Structural and dielectric properties of green synthesized SnO₂ nanoparticles

Abstract The present research study provides an analysis of the structural and dielectric characteristics of SnO 2 nanoparticles (SnO 2 -NPs) synthesized by the green synthesis approach. Powder x-ray diffraction (PXRD) investigation indicates the existence of a single tetragonal phase with the P42/mnm space group. The crystallite size and lattice strain of the tetragonal SnO 2 -NPs were determined through x-ray peak broadening analysis. The average crystallite size calculated by high-resolution transmission electron microscopy (HR-TEM) was 16 nm. Fourier transform infrared spectroscopy (FTIR) within the 530 to 644 cm −1 range confirms the vibration modes of Sn-O-Sn and Sn-O. The vibrational modes observed in the Raman spectra confirm the tetragonal rutile-type structure of the synthesized SnO 2 -NPs. The dielectric characteristics of SnO 2 -NPs were investigated within a temperature range of 353–433 K and a frequency range of 50 Hz –5 MHz. The total conductivity exhibits frequency dependence according to Jonscher’s power law <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>σ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>t</mml:mi> </mml:mrow> </mml:msub> <mml:mrow> <mml:mfenced close=")" open="("> <mml:mrow> <mml:mi>ω</mml:mi> </mml:mrow> </mml:mfenced> </mml:mrow> <mml:mo>=</mml:mo> <mml:msub> <mml:mrow> <mml:mi>σ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">dc</mml:mi> </mml:mrow> </mml:msub> <mml:mo>+</mml:mo> <mml:mi>A</mml:mi> <mml:msup> <mml:mrow> <mml:mi>ω</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> </mml:msup> <mml:mo stretchy="false">)</mml:mo> </mml:math> . The correlated barrier hopping (CBH) model is found to be the dominant conduction mechanism in the studied material. The direct current (DC) conductivity appears to be thermally activated, with an activation energy of 307 mev. The analysis of dielectric characteristics demonstrated that the real ( ε′ ) and imaginary ( ε ″) parts of the dielectric constant drop with frequency and increase with temperature. The dielectric modulus indicates the presence of non-Debye relaxation within the material. The relaxation time, based on the analysis of the imaginary component of the modulus (M″), follows the Arrhenius equation. An equivalent-circuit model was used to analyze the impedance spectroscopy results, which indicated the existence of a temperature-dependent electrical relaxation phenomena of the non-Debye nature.