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High oil sorption, dynamic oil/water selectivity and oil retention are essential for advanced materials to remediate offshore oil spills. In this context, superoleophilic-hydrophobic kapok bundles, synthesized via a simple, one-step and energy efficient carbonization (300°C), were investigated as effective oil sorbents. It was shown that the surface roughness and intrinsic graphite phase of the kapok bundles were tunable by varying the carbonization temperature, thereby enhancing their oil sorption and retention. Lumen preservation enables the carbonaceous kapok bundles to exhibit tunable oil sorption capacities of 34.0 g/g – 95.5 g/g for various types of oil, unrivaled among other oil spill recovery methods. The origin of oil permeability into lumen is attributed to nanopores observed for the first time on the carbonaceous kapok fibers. The kapok bundles selectively absorbed oil slick under vigorous water vortex and demonstrated distinctly high oil retention of 100% under gravitation force. Multiple oil sorption-desorption and compression cycles (up to 15 times) demonstrate a considerable promise of the carbonaceous kapok bundles for high reusability with low environmental impact.

High oil sorption, dynamic oil/water selectivity and oil retention are essential for advanced materials to remediate offshore oil spills. In this context, superoleophilic-hydrophobic kapok bundles, synthesized via a simple, one-step and energy efficient carbonization (300°C), were investigated as effective oil sorbents. It was shown that the surface roughness and intrinsic graphite phase of the kapok bundles were tunable by varying the carbonization temperature, thereby enhancing their oil sorption and retention. Lumen preservation enables the carbonaceous kapok bundles to exhibit tunable oil sorption capacities of 34.0 g/g – 95.5 g/g for various types of oil, unrivaled among other oil spill recovery methods. The origin of oil permeability into lumen is attributed to nanopores observed for the first time on the carbonaceous kapok fibers. The kapok bundles selectively absorbed oil slick under vigorous water vortex and demonstrated distinctly high oil retention of 100% under gravitation force. Multiple oil sorption-desorption and compression cycles (up to 15 times) demonstrate a considerable promise of the carbonaceous kapok bundles for high reusability with low environmental impact.

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.

Green nanoparticles are receiving great attention due to their broad fields of application. Plant extracts are promising sources, since the synergizing process is easy and cost-effective. Green synergism offers safer nanomaterials for both human health and the environment. The antimicrobial application of prepared nanoparticles is due to special capabilities at the nanoscale size. Green zinc oxide nanoparticles (ZnONPs) from lemongrass and turmeric revealed good antibacterial properties. Antibacterial active compounds were extracted from lemongrass and turmeric using methanol as a solvent. The extracts were introduced to zinc oxide solution to create synergized green ZnONPs and tested for their antibacterial properties. The samples were characterized by means of XRD, SEM, FTIR, and GC-MS. The zones of inhibition of synergized green ZnONPs were successfully measured using the disc diffusion method. The findings using gram-negative bacteria Escherichia coli. showed a higher antibacterial inhibition zone, with a diameter of 1.6 cm. The gram-positive bacteria, Staphylococcus aureus., showed low antibacterial inhibition. The addition of ZnO had positively revealed greater inhibition. Green ZnONPs synthesized using plant extracts will be further tested for various applications.

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.

Green nanoparticles are receiving great attention due to their broad fields of application. Plant extracts are promising sources, since the synergizing process is easy and cost-effective. Green synergism offers safer nanomaterials for both human health and the environment. The antimicrobial application of prepared nanoparticles is due to special capabilities at the nanoscale size. Green zinc oxide nanoparticles (ZnONPs) from lemongrass and turmeric revealed good antibacterial properties. Antibacterial active compounds were extracted from lemongrass and turmeric using methanol as a solvent. The extracts were introduced to zinc oxide solution to create synergized green ZnONPs and tested for their antibacterial properties. The samples were characterized by means of XRD, SEM, FTIR, and GC-MS. The zones of inhibition of synergized green ZnONPs were successfully measured using the disc diffusion method. The findings using gram-negative bacteria Escherichia coli. showed a higher antibacterial inhibition zone, with a diameter of 1.6 cm. The gram-positive bacteria, Staphylococcus aureus., showed low antibacterial inhibition. The addition of ZnO had positively revealed greater inhibition. Green ZnONPs synthesized using plant extracts will be further tested for various applications.

This study aims to fabricate low-cost foam glass-ceramic using soda-lime-silica (SLS) glass waste and clamshells (CS) as foaming agent in content between 1 and 12 wt.% by conventional powder processing method. The samples were undergoing sintering process between 700 and 1000 °C with holding time of 30 minutes and characterized according to the physical and structural properties. Samples containing 3 wt.% CS treated at 800 °C show the greatest size of porosity. As the sintering temperature increased, the samples tend to become less dense. However, for the samples sintered at 900 and 1000 °C, the trend of the density changes because of the excess CO2 gases generated during the heat treatment process promotes an increase in internal pressure, which results in the rupture of the pore walls. For linear expansion, for samples with a sintering temperature of 800 °C and higher, the increment of the temperature will lead to the decrement of linear expansion (%). As the sintering temperature increases from 700 to 800 °C, the water absorption (%) increases. However, the percentage of water absorption decreases with the further increment of sintering temperature. The XRD characterization showed the formation of wollastonite phase (CaSiO3) and further revealed the formation of greater peaks of CaSiO3 at the higher sintering temperatures. The results of compressive mechanical strength between 0.15 and 1.50 MPa indicate that the obtained glass-ceramic foams have potential for building material applications.

This study aims to fabricate low-cost foam glass-ceramic using soda-lime-silica (SLS) glass waste and clamshells (CS) as foaming agent in content between 1 and 12 wt.% by conventional powder processing method. The samples were undergoing sintering process between 700 and 1000 °C with holding time of 30 minutes and characterized according to the physical and structural properties. Samples containing 3 wt.% CS treated at 800 °C show the greatest size of porosity. As the sintering temperature increased, the samples tend to become less dense. However, for the samples sintered at 900 and 1000 °C, the trend of the density changes because of the excess CO2 gases generated during the heat treatment process promotes an increase in internal pressure, which results in the rupture of the pore walls. For linear expansion, for samples with a sintering temperature of 800 °C and higher, the increment of the temperature will lead to the decrement of linear expansion (%). As the sintering temperature increases from 700 to 800 °C, the water absorption (%) increases. However, the percentage of water absorption decreases with the further increment of sintering temperature. The XRD characterization showed the formation of wollastonite phase (CaSiO3) and further revealed the formation of greater peaks of CaSiO3 at the higher sintering temperatures. The results of compressive mechanical strength between 0.15 and 1.50 MPa indicate that the obtained glass-ceramic foams have potential for building material applications.

It is necessary to investigate the electronic states of ceramic based ZnO vasristor and effect of doped impurities at different concentration. Band gap (Eg) of the ceramic (99-x) mol% ZnO+0.5 mol% Bi2O3+0.5 mol% TiO2+ xCo3O4 where x = 0, 0.2, 0.4, 0.6 and 0.8 mol%, were determined using UV-Vis spectrophotometer. The samples were prepared via solid-state route and sintered at the sintering temperature at 1110, 1140 and 1170 °C for 45 and 90 min in open air. At no doping of Co3O4, the values of Eg are 2.991 ± 0.001, 2.989 ± 0.001 eV for 45 and 90 min sintering time; respectively. Eg was decreased to 2.368 ± 0.002 and 2.352 ± 0.001 eV at 0.8 mol% Co3O4 for 45 and 90 min sintering time; respectively. XRD analysis indicates that two main phases existed at all concentrations which are ZnO and secondary phases, Bi12TiO20, Zn2Ti3O8, ZnCo2O4 and Co3Ti3O. Relative density decreases with the addition of Co3O4 compared to that of undoped at all doping level. When Co3O4 is added in the ceramics, relative density increases with the increase of doping level at both 45 and 90 min sintering time. The variation of sintering temperatures and XRD findings of steepness factor are correlated with the UV-Vis spectrophotometer results of based ZnO varistor doped with Co3O4 due to the growth of interface states.

It is necessary to investigate the electronic states of ceramic based ZnO vasristor and effect of doped impurities at different concentration. Band gap (Eg) of the ceramic (99-x) mol% ZnO+0.5 mol% Bi2O3+0.5 mol% TiO2+ xCo3O4 where x = 0, 0.2, 0.4, 0.6 and 0.8 mol%, were determined using UV-Vis spectrophotometer. The samples were prepared via solid-state route and sintered at the sintering temperature at 1110, 1140 and 1170 °C for 45 and 90 min in open air. At no doping of Co3O4, the values of Eg are 2.991 ± 0.001, 2.989 ± 0.001 eV for 45 and 90 min sintering time; respectively. Eg was decreased to 2.368 ± 0.002 and 2.352 ± 0.001 eV at 0.8 mol% Co3O4 for 45 and 90 min sintering time; respectively. XRD analysis indicates that two main phases existed at all concentrations which are ZnO and secondary phases, Bi12TiO20, Zn2Ti3O8, ZnCo2O4 and Co3Ti3O. Relative density decreases with the addition of Co3O4 compared to that of undoped at all doping level. When Co3O4 is added in the ceramics, relative density increases with the increase of doping level at both 45 and 90 min sintering time. The variation of sintering temperatures and XRD findings of steepness factor are correlated with the UV-Vis spectrophotometer results of based ZnO varistor doped with Co3O4 due to the growth of interface states.

In this research, dye sensitized solar cell is fabricated by a combination of inorganic titanium dioxide nanoparticles sensitized by a locally available natural dye extract from organic Areca Catechu nut. This hybrid solar cells are fabricated accordingly by deposition of ITO/TiO2/P3HT/Areca Catechu/Au by using electrochemical method. The deposition rates of TiO2 are varied from 0.05, 0.07, 0.09 to 0.11 vs-1 whereas the number of scan of each layers are fixed to 5. The absorption spectra analysis is carried out in the wavelength range 200 to 600 nm, showed a wide and significant absorption spectrum in UV and visible regions. Analysis shows that scan rate affects the electrical conductivity of hybrid solar cell. The highest conductivity is recorded at 0.278 Scm-1 corresponding to the scan rate of 0.07 Vs-1at a potential value of 3.5 V.

Zinc oxide based varistor are widely used as circuit protective devices by literally absorbs these dangerous surge and spikes or grounding this unwanted magnitudes. In this research, zinc oxide is added with 20 mol% calcium manganite (CaMnO3) as an additive and Cobalt oxide (CoO) as doping material. Citrate-gel method is used as fabrication method compared to conventional solid-state method. This compound (ZnO-CaMnO3 -CoO) undergoes pre-sintering at 500 °C for 2 hours. In the sintering process, sintering temperature at 1300 °C, while the sintering time are setting at 1.5 hours. X-ray diffraction (XRD) patterns shows the components and phases of the compounds. The change of functional group was observed by Furrier transform infra-red (FTIR). I-V characteristic shows the value of nonlinear coefficient in the range of 1.0-2.0.

In this research, the effect of scan numbers of titania nanocrystals (TiO2 NCs) on the morphological and electrical characteristics of hybrid thin-films is investigated. These hybrid thin-films consist of a combination of organic (Piper Betle Linn extraction and Poly (3-hexytlthiophene) (P3HT)) and inorganic TiO2 NCs (anatase structure) materials. These hybrid thin-films are fabricated in bilayer heterojunction of ITO/TiO2 NCs/P3HT/Piper Betle Linn via electrochemistry method using Electrochemical Impedance Spectroscopy (EIS). The scan numbers of TiO2 NCs are varied by 1, 3 and 5 number of scans. The morphological characterization is carried out via Field Emission Scanning Electron Microscopy (FESEM) meanwhile the electrical characteristic of the hybrid thin-film is measured by using four point probes. FESEM image indicates the particle size was found to be around 17-34 nm. The increment of scan number of TiO2 NCs from one to five scan numbers of TiO2 NCs in bilayers thin films showed that the atomic percentage of titanium decrease from 5.23% to 2.20%. This result indicates that as the thickness of thin films increases, the electrons required more energy to excite into conduction band of TiO2. Meanwhile, the electrical conductivities of hybrid solar cell increase from 0.385 Scm-1 to 0.389 Scm-1 as the scan numbers of TiO2 increase from one to three, however the electrical conductivity decrease to 0.346 Scm-1 at five scan numbers. As a conclusion, this study shows that the morphological and electrical properties of hybrid thin-films can be significantly affected by the scan number of TiO2 NCs.

The vulnerability of varistor ceramics to electrical degradation during operation not only affects their nonlinear properties but also leads to shortening of device’s lifetime by increasing the risk of failures including melting, fire or even explosions. In this study, ZnO-Pr6O11-Cr2O3 varistor ceramics were prepared through modified citrate gel method and solid state-sintering at 1250 °C for 1 hour. The stability of their nonlinear properties under prolonged application of DC electrical field in high temperature ambient was investigated. Degradation process was accelerated by applying direct current (DC) electrical field of 15 % below the breakdown field point of ceramics for 54 hours consecutively at temperature of 30 to 125 °C. The findings indicate that ZnO-Pr6O11-Cr2O3 ceramics exhibited its susceptibility to electrical degradation after prolonged electrical and thermal stresses application. Its nonlinear coefficient has reduced by 4.4 % reduction, the breakdown field has reduced by 9.9 % and the leakage current density increased by 13.7 % in comparison to its initial value. Degradation process in varistor ceramics of ZnO-Pr6O11-Cr2O3 was a direct response to collapsed Double Schottky Barrier at ZnO grain boundary.

The AIP In this research, hybrid solar cell are produce by a combination of organic (Areca Catechu) extraction and Poly (3-hexylthiophene) (P3HT) and inorganic Titanium Dioxide, TiO2 materials. These hybrid solar cells are fabricated accordingly by layered of ITO/TiO2/P3HT/Areca Catechu/Au by using electrochemical method. The deposition of each layered by EIS was different by varied the scan rate of TiO2 deposition which are 0.05, 0.07, 0.09 and 0.11 vs-1 whereas the number of scans of each layers are fixed to 5 numbers of scans. Nanocrystals TiO2 (anatase structured) was prepared by dissolving the TiO2 nanoparticles with acetic acid which acts as capping agent in order to gain TiO2 nanostructures with better-controlled size and shape. Field Emission Scanning Electron Microscope (FESEM) images indicates that the TiO2 nanoparticles size was found to be around 15-34 nm. The XRD patterns indicate that the TiO2 film was highly crystalline and the anatase structure of TiO2 remains unchanged after annealed process took place at 450 °C. Sheet resistivity of the ITO/TiO2/P3HT/Areca Catechu/Au hybrid solar cell are measured in the dark and under different light intensity by using four point probes and power conversion efficiency are measured by using two point probes. In conclusion, the ITO/TiO2/P3HT/Areca Catechu/Au hybrid solar cell with 0.07 v s-1 scan rate produced the highest electrical conductivity and efficiency with 0.278 Scm-1 and 0.021 % respectively.

The vulnerability of varistor ceramics to electrical degradation during operation not only affects their nonlinear properties but also leads to shortening of device’s lifetime by increasing the risk of failures including melting, fire or even explosions. In this study, ZnO-Pr6O11-Cr2O3 varistor ceramics were prepared through modified citrate gel method and solid state-sintering at 1250 °C for 1 hour. The stability of their nonlinear properties under prolonged application of DC electrical field in high temperature ambient was investigated. Degradation process was accelerated by applying direct current (DC) electrical field of 15 % below the breakdown field point of ceramics for 54 hours consecutively at temperature of 30 to 125 °C. The findings indicate that ZnO-Pr6O11-Cr2O3 ceramics exhibited its susceptibility to electrical degradation after prolonged electrical and thermal stresses application. Its nonlinear coefficient has reduced by 4.4 % reduction, the breakdown field has reduced by 9.9 % and the leakage current density increased by 13.7 % in comparison to its initial value. Degradation process in varistor ceramics of ZnO-Pr6O11-Cr2O3 was a direct response to collapsed Double Schottky Barrier at ZnO grain boundary.

In this research, the effect of scan numbers of titania nanocrystals (TiO2 NCs) on the morphological and electrical characteristics of hybrid thin-films is investigated. These hybrid thin-films consist of a combination of organic (Piper Betle Linn extraction and Poly (3-hexytlthiophene) (P3HT)) and inorganic TiO2 NCs (anatase structure) materials. These hybrid thin-films are fabricated in bilayer heterojunction of ITO/TiO2 NCs/P3HT/Piper Betle Linn via electrochemistry method using Electrochemical Impedance Spectroscopy (EIS). The scan numbers of TiO2 NCs are varied by 1, 3 and 5 number of scans. The morphological characterization is carried out via Field Emission Scanning Electron Microscopy (FESEM) meanwhile the electrical characteristic of the hybrid thin-film is measured by using four point probes. FESEM image indicates the particle size was found to be around 17-34 nm. The increment of scan number of TiO2 NCs from one to five scan numbers of TiO2 NCs in bilayers thin films showed that the atomic percentage of titanium decrease from 5.23% to 2.20%. This result indicates that as the thickness of thin films increases, the electrons required more energy to excite into conduction band of TiO2. Meanwhile, the electrical conductivities of hybrid solar cell increase from 0.385 Scm-1 to 0.389 Scm-1 as the scan numbers of TiO2 increase from one to three, however the electrical conductivity decrease to 0.346 Scm-1 at five scan numbers. As a conclusion, this study shows that the morphological and electrical properties of hybrid thin-films can be significantly affected by the scan number of TiO2 NCs.

Zinc oxide based varistor are widely used as circuit protective devices by literally absorbs these dangerous surge and spikes or grounding this unwanted magnitudes. In this research, zinc oxide is added with 20 mol% calcium manganite (CaMnO3) as an additive and Cobalt oxide (CoO) as doping material. Citrate-gel method is used as fabrication method compared to conventional solid-state method. This compound (ZnO-CaMnO3 -CoO) undergoes pre-sintering at 500 °C for 2 hours. In the sintering process, sintering temperature at 1300 °C, while the sintering time are setting at 1.5 hours. X-ray diffraction (XRD) patterns shows the components and phases of the compounds. The change of functional group was observed by Furrier transform infra-red (FTIR). I-V characteristic shows the value of nonlinear coefficient in the range of 1.0-2.0.

In this research, dye sensitized solar cell is fabricated by a combination of inorganic titanium dioxide nanoparticles sensitized by a locally available natural dye extract from organic Areca Catechu nut. This hybrid solar cells are fabricated accordingly by deposition of ITO/TiO2/P3HT/Areca Catechu/Au by using electrochemical method. The deposition rates of TiO2 are varied from 0.05, 0.07, 0.09 to 0.11 vs-1 whereas the number of scan of each layers are fixed to 5. The absorption spectra analysis is carried out in the wavelength range 200 to 600 nm, showed a wide and significant absorption spectrum in UV and visible regions. Analysis shows that scan rate affects the electrical conductivity of hybrid solar cell. The highest conductivity is recorded at 0.278 Scm-1 corresponding to the scan rate of 0.07 Vs-1at a potential value of 3.5 V.

The AIP In this research, hybrid solar cell are produce by a combination of organic (Areca Catechu) extraction and Poly (3-hexylthiophene) (P3HT) and inorganic Titanium Dioxide, TiO2 materials. These hybrid solar cells are fabricated accordingly by layered of ITO/TiO2/P3HT/Areca Catechu/Au by using electrochemical method. The deposition of each layered by EIS was different by varied the scan rate of TiO2 deposition which are 0.05, 0.07, 0.09 and 0.11 vs-1 whereas the number of scans of each layers are fixed to 5 numbers of scans. Nanocrystals TiO2 (anatase structured) was prepared by dissolving the TiO2 nanoparticles with acetic acid which acts as capping agent in order to gain TiO2 nanostructures with better-controlled size and shape. Field Emission Scanning Electron Microscope (FESEM) images indicates that the TiO2 nanoparticles size was found to be around 15-34 nm. The XRD patterns indicate that the TiO2 film was highly crystalline and the anatase structure of TiO2 remains unchanged after annealed process took place at 450 °C. Sheet resistivity of the ITO/TiO2/P3HT/Areca Catechu/Au hybrid solar cell are measured in the dark and under different light intensity by using four point probes and power conversion efficiency are measured by using two point probes. In conclusion, the ITO/TiO2/P3HT/Areca Catechu/Au hybrid solar cell with 0.07 v s-1 scan rate produced the highest electrical conductivity and efficiency with 0.278 Scm-1 and 0.021 % respectively.

Binary zinc phosphate glass system with composition of (ZnO)x(P2O5)1−x, ( = 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mol%) was successfully prepared using a conventional melt-quenching method. Composition dependence of physical properties and elastic properties in the (ZnO)x(P2O5)1−x were discussed in association with the effects of adding zinc oxide (ZnO) as a modifier. The addition of ZnO modifier was expected to produce substantial changes on physical properties of the phosphate glasses. An increase in density values of the phosphate glasses was observed. Elastic moduli were studied by measuring ultrasonic longitudinal and shear velocities ( and ) of the glasses at room. Longitudinal modulus, shear modulus, bulk modulus, Young’s modulus, Poisson’s ratio, and Debye temperature were derived from both data of velocities and respective density of all of the samples. Findings from present work showed dependence of density and elastic moduli of each ZnO-P2O5 series on glass composition.

Binary zinc phosphate glass system with composition of (ZnO)x(P2O5)1−x, ( = 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mol%) was successfully prepared using a conventional melt-quenching method. Composition dependence of physical properties and elastic properties in the (ZnO)x(P2O5)1−x were discussed in association with the effects of adding zinc oxide (ZnO) as a modifier. The addition of ZnO modifier was expected to produce substantial changes on physical properties of the phosphate glasses. An increase in density values of the phosphate glasses was observed. Elastic moduli were studied by measuring ultrasonic longitudinal and shear velocities ( and ) of the glasses at room. Longitudinal modulus, shear modulus, bulk modulus, Young’s modulus, Poisson’s ratio, and Debye temperature were derived from both data of velocities and respective density of all of the samples. Findings from present work showed dependence of density and elastic moduli of each ZnO-P2O5 series on glass composition.

There were few reports of fabrication of varistor ceramics that used as a protective device for electrical equipments from transient voltage surges, using other method than conventional solid-state. Hence, it is useful to characterize in terms of morphology, electrical non-linearity characteristics, and optical properties of it prepared by using co-precipitation processing, as this produces fine and homogenous powder, as well as conventional solid-state route. The objectives of the study are; to prepare four systems of ZnO based varistor ceramics through conventional solid-state route and co-precipitation technique to determine which factors affect most on electrical non-linearity behavior; secondly to carry out optical study of four systems of ZnO based varistor ceramics obtain from conventional solid-state route and co-precipitation technique to elucidate the structure arrangement; and thirdly to investigate the degradation behavior of one system of ZnO based varistor ceramics (ZnO-Bi2O3-TiO2) to ascertain which preparation technique produce most stable electrical non-linearity coefficient. For the methodology, the prepared samples from co-precipitation and solid-state route were examined with EDX microanalysis for chemical and physical examinations, SEM and FESEM for morphological examinations, XRD and optical microscopy for crystallographic examinations, UV-visible spectroscopy for optical band gap measurements and structure arrangement observation, and the I-V measurements for non-linearity characteristic. The selected samples were subjected simultaneously to stresses of specific temperature, and DC voltage over certain duration to study the degree of degradation. In this study, with the use of different additives, secondary phases are developed and coexisted in the varistor ceramics that are Bi4Ti3O12, Zn2TiO4, and Zn7Sb2O12 as a grain inhibitor and segregated at the grain boundaries and the triple point junctions. The development of these secondary phases inf

There were few reports of fabrication of varistor ceramics that used as a protective device for electrical equipments from transient voltage surges, using other method than conventional solid-state. Hence, it is useful to characterize in terms of morphology, electrical non-linearity characteristics, and optical properties of it prepared by using co-precipitation processing, as this produces fine and homogenous powder, as well as conventional solid-state route. The objectives of the study are; to prepare four systems of ZnO based varistor ceramics through conventional solid-state route and co-precipitation technique to determine which factors affect most on electrical non-linearity behavior; secondly to carry out optical study of four systems of ZnO based varistor ceramics obtain from conventional solid-state route and co-precipitation technique to elucidate the structure arrangement; and thirdly to investigate the degradation behavior of one system of ZnO based varistor ceramics (ZnO-Bi2O3-TiO2) to ascertain which preparation technique produce most stable electrical non-linearity coefficient. For the methodology, the prepared samples from co-precipitation and solid-state route were examined with EDX microanalysis for chemical and physical examinations, SEM and FESEM for morphological examinations, XRD and optical microscopy for crystallographic examinations, UV-visible spectroscopy for optical band gap measurements and structure arrangement observation, and the I-V measurements for non-linearity characteristic. The selected samples were subjected simultaneously to stresses of specific temperature, and DC voltage over certain duration to study the degree of degradation. In this study, with the use of different additives, secondary phases are developed and coexisted in the varistor ceramics that are Bi4Ti3O12, Zn2TiO4, and Zn7Sb2O12 as a grain inhibitor and segregated at the grain boundaries and the triple point junctions. The development of these secondary phases inf

High demands on low-voltage electronics have increased the need for zinc oxide (ZnO) varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synthesis mechanism for obtaining praseodymium oxide (Pr6O11) based ZnO varistor ceramics having breakdown voltages of 2.8 to 13.3 V/mm through employment of direct modified citrate gel coating technique. Precursor powder and its ceramics were examined by means of TG/DTG, FTIR, XRD and FESEM analyses. The electrical properties as a function of Pr6O11 addition were analyzed on the basis of I-V characteristic measurement. The breakdown voltage could be adjusted from 0.01 to 0.06 V per grain boundary by controlling the amount of Pr6O11 from 0.2 to 0.8 mol%, without alteration of the grain size. The non-linearity coefficient, α, varied from 3.0 to 3.5 and the barrier height ranged from 0.56 to 0.64 eV. Breakdown voltage and α lowering with increasing Pr6O11 content were associated to reduction in the barrier height caused by variation in O vacancies at grain boundary.

This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS) glass combined with zinc oxide (ZnO) that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible) region were recorded at room temperature. The results show that the densities of the glass samples increased as the ZnO weight percentage increased. The molar volume of the glasses shows the same trend as the density: the molar volume increased as the ZnO content increased. The optical band gaps were calculated from the absorption edge, and it was found that the optical band gap decreased from 3.20 to 2.32 eV as the ZnO concentration increased.

This manuscript reports on the physical properties and optical band gap of five samples of soda lime silicate (SLS) glass combined with zinc oxide (ZnO) that were prepared by a melting and quenching process. To understand the role of ZnO in this glass structure, the density, molar volume and optical band gaps were investigated. The density and absorption spectra in the Ultra-Violet-Visible (UV-Visible) region were recorded at room temperature. The results show that the densities of the glass samples increased as the ZnO weight percentage increased. The molar volume of the glasses shows the same trend as the density: the molar volume increased as the ZnO content increased. The optical band gaps were calculated from the absorption edge, and it was found that the optical band gap decreased from 3.20 to 2.32 eV as the ZnO concentration increased.

CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO2 + 0.4Co3O4 + xV2O5), x = 0–1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300–800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (Eg) was 2.11 eV for 0.3 mol% V2O5 at a sintering temperature of 1025 °C as determined from the plot (ρhυ)2 versus hυ. With a further increase in V2O5, the value of Eg was found to be 2.59 eV. Steepness factor ‘σA’ and ‘σB’, which characterize the slope of exponential optical absorption, is discussed with reference to the variation of Eg. XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.

Two different concentrations of CdCl 2 and (NH 2) 2CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD) technique. CdCl 2 (0.000312 M and 0.000625 M) was employed as a source of Cd 2+ while (NH 2) 2CS (0.00125 M and 0.000625 M) for S 2- at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl 2 (0.000312 M). Optical energy band gap (E g), Urbach energy (E u) and absorption coefficient (α) have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97%) was obtained for the air-annealed films at higher temperature at CdCl 2 (0.000312 M).

Characteristics of different Pr6O11 ceramic composites were studied using photopyroelectric spectroscopy. The amount of Pr6O11 in the composite was varied from 0.1 to 0.75 mol% at the sintering temperature of 1190 and 1270°C. It was found that optical energy band-gap (Eg) of the composite is reduced by increasing the amount of Pr6O11 in the composite at both sintering temperatures. However, the decrease in Eg was relatively less at a sintering temperature of 1270°C as compared to that of 1190°C. XRD analysis showed that all samples have two phases, that is ZnO and intergranular layers composed of Pr6O11 and few small peaks of Pr2O3. EDAX results further showed that the Pr6O11 and Pr2O3 were segregated in the grain boundaries. Maximum grain size of 5.85 μm and relative density of 94.5% were found in these ceramics at x = 0.1 and 0.5 mol%, respectively, for 1270°C sintering temperature.

Two different concentrations of CdCl 2 and (NH 2) 2CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD) technique. CdCl 2 (0.000312 M and 0.000625 M) was employed as a source of Cd 2+ while (NH 2) 2CS (0.00125 M and 0.000625 M) for S 2- at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl 2 (0.000312 M). Optical energy band gap (E g), Urbach energy (E u) and absorption coefficient (α) have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97%) was obtained for the air-annealed films at higher temperature at CdCl 2 (0.000312 M).

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO2 + 0.4Co3O4 + xV2O5), x = 0–1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300–800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (Eg) was 2.11 eV for 0.3 mol% V2O5 at a sintering temperature of 1025 °C as determined from the plot (ρhυ)2 versus hυ. With a further increase in V2O5, the value of Eg was found to be 2.59 eV. Steepness factor ‘σA’ and ‘σB’, which characterize the slope of exponential optical absorption, is discussed with reference to the variation of Eg. XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.

Thin and transparent films of doped cadmium sulfide (CdS) were obtained on commercial glass substrates by Chemical Bath Deposition (CBD) technique. The films were doped with low concentration of Sn, and annealed in air at 300 °C for 45 min. The morphological characterization of the films with different amounts of dopant was made using SEM and EDAX analysis. Optical properties of the films were evaluated by measuring transmittance using the UV-vis spectrophotometer. A comparison of the results revealed that lower concentration of Sn doping improves transmittance of CdS films and makes them suitable for application as window layer of CdTe/CIGS solar cells.

The optical band-gap energy (Eg) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. Eg of the ceramic ZnO + xBi2O3 + xTiO2, where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. Eg was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.

Thin and transparent films of doped cadmium sulfide (CdS) were obtained on commercial glass substrates by Chemical Bath Deposition (CBD) technique. The films were doped with low concentration of Sn, and annealed in air at 300 °C for 45 min. The morphological characterization of the films with different amounts of dopant was made using SEM and EDAX analysis. Optical properties of the films were evaluated by measuring transmittance using the UV-vis spectrophotometer. A comparison of the results revealed that lower concentration of Sn doping improves transmittance of CdS films and makes them suitable for application as window layer of CdTe/CIGS solar cells.

The optical band-gap energy (Eg) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. Eg of the ceramic ZnO + xBi2O3 + xTiO2, where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. Eg was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.

The CdCl2 and (NH2)2CS were used to prepare CdS thin films, to be deposited, on glass substrate by chemical bath deposition (CBD) technique employing CdCl2 (0.005 M) and NH2)2CS (0.01 M) as a source of Cd2+ and S2-, respectively at constant bath temperature 70 oC. The films were air-annealed at 200 to 360 oC for 1 hour. XRD analyses reveal that the films were cubic along with two feeble peaks of orthorhombic CdSO4 at the annealing temperature 320 and 360 oC. The crystallite size of the films was increased from 59.2 to 67 nm with the increase of annealing temperature. Optical energy band gap (Eg) and absorption coefficient (α) were chosen as parameters of characterization, calculated from the transmission spectral data and were discussed as function of annealing temperature.

The effects of ZnO on longitudinal and transverse ultrasonic wave velocities of soda lime silicate (SLS) glasses have been measured using the pulse-echo method at 5 MHz frequency at room temperature. The elastic properties: Longitudinal modulus, shear modulus, Young's modulus, bulk modulus, Poisson's ratio, and Debye temperature are found to be rather sensitive to the glass composition. Experiments showed that these parameters depend upon the ZnO-modifier content.

CdS films were deposited on glass substrate by chemical bath deposition (CBD) from a bath containing very low concentrations of CdCl2 and (NH2)2CS. The adhesion of the deposited films was very good for all solution concentrations. The films were thermally annealed in air at the temperature 240 °C for 1 hour. The maximum and minimum film thickness 75.6 nm, 33 nm was observed, respectively. XRD analyses show that the films were cubic along with few feeble peaks of hexagonal phase at lower solution concentrations. The crystallite size was increased from 17 to 51 nm with the increase of the solution concentration. The optical energy band gap (Eg), Urbach energy (Eoo) and absorption coefficient (a) was calculated from the transmission spectral data. The best transmission (> 94 %) was obtained in this experiment.

The effects of ZnO on longitudinal and transverse ultrasonic wave velocities of soda lime silicate (SLS) glasses have been measured using the pulse-echo method at 5 MHz frequency at room temperature. The elastic properties: Longitudinal modulus, shear modulus, Young's modulus, bulk modulus, Poisson's ratio, and Debye temperature are found to be rather sensitive to the glass composition. Experiments showed that these parameters depend upon the ZnO-modifier content.

CdS films were deposited on glass substrate by chemical bath deposition (CBD) from a bath containing very low concentrations of CdCl2 and (NH2)2CS. The adhesion of the deposited films was very good for all solution concentrations. The films were thermally annealed in air at the temperature 240 °C for 1 hour. The maximum and minimum film thickness 75.6 nm, 33 nm was observed, respectively. XRD analyses show that the films were cubic along with few feeble peaks of hexagonal phase at lower solution concentrations. The crystallite size was increased from 17 to 51 nm with the increase of the solution concentration. The optical energy band gap (Eg), Urbach energy (Eoo) and absorption coefficient (a) was calculated from the transmission spectral data. The best transmission (> 94 %) was obtained in this experiment.

Photopyroelectric (PPE) spectroscopy is a useful tool for examining optical properties in semiconductor materials. The ceramic (ZnO - xTiO₂) was sintered at 1270⁰C for 1 and 3 hours to investigate the variations of energy band-gap with respect to mol % of dopant TiO₂. The X-ray diffractrometry shows that the crystal structure of ZnO doped at low level remains to be of hexagonal type but has developed second phase, Zn₂TiO₄, at high level. Microstructure and compositional analysis of the selected areas are analyzed using SEM and EDAX. The maximum grain size obtained were 26.8, 52.4 µm at 0.4 mol % of TiO₂ for 1 and 3 hours sintering time, respectively. The band-gap determined from the photopyroelectric spectrum has the value of 2.82 ± 0.01 eV for samples sintered for 1 and 3 hours at the doping level of 0.4 mol % of TiO₂ and decreases with the increase of TiO₂.