Magnesium Ferrite Sensor for H2S Detection

Abstract

The composite effects of p-type MgO and n-type MgFe 2 O 4 on H 2 S detection were investigated. The mixture state of these oxides was fixed under coprecipitation conditions: mixture ratio of iron source to magnesium source, and pH control of precursor solution by dropping of an alkaline solution. The composite mixture of MgO, Fe 2 O 3 , and MgFe 2 O 4 was obtained by adjusting the mixture ratio of Fe to Mg. The resistance in air monotonically increased with increasing MgO content in the matrix of MgFe 2 O 4 . In contrast, the resistance in air decreased with increasing Fe 2 O 3 content. The sensing properties of these composites to 3 ppm H 2 S were evaluated as a sensor response (S), defined as the ratio of the resistance in air (R a ) to that in the gas mixture of H 2 S and air (R g ). The sensor response depended on the composite state of MgFe 2 O 4 and MgO because the amount of H 2 S adsorbed on the composite was increased by the formation of the p-n junction. In contrast, the sensor response was not improved in the presence of excess MgO in the matrix of MgFe 2 O 4 , suggesting that the excess MgO serves as an insulator in the electron transfer between the semiconductor composite MgO-MgFe 2 O 4 and an interdigitated Pt microelectrode.

Synthesis of Mg-Ferrite nanoparticles via auto combustion method and investigation their structural, morphological and magnetic properties

“…[4][5][6]. Among the known magnetic nanoparticles, magnesium ferrite, MgFe 2 O 4 , a well-known soft magnetic, n-type semiconductor [7], So it has much application such as heterogeneous catalysis, photoelectrical, sensors, and magnetic technologies [8][9][10][11][12][13][14][15][16]. Conventionally, MgFe 2 O 4 is usually synthesized by sol-gel auto combustion method [17][18][19][20], thermal treatment [21], coprecipitation method [22], hydrothermal synthesis [23], high energy ball milling [24] and spray pyrolysis [25], have been extensively investigated for the synthesis of welldispersed MgFe 2 O 4 nanoparticles.…”