Microstructural, Magnetic, and Optical Properties of Pr-Doped Perovskite Manganite La0.67Ca0.33MnO3 Nanoparticles Synthesized via Sol-Gel Process

Abstract

We report on microstructural, magnetic, and optical properties of Pr-doped perovskite manganite (La1 − xPrx)0.67Ca0.33MnO3 (LPCMO, x = 0.0–0.5) nanoparticles synthesized via sol-gel process. Structural characterizations (X-ray and electron diffraction patterns, (high resolution) TEM images) provide information regarding the phase formation and the single-crystalline nature of the LPCMO systems. X-ray and electron diffraction patterns reveal that all the LPCMO samples crystallize in perovskite crystallography with an orthorhombic structure (Pnma space group), where the MnO6 octahedron is elongated along the b axis due to the Jahn-Teller effect. That is confirmed by Raman spectra. Crystallite sizes and grain sizes were calculated from XRD and TEM respectively, and the lattice fringes resolved in the high-resolution TEM images of individual LPCMO nanoparticle confirmed its single-crystalline nature. FTIR spectra identify the characteristic Mn–O bond stretching vibration mode near 600 cm− 1, which shifts towards high wavenumbers with increasing post-annealing temperature or Pr-doping concentration, resulting in further distortion of the MnO6 octahedron. XPS revealed dual oxidation states of Mn3+ and Mn4+ in the LPCMO nanoparticles. UV-vis absorption spectra confirm the semiconducting nature of the LPCMO nanoparticles with optical bandgaps of 2.55–2.71 eV. Magnetic measurements as a function of temperature and magnetic field at field cooling and zero-field cooling modes, provided a Curie temperature around 230 K, saturation magnetization of about 81 emu/g, and coercive field of 390 Oe at 10 K. Such magnetic properties and the semiconducting nature of the LPCMO nanoparticles will make them as suitable candidate for magnetic semiconductor spintronics.

Effect of ferroelectric polarization on piezo/photocatalysis in Ag nanoparticles loaded 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.1Ti0.9)O3 composites towards the degradation of organic pollutants

“…For calcium, 2p 3/2 and 2p 1/2 peaks are observed at 347.20 and 350.98 eV. Here Ca is present in the +2 oxidation state, as shown in Figure 2C 30 . For Zr, three peaks were found upon deconvolution.…”

“…Here Ca is present in the +2 oxidation state, as shown in Figure 2C. 30 For Zr, three peaks were found upon deconvolution. The first peak is at 178.00 eV, which matches with metallic Zr 0 3d 5/2 .…”

Structural characterization and magnetic properties of single‐crystalline (La0.6Pr0.4)0.67Ca0.33MnO3 nanowires

“…The unit cell anisotropy is equal to 2.738 × 10 −3 ( δ = 0 for a cubic cell). The unit cell volume ( V ) is larger than that of the nanoparticle counterpart ( V = 227.233) 42 . To describe the degree of structural distortion in the (La 0.6 Pr 0.4 ) 0.67 Ca 0.33 MnO 3 nanowires, Goldschmidt tolerance factor ( t ) was employed, which is defined as follows: 43 where represent the effective ionic radii of the A‐ and B‐site cations, respectively, and is the ionic radius of the oxygen anion.…”

“…). 42 To describe the degree of structural distortion in the (La 0.6 Pr 0.4 ) 0.67 Ca 0.33 MnO 3 nanowires, Goldschmidt tolerance factor (t) was employed, which is defined as follows: 43 where r A and r B represent the effective ionic radii of the Aand B-site cations, respectively, and r O is the ionic radius of the oxygen anion. In a unit cell of (La 0.6 Pr 0.4 ) 0.67 Ca 0.33 MnO 3 nanowires with an orthorhombic perovskite structure, La, Pr, and Ca ions at the A-site have 12-fold coordination numbers with four O(1) and eight O(2) anions, and the Mn cations at the B-site have six-fold coordination numbers with two O(1) and four O(2) anions.…”

Recent Advances in Perovskite Catalysts for Efficient Overall Water Splitting

“…The microstructure, morphology, physicochemical property, specific surface area, and transport property of perovskite oxides are closely related to the synthesis strategy and further influence the electrocatalytic activity. Recently, several approaches have been developed to synthesize perovskite oxides, including conventional synthetic methods (i.e., the solid-state method, combustion synthesis, and high-pressure synthesis) [69,70], wet chemistry methods (i.e., the sol-gel process, co-precipitation method, and hydrothermal synthesis) [71][72][73], deposition approaches (i.e., physical vapor deposition, chemical va-por deposition, and electrodeposition) [74][75][76], electrospinning [77], the polymer-assisted approach [78], and so on.…”