This work involves preparing polymer nanocomposites to improve thermal and dielectric properties. X-ray diffraction, SEM, FTIR, TGA and dielectric measurements were applied for these films. The cubic crystal structure of appeared in XRD spectra and the average size was 39 nm. The sample with a concentration of 1.0 wt% achieved the highest intensity of the β-phase peak at 20.2°. The surface images of these samples were of high homogeneity as recorded by SEM microscopy. FTIR analysis showed absorption bands correlated with α, β and γ-phase. The percentage in β-phase in the nanocomposite films improved with an increase in the ratio from 1.0 to 3.0 wt%, especially at 1.0 wt%. From TGA analyzes, it was confirmed that the thermal stability improved with an increase in the yttrium oxide percentage. All of the nanocomposite films had higher values ​​of ΔS, ΔH and ΔG than the pure PVDF film. The dielectric permittivity and energy density of the nanocomposite films improved, especially at 1.0 wt%. The energy density at 0.1 Hz has the values​​ and at the ratios 0.0, 1.0, 2.0 and 3.0 wt% of This work involves preparing polymer nanocomposites to improve thermal and dielectric properties. X-ray diffraction, SEM, FTIR, TGA and dielectric measurements were applied for these films. The cubic crystal structure of appeared in XRD spectra and the average size was 39 nm. The sample with a concentration of 1.0 wt% achieved the highest intensity of the β-phase peak at 20.2°. The surface images of these samples were of high homogeneity as recorded by SEM microscopy. FTIR analysis showed absorption bands correlated with α, β and γ-phase. The percentage in β-phase in the nanocomposite films improved with an increase in the ratio from 1.0 to 3.0 wt%, especially at 1.0 wt%. From TGA analyzes, it was confirmed that the thermal stability improved with an increase in the yttrium oxide percentage. All of the nanocomposite films had higher values ​​of ΔS, ΔH and ΔG than the pure PVDF film. The dielectric permittivity and energy density of the nanocomposite films improved, especially at 1.0 wt%. The energy density at 0.1 Hz has the values​​ and at the ratios 0.0, 1.0, 2.0 and 3.0 wt% of This work involves preparing polymer nanocomposites to improve thermal and dielectric properties. X-ray diffraction, SEM, FTIR, TGA and dielectric measurements were applied for these films. The cubic crystal structure of appeared in XRD spectra and the average size was 39 nm. The sample with a concentration of 1.0 wt% achieved the highest intensity of the β-phase peak at 20.2°. The surface images of these samples were of high homogeneity as recorded by SEM microscopy. FTIR analysis showed absorption bands correlated with α, β and γ-phase. The percentage in β-phase in the nanocomposite films improved with an increase in the ratio from 1.0 to 3.0 wt%, especially at 1.0 wt%. From TGA analyzes, it was confirmed that the thermal stability improved with an increase in the yttrium oxide percentage. All of the nanocomposite films had higher values ​​of ΔS, ΔH and ΔG than the pure PVDF film. The dielectric permittivity and energy density of the nanocomposite films improved, especially at 1.0 wt%. The energy density at 0.1 Hz has the values​​ and at the ratios 0.0, 1.0, 2.0 and 3.0 wt% of Y2O3. The loss tangent values for these nanocomposite films decreased at low frequencies while increased at higher frequencies as the content of increased. A marked improvement in εs, ε∞, Δε, AC and DC conductivity was observed with an increase in content.. The loss tangent values for these nanocomposite films decreased at low frequencies while increased at higher frequencies as the content of increased. A marked improvement in εs, ε∞, Δε, AC and DC conductivity was observed with an increase in content.. The loss tangent values for these nanocomposite films decreased at low frequencies while increased at higher frequencies as the content of increased. A marked improvement in εs, ε∞, Δε, AC and DC conductivity was observed with an increase in content.