Temperature and deposition time dependence of the geometrical properties of tin oxide nanostructures

Tin oxide nanomaterial was synthesized using the horizontal vapor phase growth (HVPG) technique. The study investigated the optimum growth parameters by varying the growth temperature from 900 C to 1200 C and growth time of 1 hour to 5 hours. The SnO2 bulk powder with purity rate of 99.99% were placed in a sealed quartz tube with a vacuum pressure of≈ 10-5 Torr and baked with the desired growth parameters. The resulting nanocrystals displayed different structures ranging from nanobelts to nanorods as confirmed by the SEM. Results from EDX and DTA showed that indeed the grown samples were congruent based on the atomic composition and thermal property of the nanomaterials. The XRD also verified that the crystal structure was rutile but with low indexed peaks. Using the same growth technique, samples were grown on Silicon (100) substrate and exhibited nanorods and nanobelts. The SnO2 nanomaterial also displayed fluorescence and photoluminescence signals. The photoluminescence spectrum has a broad emission in the visible region with peaks at 558 nm and 666 nm. The visible light emission was known to be related to defect levels within the band gap of SnO2, associated with O vacancies or Sn interstitials that have formed during the synthesis process

Bi2S3 nanowires fabricated via HVPC growth technique for photosensor application

Bi2S3 Nanowires was successfully fabricated using Horizontal Vapor Phase Crystal growth technique for photosensor application. A 35 mg of bismuth sulfide powder with purity rate of 99.9% was utilized. The growth temperature was varied at 600 oC to 1200 oC with growth time of 4 to 8 hours where the ramp time was set at 60 minutes. The as-prepared products were characterized using an SEM, EDX, and Applied Spectral Imaging. The optimum growth was at 1200 C deposited on zone 2 on a fused silica tube. The energy band gap was 2.58 eV which has blue spectra. The nanowires demonstrated its functionality as photosensor in a metalsemiconductor-metal planar structure based on the voltage time spectra obtained

Mapping DLSU\u27s microclimates

A microclimate is a local atmospheric zone where the climate differs from its surrounding area. This may refer to areas as small as a few square meters like a garden bed or as large as many square meters like the De La Salle University campus in Taft Avenue, Metro Manila.This paper presents the different microclimates that can be found in the DLSU campus. Various data readings such as air temperature, wind speed, relative humidity, and barometric pressure, are taken at six (6)different areas. Also, GPS position coordinates are recorded at every location. Using MyWorld GIS, the data are mapped showing the various data readings

Catalyst-free synthesis of zinc oxide (ZnO) nanostructures through the horizontal vapor phase crystal growth

Zinc oxide nanomaterials were grown on quartz through noncatalytic horizontal vapor phase crystal growth from 600°C to 1200°C. The growth time was also varied between two to eight hours in two-hour increments while the ramp time was synchronized from 20 to 80 minutes. Scanning electron microscopy revealed that nanowires with lengths of a few microns and width of 40-130 nm were synthesized at lower temperatures and nanoblades of width 200 nm are formed at higher temperatures. Slow ramping rate was found to yield nanostructures that have smaller widths while less unreacted ZnO powder were observed at higher temperature and longer growth time

An investigation on the effects of growth temperature, growth time and ramping rate on the structure of zinc oxide (ZnO) nanomaterials synthesized through horizontal vapor phase crystal growth

Zinc Oxide (ZnO) nanomaterials were grown on glass substrate through the non-catalytic horizontal vapor phase crystal growth at temperature of 6000C, 8000C, 10000C, and 12000C. The growth time was varied from two to eight hours in two-hour increments while the ramp time was adjusted from 20 minutes (fast) to 80 minutes (slow). Scanning electron microscopy reveals that nanowires with lengths of a few microns and width of 40-130 nm are synthesized at lower temperatures and nanoblades of width 200 nm are formed at higher temperatures. Moreover, the length of the grown nanostructures increased from 5 to 10 microns as the growth time is increased from two to eight hours. Slow ramping rate was found to yield nanostructures that have smaller widths while less unreacted ZnO powder were observed at higher temperature and longer growth time

Non-catalytic synthesis of zinc oxide (ZnO) nanomaterials and their photoluminescence properties

Zinc Oxide nanomaterials were synthesized on glass substrate through the non-catalytic horizontal vapor phase growth method. Nanobells with average width of 200 nm were grown when the growth temperature was set at 12000C and 10000C. Nanowires with mean diameter of 100 nm were dominant at growth temperatures of 8000C and 6000C. Shorter growth time resulted in the formation of needle-like structures which are 2 micrometers in length. Increasing the growth time corresponded to the growth of nanowires with average length of 10 micrometers. XRD measurements showed that the synthesized nanostructures have a hexagonal wurtzite structure with growth preference in the (001), (101) and (10 1) directions. The room temperature photoluminescence spectra showed an intense ultraviolet emission (UV) at 3.26 eV with weak emissions in the visible light regime. The strong UV emission can be attributed to the recombination of free excitons though an exciton-exciton collision process. Meanwhile, the deep level emissions are caused by oxygen vacancies in ZnO and the emission results in the recombination of the photogenarated hole with an electron occupying the oxygen vacancy. It is proposed that growth mechanism involved in the formation of ZnO nanostructures is the vapor-solid process because no catalyst was used

Synthesis and characterization of Fe2O3 nanomaterials using HVPC growth technique for glucose sensing application

This study investigated the capability of the grown Iron Oxide nanoparticles (NPs) for faster glucose detection. Horizontal Vapor Phase Crystal (HVPC) Growth Technique was utilized in the synthesis of Iron Oxide NPs from 99.99% purity Magnetite–Iron Oxide (Sigma-Aldrich) bulk material. Different parameters were varied such as the growth environment (without external magnetic field, with external magnetic field), size of the sealed tube (10cm, 12cm, 14cm), growth temperature (1000 C, 1100 C, 1200 C) and dwell time (8hr, 9 hr, 10 hr). Scanning electron Microscope (SEM) and Energy Dispersive X-ray (EDX) confirmed that the Iron Oxide nanowires and almost uniform size nanoparticles approximately 50nm in diameter were formed utilizing the optimum parameters such as 1000 C growth temperature, 8 hours dwell time, 12 cm size of sealed tube and the presence of external magnetic field in the growth environment. The application of the external magnetic field enhanced the Superparamagnetic (SPM) property of the grown Iron Oxide NPs above the Curie temperature. The net magnetic moment determined the direction of magnetic force of attraction present in the grown NPs. Particles to particles-chain assembly were observed in which some NPs were interconnected forming nanowires/agglomerated nanowires in the vapor-solid phase nucleation. The magnetic field also lessened the effect of gravity which aligned the formation along the field. Glucose oxidase (GOx) and chitosan have been immobilized by physical adsorption onto electrode with Iron Oxide NPs. Amperometric–electrochemical circuit setup was used to determine the glucose sensing ability of the modified electrode with iron oxide NPs while varying some factors such as glucose concentration, applied DC potential and electrolyte solution. At α= 0.05, since F (27.52; 54.48)\u3e FC (3.29; 4.49), two-way ANOVA reveals that there was a significant difference between the current responses while varying the electrolytes for different modified electrodes. Among the modified electrodes, G/FeO/CH/GOx and SS/FeO/GOx showed highest sensitivity and longest limit of detection correspondingly. The correlation coefficients (ave. r= 0.74; 0.99) indicates that there was a linear relationship between the response current versus varying concentrations and applied DC potential. Iron Oxide NPs integrated in modified electrode in an amperometric-electrochemical circuit also showed low detection limit (0.008 mM), fast response time (\u3c 5s), usage repeatability (≈ 20 times) and longest detection limit range of 0.008 mM to 32mM. Based on the results, modified electrode with Iron Oxide NPs showed high surface reaction and catalytic activity, large surface-to-volume ratio and strong adsorption ability that are beneficial in the immobilization of glucose oxidase. The Iron Oxide NPs’ magnetic property was considered in the modification of the electrode for Amperometric-Electrochemical circuit for glucose sensing application since the magnetic field reinforces the attraction of the particles to the electrode’s surface

Growth mechanism of SnO2 nanomaterials derived from backscattered electron image and EDX observations

SnO2 nanomaterials were synthesized using the unseeded, non-catalytic horizontal vapor phase growth (HVPG) deposition. The sample was synthesized at a growth temperature of 1200oC and growth time of 6 hours. The resulting nanostructures ranges from nano- wires, nanorods to nanobelts as confirmed by JEOL JSM 5310-SEM. Backscattered electron image observations show that nanobelts has less intense brightness compared to nanorod and nanowire images. This suggests that the nanobelts are of lighter composition. Using energy dispersive X-ray (EDX) analysis, it was confirmed that the nanobelts are oxygen deficient, being made up of SnO while the nanorods and nanowires are made of the more common SnO2. From these findings, a growth mechanism was proposed detailing the transition of the SnO2 nanostructures from the powder SnO2 source material