV
L Haritha, K Chandra Sekhar, R Nagaraju, G Ramadevudu, Vasanth G Sathe, and Md. Shareefuddin
IOP Publishing
Fluoride based glasses with composition CaF2–ZnF2–Bi2O3–B2O3 doped with chromium ions have been investigated using physical, optical, electron paramagnetic resonance (EPR), Fourier-transform infrared spectroscopy (FTIR), and Raman studies. The amorphous nature of samples was confirmed from x-ray diffraction spectra. The density is evaluated from the Archimedes principle and the values of optical band gap and Urbach energy values were evaluated from the optical absorption spectra. Thus, molar volume, refractive index, etc., were also evaluated. The observed decrease in density and the optical band gap with CaF2 is explained using the crystalline density of metal fluorides and the ionicity of fluorine ions, respectively. The three peaks near 450 nm, 606 nm, and 720 nm, which are shown in the absorption spectra, are accredited to 4A2g → 4T1g, 4A2g → 4T2g, 4A2g → 2E transitions, respectively. Resonance signals at g ≈ 4.82 and g ≈ 1.99 were observed in EPR spectra which are assigned. FTIR and Raman analysis were carried out to examine the impact of metal fluorides on the structure of bismuth borate glasses.
B. Srinivas, R.Vijaya kumar, Abdul Hameed, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Elsevier BV
B. Ashok, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Elsevier BV
K. Chandra Sekhar, Abdul Hameed, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
World Scientific Pub Co Pte Lt
Lead halo borate glass systems containing manganese ions have been investigated to study the role of halide ions on the physical, optical and EPR studies. The amorphous phase of the prepared glass samples [Formula: see text]PbX2–(30[Formula: see text])PbO–69.5B2O3–0.5MnO2 with X = F, Cl and Br and [Formula: see text] mol% was confirmed from their X-ray diffraction spectra. Ionic radii of the halides played an important role in the physical properties. From the optical absorption spectra, optical band gap and Urbach energy values were evaluated. The EPR spectra have shown a six-line hyperfine (HF) structure centered at [Formula: see text] and attributed to Mn[Formula: see text] centers in octahedral symmetry. The other signals at [Formula: see text] and 4.3 were attributed to the rhombic surroundings of Mn[Formula: see text] ions. The negative shift in [Formula: see text]-value revealed highly ionic environment around the Mn[Formula: see text] ion in the glass hosts. The HF splitting constant (A), number of spins (N) and susceptibility [Formula: see text] values of the prepared glasses were also reported.
Samdani, G. Ramadevudu, M. Narasimha Chary, and Md. Shareefuddin
Elsevier BV
Abdul Hameed, G. Ramadevudu, Md. Shareefuddin, and M. Narasimha Chary
AIP Publishing LLC
Electron Paramagnetic Resonance (EPR) studies at room temperature in the x-band frequencies on xZnO−10Li2O−10Na2O−10K2O−(69−x)B2O3−1CuO (x=0,2,4,6 and 8 mole%) glass systems were reported. The non-linear variation of spin-Hamiltonian parameters with ZnO content indicated the change in the ligand field strength around Cu2+ ions in the host glass. The ground state of Cu2+ ions in the glass is designated as dx2−y2 orbital (2B1g) while the observed symmetry around it is tetragonally distorted octahedral. The molecular orbital coefficients α2, β2 and β12 are evaluated for Cu2+ doped samples. The non-linear variation in the values of parameters indicated mixed alkali effect in the glasses.
L. Balachander, G. Ramadevudu, Md. Shareefuddin, R. Sayanna, and Y.C. Venudhar
Science Society of Thailand
FTIR investigations on borate glasses containing three alkali oxides, x Li2O x Na2O x K2O (50 3x) PbO 50 B2O3 (x = 8, 10, 12, 14, and 16 mol%), 10 Li2O 10 Na2O 10 K2O y PbO (70 y) B2O3 (y = 25, 30, 35, 40, and 50 mol%), and x Li2O x Na2O x K2O (50 3x) Bi2O3 50 B2O3 (x = 8, 10, 12, 14, and 16 mol%) are reported. The present glasses contain mainly BO3 and BO4 structural units. The presence of fingerprints of both BiO3 and BiO6 structural units in bismuth alkali borate glasses was confirmed. The presence of varied types like di, tetra, penta, and ortho borate groups are confirmed in the glass matrix. Glasses with low PbO content contained more BO3 units than BO4 units.
G. RAMADEVUDU, MD. SHAREEFUDDIN, M. NARASIMHA CHARY, and M. LAKSHMIPATHI RAO
World Scientific Pub Co Pte Lt
EPR and DSC studies were carried out on MgO – R 2 O – B 2 O 3– V 2 O 5 glasses. The electron paramagnetic resonance spectra of V 4+ ion in the ternary glass system x MgO –(30-x) R 2 O –70 B 2 O 3 ( R = Li, Na, K ) were recorded at X-band frequencies at 303 K. The V 4+ ions in the present glass system exists as VO 2+ ions in octahedral coordination with tetragonal compression. The site symmetry of vanadyl is C 4v and the ground state of 3d1 ion is dxy. Tetragonality (Δg‖/Δg⊥) of V 4+ ion sites show a nonlinear variation with MgO content in the glasses. The covalency rates indicate moderate covalency for σ and π-bonds. The optical basicity values were also reported. Glass transition temperatures (Tg) of the glasses were found to increase linearly with increasing MgO content.
G Ramadevudu, Md Shareefuddin, N Sunitha Bai, M Lakshmipathi Rao, and M Narasimha Chary
Elsevier BV
Md. Shareefuddin, Md. Jamal, G. Ramadevudu, M. Lakshmipati Rao, and M. Narasimha Chary
Elsevier BV