Vaibhav Shrivastava
GNIT, Greater Noida UP, R&D, Department Member
- Shiv Nadar University, Physics, Faculty Memberadd
- I am a materials scientist and a physics teacher who is passionate about taking risks. I love to explore complex issu... moreI am a materials scientist and a physics teacher who is passionate about taking risks. I love to explore complex issues using fundamentals steps and excited in making right content available for young scholars. I am an optimist who would wish the world to witness beauty of nature as mother teacher through my eyes. Physics is a wonderful tool that can be used to realize presence of life functioning at a very elementary level as well as to gigantic scales. I aspire to venture into new areas of materials research to face close encounter with science working at femto levels to a few milimeters.edit
Research Interests:
In this paper, effects of lattice strain on dielectric properties of Sr[Formula: see text]CaxBi2Nb2O9 ([Formula: see text]–0.5 in steps of 0.1) ceramics are reported. High frequency dipolar polarization is observed to increase for 10%... more
In this paper, effects of lattice strain on dielectric properties of Sr[Formula: see text]CaxBi2Nb2O9 ([Formula: see text]–0.5 in steps of 0.1) ceramics are reported. High frequency dipolar polarization is observed to increase for 10% calcium addition and suppresses thereafter on higher calcium concentrations. The dielectric loss values for all doped samples were lower compared to undoped one at frequencies beyond 1[Formula: see text]kHz. The sample with [Formula: see text] shows room temperature dielectric constant in the range (130[Formula: see text][Formula: see text][Formula: see text]12) over a wide frequency range from 50[Formula: see text]Hz to 1[Formula: see text]MHz also minimum dielectric loss among all other sample for the same frequency range. Remarkable increase in Curie temperature ([Formula: see text]) by 50[Formula: see text]C is recorded in the present work by increasing 10% calcium content in SBN compostion. All higher doped samples indicate increase in [Formula: s...
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Research Interests: Condensed Matter Physics, Materials Science, Quantum Physics, Lanthanum oxide, Relaxor ferroelectrics, and 10 morePhase transition, Ceramic, Nano Dielectrics, Dielectric Relaxation, Curie temperature, Dielectric Loss, Ferroelectricity, Microstructures, Space Charge, and Negative Temperature Coefficient
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Aurivillius type bismuth layer structured ferroelectrics (BLSF) have been found to possess strong relationship between tetragonal strain (c/a) and extrinsic/ intrinsic conductivity. The extrinsic part of the conductivity is known to... more
Aurivillius type bismuth layer structured ferroelectrics (BLSF) have been found to possess strong relationship between tetragonal strain (c/a) and extrinsic/ intrinsic conductivity. The extrinsic part of the conductivity is known to depend upon space charge in the sample. The present ...
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Abstract Microwave synthesized strontium bismuth niobate Sr1-xSnxBi1.95La0.05Nb2O9 (SSBLN) materials are investigated for non-Debye conduction and photocatalytic response. Lone electron pair repulsions between doping tin (Sn2+) and layer... more
Abstract Microwave synthesized strontium bismuth niobate Sr1-xSnxBi1.95La0.05Nb2O9 (SSBLN) materials are investigated for non-Debye conduction and photocatalytic response. Lone electron pair repulsions between doping tin (Sn2+) and layer bismuth (Bi3+) generate optimal lattice strain. Lattice oxygen, that is critical in photocatalytic applications, is observed to fold along a-c plane on introducing tin. SSBLN compositions possess higher porosity with reduced dimensions. Porosity derived capacitive boundaries promote polaronic hopping in SSBLN materials over diffused ionic conduction. The visible spectrum photocatalytic response is better after doping tin in SSBLN compositions. Mesoporous network and electron-hole pair generation play crucial role in augmented photocatalytic behaviour of SSBLN materials.
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Research Interests:
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First layer Aurivillius Bismuth Molybdate Tungstate ceramic [Bi2Mo1-xWxO6 (BMoW); x=0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.10] compositions are prepared using deep penetrating microwave sintering in air. All samples show... more
First layer Aurivillius Bismuth Molybdate Tungstate ceramic [Bi2Mo1-xWxO6 (BMoW); x=0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.10] compositions are prepared using deep penetrating microwave sintering in air. All samples show known perovskite phase formation just after 5 hours calcinations at 575°C. X-ray diffraction and transmission electron microscopy based energy dispersive spectroscopy are used to confirm the phase-purity and gross elemental concentration change besides particle size. Nearly double ϵ^'-values are obtained for investigated BMoW materials compared to earlier reported values. Silver percolation through electrodes in bismuth oxide deficient surfaces of BMoW ceramic powders induces radio wave absorption in the frequency range 2 to 4 MHz. Characteristic third phase transition (γ→γ^''') of Bi2MoO6 material dissolves gradually on increasing tungsten concentration. The introduction of tungsten in BMo matrix increases the dipolar strength of MoO6 octahedrons bending against infrared absorption as evidenced from FTIR analysis. Additionally appearing FTIR peaks provide a strong indication of CO and CO2 contamination on exposed powder surfaces useful for photocatalytic applications.
Research Interests: Materials Engineering, FTIR spectroscopy, Transmission Electron Microscopy, Impedance Spectroscopy, FTIR Absorption Spectroscopy, and 7 moreDielectric Spectroscopy, Microwave Synthesis, Ferroelectricity, Carbon monoxide oxidation, Dielectric and ferroelectric materials, Third Phase, and Differential Scanning Calorimetry (DSC)
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Research Interests:
Studies on the effect of 10 - 50 atomic % Ca doping on structural distortions are reported in the present work. Bismuth layered structured ferroelectrics oxides of the composition Sr1-xCaxBi2Nb2O9; with x = 0.0 - 0.5 were synthesized by... more
Studies on the effect of 10 - 50 atomic % Ca doping on structural distortions are reported in the present work. Bismuth layered structured ferroelectrics oxides of the composition Sr1-xCaxBi2Nb2O9; with x = 0.0 - 0.5 were synthesized by the solid-state reaction method. X-ray diffraction analysis revealed the formation of perovskite ferroelectric ceramic sample and a few additional peaks were
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In this paper effects of lead doping on the lattice response and phase transitions of bismuth-layered structure Sr 1−x Pb x Bi 2 Nb 2 O 9 (x = 0.0 to 0.5 in steps of 0.1) ferroelectric ceramic are reported. It is observed that structure... more
In this paper effects of lead doping on the lattice response and phase transitions of bismuth-layered structure Sr 1−x Pb x Bi 2 Nb 2 O 9 (x = 0.0 to 0.5 in steps of 0.1) ferroelectric ceramic are reported. It is observed that structure attains more tetragonality with doping of lead up to ...
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Microwave synthesized strontium bismuth niobate Sr 1-x Sn x Bi 1.95 La 0.05 Nb 2 O 9 (SSBLN) materials are investigated for non-Debye conduction and photocatalytic response. Lone electron pair repulsions between doping tin (Sn 2þ) and... more
Microwave synthesized strontium bismuth niobate Sr 1-x Sn x Bi 1.95 La 0.05 Nb 2 O 9 (SSBLN) materials are investigated for non-Debye conduction and photocatalytic response. Lone electron pair repulsions between doping tin (Sn 2þ) and layer bismuth (Bi 3þ) generate optimal lattice strain. Lattice oxygen, that is critical in photocatalytic applications , is observed to fold along a-c plane on introducing tin. SSBLN compositions possess higher porosity with reduced dimensions. Porosity derived capacitive boundaries promote polaronic hopping in SSBLN materials over diffused ionic conduction. The visible spectrum photocatalytic response is better after doping tin in SSBLN compositions. Mesoporous network and electron-hole pair generation play crucial role in augmented photo-catalytic behaviour of SSBLN materials.
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Microwave synthesis was optimized for preparing novel monoclinic Tin-doped barium niobate ceramics (Ba1-xSnxNb2O6; x = 0.0, 0.01, 0.05, 0.1, 0.2, 0.3) BSN. The intensity of monoclinic phase formation was observed to decrease on increasing... more
Microwave synthesis was optimized for preparing novel monoclinic Tin-doped barium niobate ceramics (Ba1-xSnxNb2O6; x = 0.0, 0.01, 0.05, 0.1, 0.2, 0.3) BSN. The intensity of monoclinic phase formation was observed to decrease on increasing tin as dopant indicating decreased crystallinity. Strained crystalline phase was observed in undoped sample that became severe on doping tin. Monoclinic metal alloy Sn2O3 formation was confirmed on increasing tin doping beyond 5%. Electronic configuration of tin (II) oxide supports the local site-wise monoclinic disorder in crystal structure due to sterically active lone pair. Such a disorder arranges increased number of degenerate energy states and reduce effective energy gap between conduction band minimum and valence band maximum. All BSN compositions were investigated for monoclinic phase stabilization, ultra-violet absorption, dielectric response, raman modes and type of carrier concentration along with hall resistivity. All measurements possessed inflexion corresponding to 5% tin doping indicating successful site substitution and estimated Sn2O3 metal formation beyond this. The values of reducing optical energy band gap, transparency to visible spectrum, hall resistivity and dc conductivity indicated utility of these materials as a target for growing transparent conducting oxide (TCO) films for substituting well-known indium tin oxide (ITO).
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Pulp and paper industry generates large wastewater volumes containing recalcitrant and toxic compounds in various forms. These compounds are highly toxic and standard primary/secondary treatments are unable to filter heavy metal... more
Pulp and paper industry generates large wastewater volumes containing recalcitrant and toxic compounds in various forms. These compounds are highly toxic and standard primary/secondary treatments are unable to filter heavy metal contaminants besides organic species. An emerging demand of advance level treatment is the motivation of current work that explores possibility of using thick sand of deep aquifers as an adsorbent to remove inorganic and organic contaminants simultaneously from wastewater besides desalination. Popular ultrasonic cavitation is used to accelerate degradation of toxic organic effluent into less toxic open ring structures besides curing heavy metals to form new bonds during adsorption. Because of extreme local environment due to cavitation, heavy metals coagulate in silicon-aluminum atomic meshes and carbon nano tubes for less toxic new
crystalline structure. Significant changes in physico-chemical investigations like pH, chemical oxygen demand and colour towards drinkable water standards indicate effective adsorption resulting into wastewater purification.
crystalline structure. Significant changes in physico-chemical investigations like pH, chemical oxygen demand and colour towards drinkable water standards indicate effective adsorption resulting into wastewater purification.
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Hume-Rothery rules along with Vegard’s law form the basis of systematic doping variation resulting into similar changes in unit cell parameters and volume. Many recent reports have highlighted positive–negative departure from Vegard’s law... more
Hume-Rothery rules along with Vegard’s law form the basis of systematic doping variation resulting into similar changes in unit cell parameters and volume. Many recent reports have highlighted positive–negative departure from Vegard’s law in binary semiconducting systems and a few oxide alloys as well. The current work targets investigations on the missing response of bismuth molybdate on low tungsten doping onto molybdenum sites (Bi2Mo1xWxO6). Bismuth molybdate
and bismuth tungstate have been widely reported for lattice oxygen migration driven photocatalytic response and pressure-sensitive Raman scattering. Octahedral tilting in low-tungsten-doped Bi2Mo0.94W0.06O6 carries an interesting lattice oxygen folding toward a–c plane. As a result, unit cell polarity increases drastically and becomes a source for intense Raman scattering phase that is normally observable at pressures around 8.3 GPa. An interesting departure from Vegard’s law behavior at around 5–6% tungsten doping confirms nearly identical unit cell structure rather than mix unit cell-based alloy formation.
and bismuth tungstate have been widely reported for lattice oxygen migration driven photocatalytic response and pressure-sensitive Raman scattering. Octahedral tilting in low-tungsten-doped Bi2Mo0.94W0.06O6 carries an interesting lattice oxygen folding toward a–c plane. As a result, unit cell polarity increases drastically and becomes a source for intense Raman scattering phase that is normally observable at pressures around 8.3 GPa. An interesting departure from Vegard’s law behavior at around 5–6% tungsten doping confirms nearly identical unit cell structure rather than mix unit cell-based alloy formation.
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In this work, layered perovskite SBN was investigated in a new-doped form for hole as well as electron transport layer (HTL/ETL) in perovskite solar cells. This work was targeted to determine utility of bismuth layer SBN materials as an... more
In this work, layered perovskite SBN was investigated in a new-doped form for hole as well as electron transport layer (HTL/ETL) in perovskite solar cells. This work was targeted to determine utility of bismuth layer SBN materials as an active layer in hybrid perovskite solar cells. Thoroughly hard ball-milled compositions Sr1−xSnxBi1.95La0.05Nb2O9 (x = 0.0, 0.01, 0.03, 0.05, 0.1 and 0.2) were prepared by microwave synthesis to obtain fine (~ 10–60 nm) mesoporous particle network of atomic level substitutions. Microwave synthesis was crucial in modifying dielectric, semiconducting and optical characteristics of prepared SBN materials. The optical energy band gap and hall resistivity decreased in continuous manner on tin doping. The role of metallic tin as dopant in sharpening redox peaks and decreasing capacitive reactance of grain boundaries was investigated in detail using cyclic voltammetry and impedance spectroscopy respectively. The tin being more polar covalent
than strontium augmented dielectric response too.
than strontium augmented dielectric response too.
Research Interests:
First layer Aurivillius Bismuth Molybdate Tungstate ceramic [Bi2Mo1−xWxO6 (BMoW); x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.10] compositions are prepared using deep penetrating microwave sintering in air. All samples show... more
First layer Aurivillius Bismuth Molybdate Tungstate ceramic [Bi2Mo1−xWxO6 (BMoW); x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08 and 0.10] compositions are prepared using deep penetrating microwave sintering in air. All samples show known perovskite phase formation just after 5 h calcinations at 575 °C. X-ray diffraction and transmission electron microscopy based energy dispersive spectroscopy are used to confirm the phase-purity and gross elemental concentration change besides particle size. Nearly double -values are obtained for investigated BMoW materials compared to earlier reported values.
Silver percolation through electrodes in bismuth oxide deficient surfaces of BMoW ceramic powders induces radio wave absorption in the frequency range 2 to 4 MHz. Characteristic third phase transition ( →
) of Bi2MoO6 material dissolves gradually on increasing tungsten concentration. The introduction of tungsten in BMo matrix increases the dipolar strength of MoO6 octahedrons bending against infrared absorption as evidenced from FTIR analysis. Additionally appearing FTIR peaks provide a strong indication of CO and CO2 contamination on exposed powder surfaces useful for photocatalytic applications.
Silver percolation through electrodes in bismuth oxide deficient surfaces of BMoW ceramic powders induces radio wave absorption in the frequency range 2 to 4 MHz. Characteristic third phase transition ( →
) of Bi2MoO6 material dissolves gradually on increasing tungsten concentration. The introduction of tungsten in BMo matrix increases the dipolar strength of MoO6 octahedrons bending against infrared absorption as evidenced from FTIR analysis. Additionally appearing FTIR peaks provide a strong indication of CO and CO2 contamination on exposed powder surfaces useful for photocatalytic applications.
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In this paper, effects of lattice strain on dielectric properties of Sr1-xCax Bi2Nb2O9 (x= 0-0.5 in steps of 0.1) ceramics are reported. High frequency dipolar polarization is observed to increase for 10% calcium addition and suppresses... more
In this paper, effects of lattice strain on dielectric properties of Sr1-xCax Bi2Nb2O9 (x= 0-0.5 in steps of 0.1) ceramics are reported. High frequency dipolar polarization is observed to increase for 10% calcium addition and suppresses thereafter on higher calcium concentrations. The dielectric loss values for all doped samples were lower compared to undoped one at frequencies beyond 1 kHz. The sample with x= 0:1 shows room temperature dielectric constant in the range (130 AE 12) over a wide frequency range from 50 Hz to 1 MHz also minimum dielectric loss among all other sample for the same frequeny range. Remarkable increase in Curie temperature (T c) by 50 C is recorded in the present work by increasing 10% calcium content in SBN compostion. All higher doped samples indicate increase in T c by further higher amount. In addition, dc conductivity of all samples is measured for all samples and increase in calcium content is observed to generate more insulating compositions compared to undoped SBN with higher intrinsic activation energies.
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Microwave processing of SrBi 2 Nb 2 O 9 ferroelectric ceramics was targeted in the current work. In particular , Curie temperature, dielectric constant, dielectric loss and dc conductivity were studied for microwave sintered SrBi 2 Nb 2 O... more
Microwave processing of SrBi 2 Nb 2 O 9 ferroelectric ceramics was targeted in the current work. In particular , Curie temperature, dielectric constant, dielectric loss and dc conductivity were studied for microwave sintered SrBi 2 Nb 2 O 9 ferroelectric ceramics in the range 1050-1200°C. The space charge di-electric relaxation was found noticeable in all sintered samples and electrical properties like dielectric constant, loss and dc conductivity were significantly affected due to this dielectric relaxation. An optimum processing condition was targeted by investigating frequency and temperature dependent di-electric responses along with dc conductivity.
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Aurivillius type bismuth layer structured ferroelectrics (BLSF) have been found to possess strong relationship between tetragonal strain (c/a) and extrinsic/ intrinsic conductivity. The extrinsic part of the conductivity is known to... more
Aurivillius type bismuth layer structured ferroelectrics (BLSF) have been found to possess strong relationship between tetragonal strain (c/a) and extrinsic/ intrinsic conductivity. The extrinsic part of the conductivity is known to depend upon space charge in the sample. The present paper discusses effects of 30 atomic % doping of Ca, La and Pb on tetragonal strain, conductivity and dielectric constant/loss with temperature and
frequency. Tetragonal strain increases on doping calcium and lead while it shows a decrease on doping lanthanum. The calcium and lanthanum doped samples show pronounced space charge part of dielectric constant while lead doped sample shows nearly constant permittivity values. No phase transition is observed in the calcium doped sample
up to 600◦C while for the lanthanum doped sample a decrease of 141◦C is observed in the value of Curie temperature compared to that for the undoped sample.
frequency. Tetragonal strain increases on doping calcium and lead while it shows a decrease on doping lanthanum. The calcium and lanthanum doped samples show pronounced space charge part of dielectric constant while lead doped sample shows nearly constant permittivity values. No phase transition is observed in the calcium doped sample
up to 600◦C while for the lanthanum doped sample a decrease of 141◦C is observed in the value of Curie temperature compared to that for the undoped sample.
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In this paper, structural and dielectric studies of Sr1−xAxBi2Nb2O9 (A=La, Pb and x=0.2) ceramics are reported. Tetragonal strain decreases on introduction of lanthanum while it increases for the lead doped sample. Addition of lead... more
In this paper, structural and dielectric studies of Sr1−xAxBi2Nb2O9 (A=La, Pb and x=0.2) ceramics are reported. Tetragonal strain
decreases on introduction of lanthanum while it increases for the lead doped sample. Addition of lead increases Curie temperature and sample
with lanthanum content shows remarkable decrease in Curie temperature with broadened dielectric peak. The sample with x=0.0 shows a rapid fall in dielectric constant value above 100 KHz. The lanthanum and lead doped samples show reduced dielectric loss values with frequency.
decreases on introduction of lanthanum while it increases for the lead doped sample. Addition of lead increases Curie temperature and sample
with lanthanum content shows remarkable decrease in Curie temperature with broadened dielectric peak. The sample with x=0.0 shows a rapid fall in dielectric constant value above 100 KHz. The lanthanum and lead doped samples show reduced dielectric loss values with frequency.
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In this paper, structural and electrical studies of A-site lanthanum-substituted Sr1xLaxBi2Nb2O9; x ¼ 0:020:5 ceramics are reported. The introduction of lanthanum produces pore-free microstructure upto x =0.3. A diffuse ferroelectric to... more
In this paper, structural and electrical studies of A-site lanthanum-substituted Sr1xLaxBi2Nb2O9; x ¼ 0:020:5 ceramics are reported.
The introduction of lanthanum produces pore-free microstructure upto x =0.3. A diffuse ferroelectric to paraelectric phase transition is
observed in the doped samples and positive temperature coefficient of resistance (PTCR) is observed in x= 0.0, 0.4 and 0.5 samples
whereas x= 0.1, 0.2, 0.3 samples show negative temperature coefficient of resistance (NTCR). Curie temperature decreases continuously
with increase in lanthanum content.
The introduction of lanthanum produces pore-free microstructure upto x =0.3. A diffuse ferroelectric to paraelectric phase transition is
observed in the doped samples and positive temperature coefficient of resistance (PTCR) is observed in x= 0.0, 0.4 and 0.5 samples
whereas x= 0.1, 0.2, 0.3 samples show negative temperature coefficient of resistance (NTCR). Curie temperature decreases continuously
with increase in lanthanum content.
Research Interests:
In this paper, effects of lead doping on the lattice response and phase transitions of Sr1KxPbxBi2Nb2O9 (x=0.0–0.5 in steps of 0.1) ferroelectric ceramics are reported. It is observed that structure attains more tetragonality with doping... more
In this paper, effects of lead doping on the lattice response and phase transitions of Sr1KxPbxBi2Nb2O9 (x=0.0–0.5 in steps of 0.1) ferroelectric ceramics are reported. It is observed that structure attains more tetragonality with doping of lead up to 40%. Increased orthorhombic distortion is observed for undoped SBN and 50 at.% lead substituted SBN. Phase transitions for all samples were studied using Curie temperature measurements and are explained in terms of lattice response of these ceramics. Sample with x=0.5 shows decreased tetragonal strain and Curie temperature. Relationship of polarization with lattice response is discussed.
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It is a text book for 4th semester electrical engineering undergraduates of Abdul Kalam Technical University Uttar Pradesh Lucknow. The book contains chapters on crystal structure, band theory of solids, electrical properties of metals,... more
It is a text book for 4th semester electrical engineering undergraduates of Abdul Kalam Technical University Uttar Pradesh Lucknow. The book contains chapters on crystal structure, band theory of solids, electrical properties of metals, semiconductor materials, and magnetic materials.
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It is text book for 2nd year engineering undergraduates of electronics and communication engineering department of Abdul Kalam Technical University Lucknow Uttar Pradesh India. The book was co-written by eminent scientist/engineer of... more
It is text book for 2nd year engineering undergraduates of electronics and communication engineering department of Abdul Kalam Technical University Lucknow Uttar Pradesh India. The book was co-written by eminent scientist/engineer of University Science Instrumentation Centre University of Delhi Prof. Dinesh. The book contains chapters on semiconductor materials, crystal structure, bonding forces, charge carriers, excess carriers, junction properties, field effect transistors, bipolar junction transistor, optoelectronic devices and materials, negative conductance microwave devices and four layer power devices.
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It is a 2nd semester text book for first year engineering undergraduates of Abdul Kalam Technical University Lucknow. The book contains chapters on wave mechanics, x-rays, dielectric materials, magnetic materials, ultrasonics,... more
It is a 2nd semester text book for first year engineering undergraduates of Abdul Kalam Technical University Lucknow. The book contains chapters on wave mechanics, x-rays, dielectric materials, magnetic materials, ultrasonics, electromagnetic wave theory, superconductivity and nano materials.
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It is a text book for first year engineering undergraduates of affiliated engineering colleges under Abdul Kalam Technical University Lucknow Uttar Pradesh India. Very first edition of book had circulation of about 4000 copies. The book... more
It is a text book for first year engineering undergraduates of affiliated engineering colleges under Abdul Kalam Technical University Lucknow Uttar Pradesh India. Very first edition of book had circulation of about 4000 copies. The book contains chapters on relativistic mechanics, interference, diffraction, polarization, lasers, fibre optics and holography.