The Open Chemical and Biomedical Methods Journal, 2010
Synthesis of TiO 2 nanopowder via a low cost ultrasonic spray pyrolysis technique is reported and... more Synthesis of TiO 2 nanopowder via a low cost ultrasonic spray pyrolysis technique is reported and the nanopowder is used for the surface modification of glassy carbon electrode. The structural characterization of nanopowder by high temperature XRD clearly shows the phase transformation from anatase to rutile phase on increasing temperature. The morphological structure is characterized by field emission scanning electron microscope and high resolution transmission electron microscope. The modified electrode is used for the determination of dopamine in the presence of excess of ascorbic acid/ uric acid using square-wave voltammetry. The voltammograms obtained during the oxidation studies revealed that nano TiO 2 exhibits better catalytic function towards the oxidation of dopamine and ascorbic acid/uric acid. The overlapping voltammetric response of all the biomolecules at the bare electrode gets resolved into well defined voltammetric peaks with lowered oxidation potential and enhanced oxidation currents. Linear calibration curves for dopamine are obtained over the concentration range 75 nM-2.5 μM in 0.1M phosphate buffer solution at pH 7.2 with a correlation coefficient of 0.9940 and the detection limit (3) is estimated to be 13.8 nM.
We report the structural and optical properties of nanocrystalline thin films of vanadium oxide p... more We report the structural and optical properties of nanocrystalline thin films of vanadium oxide prepared via evaporation technique on amorphous glass substrates. The crystallinity of the films was studied using X-ray diffraction and surface morphology of the films was studied using scanning electron microscopy and atomic force microscopy. Deposition temperature was found to have a great impact on the optical and structural properties of these films. The films deposited at room temperature show homogeneous, uniform and smooth texture but were amorphous in nature. These films remain amorphous even after postannealing at 300°C. On the other hand the films deposited at substrate temperature T S N 200°C were well textured and c-axis oriented with good crystalline properties. Moreover colour of the films changes from pale yellow to light brown to black corresponding to deposition at room temperature, 300°C and 500°C respectively. The investigation revealed that nanocrystalline V 2 O 5 films with preferred 001 orientation and with crystalline size of 17.67 nm can be grown with a layered structure onto amorphous glass substrates at temperature as low as 300°C. The photograph of V 2 O 5 films deposited at room temperature taken by scanning electron microscopy shows regular dot like features of nm size.
A new method for the determination of salbutamol has been developed using fullerene C 60-modified... more A new method for the determination of salbutamol has been developed using fullerene C 60-modified glassy carbon electrode and validated using GC-MS. The presence of graphite and metallic impurities in C 60 are found to diminish the peak. The oxidation of salbutamol was observed in a single well-defined, diffusion-controlled process using square wave voltammetry. The peak potential of oxidation peak was dependent on pH and determination was carried out at physiological pH 7.4. The peak current versus concentration plot was linear in the range 100-2000 ng/ml of salbutamol. The detection limit was found to be 40 ng/ml. The determination of salbutamol was carried out in human blood and urine samples and common interferents such as dopamine, ascorbic acid and uric acid do not interfere. The method proved to be specific, rapid, and accurate and can be easily applied for detecting cases of doping. A cross-validation of the observed results with GC-MS indicated a good agreement.
Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputteri... more Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputtering to improve the corrosion and mechanical properties of NiTi based shape memory alloys without sacrificing the phase transformation effect. Interestingly, the preferential orientation of the TiN films was observed to change from (1 1 1) to (2 0 0) with change in nature of sputtering gas from 70% Ar + 30% N 2 to 100% N 2. In present study the influence of crystallographic orientation of TiN on mechanical and corrosion properties of TiN/NiTi thin films was investigated. TiN (2 0 0)/NiTi films were found to exhibit high hardness, high elastic modulus, and thereby better wear resistance as compared to pure NiTi and TiN (1 1 1)/NiTi films. Electrochemical test revealed that TiN coated NiTi film exhibits better corrosion resistance in 1 M NaCl solution as compared to uncoated NiTi film. The application of TiN/NiTi films in the electrochemical sensing of dopamine, which has a critical physiological importance in Parkinson's disease, has been demonstrated. A comparison of voltammetric response of dopamine at silicon based electrodes modified with different nanocrystalline coatings indicated that these films catalyze the oxidation of dopamine.
Titanium oxide (TiO 2) nanocrystalline thin films have been grown on different substrates LaAlO 3... more Titanium oxide (TiO 2) nanocrystalline thin films have been grown on different substrates LaAlO 3 (0 0 1) and a-Al 2 O 3 (0 0 0 1) by dc magnetron sputtering in an Ar+O 2 gas mixture. Pure rutile or anatase or mixed (rutile and anatase) phase of TiO 2 can be grown at fixed sputtering pressure and substrate temperature on various substrates. XRD and TEM studies of the films deposited at fixed pressure of 2 Â 10 À2 Torr and substrate temperature of 650 1C revealed that preferred (0 0 4) oriented anatase phase was observed in case of films grown over LaAlO 3 substrates and rutile phase with preferred (2 0 0) orientation was observed in case of films deposited over the sapphire substrate. The results indicate that the film growth direction is highly affected with nature of substrate and substrate orientation. Further, AFM and FESEM images showed that nanostructured TiO 2 films could be grown on all substrates.
Nanocrystalline iron oxide thin films have been deposited on various substrates such as quartz, M... more Nanocrystalline iron oxide thin films have been deposited on various substrates such as quartz, MgO(100), and Si(100) by pulsed laser deposition technique using excimer KrF laser (248 nm). The orientations, crystallite size and lattice parameters were studied using X-ray diffraction. The XRD results show that the films deposited on MgO and Si substrates are highly oriented and show only (400) and (311) reflections respectively. On the other hand, the orientation of the films deposited on quarts substrate changed from (311) to (400) with an increase in the substrate temperature from 400 C to 600 C, indicating thereby that the film growth direction is highly affected with nature of substrate and substrate temperature. The surface morphology of the deposited films was studied using Atomic Force Microscopy (AFM) and spherical ball like regular features of nanometer size grains were obtained. The magnetic properties were studied by Superconducting Quantum Interference Device (SQUID) magnetometer in the magnetic field ±6 Tesla. The magnetic field dependent magnetization (M-H) curves of all the Fe 3 O 4 thin films measured at 5 K and 300 K show the ferrimagnetic nature. The electrochemical sensing of dopamine studied for these films shows that the film deposited on MgO substrate can be used as a sensing electrode.
ABSTRACT In the present study, Fe2O3 nanopowder has been grown by Ultrasonic mist chemical vapor ... more ABSTRACT In the present study, Fe2O3 nanopowder has been grown by Ultrasonic mist chemical vapor deposition (UM-CVD), which is a promising method for large area deposition at low temperatures taking in to account of its simplicity, inexpensiveness and safety. Room temperature XRD results revealed prominent hematite phase with intense (104) reflection and was also in agreement with the HR-TEM results. In situ high temperature X-ray diffraction (XRD) studies clearly indicated the change of phase from hematite to magnetite as the temperature increases above 300 °C. The surface morphology and particle size distribution of Fe2O3 nanopowder were characterized using field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HR-TEM), which revealed that the particles were spherical in nature and distributed in range of 50–100 nm. SQUID magnetometry results indicate the ferromagnetic nature of the nanopowder with crystallite size of 6 nm as calculated from M–H curve. Transmittance of approximately 55% and estimated direct band gap of 2.5 eV was observed. Further, the nanopowder was used to modify glassy carbon electrode (GCE) and the modified electrode was found to exhibit electrocatalytic activity for the oxidation of dopamine. It is expected that the nanopowder will exhibit promising applications in the development of sensors.
The electrochemical behavior of mometasone furoate (MF) has been studied at single-walled carbon ... more The electrochemical behavior of mometasone furoate (MF) has been studied at single-walled carbon nanotubes modified pyrolytic graphite electrode (MPG). Addition of cationic surfactant (cetyltrimethylammonium bromide, CTAB) was found to enhance the reduction current signal of MF, whereas, anionic (sodium dodecylsulfate, SDS) and non-ionic (Tween 60) surfactants exhibited opposite effect. A sensitive and selective electrochemical determination of mometasone furoate (MF) by square wave voltammetry and cyclic voltammetry in phosphate buffer of pH 7.2 has been carried out in the presence of CTAB. The cathodic peak current showed a linear response for MF reduction in the concentration range 10-1000 lM and using an electrode with effective surface area 0.225 cm 2 , a sensitivity and detection limit of 0.017 lA/ lM and 1.23 lM, respectively were observed. The reduction site in MF was established by the separation and characterization of the product of reduction by 1 H NMR and FT-IR spectroscopic measurements and found to be carbonyl group at position 3. The developed method was successfully applied for the determination of MF in pharmaceutical preparations and in human urine.
In this paper, we report the preparation and characterization of both the ZnO nanocrystalline thi... more In this paper, we report the preparation and characterization of both the ZnO nanocrystalline thin films and nanopowder by ultrasonic spray pyrolysis technique. ZnO films were grown on polished Si(1 0 0) and amorphous glass substrates at different deposition temperature range varying from 200 to 500 1C. Both orientation and the size of the crystallites were found to depend on the substrate and substrate temperature. XRD patterns of the films deposited on glass show strong c-axis oriented crystal structure with preferred (0 0 2) orientation, while those deposited on Si show predominant (1 0 0) orientation. Field emission scanning electron microscopy (FESEM) further confirms the a-and b-axis orientation in ZnO films on Si substrate with hexagonal columnar like grains and c-axis orientation in case of glass substrate with grains perpendicular to the substrate. The morphology and crystallite size of the ZnO nanopowder characterized by FESEM and TEM revealed that the powder consisted of the mixture of nanoparticles with particle size of 50-100 nm. The XRD results indicated that the synthesized ZnO powder had the pure wurtzite structure with lattice parameters a and c of 3.244 and 5.297 nm, respectively. High-temperature XRD studies of ZnO nanopowder showed that the crystallite size increased with increasing temperature with a systematic shift in peak positions towards lower 2y values due to change in lattice parameters. Temperature dependence of the lattice constants shows linear increase in their values. Diffraction patterns of ZnO nanopowder obtained from TEM were also in agreement with the XRD results. The synthesized powder exhibited the estimated direct band gap (E g) of 3.43 eV.
Ultrasonic spray pyrolysis technique has been used to deposit both in situ and ex situ high tempe... more Ultrasonic spray pyrolysis technique has been used to deposit both in situ and ex situ high temperature superconducting films (HTSC) of Y 1 Ba 2 Cu 3 O x (YBCO) and Bi 2 Sr 2 CaCu 2 O x (BSCCO) compounds over various substrates. Nitrate precursor solutions are used to deposit films of $10 lm thickness. Both low temperature spray with substrate temperature T s < 500°C and high temperature deposition with T s = 550-900°C are carried out. Superconducting properties of these films are observed to vary with various parameters such as concentration of spray solution, deposition temperature and nature of substrate and annealing process. Best quality films show T c (R = 0) of 89 K and J c of $4 • 10 4 A/cm 2 at 77 K and $ 10 5 A/cm 2 at 20 K. X-ray diffraction pattern reveals that the films are textured along c-axis. Successful attempt has been made to deposit in situ superconducting films over polycrystalline Ag for coated conductor applications. Various deposition and annealing conditions are optimized to control the diffusion of Ag from substrate to film, which otherwise can segregate into the grain boundaries and make the films non-superconducting.
In this paper, we report on the synthesis and characterization of ZnO nanocrystalline powder grow... more In this paper, we report on the synthesis and characterization of ZnO nanocrystalline powder grown by ultrasonic mist-chemical vapour deposition (UM-CVD) which is a promising method for large-area deposition at low temperatures taking into account of its simplicity, inexpensiveness and safety. The morphology and crystallite size of the ZnO nanopowder characterized by FESEM and TEM revealed that the powder consisted of the mixture of nanoparticles with particle size of 50-100 nm. The XRD results indicated that the synthesized ZnO powder had the pure wurtzite structure with lattice parameters a and c of 3.244 and 5.297 nm, and c/a ratio of 1.6, respectively. High temperature XRD studies of ZnO nanopowder showed that the crystallite size increased with increasing temperature with a systematic shift in peak positions towards lower 2h values due to change in lattice parameters. Temperature dependence of the lattice constants shows linear increase in their values. Diffraction patterns of ZnO nanopowder obtained from TEM were also in agreement with the XRD results. The synthesized powder exhibited the estimated direct band gap (E g) of 3.43 eV. The optical band gap calculated from Tauc's relation and the band gap calculated from the particle size inferred from XRD were in agreement with each other.
The Open Chemical and Biomedical Methods Journal, 2010
Synthesis of TiO 2 nanopowder via a low cost ultrasonic spray pyrolysis technique is reported and... more Synthesis of TiO 2 nanopowder via a low cost ultrasonic spray pyrolysis technique is reported and the nanopowder is used for the surface modification of glassy carbon electrode. The structural characterization of nanopowder by high temperature XRD clearly shows the phase transformation from anatase to rutile phase on increasing temperature. The morphological structure is characterized by field emission scanning electron microscope and high resolution transmission electron microscope. The modified electrode is used for the determination of dopamine in the presence of excess of ascorbic acid/ uric acid using square-wave voltammetry. The voltammograms obtained during the oxidation studies revealed that nano TiO 2 exhibits better catalytic function towards the oxidation of dopamine and ascorbic acid/uric acid. The overlapping voltammetric response of all the biomolecules at the bare electrode gets resolved into well defined voltammetric peaks with lowered oxidation potential and enhanced oxidation currents. Linear calibration curves for dopamine are obtained over the concentration range 75 nM-2.5 μM in 0.1M phosphate buffer solution at pH 7.2 with a correlation coefficient of 0.9940 and the detection limit (3) is estimated to be 13.8 nM.
We report the structural and optical properties of nanocrystalline thin films of vanadium oxide p... more We report the structural and optical properties of nanocrystalline thin films of vanadium oxide prepared via evaporation technique on amorphous glass substrates. The crystallinity of the films was studied using X-ray diffraction and surface morphology of the films was studied using scanning electron microscopy and atomic force microscopy. Deposition temperature was found to have a great impact on the optical and structural properties of these films. The films deposited at room temperature show homogeneous, uniform and smooth texture but were amorphous in nature. These films remain amorphous even after postannealing at 300°C. On the other hand the films deposited at substrate temperature T S N 200°C were well textured and c-axis oriented with good crystalline properties. Moreover colour of the films changes from pale yellow to light brown to black corresponding to deposition at room temperature, 300°C and 500°C respectively. The investigation revealed that nanocrystalline V 2 O 5 films with preferred 001 orientation and with crystalline size of 17.67 nm can be grown with a layered structure onto amorphous glass substrates at temperature as low as 300°C. The photograph of V 2 O 5 films deposited at room temperature taken by scanning electron microscopy shows regular dot like features of nm size.
A new method for the determination of salbutamol has been developed using fullerene C 60-modified... more A new method for the determination of salbutamol has been developed using fullerene C 60-modified glassy carbon electrode and validated using GC-MS. The presence of graphite and metallic impurities in C 60 are found to diminish the peak. The oxidation of salbutamol was observed in a single well-defined, diffusion-controlled process using square wave voltammetry. The peak potential of oxidation peak was dependent on pH and determination was carried out at physiological pH 7.4. The peak current versus concentration plot was linear in the range 100-2000 ng/ml of salbutamol. The detection limit was found to be 40 ng/ml. The determination of salbutamol was carried out in human blood and urine samples and common interferents such as dopamine, ascorbic acid and uric acid do not interfere. The method proved to be specific, rapid, and accurate and can be easily applied for detecting cases of doping. A cross-validation of the observed results with GC-MS indicated a good agreement.
Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputteri... more Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputtering to improve the corrosion and mechanical properties of NiTi based shape memory alloys without sacrificing the phase transformation effect. Interestingly, the preferential orientation of the TiN films was observed to change from (1 1 1) to (2 0 0) with change in nature of sputtering gas from 70% Ar + 30% N 2 to 100% N 2. In present study the influence of crystallographic orientation of TiN on mechanical and corrosion properties of TiN/NiTi thin films was investigated. TiN (2 0 0)/NiTi films were found to exhibit high hardness, high elastic modulus, and thereby better wear resistance as compared to pure NiTi and TiN (1 1 1)/NiTi films. Electrochemical test revealed that TiN coated NiTi film exhibits better corrosion resistance in 1 M NaCl solution as compared to uncoated NiTi film. The application of TiN/NiTi films in the electrochemical sensing of dopamine, which has a critical physiological importance in Parkinson's disease, has been demonstrated. A comparison of voltammetric response of dopamine at silicon based electrodes modified with different nanocrystalline coatings indicated that these films catalyze the oxidation of dopamine.
Titanium oxide (TiO 2) nanocrystalline thin films have been grown on different substrates LaAlO 3... more Titanium oxide (TiO 2) nanocrystalline thin films have been grown on different substrates LaAlO 3 (0 0 1) and a-Al 2 O 3 (0 0 0 1) by dc magnetron sputtering in an Ar+O 2 gas mixture. Pure rutile or anatase or mixed (rutile and anatase) phase of TiO 2 can be grown at fixed sputtering pressure and substrate temperature on various substrates. XRD and TEM studies of the films deposited at fixed pressure of 2 Â 10 À2 Torr and substrate temperature of 650 1C revealed that preferred (0 0 4) oriented anatase phase was observed in case of films grown over LaAlO 3 substrates and rutile phase with preferred (2 0 0) orientation was observed in case of films deposited over the sapphire substrate. The results indicate that the film growth direction is highly affected with nature of substrate and substrate orientation. Further, AFM and FESEM images showed that nanostructured TiO 2 films could be grown on all substrates.
Nanocrystalline iron oxide thin films have been deposited on various substrates such as quartz, M... more Nanocrystalline iron oxide thin films have been deposited on various substrates such as quartz, MgO(100), and Si(100) by pulsed laser deposition technique using excimer KrF laser (248 nm). The orientations, crystallite size and lattice parameters were studied using X-ray diffraction. The XRD results show that the films deposited on MgO and Si substrates are highly oriented and show only (400) and (311) reflections respectively. On the other hand, the orientation of the films deposited on quarts substrate changed from (311) to (400) with an increase in the substrate temperature from 400 C to 600 C, indicating thereby that the film growth direction is highly affected with nature of substrate and substrate temperature. The surface morphology of the deposited films was studied using Atomic Force Microscopy (AFM) and spherical ball like regular features of nanometer size grains were obtained. The magnetic properties were studied by Superconducting Quantum Interference Device (SQUID) magnetometer in the magnetic field ±6 Tesla. The magnetic field dependent magnetization (M-H) curves of all the Fe 3 O 4 thin films measured at 5 K and 300 K show the ferrimagnetic nature. The electrochemical sensing of dopamine studied for these films shows that the film deposited on MgO substrate can be used as a sensing electrode.
ABSTRACT In the present study, Fe2O3 nanopowder has been grown by Ultrasonic mist chemical vapor ... more ABSTRACT In the present study, Fe2O3 nanopowder has been grown by Ultrasonic mist chemical vapor deposition (UM-CVD), which is a promising method for large area deposition at low temperatures taking in to account of its simplicity, inexpensiveness and safety. Room temperature XRD results revealed prominent hematite phase with intense (104) reflection and was also in agreement with the HR-TEM results. In situ high temperature X-ray diffraction (XRD) studies clearly indicated the change of phase from hematite to magnetite as the temperature increases above 300 °C. The surface morphology and particle size distribution of Fe2O3 nanopowder were characterized using field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HR-TEM), which revealed that the particles were spherical in nature and distributed in range of 50–100 nm. SQUID magnetometry results indicate the ferromagnetic nature of the nanopowder with crystallite size of 6 nm as calculated from M–H curve. Transmittance of approximately 55% and estimated direct band gap of 2.5 eV was observed. Further, the nanopowder was used to modify glassy carbon electrode (GCE) and the modified electrode was found to exhibit electrocatalytic activity for the oxidation of dopamine. It is expected that the nanopowder will exhibit promising applications in the development of sensors.
The electrochemical behavior of mometasone furoate (MF) has been studied at single-walled carbon ... more The electrochemical behavior of mometasone furoate (MF) has been studied at single-walled carbon nanotubes modified pyrolytic graphite electrode (MPG). Addition of cationic surfactant (cetyltrimethylammonium bromide, CTAB) was found to enhance the reduction current signal of MF, whereas, anionic (sodium dodecylsulfate, SDS) and non-ionic (Tween 60) surfactants exhibited opposite effect. A sensitive and selective electrochemical determination of mometasone furoate (MF) by square wave voltammetry and cyclic voltammetry in phosphate buffer of pH 7.2 has been carried out in the presence of CTAB. The cathodic peak current showed a linear response for MF reduction in the concentration range 10-1000 lM and using an electrode with effective surface area 0.225 cm 2 , a sensitivity and detection limit of 0.017 lA/ lM and 1.23 lM, respectively were observed. The reduction site in MF was established by the separation and characterization of the product of reduction by 1 H NMR and FT-IR spectroscopic measurements and found to be carbonyl group at position 3. The developed method was successfully applied for the determination of MF in pharmaceutical preparations and in human urine.
In this paper, we report the preparation and characterization of both the ZnO nanocrystalline thi... more In this paper, we report the preparation and characterization of both the ZnO nanocrystalline thin films and nanopowder by ultrasonic spray pyrolysis technique. ZnO films were grown on polished Si(1 0 0) and amorphous glass substrates at different deposition temperature range varying from 200 to 500 1C. Both orientation and the size of the crystallites were found to depend on the substrate and substrate temperature. XRD patterns of the films deposited on glass show strong c-axis oriented crystal structure with preferred (0 0 2) orientation, while those deposited on Si show predominant (1 0 0) orientation. Field emission scanning electron microscopy (FESEM) further confirms the a-and b-axis orientation in ZnO films on Si substrate with hexagonal columnar like grains and c-axis orientation in case of glass substrate with grains perpendicular to the substrate. The morphology and crystallite size of the ZnO nanopowder characterized by FESEM and TEM revealed that the powder consisted of the mixture of nanoparticles with particle size of 50-100 nm. The XRD results indicated that the synthesized ZnO powder had the pure wurtzite structure with lattice parameters a and c of 3.244 and 5.297 nm, respectively. High-temperature XRD studies of ZnO nanopowder showed that the crystallite size increased with increasing temperature with a systematic shift in peak positions towards lower 2y values due to change in lattice parameters. Temperature dependence of the lattice constants shows linear increase in their values. Diffraction patterns of ZnO nanopowder obtained from TEM were also in agreement with the XRD results. The synthesized powder exhibited the estimated direct band gap (E g) of 3.43 eV.
Ultrasonic spray pyrolysis technique has been used to deposit both in situ and ex situ high tempe... more Ultrasonic spray pyrolysis technique has been used to deposit both in situ and ex situ high temperature superconducting films (HTSC) of Y 1 Ba 2 Cu 3 O x (YBCO) and Bi 2 Sr 2 CaCu 2 O x (BSCCO) compounds over various substrates. Nitrate precursor solutions are used to deposit films of $10 lm thickness. Both low temperature spray with substrate temperature T s < 500°C and high temperature deposition with T s = 550-900°C are carried out. Superconducting properties of these films are observed to vary with various parameters such as concentration of spray solution, deposition temperature and nature of substrate and annealing process. Best quality films show T c (R = 0) of 89 K and J c of $4 • 10 4 A/cm 2 at 77 K and $ 10 5 A/cm 2 at 20 K. X-ray diffraction pattern reveals that the films are textured along c-axis. Successful attempt has been made to deposit in situ superconducting films over polycrystalline Ag for coated conductor applications. Various deposition and annealing conditions are optimized to control the diffusion of Ag from substrate to film, which otherwise can segregate into the grain boundaries and make the films non-superconducting.
In this paper, we report on the synthesis and characterization of ZnO nanocrystalline powder grow... more In this paper, we report on the synthesis and characterization of ZnO nanocrystalline powder grown by ultrasonic mist-chemical vapour deposition (UM-CVD) which is a promising method for large-area deposition at low temperatures taking into account of its simplicity, inexpensiveness and safety. The morphology and crystallite size of the ZnO nanopowder characterized by FESEM and TEM revealed that the powder consisted of the mixture of nanoparticles with particle size of 50-100 nm. The XRD results indicated that the synthesized ZnO powder had the pure wurtzite structure with lattice parameters a and c of 3.244 and 5.297 nm, and c/a ratio of 1.6, respectively. High temperature XRD studies of ZnO nanopowder showed that the crystallite size increased with increasing temperature with a systematic shift in peak positions towards lower 2h values due to change in lattice parameters. Temperature dependence of the lattice constants shows linear increase in their values. Diffraction patterns of ZnO nanopowder obtained from TEM were also in agreement with the XRD results. The synthesized powder exhibited the estimated direct band gap (E g) of 3.43 eV. The optical band gap calculated from Tauc's relation and the band gap calculated from the particle size inferred from XRD were in agreement with each other.
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Papers by Davinder Kaur