BR-102024017825-A2 - Obtaining Banb2O6 through high-energy milling at room temperature, with properties that allow its use as a solid-state electrolyte for energy storage and an electrochemical sensor.

Abstract

This patent application describes the synthesis of barium niobate (BaNb2O6) by mechanical milling of niobium pentoxide (Nb2O5) and barium carbonate (BaCO3), without additional heat treatment. This synthesis route is novel in laboratories and industries for this compound. The proposed material is intended for use as a solid-state electrolyte for energy storage and an electrochemical sensor. Characterization of the synthesized materials, at different synthesis times, was performed by X-ray diffraction and Rietveld refinement, confirming a highly crystalline orthorhombic structure after 3 hours of synthesis. The main vibrational modes were identified by Raman spectroscopy, while diffuse reflectance UV-vis spectroscopy revealed a band gap of 3.21(4) eV for the sample synthesized after 3 hours of milling. Electrochemical tests using a BaNb2O6-modified glassy carbon electrode, synthesized for 3 hours, showed a nearly reversible profile in the cyclic voltammetry curves in potassium ferrocyanide, in the scan rate range of 1 to 100 mVs-1. The decomposition of capacitive and controlled diffusion contributions indicated the predominance of controlled diffusion in the redox processes. Therefore, it is suggested that the BaNb2O6 sample synthesized by this route exhibits promising properties for applications as a solid-state electrolyte for energy storage and as an electrochemical sensor.

Inventors

• JOSÉ FÁBIO DE LIMA NASCIMENTO
• FRANCISCO XAVIER NOBRE
• JOÃO NAZARENO NONATO QUARESMA

Assignees

• UNIVERSIDADE FEDERAL DO PARÁ

Dates

Publication Date

20260310

Application Date

20240829

Claims (1)

1. 1. OBTAINING BaNb2O6 THROUGH HIGH-ENERGY MILLING AT ROOM TEMPERATURE, WITH PROPERTIES THAT ALLOW ITS USE AS A SOLID-STATE ELECTROLYTE FOR ENERGY STORAGE AND/OR ELECTROCHEMICAL SENSOR, characterized by the use of the high-energy milling synthesis technique at room temperature to obtain barium niobate (BaNb2O6) from the precursors niobium pentoxide (Nb2O5) and barium carbonate (BaCO3), where the mass proportions of the precursors Nb2O5 and BaCO3 vary between 35% and 45% and 55% and 65%, respectively, and are subjected to high-energy milling for periods of 0.5 to 8 hours, in a free or controlled atmosphere, with a mass/ball ratio between 1:8 and 1:20.

Description

Field of Invention [001] The present invention relates to a new process for the production of barium niobate (BaNb2O6) by means of mechanical milling of the precursors niobium pentoxide (Nb2O5) and barium carbonate (BaCO3) at room temperature, with application in the area of manufacturing solid-state electrolytes for energy storage and electrochemical sensors. The proposed technique for the synthesis of BaNb2O6 stands out for its low cost, due to the short synthesis time, approximately 3 hours, to reach the desired phase and the absence of the need for heat treatment after milling the precursors. Fundamentals of the invention [002] Barium niobates (BaNb2O6) have a perovskite-type crystal structure, which confers interesting properties in various applications, such as piezoelectricity, pyroelectricity, electro-optics, ceramic capacitors, and as catalysts in photocatalytic processes. Currently, several methods have been adopted for the synthesis of alkaline earth metal niobates, such as BaNb2O6, including solid-state synthesis, hydrothermal, solvothermal, and sol-gel techniques. However, the high temperatures, long synthesis time, and the addition of surfactants or organic solvents are the main disadvantages of chemical synthesis. [003] In this context, the high-energy milling method emerges as a promising approach to obtain high-entropy nanomaterials or semiconductors that crystallize at high temperatures. Direct synthesis by high-energy milling reduces synthesis time, allowing the use of oxides or carbonates as precursors for the production of powders on nanometric scales (BR102017017416-6). [004] Barium niobate (BaNb2O6) is used in the production of electronic devices, such as high-capacitance capacitors and piezoelectric materials. In addition, it is possible to dope this compound with other elements in order to alter its properties. For example, the introduction of rare earth ions can result in the creation of materials capable of emitting visible or infrared light. [005] In order to evaluate the electrical energy storage capacity of the ceramic material BaNb2O6 (BN) with different sintering times, BN was synthesized by the solid-state reaction method. High-purity precursors BaCO3 and Nb2O5 were used in stoichiometric proportions as starting materials. The powder mixture was manually ground using an agate mortar and pestle for 6 hours in a humid medium (acetone + distilled water). The mixed powder was dried under an infrared lamp to obtain a paste, which was calcined in a closed alumina crucible inside a programmable furnace at different temperatures: 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C and 1150°C for 6 hours to study the phase formation of the material. The calcination process corresponding to each temperature was carried out on a freshly mixed initial precursor. The formation of the phase was confirmed by analyzing the X-ray diffraction pattern, revealing the desired crystalline phase in the temperature range above 1100 °C (KUSHVAHA, D. K.; TIWARI, B.; ROUT, S. K., 2020, “Enhancement of electrical energy storage ability by controlling grain size of polycrystalline BaNb2O6 for high density capacitor application”, Journal of Alloys and Compounds, v. 829). [006] To study the structural, microstructural, and electrical behavior of the Bio,5(Nao,8Ko,2)o,5Tiθ3-BaNb2θ6 (BNKT-BN) composite, the individual polycrystalline phases of BNKT and BN were prepared separately by the solid-state reaction method. For the synthesis of BaNb2O6 (BN), high-purity precursors, BaCO3 and Nb2O5, were used in the appropriate stoichiometric ratio. The powder mixture was manually ground using an agate mortar and pestle for 6 hours in a moist medium (acetone + distilled water). The mixed powder was dried under an infrared lamp to obtain a paste, which was calcined in a closed alumina crucible inside a programmable furnace at a temperature of 1150 °C for 4 hours. The calcined BNKT powder, heated at 950 °C for 2 hours, and the BN powder, heated at 1150 °C for 4 hours, were mixed and ground for 6 hours in a moist medium (acetone and distilled water) to prepare the composite (KUSHVAHA, D. K.; ROUT, S. K.; TIWARI, B., 2022, “Significant modulation in field-induced energy storage capability of BNKT-BN ceramics”, Physica B: Condensed Matter, v. 640). [007] To study the ferroelectric and piezoelectric properties of the Bao,9Sro,iTio,9Zro,iθ3-BaNb2θ6 (BSTZ-BNO) composite, the individual polycrystalline phases of BSTZ and BNO were prepared separately by the high-energy ball milling method. For the synthesis of barium niobate (BNO), high-purity chemicals were used as precursors; barium carbonate (purity: 99.99%) and niobium pentoxide (purity: 99.99%) in stoichiometric proportion were milled together with toluene to synthesize the BaNb2O6 solid solution for 24 hours at room temperature. The milled powder was calcined at 625°C for 1 h, followed by high-temperature sintering at 1200°C for 5 h. Subsequently, the solid solution composed of B