Tailoring the dielectric constant, optical, and magnetic properties of La(OH)₃ nanostructures for microwave dielectric applications

Lanthanum hydroxide [La(OH)₃] nanoparticles with high dielectric constant and low dielectric loss are precious for developing microwave dielectric applications. In this work, La(OH)₃ nanoparticles were produced in three different molar concentrations (0.5 M, 1 M, 1.5 M) of oxidant and fuel using a simple urea-assisted combustion process. The synthesized La(OH)₃ samples were characterized by X-ray diffraction, High-resolution transmission electron microscopy (HR-TEM) spectroscopy, Selected area electron diffraction (SAED), Energy-dispersive X-ray absorption spectroscopy (EDAX), Impedance Spectroscopy (IS), Photoluminescence (PL) spectroscopy, and Vibrating sample magnetometer techniques. The X-ray diffraction peaks confirmed that the prepared La(OH)₃ nanoparticles were highly crystalline and revealed a hexagonal structure for all the three molar concentrations that belong to the space group of P63/m. HR-TEM images of La(OH)₃ nanoparticles prepared at 1M revealed the degree of coalescence with similar distributions of sizes, and its SAED pattern of La(OH)₃ nanoparticles confirmed that the prepared sample is a polycrystalline nature. EDAX spectra showed that the elements of the synthesized compound La and O are present in all three molar concentrations. The Impedance Spectroscopy (IS) investigation showed the dispersive nature of grain boundaries caused by space charge polarization with an increase in molar concentrations. The dielectric constant and dielectric loss of La(OH)₃ nanoparticles were explored using the frequency dependence curve with a high dielectric constant and loss of the sample prepared with 1 molar ratio, making it suitable for microwave dielectric applications. Besides these, photoluminescence spectra and magnetic analysis were also studied.