The Resistivity-Temperature Property of Transition Metal Oxide Co3O4 with In2O3 Addition

2008 ◽  
Vol 569 ◽  
pp. 193-196 ◽  
Author(s):  
Sen Liang ◽  
Ji Qiang Gao ◽  
Jian Feng Yang ◽  
Min Luo
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Transition Metal ◽  
Metal Oxide ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Average Particle Size ◽  
Average Particle ◽  
Temperature Property ◽  
B Values

The electrical and structural properties of the mixture of Co3O4 and In2O3 were studied. All the samples were added with 2% nanocrystalline SiO2 and sintered at 1000°C for 2 hours. The sintered bodies of the samples were of high density and the average particle size was ~2μm. The materials showed the NTC behavior in a wide temperature range (100-350°C). The resistivity of the materials at room temperature decreased with increase the content of the In2O3 from 0% to 10%. The thermistor constant (B) values and activation energy(E) were 7835, 6637, 5903K, and 0.675, 0.572, and 0.509 eV as the content of In2O3 were 0%, 5% and 10%, respectively.

Nitrocellulose Catalyzed With Manganese Oxide Nanoparticles: Advanced Energetic Nanocomposite With Superior Decomposition Kinetics

2021 ◽  
Author(s):  
Sherif Elbasuney ◽  
M. Yehia ◽  
Shukri Ismael ◽  
Yasser El-Shaer ◽  
Ahmed Saleh
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Manganese Oxide ◽  
Energetic Materials ◽  
Average Particle Size ◽  
Active Surface ◽  
Propagation Rate ◽  
Hydroxyl Groups ◽  
Average Particle ◽  
Decomposition Enthalpy

Abstract Nanostructured energetic materials can fit with advanced energetic first-fire, and electric bridges (microchips). Manganese oxide, with active surface sites (negatively charged surface oxygen, and hydroxyl groups) can experience superior catalytic activity. Manganese oxide could boost decomposition enthalpy, ignitability, and propagation rate. Furthermore manganese oxide could induce vigorous thermite reaction with aluminium particles. Hot solid or liquid particles are desirable for first-fire compositions. This study reports on the facile fabrication of MnO2 nanoparticles of 10 nm average particle size; aluminium nanoplates of 100 nm average particle size were employed. Nitrocellulose (NC) was adopted as energetic polymeric binder. MnO2/Al particles were integrated into NC matrix via co-precipitation technique. Nanothermite particles offered an increase in NC decomposition enthalpy by 150 % using DSC; ignition temperature was decreased by 8 0C. Nanothemrite particles offered enhanced propagation index by 261 %. Kinetic study demonstrated that nanothermite particles experienced drastic decrease in NC activation energy by - 42, and - 40 KJ mol-1 using Kissinger and KAS models respectively. This study shaded the light on novel nanostructured energetic composition, with superior combustion enthalpy, propagation rate, and activation energy.

Minimum Particle Diameter of the Vanadium/Iron Co-Doped Nano TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 989-994 ◽  
pp. 611-614
Author(s):  
Ling Li ◽  
Wen Ming Zhang ◽  
Hua Yan Zhang ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Ferric Nitrate ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Vanadium Iron ◽  
Co Doped

Vanadium/iron co-doped nanoTiO2 transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, ferric nitrate, ammonium metavanadate, etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, EDS, nanolaser particle size analyzer, and UV-Vis spectrophotometer. The photocatalytic properties of V/Fe doped TiO2 were studied through degrading acid 3R dye, and the results show that when the content of V/Fe was 0.5%, the degradation rate reached more than 96% under irridation for 60 min.

scholarly journals Monodispersed ZnO Nanoparticles and Their Use in Heterojunction Solar Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Dinesh Patidar ◽  
Anusaiya Kaswan ◽  
N. S. Saxena ◽  
Kananbala Sharma
Keyword(s):  
Particle Size ◽  
Solar Cell ◽  
Ethylene Glycol ◽  
Zno Nanoparticles ◽  
Ultrasonic Treatment ◽  
Room Temperature ◽  
Power Conversion ◽  
Average Particle Size ◽  
Hexagonal Wurtzite Structure ◽  
Average Particle

Monodispersed ZnO nanoparticles have been synthesised in ethylene glycol medium using zinc acetate and sodium hydroxide at room temperature through ultrasonic treatment. The monodispersed ZnO nanoparticles were characterized by XRD, TEM, SEM, and optical spectroscopy. The results indicate that ZnO shows the hexagonal wurtzite structure having 8 nm average particle size with the band gap of 3.93 eV. ZnO nanoparticles blended with P3HT show the improvement in the interchains and intrachains ordering as compared to pure P3HT. The power conversion efficiency of P3HT/ZnO solar cell is found to be 0.88%, which is comparable with the result obtained by other researchers.

Development of Heterostructured Ferroelectric SrZrO3/CdS Photocatalysts with Enhanced Surface Area and Photocatalytic Activity

2020 ◽  
Vol 20 (6) ◽  
pp. 3770-3779 ◽  
Author(s):  
Umar Farooq ◽  
Farheen Naz ◽  
Ruby Phul ◽  
Nayeem Ahmad Pandit ◽  
Sapan Kumar Jain ◽  
...  
Keyword(s):  
Particle Size ◽  
Dielectric Constant ◽  
Photocatalytic Activity ◽  
Surface Area ◽  
Room Temperature ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Bet Surface Area ◽  
Cds Nanoparticles ◽  
Average Particle

This paper reports the attempt to develop an efficient heterostructure photocatalyst by employing SrZrO3 as ferroelectric substrate with deposited nanostructured CdS semiconductor on the surface. Primarily bare SrZrO3 and CdS nanoparticles were synthesized by using polymeric citrate precursor and co-precipitation routes, respectively. The chemical deposition technique was used to develop the CdS over the surface of the pre-synthesized SrZrO3 nanoparticles. The synthesized bare nanoparticles and their heterostructure were characterized by XRD which shows the formation of orthorhombic and face centred cubic (FCC) phases of SrZrO3 and CdS, respectively. TEM was used to estimate the morphology and particle size of as-synthesized nanoparticles, which shows the average particle size of 14, 24 and 25 nm for SrZrO3, CdS and SrZrO3/CdS, respectively. The BET surface area of SrZrO3, CdS and SrZrO3/CdS samples was found to be 299, 304 and 312 m2/g respectively. Methylene blue was used as model pollutant to determine the photocatalytic activity of the synthesized nanomaterials. The heterostructure shows an enhanced activity as compared to bare nanoparticles. Dielectric constant and dielectric loss of the nanoparticles was investigated as a function of frequency at room temperature and as a function of temperature at 500 kHz. The room temperature dielectric constant for SrZrO3, CdS and SrZrO3/CdS was found to be 13.2, 17.8 and 25.5 respectively at 100 kHz.

Differential Photosensor Activities for the L-Cysteine and L-Serine Capped ZnS:Mn Nanocrystals in the Detection of Divalent Transition Metal Ions in Aqueous Solution

2020 ◽  
Vol 20 (11) ◽  
pp. 6723-6731
Author(s):  
Mi Choi ◽  
Cheong-Soo Hwang
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Transition Metal ◽  
Metal Ions ◽  
Average Particle Size ◽  
Transition Metal Ions ◽  
Average Particle ◽  
Quenching Effect ◽  
Transmission Electron ◽  
Particle Size Analyzer

Colloidal ZnS:Mn nanocrystals (NCs) were synthesized in water by capping the NC surface with conventional amino acids: L-cysteine (Cys) and L-serine (Ser) molecules, which have very similar structures but different terminal functional groups. The optical properties were investigated by using UV-Visible and photoluminescence (PL) spectroscopy. The PL spectra for both ZnS:Mn-Cys and ZnS:Mn-Ser NCs showed broad emission peaks at 590 nm. The measured average particle size from the high-resolution transmission electron microscopy (HR-TEM) images were 4.38 nm (ZnS:Mn-Cys) and 5.57 nm (ZnS:Mn-Ser), which were also supported by Debye-Scherrer calculations. In addition, the surface charge of the NCs in aqueous solutions were measured using zeta-particle size analyzer spectroscopy, which showed formation of negatively charged surface for the ZnS:Mn-Cys (−43.93 mV) and ZnS:Mn-Ser (−8.21 mV) NCs in water. In this present study those negatively charged NCs were applied as photosensors for the detection of specific divalent transition metal cations in aqueous solution at the same condition. Consequently, the ZnS:Mn-Cys and ZnS:Mn-Ser NCs showed totally different photosensor activities upon the addition of first-row divalent transition metal ions. The former NCs showed luminescence quenching for most added metal ions except for Zn (II) ions; whereas the latter NCs showed exclusive quenching effect for Cu (II) ions at the same conditions. These results suggested that those NCs can be applied as Zn2+ and Cu2+ ion sensors in water.

scholarly journals Improving the CO and CH4 Gas Sensor Response at Room Temperature of α-Fe2O3(0001) Epitaxial Thin Films Grown on SrTiO3(111) Incorporating Au(111) Islands

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 848
Author(s):  
Aída Serrano ◽  
Jesús López-Sánchez ◽  
Iciar Arnay ◽  
Rosalía Cid ◽  
María Vila ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Gas Sensing ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Average Particle ◽  
Epitaxial Thin Films ◽  
Before And After ◽  
Crystallographic Axes ◽  
Gas Exposure

In this work, the functional character of complex α-Fe2O3(0001)/SrTiO3(111) and Au(111) islands/α-Fe2O3(0001)/SrTiO3(111) heterostructures has been proven as gas sensors at room temperature. Epitaxial Au islands and α-Fe2O3 thin film are grown by pulsed laser deposition on SrTiO3(111) substrates. Intrinsic parameters such as the composition, particle size and epitaxial character are investigated for their influence on the gas sensing response. Both Au and α-Fe2O3 layer show an island-type growth with an average particle size of 40 and 62 nm, respectively. The epitaxial and incommensurate growth is evidenced, confirming a rotation of 30° between the in-plane crystallographic axes of α-Fe2O3(0001) structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au(111) and those of α-Fe2O3(0001) structure. α-Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural characteristics are also preserved after Au deposition, with minor changes at short-range order. Conductance measurements of Au(111)/α-Fe2O3(0001)/SrTiO3(111) system show that the incorporation of epitaxial Au islands on top of the α-Fe2O3(0001) layer induces an enhancement of the gas-sensing activity of around 25% under CO and 35% under CH4 gas exposure, in comparison to a bare α-Fe2O3(0001) layer grown on SrTiO3(111) substrates. In addition, the response of the heterostructures to CO gas exposure is around 5–10% higher than to CH4 gas in each case.

Molten Salt Synthesis of Anisotropy BaBi4Ti4O15 Powders in K2SO4-Na2SO4 Flux

2011 ◽  
Vol 687 ◽  
pp. 333-338 ◽  
Author(s):  
Yong Jun Gu ◽  
Jin Liang Huang ◽  
Li Hua Li ◽  
Ke Zhang ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Molten Salt ◽  
Process Parameters ◽  
Average Particle Size ◽  
Particle Growth ◽  
Molten Salt Synthesis ◽  
Average Particle ◽  
Synthesis Conditions ◽  
Arrhenius Dependence

Anisotropic BaBi4Ti4O15 powder was synthesized by a molten salt synthesis (MSS) method in K2SO4-Na2SO4flux and the effects of different process parameters such as calcining temperature, and ratio of salt to reactant (R) on the phase formation and morphology of anisotropic BaBi4Ti4O15particles were also investigated. The as-synthesized powder calcined at 850-950°C exhibits a single tetragonal BaBi4Ti4O15phase. The morphology of BaBi4Ti4O15powder could be adjusted by changing the synthesis conditions. The average particle size (APS) of BaBi4Ti4O15powder increased with R changing from 0.8 to 1.0, while it decreased with further increasing of R to 1.2. In addition, the APS increased with increasing calcining temperature and it showed an Arrhenius dependence on the temperature. The corresponding apparent activation energy for particle growth is 31.9kJ/mol for calcining temperature of 850-1000°C.

Minimum Particle Diameter of the Sulfur-Doped Nano-TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 587-589 ◽  
pp. 788-791
Author(s):  
Ling Li ◽  
Hua Yan Zhang ◽  
Xiao Wei Li ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Photocatalytic Performance ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Synthesis Process ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Particle Size Analyzer

Sulfur-doped nanoTiO2transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, thiourea, organic carboxylic acid, NH3H2O, D-sorbitol etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, nanolaser particle size analyzer, ultraviolet-visible spectrophotometer. In addition, the influence of reaction conditions in the synthesis process was also studied. The results indicate that when nanoparticle doped with 0.5% S, and the reflux time was 15 min, the photocatalytic performance of sulfur-doped TiO2hydrosol was best.

Ultrafine TiO2 Powders Prepared from Aqueous TiCl4 Solutions at Room Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 2135-2138
Author(s):  
Hong Liang Yi ◽  
Jie Zhang ◽  
Ming Tu Ma ◽  
Hao Zhang ◽  
Bong Ho Lee ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Ph Value ◽  
Anatase Phase ◽  
Average Particle Size ◽  
Rutile Phase ◽  
Average Particle ◽  
Spectral Peaks ◽  
Scherrer Formula ◽  
Stock Solutions

Ultrafine TiO2 powders as rutile and anatase phase were simply precipitated at room temperature for only tens of hours by simply controlling the pH value and Ti4+ concentration via aqueous TiCl4 solution. Under the optimal pH value and Ti4+ concentration, the average particle size of powders with rutile phase was 3.7nm, while that of powders with anatase phase was 3.0nm. The average particle size was calculated from the broadening of corresponding X-ray spectral peaks by Scherrer formula. In addition, 3.0 mol.l-1 are suggested to be used as concentration of stock solutions instead of the current concentration 2.0 mol.l-1.

scholarly journals Preparation and Evaluation of Sunflower Oil Nanoemulsion As a Sunscreen

2019 ◽  
Vol 7 (22) ◽  
pp. 3757-3761
Author(s):  
Anayanti Arianto ◽  
Cindy Cindy
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Low Temperature ◽  
Sunflower Oil ◽  
Room Temperature ◽  
Ph Value ◽  
Average Particle Size ◽  
Tween 80 ◽  
Average Particle ◽  
Spontaneous Emulsification

BACKGROUND: There are a lot of different types of sunscreen products (oils, sticks, gels, creams, lotions) which can be found on the world's market. Sunscreen product that contains active chemical ingredients sometimes has harmful effects on the skin. Sunflower oil contains vitamin E and acts as a natural sunscreen which can absorb UVB light. The average droplet size of nanoemulsion is between 100 and 500 nm and do not show the problems of stability (creaming, flocculation, coalescence, and sedimentation), which are commonly associated with macroemulsions. AIM: The aim of this study was to prepare and evaluate the sunflower oil nanoemulsion as a sunscreen. METHODS: Sunflower oil nanoemulsions were prepared by spontaneous emulsification method with 3 formulas F1 (Tween 80 38%, sorbitol 22%), F2 (Tween 80 36%, sorbitol 24%), F3 (Tween 80 34%, sorbitol 26%) and 5% sunflower oil as a sunscreen substance. The nanoemulsions were evaluated for particle size, physical stability in room temperature (25 ± 2°C), low temperature (4 ± 2°C) and high temperature (40 ± 2°C) during experiment for 12 weeks of storage, centrifugation at 3750 rpm for 5 hours, viscosity, pH, freeze-thaw test and sun protection value (SPF) value by in vitro. RESULTS: The results of nanoemulsion evaluation showed that nanoemulsion formula F1 had the smallest average particle size of 124.47 nm with yellowish colour, clear, transparent, pH value (6.5 ± 0.1), viscosity value (225 ± 25 cP), did not show any separation or creaming in the centrifugation, and stable during experiment for 12 weeks of storage at room temperature, low temperature and high temperature. The SPF value of all nanoemulsion preparations was higher than that of the emulsion. CONCLUSION: The preparation of the sunflower oil nanoemulsion with a ratio of Tween 80 and sorbitol (38: 22) produces a stable nanoemulsion during the experiment for 12 weeks storage at the room, low and high temperature. The nanoemulsion preparation has higher SPF values compared to the emulsion. This nanoemulsion formulation could be considered more effective in sunscreen cosmetic use compare to the emulsion.

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