Combustion synthesis of LaFeO3 sensing nanomaterial

Abstract

Since industrial revolution, human activities drive towards unsustainable global economy due to the overexploitation of natural resources and the unacceptable emissions of pollution and greenhouse gases. In order to address that issue, engineering research has been focusing on gas sensors development for monitoring gas emissions and controlling the combustion process sustainability. Semiconductors metal oxides sensors are attractive technology because they require simple design and fabrication, involving high accessibility, small size and low cost. Perovskite oxides are the most promising sensing materials because sensitivity, selectivity, stability and speed-response can be modulated and optimized by changing the chemical composition. One of the most convenient synthesis process of perovskite is the citrate-nitrate auto-combustion method, in which nitrate is the oxidizing agent and citrate is the fuel and the chelating argent in the same time. Since the sensibility of perovskite oxides depends on the defective crystallographic structure and the nanomorphology, the experimental was designed in order to study the dependence of powder properties on the synthesis conditions, such as the solution acidity and the relative amount of metals, nitrates and citric acid. Crystalline structure was studied in depth for defining the effects of synthesis conditions on size, morphology and crystallographic structure of nanopowders of LaFeO3

Subtle Structural Changes in LaFeO3 at High Pressure

“…[ 29 ] At ambient pressure, the octahedral tilt angles are 7.06(2)° and 12.16(3)°, in agreement with those published previously. [ 27,30 ] The antiferromagnetic order in LaFeO 3 contributes strongly to the pattern with additional peak intensity arising from the magnetic scattering, most noticeably overlapping a weak nuclear peak close to ≈4.5 Å in Figure 2. The Rietveld fit to the pattern is consistent with the G‐type antiferromagnetic model previously reported for LaFeO 3 [ 10,13,14 ] and the refined total magnetic moment, , has its largest contribution along the c ‐direction.…”

Perovskite sensing materials for syngas composition monitoring and biomass gasifier numerical model validation: A preliminary approach

“…XRD patterns were useful also to evaluate crystallite's diameter. Since it is possible to assume the lattice strain effects on peak broadening very negligible [23] and thus ascribe it only to crystallite size effects, average crystallites dimensions were estimated with Scherrer equation [36] β hkl [strain]=kλ/ (D hkl cosθ hkl ), where D hkl is the average crystallites size in nanometers along the direction normal to the diffraction plane (hkl), K is the shape factor equal to 0.9, λ is the x-ray wavelength of Cu-K α equal to 0.1540593 nm and θ hkl is the Bragg angle in radians for the crystallographic plane (hkl). Average crystallites sizes of all obtained sample are listed in Table 1: note that the experiment 1 reports no value for crystallites diameter, since the relative sample have not a crystalline structure.…”

“…Powders of LaFeO 3 perovskite-type oxides were synthetized by means of solution combustion synthesis via citrate-nitrate technique, in order to obtain nano-dimensional and high specific surface area materials [23]. For the evaluation of the synthesis parameters effects on materials properties, chemometric analysis was carried out.…”

Optimization of Working Conditions for Perovskite-Based Gas Sensor Devices by Multiregression Analysis

“…Tisubstituted lanthanum ferrite perovskites, LaFe 0.8 Ti 0.2 O 3 , have been synthesized and the effect of sensor operating conditions, such as target gas concentration, C, working temperature, T, and inlet-gas flow rate, φ, has been studied on the performances of the sensor device. Nanostructured perovskite oxides were obtained by means of the autocombustion method [26], which is a fast, easy, scalable, and reliable way for the synthesis of nanopowder. Since the sensor performance depends on multiple factors, whose effects can be both direct and indirect, chemometric analyses were executed in order to define the most useful operating condition for having sensor response with high quality, in agreement with the Quality-by-Design principles [27].…”