Humidity-sensing properties of nanocrystalline haematite thin films prepared by sol-gel processing

Chauhan, Pratima; Annapoorni, S.; Trikha, S. K.

doi:10.1016/s0040-6090(98)01771-4

Cited by 121 publications

(51 citation statements)

References 10 publications

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“…The room temperature resistivity ( RT ) of the unsintered sample was found to be 1.03 Â 10 6 cm. Resistivity increased up to 5.0 Â 10 6 cm at 95 C. This increase in resistivity of this sample from ambient temperature to 95 C might be attributed to the presence of open porosity and loose agglomeration of nanoparticles (as evident in Figure 4a) and entrapped moisture inside the pores of the as-synthesised nanopowders [24,25]. Humidity recorded in the laboratory was $90% at 27 C. Increase of temperature up to 95 C was likely to have caused the evaporation of moisture from the sample and therefore, maximum resistivity was attained.…”

Section: Resistivity Measurementmentioning

confidence: 76%

Synthesis and characterisation of pure single-phase CoFe₂O₄ nanopowder via a simple aqueous solution-based EDTA-precursor route

Rajput

Hazra

Ghosh

2012

Journal of Experimental Nanoscience

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Single-phase cobalt ferrite (CoFe 2 O 4 ) nanopowder, with average particle size �20 nm, has been synthesised using an ethylene diamine tetra acetic acid precursor-based method. CoFe 2 O 4 nanopowder was obtained by calcining precursor at 550 � C for 4 h in air. The change of microstructure of the synthesised CoFe 2 O 4 with increasing sintering temperature was studied using scanning electron microscopy. DC electrical resistivities of unsintered and sintered samples were measured using a two-probe method. Room temperature magnetic hysteresis measurement revealed that the synthesised CoFe 2 O 4 nanopowder exhibited ferromagnetic behaviour at room temperature with saturation magnetisation of 67.55 emu/g and coercivity of 1645.24 Oe.

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Section: Resistivity Measurementmentioning

confidence: 76%

Synthesis and characterisation of pure single-phase CoFe₂O₄ nanopowder via a simple aqueous solution-based EDTA-precursor route

Rajput

Hazra

Ghosh

2012

Journal of Experimental Nanoscience

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“…At low relative humidity, the increase in σ for the powdered samples is related to the absorption of water molecules on the surface and the boundaries of the grains. The absorbed water molecules increase the active sites of conduction and produce more charge carriers for electrical conduction and hence the electrical conductivity increases 16 . The number of absorbed water molecules depends on the method of preparation, drying condition and the structure of the products.…”

Section: Methodsmentioning

confidence: 99%

Rare Earth Phosphates as Humidity Sensors

Hanna

Ashraf

Ali

et al. 2007

Phosphorus Research Bulletin

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The aim of this work is preparation, characterization, and evaluation of some rare earth phosphates REPO 4 (RE= La, Sm, Gd) to be used as humidity sensors. Their substitution with Na + or Ca 2+ were prepared by both wet and dry methods. The produced samples were characterized by using the classical methods. The X-ray data shows that different compounds and different phases were formed depending on the method of preparation and the control conditions. The electrical conductivity of the samples were measured at 25-300°C and different relative humidity ranges of 30 to 92%. The dependence of electrical conductivity on temperature indicates that, the rare earth phosphates behave as semiconductor materials whatever they prepared by wet or dry method. It is found that the electrical conductivity of most phosphate samples increase smoothly as the relative humidity increase. This behavior may due to the protonic conduction at low humidity values and to the protonic and electrolytic conductions at high humidities. From the analysis of the obtained results, it may conclude that, the humidity sensors with high sensitivity and thermal stability could be developed from some rare earth phosphates.

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“…It is widely used in solar cells to increase the photo-conversion efficiency [8], lithium ion battery to improve the lithium intercalation performance [9], gas sensors due to the differences in electrical resistivity in oxidizing/reducing gases [10], photo-catalysts under visible-light irradiation [11], field emission devices due to the high emission current density [12], field effect transistors when hematite is doped with zinc to achieve p-or enhance n-type semiconducting property [13] and as photo-catalyst for photon emitted water splitting [14] due to its low cost and high resistance to corrosion.…”

Section: Introductionmentioning

confidence: 99%

Ion-exchange kinetics and thermal decomposition characteristics of Fe2+-exchanged alginic acid membrane for the formation of iron oxide nanoparticles

et al. 2014

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The ion-exchange kinetics of Fe 2+ cations in aqueous solution with H + from alginic acid have been analyzed in this study as a function of contact time lengths using Inductively Coupled Plasma -Atomic Emission Spectrometry analysis (ICP-AES). The kinetic parameters have been evaluated using pseudo 1 st or 2 nd order models and a consistent ion-exchange mechanism is suggested. Furthermore, an insight into the calcination of Fe 2+ ion-exchanged alginic acid process has been obtained by using simultaneous Thermo-Gravimetric Analysis and Differential Scanning Calorimetry (TGA/DSC) and High Temperature X-ray diffraction (HT-XRD).

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Humidity-sensing properties of nanocrystalline haematite thin films prepared by sol-gel processing

Cited by 121 publications

References 10 publications

Synthesis and characterisation of pure single-phase CoFe₂O₄ nanopowder via a simple aqueous solution-based EDTA-precursor route

Synthesis and characterisation of pure single-phase CoFe₂O₄ nanopowder via a simple aqueous solution-based EDTA-precursor route

Rare Earth Phosphates as Humidity Sensors

Ion-exchange kinetics and thermal decomposition characteristics of Fe2+-exchanged alginic acid membrane for the formation of iron oxide nanoparticles

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Humidity-sensing properties of nanocrystalline haematite thin films prepared by sol-gel processing

Cited by 121 publications

References 10 publications

Synthesis and characterisation of pure single-phase CoFe2O4 nanopowder via a simple aqueous solution-based EDTA-precursor route

Synthesis and characterisation of pure single-phase CoFe2O4 nanopowder via a simple aqueous solution-based EDTA-precursor route

Rare Earth Phosphates as Humidity Sensors

Ion-exchange kinetics and thermal decomposition characteristics of Fe2+-exchanged alginic acid membrane for the formation of iron oxide nanoparticles

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Product

Resources

About

Synthesis and characterisation of pure single-phase CoFe₂O₄ nanopowder via a simple aqueous solution-based EDTA-precursor route

Synthesis and characterisation of pure single-phase CoFe₂O₄ nanopowder via a simple aqueous solution-based EDTA-precursor route