Humidity response of Li-substituted magnesium ferrite

Kotnala, R.K.; Singh, Brijesh Kumar; Kishan, H.; Singh, Shiva Kumar; Dhawan, S. K.; Sengupta, A.K.

doi:10.1016/j.snb.2007.10.002

Cited by 112 publications

(60 citation statements)

References 9 publications

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“…The high-frequency band (� 1 ) lies in the 580-600 cm �1 range and the low-frequency band (� 2 ) in the 400-436 cm -1 range. This difference in the band position is attributed to the vibration of tetrahedral and octahedral components in the spinel ferrites [16,18,19].…”

Section: Humidity Measurementsmentioning

confidence: 96%

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Synthesis of metal ferrite (MFe₂O₄, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Jeseentharani¹,

George²,

Jeyaraj³

et al. 2013

Journal of Experimental Nanoscience

146

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Humidity sensitivity of metal ferrite nanoparticles [MFe 2 O 4 , M (II) ¼ Co, Cu, Mg, Ni and Zn] prepared by solid-state reaction of inorganic precursors was studied. The process was convenient, environmentally-friendly, inexpensive and efficient. The spinel structure of the compounds prepared by this method was confirmed by XRD and FT-IR studies. The surface morphology was observed by scanning electron microscopy, and the surface area was analysed by the nitrogen adsorption/desorption study by the Brunauer-Emmett-Teller (BET) method. All the samples were subjected to dc electrical conductivity studies at room temperature. The resistance measurements as a function of relative humidity in the range of 5-98% and the sensitivity factor (S f ¼ R 5% / R 98% ) were calculated. Among all the metal ferrites, zinc ferrite (ZnFe 2 O 4 ) possessed the highest humidity sensitivity factor of 2895 � 85, whereas the other compounds possessed a very low sensitivity factor. The response and recovery times of ZnFe 2 O 4 were 330 and 80 s.

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Section: Humidity Measurementsmentioning

confidence: 96%

“…Aggregation of smaller grains was observed with the formation of lesser pores. The SEM micrographs exhibited some dissolved ferrites that precipitated during cooling to form barely resolvable particles that had insufficient time to migrate to grain boundaries [16].…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Synthesis of metal ferrite (MFe₂O₄, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Jeseentharani¹,

George²,

Jeyaraj³

et al. 2013

Journal of Experimental Nanoscience

146

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“…3 showes the infrared feature of LiYO 2 which displays a broad band at around 3450 cm -1 related to the O-H stretching vibration mode of water [27]. The presence of O-H vibration for sample heated at 1000˚C is due to the moisture sensitive of Li + ion [28]. A closer examination of frequency bands at 3075, 2642 and 2540 cm -1 and the typical vibration at 1715 cm -1 indicates that the shoulder exists around 3000-2800 cm -1 could be attributed to the stretching vibrations of C-H and COO-H vibration of citric acid, which proves that no complexes were formed even after 125 hours.…”

Section: Ft-ir Characterization Of Liyomentioning

confidence: 96%

Sol-Gel Synthesis and Characterization of Lithium Yttrium Oxide

Loembe¹

2015

IJRET

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“…Increase (for p-type) or decrease (for n-type) of the resistance is attri buted to desorption of chemisorbed water [19]. Adsorption of water traps e -from metal oxide semiconductor conduction or valence band in case of n-type or p-type semiconductor according to the equation H 2 O + e -↔ OH - [20]. Desorption at higher temperatures returns e -and hence increases (p-type) or decreases (n-type) resistance of the material OH --e -↔ H 2 O [20].…”

mentioning

confidence: 99%

“…Adsorption of water traps e -from metal oxide semiconductor conduction or valence band in case of n-type or p-type semiconductor according to the equation H 2 O + e -↔ OH - [20]. Desorption at higher temperatures returns e -and hence increases (p-type) or decreases (n-type) resistance of the material OH --e -↔ H 2 O [20]. Desorption of chemisorbed water will promote oxygen adsorption and enhance sensitivity [21].…”

mentioning

confidence: 99%

Gas sensitivity of stoichiometric and excess-iron Ni-Zn ferrite prepared by sol-gel auto-combustion

Šutka¹,

Mežinskis²,

Strīķis³

et al. 2012

Energetika

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Application of new materials offers more sensitive, selective and long-term stable sensor materials. The aim of the present work is to compare gas response to acetone of nanostructured sol-gel auto-combustion derived stoichiometric and excess-iron cubic spinel type nickel-zinc ferrite (Ni 0.3 Zn 0.7 Fe 2+z O 4 where z = 0 and 0.1). Detailed synthesis steps and gas sensing measurement methodology were described. The sensor material was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and direct current (DC) resistance measurements. XRD analysis confirms that samples form the single-phased cubic spinel structure, SEM reveals nanosized grains less than 100 nm in diameter. Plots of resistance versus temperature show adsorbed water contribution to the conductance. With excess-iron, Ni-Zn ferrite changes its DC electrical resistivity, type of conductivity, as well as response to reducing gas (more than 2 times). Obtained relationships can be explained with Fe 2+ formation in the material, thus increasing charge carrier (electron) concentration. This leads down to higher oxygen adsorption ability which can act with test gas.Key words: nickel-zinc ferrite, non-stoichiometry, gas sensor, combustion synthesis [2][3][4][5][6][7]. At the same time information about ferrite gas sensors in comparison with single metal oxide gas sensors is still limited and does not contain data about gas sensing properties of complex or non-stoichiometric iron deficient or excess-iron spinel ferrite compounds, which have essentially different electrical properties. INTRODUCTIONThe conductivity in spinel ferrites is due to hopping of charge carriers (electrons or holes) between cations presented by more than one valence state occupying the octahedral sites [8]. Zinc or cadmium ions show strong affinity to the tetrahedral site, but iron, nickel, manganese, and cobalt ions, for example, show tendency to occupy octahedral sites. Electron hopping between Fe 3+ and Fe 2+ provides ntype, but hole hopping between Ni 3+ ↔ Ni 2+ , Mn 3+ ↔ Mn 2+ , Co 3+ ↔ Co 2+ provides p-type conductivity.The gas sensitivity of metal oxide semiconductor sensors is highly affected by their electric and transport properties [9]. In our previous works, influence of zinc ion concentration on resistance and sensitivity of p-type nickel ferrite [10], as well as iron ion non-stoichiometry effect on resistance and sensitivity of n-type zinc ferrite [11] were investigated. It was found that with zinc addition to nickel ferrite, response to different VOCs decreases, attributed to extinguishing p-type charge carriers (holes) and carrying a small amount of dopants in the semiconductor 167 Gas sensitivity of stoichiometric and excess-iron Ni-Zn ferrite prepared by sol-gel auto-combustion structure. This was confirmed with change of conductivity type by increasing temperature. In case of zinc ferrite response increased by going from iron deficiency to excess due to an increase of Fe 2+ concentration, the charge carrier (electron) concentration increased,...

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Humidity response of Li-substituted magnesium ferrite

Cited by 112 publications

References 9 publications

Synthesis of metal ferrite (MFe₂O₄, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Synthesis of metal ferrite (MFe₂O₄, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Sol-Gel Synthesis and Characterization of Lithium Yttrium Oxide

Gas sensitivity of stoichiometric and excess-iron Ni-Zn ferrite prepared by sol-gel auto-combustion

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Humidity response of Li-substituted magnesium ferrite

Cited by 112 publications

References 9 publications

Synthesis of metal ferrite (MFe2O4, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Synthesis of metal ferrite (MFe2O4, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Sol-Gel Synthesis and Characterization of Lithium Yttrium Oxide

Gas sensitivity of stoichiometric and excess-iron Ni-Zn ferrite prepared by sol-gel auto-combustion

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Product

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Synthesis of metal ferrite (MFe₂O₄, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Synthesis of metal ferrite (MFe₂O₄, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials