Influence of Temperature on Reducing Gas Sensing Performance of Nanocrystalline Zinc Ferrite

Abstract

Pure phase, zinc ferrite (ZnFe 2 O 4 ) nanoparticles were synthesized at lower temperature (80°C) by auto combustion synthesis method. The resulting 'as synthesized' powder was heat treated (HT) at 560°C for 2 h in air atmosphere. As-synthesized particles had sizes *10 nm with spherical shape. Further, these spherically shaped nanoparticles tended to change their morphology to hexagonal plate shape with increasing HT temperature. The band gap of the 'as synthesized' and HT zinc ferite, as determined by using UVVis spectroscopy were found to be 1.92 and 1.86 eV respectively. Gas responses of the ZnFe 2 O 4 nanoparticles were measured by exposing them to ethanol gas vapors. It was found that the zinc ferrite nanoparticles exhibited various sensing responses to ethanol gas at different operating temperature. The best sensitivity was observed at low temperature for 'as synthesized' ferrite nanoparticles than HT zinc ferrite nanoparticles. Sensing material that had smaller particle size and larger specific surface area was observed to have larger gas sensitivity and vice-versa.

Synthesis and structural characterization of ZnxFe3−xO4 ferrite nanoparticles obtained by an electrochemical method

“…Several samples were synthesized applying a xed current intensity of 100 mA to the Fe anode whilst varying it for the Zn anode (5,10,20,30,40 and 50 mA). The chemical analysis calculated by ICP of the samples reveals that, in effect, there is a linear dependence between the current intensity applied to the Zn anode and the quantity of Zn incorporated into the ferrite structure (x), dening the zinc ferrite formula as Zn x -Fe (3Àx) O 4 (see Fig.…”

“…Among the spinel ferrites, zinc ferrite has long been the subject of studies due to its unique properties such as its chemical and thermal stability 7 and the reduced toxicity of Zn over other metals. 8 Zinc ferrite encompasses a large number of technological applications, such as magnetic materials, 9 gas sensors, 10 photocatalysts, 11 high density magnetic recording devices 12 and biomedical applications such as MRI contrast agents 13 or magnetic uid hyperthermia, 14 among others. Furthermore, its remarkable nature is also due to its unusual and versatile magnetic behaviour in nanoregime.…”

Band alignment and depletion zone at ZnO/CdS and ZnO/CdSe hetero-structures for temperature independent ammonia vapor sensing

“…[1][2][3] The metal oxide based sensors are capable of sensing a wide range of hazardous gas molecules (methane, liquefied petroleum gas (LPG), hydrogen peroxide (H 2 O 2 ), ethanol, ammonia, hydrochloric acid (HCl), trimethylamine, hydrogen sulphide (H 2 S), toluene) with varying response time. 4,5 To accomplish high sensitivity, high selectivity, and fast responsivity many proposals and techniques have been adopted, such as doping the metal oxide with additives, 6 incorporating a noble metal catalyst, 7 controlling the sensor operating temperature, 8 applying an external driving force (electric field and magnetic field), 9 incorporating conducting polymers, 10 irradiating the sensor with ultraviolet and visible radiation, 11 nanocomposite formation 12 and assembling small sized particles on the material surface. 13 Among them, the hierarchical structural assembly of the nanoparticles on the metal oxide surface for tuning the surface activities/properties is gaining great insight into the present sensor fabrication.…”