Fabrication and Characterization of Dielectric ZnCr2O4 Nanopowders and Thin Films for Parallel-Plate Capacitor Applications
Vasyl MykhailovychGabriel CaruntuAdrian GraurMariia MykhailovychP. FochukІ. М. ФодчукG.‐M. RotaruAurelian Rotaru
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We report here the successful shape-controlled synthesis of dielectric spinel-type ZnCr2O4 nanoparticles by using a simple sol-gel auto-combustion method followed by successive heat treatment steps of the resulting powders at temperatures from 500 to 900 °C and from 5 to 11 h, in air. A systematic study of the dependence of the morphology of the nanoparticles on the annealing time and temperature was performed by using field effect scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD) and structure refinement by the Rietveld method, dynamic lattice analysis and broadband dielectric spectrometry, respectively. It was observed for the first time that when the aerobic post-synthesis heat treatment temperature increases progressively from 500 to 900 °C, the ZnCr2O4 nanoparticles: (i) increase in size from 10 to 350 nm and (ii) develop well-defined facets, changing their shape from shapeless to truncated octahedrons and eventually pseudo-octahedra. The samples were found to exhibit high dielectric constant values and low dielectric losses with the best dielectric performance characteristics displayed by the 350 nm pseudo-octahedral nanoparticles whose permittivity reaches a value of ε = 1500 and a dielectric loss tan δ = 5 × 10−4 at a frequency of 1 Hz. Nanoparticulate ZnCr2O4-based thin films with a thickness varying from 0.5 to 2 μm were fabricated by the drop-casting method and subsequently incorporated into planar capacitors whose dielectric performance was characterized. This study undoubtedly shows that the dielectric properties of nanostructured zinc chromite powders can be engineered by the rational control of their morphology upon the variation of the post-synthesis heat treatment process.Keywords:
Dielectric loss
Rietveld Refinement
Novel polymer-based composites with high dielectric constant and low dielectric loss were prepared by simply mixing polyvinylidene fluoride (PVDF) with semiconductor vanadium pentoxide (V2O5) filler. V2O5 nanobelts with diameter around 50 nm and length up to micrometer scale were uniformly distributed in PVDF matrix without serious aggregation. The PVDF/V2O5 composites show excellent dielectric properties. When the volume fraction of V2O5 is 0.15 and the frequency is 100 Hz, the dielectric constant of the composites can reach as high as 140 and the dielectric loss is 0.7. Both dielectric constant and dielectric loss of the composites show but sharp increase when the volume fraction of V2O5 is above 0.15. Furthermore, the dependences of the dielectric constant and dielectric loss on frequency were also studied. With the increase of frequency from 102 to 107 Hz, dielectric constant of the PVDF/V2O5 composites decreases, while the dielectric loss increases slightly. The results indicate that the PVDF/V2O5 composites are promising materials for capacitors.
Polyvinylidene fluoride
Dielectric loss
High-κ dielectric
Volume fraction
Pentoxide
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This project studied the effect of MgTi03 (MT) addition on CaCu3Ti40i2 (CCTO). Recently an oxide ceramic CCTO was reported that exhibits very high dielectric constant value, which is desirable for many microelectric applications. However, the dielectric loss of the material is relatively and become less useable. Therefore, in this work, CCTO is doped with MT in order to lower the dielectric loss. The MT-doped CCTO was prepared by using solid state reaction method. The MT doped with CCTO, calcining at 1000°C for 12 hours and sintered at 1100°C for 24 hours. Effect of MT dopant to the dielectric properties of CCTO had been studied. The high dielectric constant and low dielectric loss was observed at 0.1, and 0.2 MT dopant compared from its pure samples (X= 0). However for 0.3 MT dopant was dropped from high value of dielectric constant to the lowest value and result in high dielectric loss. Over the wide frequency range, 0.1 MT was more stable then other samples that always present high dielectric constant and low dielectric constant compared with undoped CCTO and other sample. This result indicates that certain MT dopant can be used to improve the dielectric properties of CCTO.
Dielectric loss
High-κ dielectric
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Dielectric loss
Thermal Stability
High-κ dielectric
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Rietveld Refinement
Powder Diffraction
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Dielectric loss
Diffractometer
High-κ dielectric
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Dielectric loss
Thermal Stability
High-κ dielectric
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Dissipation factor
Dielectric loss
Atmospheric temperature range
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A new A site complex lead-free ferroelectric ceramics of(1-x-y)BNT-xBKT-yBiCoO3 was prepared by a conventional ceramic sintering technique.The relation between composition and dielectric properties,dielectric properties and frequency were investigated.It was found that the dielectric constant and dielectric loss of unpoled samples is higher that those of poled samples.The dielectric constant and dielectric loss of unpoled samples decrease with the increase content of BiCoO3.The dielectric constant and dielectric loss of unpoled and poled samples increase with the content of BKT increasing.The dielectric constant decreases with frequency increasing,and the decreasing trend become slowly.The dielectric loss first decrease and then increase with increasing frequency.
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Ferroelectric ceramics
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Dielectric loss
Atmospheric temperature range
High-κ dielectric
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In order to develop infinite capacitive materials with high dielectric constant and low dielectric loss, influences of Y/Mn co-doping and ZrO 2 coating on the dielectric properties of barium strontium tinanate/polyvinylidene fluoride (BST/PVDF) composite films were systematically investigated with fixing Y concentration as 0.3 at.% and varying Mn concentration from 1 at.% to 4 at.%. The experimental results show that the dielectric constant of BST@ZrO 2 /PVDF composite increases by 50% relative to BST/PVDF and the dielectric loss is evidently depressed. In comparison with BST@ZrO 2 /PVDF sample, furthermore, the dielectric constant of Y/Mn co-doped BST@ZrO 2 /PVDF samples increases by about 60% and the dielectric loss further reduces at 1 kHz. The promoted dielectric performances of composite originate from the space charge separation formed by Y/Mn co-doping and the limitation of electronic mobility by coated ZrO 2 . Y/Mn co-doped BST@ZrO 2 /PVDF composite film with 3% Mn has a dielectric constant of 37.9, a dielectric loss of 0.0117, superior dielectric temperature stability (3.1% from −5[Formula: see text]C to 45[Formula: see text]C at 1 kHz), and a discharged energy density of 5.67 J/cm 3 at 600 kV/cm. The simultaneous optimization of dielectric constant and dielectric loss of BST/PVDF composite is realized in this experiment. The superior dielectric temperature stability suggests the application potential of Y/Mn co-doped BST@ZrO 2 /PVDF as wearable capacitors.
Dielectric loss
High-κ dielectric
Polyvinylidene fluoride
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