Papers by Keyword: LaFeO₃

Abstract: Nanocrystalline LaFeO₃ (LFO) perovskite material was synthesized by a co-precipitation method using water bath technique. The properties of LFO perovskite nanoparticles has been thoroughly investigated for as deposited and annealed samples. The sample prepared was annealed at 800°C in the environmental air. X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and UV-visible spectroscopy were used to study structural, morphological, compositional and optical features. The X-ray diffraction study confirmed the formation of an orthorhombic LFO nanostructure. FESEM images showed the formation of a random distribution of nanoparticles with high porosity. EDS results showed the stoichiometric amount of La, Fe and O. Using UV-visible spectra, the energy band gap of the samples was discovered to be 2.1 eV and 2.34 eV for the as-deposited and annealed sample, respectively. This finding suggests that the LFO nanostructures created by this method can function as a photocatalytic material.

Abstract: Biomorphic porous LaFeO₃ samples were prepared using aspen leaves as biotemplates. The structural and microscopy characterization has been carried out with X-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns confirm thatLaFeO₃ shows perovskite phase with orthorhombic structure. The results of SEM and TEM revealed that the the obtained LaFeO₃ with hollow and porous structure. And the porous LaFeO₃ is composed of spherical particles with the size of 50-80 nm The gas sensing performance of as-prepared LaFeO₃ nanocrystlas was investigated. It is found that porous LaFeO₃ calcined at 700°C exhibit good sensitivity to acetone with rapid response.

Abstract: Our previous study revealed that the gas sensitive property of Silver-modified Lanthanum Ferrite (Ag-LaFeO₃) is well, but the operating temperature is still high and the sensitivity also needs to be improved. This work based on our previous study. Ag-LaFeO₃ was further modified by the Carbon nanoTubes (CNTs). The Ag-LaFeO₃ powder modified with CNTs (CNTs-Ag-LaFeO₃) was prepared by a sol-gel method combined with microwave chemical synthesis. The structure and gas-sensing properties were investigated. The results show that the structure of CNTs-Ag-LaFeO₃ is of orthogonal perovskite. The sensitivity of 0.75% CNTs-Ag-LaFeO₃ powder for 1 ppm formaldehyde is 13 at 86°C. The response and recovery time are 100s and 60s, respectively. Moreover, the sensor also has an obvious response for 1ppm formaldehyde at 58°C.

Abstract: Nanocrystalline LaFeO₃ with particle size of about 50 nm was directly synthesized by sol–gel auto-combustion method at room temperature. The overall process involves three steps: formation of homogeneous sol; formation of dried gel; and combustion of the dried gel. Single phase nanocrystalline LaFeO₃ powders were successfully synthesized by the sol–gel self-propagation combustion method using glycin (C₂H₅NO₂) as the chelating agent. Discuss the synthesis products by DTA/TG, XRD and SEM. The experiment results show that the LaFeO₃ nano-powder was got from dried gel of G/M=1:1 at 300°C ignition temperature and then holding 2h at 800°C.The LaFeO₃ nano-powder is about 50nm with excellent dispersibility. The hysteretic loop show LaFeO₃ nanopowders have the character of ferromagnetism, the coercivity of the nanocrystalline LaFeO₃ is 99G, while the saturation is only 2.8 emug^-1.

Abstract: Pure nanostructured LaFeO₃ with crystallite size of around 13 nm and specific surface area of 48 m²/g were prepared using high energy ball milling. 0.4, 2 and 5 wt% of Pd was impregnated on synthesized LaFeO₃. TPD-O₂, TPD-CO and TPR-H₂ were performed to find the effect of Pd loading on perovskite oxide properties.CO gas sensing properties of doped and pure formulation were investigated. These results showed that 2 wt% Pd had optimum response ratio which had a maximum response ratio of 1200% with respect to 100 ppm CO in air at 140°C.

Abstract: The LaFeO3 nanoparticle was synthesized using Fe(NO3)3 and La(NO3)3 as starting materials by homogeneous precipitation method. The as-prepared LaFeO3 product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). XRD and SEM demonstrate the successful synthesis of single phase perovskite LaFeO3 and with 60-80 nm particle size. It was found that the as-prepared LaFeO3 shows strong visible-light absorption with absorption onset of 532 nm, indicating a narrow optical band gap of 2.33 eV. Furthermore, the as-prepared LaFeO3 shows high visible-light photocatalytic activity for decomposition of methylene blue in comparison with the commercial Degussa P25.

Abstract: Pure and Cu2+-doped LaFeO3 thin films were prepared on Al2O3 substrate by polymer complex method using La(NO3)3⋅6H2O, FeCl3⋅6H2O and Cu(NO3)2⋅3H2O as raw materials, citric acid (CA) as chelating agent and ethylene glycol (EG) as cross-linking agent. As-growth thin films were well-crystallized and the grain size was about 40nm after being annealed at 650°C. The sensitivities of pure and Cu2+- doped LaFeO3 thin films to 80 ppm acetone gas measured at 350°C were 315 and 30, respectively. Partial substitution of Fe3+ in LaFeO3 with Cu2+ could widen testing temperature of the materials.