scholarly journals Influence of SnO2 Content on the Humidity Dependent Impedance of the MgFe2O4-Fe2O3-SnO2 Compound

Chemosensors ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 39 ◽  
Author(s):  
Maria Vesna Nikolic ◽  
Miloljub D. Lukovic
Keyword(s):  
Relative Humidity ◽  
Grain Boundary ◽  
Complex Impedance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impedance Data ◽  
Analyze Sample ◽  
Relative Humidity Range ◽  
Humidity Range ◽  
Dominant Influence

A porous MgFe2O4-Fe2O3-SnO2 bulk compound with varying SnO2 content was obtained by sintering an appropriate mixture of magnesium oxide, hematite and tin oxide nanopowders at 1000 and 1100 °C. The obtained structure was confirmed by X-ray diffraction analysis. Scanning electron microscopy was used to analyze sample morphology, showing that the addition of SnO2 resulted in an inhomogeneous microstructure with smaller grain size especially at 1000 °C. Significant grain growth of hematite grains was noted at 1100 °C. The influence of relative humidity in the range 30–90% was monitored at room temperature (25 °C) in the frequency range 42 Hz- 1 MHz. The highest reduction of impedance with humidity was noted at lower frequency. Addition of low amounts of SnO2 and sintering at 1000 °C resulted in the highest sensitivity at 105 Hz of 0.391 MΩ/%RH in the RH30–90% range, while the compound with the highest amount of SnO2 showed the largest decrease in impedance with increase in relative humidity ~26 times. All samples showed low hysteresis (below 2%). Complex impedance data was analyzed using equivalent circuits reflecting the dominant influence of the grain boundary in the lower relative humidity range (30–60%) and both grain boundary and grain components in the higher relative humidity range (60–90%).

Fabrication and Failure Prediction of Carbon-alum solid composite electrolyte based humidity sensor using ANN

2018 ◽  
Vol 25 (4) ◽  
pp. 773-780 ◽  
Author(s):  
Cherry Bhargava ◽  
Vijay Kumar Banga ◽  
Yaduvir Singh
Keyword(s):  
Humidity Sensor ◽  
Low Cost ◽  
Complex Impedance ◽  
X Ray Diffraction ◽  
Arrhenius Behavior ◽  
Composite Electrolyte ◽  
Temperature Dependence Of Conductivity ◽  
Maximum Conductivity ◽  
Relative Humidity Range ◽  
Humidity Range

Abstract Using low-cost materials, carbon, and alum, a new solid composite electrolyte system was fabricated and characterized using various techniques. Complex impedance spectroscopy was used to measure its ionic conductivity. A maximum conductivity of 3.4×10−5 S/cm was obtained when alum was doped with 40% carbon. An Arrhenius behavior was reported when the temperature dependence of conductivity was analyzed. Scanning electron microscopy was used to study the surface morphology of the synthesized electrolyte. Fourier transform infrared and X-ray diffraction results confirmed the formation of composite material. The synthesized solid composite electrolyte exhibited excellent humidity sensing behavior in the relative humidity range of 15%–65%. Various humidity characteristics of the sample were measured such as hysteresis loop, recovery, and response time of the sensor. An expert system was modeled using artificial intelligence techniques and failure of the sensor was predicted with 97.2% accuracy using artificial neural networks.

Humidity Sensing Property of Al-Doped Mesoporous Silica

2012 ◽  
Vol 249-250 ◽  
pp. 992-997 ◽  
Author(s):  
Wang Chang Geng ◽  
Li Bing Duan ◽  
Qiu Yu Zhang
Keyword(s):  
Relative Humidity ◽  
Mesoporous Silica ◽  
Complex Impedance ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
Humidity Sensing ◽  
X Ray ◽  
Sensing Mechanism ◽  
Sensing Material ◽  
Complex Impedance Spectra

In order to study the humidity sensing property and sensing mechanism of Al-doped mesoporous silica SBA-15 (Al-SBA-15), Al-SBA-15 was prepared by a simple grind method following a heat-treatment process. Its structure and morphology was characterized by X-ray diffraction (XRD), Infrared (IR), scanning electron microscope (SEM). Humidity sensing response was studied and the results indicated that Al-SBA-15 displayed better sensing property when the frequency was 100 Hz. The impedance of Al-SBA-15 changes three orders of magnitude when relative humidity changes from 11% to 95%. Complex impedance spectra, the corresponding equivalent circuit under different relative humidity are carefully analyzed to explore the humidity sensing mechanism of this material. This material can be used as a promising humidity sensing material.

Structural and thermodynamic properties of nanocrystalline fcc metals prepared by mechanical attrition

1992 ◽  
Vol 7 (7) ◽  
pp. 1751-1761 ◽  
Author(s):  
J. Eckert ◽  
J.C. Holzer ◽  
C.E. Krill ◽  
W.L. Johnson
Keyword(s):  
Thermal Analysis ◽  
Grain Size ◽  
Melting Point ◽  
Grain Boundary ◽  
Bulk Modulus ◽  
Atomic Level ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fcc Metals ◽  
Mechanical Attrition

Nanocrystalline fcc metals have been synthesized by mechanical attrition. The crystal refinement and the development of the microstructure have been investigated in detail by x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy. The deformation process causes a decrease of the grain size of the fcc metals to 6–22 nm for the different elements. The final grain size scales with the melting point and the bulk modulus of the respective metal: the higher the melting point and the bulk modulus, the smaller the final grain size of the powder. Thus, the ultimate grain size achievable by this technique is determined by the competition between the heavy mechanical deformation introduced during milling and the recovery behavior of the metal. X-ray diffraction and thermal analysis of the nanocrystalline powders reveal that the crystal size refinement is accompanied by an increase in atomic-level strain and in the mechanically stored enthalpy in comparison to the undeformed state. The excess stored enthalpies of 10–40% of the heat of fusion exceed by far the values known for conventional deformation processes. The contributions of the atomic-level strain and the excess enthalpy of the grain boundaries to the stored enthalpies are critically assessed. The kinetics of grain growth in the nanocrystalline fcc metals are investigated by thermal analysis. The activation energy for grain boundary migration is derived from a modified Kissinger analysis, and estimates of the grain boundary enthalpy are given.

Structural and phase equilibria studies in the system Pt-Fe-Cu and the occurrence of tulameenite (Pt2FeCu)

1985 ◽  
Vol 49 (353) ◽  
pp. 547-554 ◽  
Author(s):  
M. Shahmiri ◽  
S. Murphy ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Critical Temperature ◽  
Grain Boundary ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe crystal structure and compositional limits of the ternary compound Pt2FeCu (tulameenite), formed either by quenching from above the critical temperature of 1178°C or by slow cooling, have been investigated using X-ray diffraction, transmission electron microscopy, differential thermal analysis and electron probe microanalysis.The crystal structure of Pt2FeCu, established using electron density maps constructed from the measured and calculated intensities of X-ray diffraction patterns of powdered specimens, has the (000) and (½½0) lattice sites occupied by Pt atoms and the (½0½) and (0½½) sites occupied by either Cu or Fe atoms in a random manner. The resulting face-centred tetragonal structure undergoes a disordering transformation at the critical temperature to a postulated non-quenchable face-centred cubic structure. Stresses on quenching, arising from the ordering reaction, are relieved by twinning along {101} planes or by recrystallization along with deformation twinning; always involving grain boundary fracturing.Phase relations in the system Pt-Fe-Cu have been investigated through the construction of isothermal sections at 1000 and 600°C. At 1000°C there is an extensive single phase region of solid solution around Pt2FeCu and extending to the binary composition PtFe. At 600°C the composition Pt2FeCu lies just outside this now reduced area of solid solution in a two-phase field. Comparison of the experimental results with data for tulameenite suggests that some observed compositions may be metastably preserved. The occurrence of fine veinlets of silicate or other gangue minerals in tulameenite is suggested to result from grain boundary fracturing on cooling below the critical temperature of 1178°C and to be evidence of a magmatic origin.

scholarly journals Bottleneck Effect Explained by Le Bail Refinements: Structure Transformation of Mg-CUK-1 by Confining H2O Molecules

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1840
Author(s):  
Elí Sánchez-González ◽  
J. Gabriel Flores ◽  
Julio C. Flores-Reyes ◽  
Ivette Morales-Salazar ◽  
Roberto E. Blanco-Carapia ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Co2 Capture ◽  
Unit Cell ◽  
Structure Transformation ◽  
X Ray Diffraction ◽  
Bottleneck Effect ◽  
X Ray ◽  
Cell Parameters ◽  
Hydrogen Bonded

The structure transformation of Mg-CUK-1 due to the confinement of H2O molecules was investigated. Powder X-ray diffraction (PXRD) patterns were collected at different H2O loadings and the cell parameters of the H2O-loaded Mg-CUK-1 material were determined by the Le Bail strategy refinements. A bottleneck effect was observed when one hydrogen-bonded H2O molecule per unit cell (18% relative humidity (RH)) was confined within Mg-CUK-1, confirming the increase in the CO2 capture for Mg-CUK-1.

scholarly journals Boltzmann-Based Empirical Model to Calculate Volume Loss during Spirit Ageing

Beverages ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 60
Author(s):  
Noemí del Toro del Toro ◽  
Fredy Fong Casas ◽  
Julio Ayan Rial ◽  
Maria Caridad Portuondo González ◽  
Harold Crespo Sariol ◽  
...  
Keyword(s):  
Boltzmann Equation ◽  
Relative Humidity ◽  
Quercus Alba ◽  
Volume Loss ◽  
Air Humidity ◽  
White Oak ◽  
The Boltzmann Equation ◽  
Relative Humidity Range ◽  
Two Parameters ◽  
Humidity Range

The Boltzmann equation is applied to fit data of volume loss for evaporation (in %) during spirit ageing in northern white oak (Quercus Alba) standard barrels of 205 L (+/− 10 L) using a temperature and humidity controlled cellar. The Boltzmann equation satisfactory fitted to the experimental data of the volume loss against temperature at constant humidity. Two parameters of the Boltzmann equation showed a linear dependency on the relative humidity of the air, while the other two parameters exhibited a constant value independently of the air humidity. The found empirical mathematical model can be used to calculate the volume loss for evaporation of spirits (40% v/v of ethanol) during ageing in terms of relative humidity (range: 40%–95%) and temperature (range: 10–30 °C) with significant accuracy.

Characterization, Optical and Impedance Study of ZnSe Nanostructure

2013 ◽  
Vol 699 ◽  
pp. 490-495
Author(s):  
Ramna Tripathi ◽  
Akhilesh Kumar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Impedance Spectroscopy ◽  
Zinc Selenide ◽  
Relaxation Times ◽  
Complex Impedance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Stability

Zinc selenide nanoparticle has been synthesized using soft chemical routes. The particles were capped using 2-mercaptoethanol to achieve the stability and avoid the coalescence. The as-obtained particles were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–VIS absorption and photoluminescence (PL) spectra. The impedance studies were carried out as a function of frequency (100 Hz–1 MHz) and temperature (298–373 K) by impedance spectroscopy. An analysis of the complex impedance (z' and z") with frequency is performed assuming a distribution of relaxation times.

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