Influence of preparation methods of microwave, sol–gel, and hydrothermal on structural and optical properties of lanthania nanoparticles

Abstract

applications involve a metal oxide as active phase, promoter, or support. In the chemical and petrochemical industries, products worth billions of dollars are generated every year through processes that use metal or metal oxide catalysts [2]. For the control of environmental pollution, catalysts or sorbents that contain metal oxides are employed to remove CO, NO x , and SO x species formed during the combustion of fossil fuels [3]. The most active areas of the semiconductor industry involve the use of metal oxides [4]. Thus, most of the chips used in computers contain a metal oxide component.When the size of a metal oxide is brought down to the nanometer regime, a number of size-dependent properties arise primarily as a result of surface chemistry [5][6][7]. Metal oxide nanoparticles (NPs) can exhibit unique physical and chemical properties due to their limited size. Particle size is expected to influence three important groups of basic properties in any material. The first one comprises the structural characteristics, namely the lattice symmetry and unit cell parameters [8]. Bulk metal oxides are usually stable systems with well-defined crystallographic structures. With decreasing particle size, thermodynamic stability and cell parameters change and structural transformations may occur [6]. The second important influence of size is related to the electronic properties. With decreasing particle size, the energy of exciton levels of a semiconductor metal oxide shifts and hence the optical band gap changes [7,9]. Structural and electronic properties obviously change the physical and chemical properties of a solid which are the third group of properties influenced by size in a simple classification [6,10].Lanthanum (III) oxide, La 2 O 3 , has the largest band gap of the rare earth oxides (4.3 eV), the lowest lattice energy, and a very high dielectric constant. These properties lead to potential applications such as dielectric layers in devices, Abstract In this work, the nearly pure hexagonal phase of lanthania nanoparticles (NPs) was successfully synthesized using three methods: microwave, sol-gel, and hydrothermal. The samples were characterized using nine techniques including powder X-ray powder diffraction, thermogravimetry, transmission electron microscopy, scanning electron microscopy, field emission microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, far infrared spectroscopy, and ultraviolet-visible absorption spectroscopy. This study showed that the method of synthesizing lanthania NPs can affect the size, which in turn has impact on structural, morphological, and optical properties.

Influence of calcination on the sol–gel synthesis of lanthanum oxide nanoparticles

“…and that of oxygen is 14.73 % while the EDX results showed on the average 75.03 % of lanthanum and 19.76 % of oxygen. These obtained results confirmed a good agreement with previous work [35]. The EDX analysis indicates no presence of any impurity.…”

“…The crystalinity of the sample material can be represented by the crystal index, Ci and can be calculated by the following equation [35]:…”

“…Amongst these methods, the sol-gel synthesis process is a facile, inexpensive and does not require any specialist equipment. Goharshadi et al synthesized lanthania nanoparticles [35] using LaCl3, 7H2O as the starting materials, ammonia solution as hydrolysis agents and hexadecyltrimethyl ammonium bromide as a surfactant using hydrothermal process. The obtained average particle size was below 30 nm.…”

Green Synthesis of CeO2 Nanoparticles from the Abelmoschus esculentus Extract: Evaluation of Antioxidant, Anticancer, Antibacterial, and Wound-Healing Activities

“…A strong and sharp diffraction peak revealed the crystalline nature of CeO 2 nanoparticles. The indexed diffraction peaks at the 2θ position of 28.43°, 33.62°, 48.38°,57.74°, 59.03°, 69.37°, 76.69°, and 79.09°, corresponding to (111), (200), (220), (311), (222), (400), (331), and (420) crystal planes agreed with the COD library with the card no 96-900-9009 [ 29 ]. The XRD planes show the cubic structure for cerium dioxide nanoparticles with the lattice constant (a) value is 5.435 Å.…”

Polyethylene glycol assisted facile sol-gel synthesis of lanthanum oxide nanoparticles: Structural characterizations and photoluminescence studies

“…Lanthanum oxide NPs, nanorods, nanowires and nanosheets can be prepared using various chemical and physical techniques including hydrothermal [14,15], solvothermal [16], microwave [16,17], sol-gel [17,18], sonochemical [19][20][21], and reveres micelles [22].Amongst these methods, the sol-gel synthesis process is a facile, inexpensiveand does not require any sophisticated, complicated and specialist equipment. Hydrothermal synthesis of lanthania nanoparticles was reported by Goharshadi et al [23] and an average particle size below 30 nm was achieved. Sol-gel synthesis of lanthanum barium copper oxide nanoparticles was carried out by S.…”