Laser-Assisted Formation for BaTiO3 Perovskite with Correlative Microscopy and Nanoparticle Simulation Study.

Commercial type laser engraving has emerged as a technique of growing interest within the scientific community due to its rapid, energy-efficient, and environmentally favorable nature for the synthesis of perovskites, with phase purity exceeding 97%, while also enabling the production of average particle sizes within the nanometric range [1]. Previous studies suggest that perovskites exhibiting particle sizes close to 50 nm could be applied in multilayer ceramic capacitors (MLCCs) [2–4]. Perovskites can accommodate nearly all elements of the periodic table, making them among the most versatile materials. The synthesis of these materials can be carried out through various methods, among the most commonly used being solid-state synthesis, the sol–gel method, chemical precipitation, hydrothermal/solvothermal synthesis, and the laser ablation technique, each with specific advantages and limitations such as synthesis temperature, phase purity, and cost [5]. In the literature, a limited number of studies address the microstructural effects associated with this method for obtaining the BaTiO3 perovskite. In the present work, BaTiO3 perovskite was synthesized using this technique, which consists of direct irradiation with a CO2 laser operating at a power of 40 W on compacted pellets formulated from abundant, low-cost precursors: TiO2 and carbonates (BaCO3). An additional advantage of this method is the elimination of prolonged thermal treatments. BaTiO3 particles were characterized by X-ray diffraction (XRD) analysis using a Panalytical X’Pert PRO MPD diffractometer. The tetragonal phase P4mm with space group 99 (card 01-080-2202) was identified using Bragg–Brentano geometry. Rietveld refinement was performed on the obtained patterns using the FullProf software [6]. A composition of 99.17% BaTiO3 was determined, along with a secondary phase of 0.85% TiO2 as a remnant, with an average crystallite size of 55 nm. For morphological characterization and image acquisition, a scanning electron microscope (SEM) model Hitachi JEOL JSM 7401F was employed. Figure 1a shows a bright field (BF-TEM) image of BaTiO3 particles with a semi-spherical morphology characteristic of high-temperature synthesis and particle sizes in the range of 50 to 150 nm. Figures 1b–c present two-dimensional (2D) and three-dimensional (3D) simulations obtained from the GFourier program (version 4.06), indicating the nanometric average crystallite size. In Figure 2a high resolution HR-TEM (blue inset fast Fourier transform FFT) and Figures 2b–c, lattice vectors were analyzed and quantified, and the planes (002), (210), and (211), characteristic of the tetragonal phase of BaTiO3, were indexed using the CrysTBox diffractGUI program [7]. XRD and TEM analyses confirm the morphology and successful formation of nanometric crystalline BaTiO3 perovskite, validating the efficiency and feasibility of the proposed approach. (a) Representative BF-TEM micrograph of BaTiO3, (b) 2D visualization of the average crystallite size in the 100 projection GFourier program and (c) 3D simulation of apparent crystallite shape for BaTiO3. (a) HR-TEM image of BaTiO3, (b) (blue box) image individual lattice vectors are crystallographically identified and the zone axis is calculated. (c) Indexing of interplanar distances.