Researching | JAD Volume 11 Issue 1,2021

Engineering of dielectric composites on electromagnetic and microwave absorbing properties for operation in the X-band

Bhoopendra Singh, Vivek Pratap, Mohit Katiyar, S. M. Abbas, Y. K. Sharma, A. M. Siddiqui, and N. Eswara Prasad

In this study, carbon black (CB) powder-loaded polyurethane (PU) composites (CB–PU composites) were prepared by melt mixing method with different volume percentages (45, 50, 55, 58 and 61 vol.%) of CB in the PU matrix. The prepared CB–PU composites had been further studied for surface morphology using the field-emissio In this study, carbon black (CB) powder-loaded polyurethane (PU) composites (CB–PU composites) were prepared by melt mixing method with different volume percentages (45, 50, 55, 58 and 61 vol.%) of CB in the PU matrix. The prepared CB–PU composites had been further studied for surface morphology using the field-emission scanning electron microscopy (FESEM) technique. Dielectric properties in terms of real permittivity (

𝜀')

and imaginary permittivity (

𝜀'')

of the fabricated composites were computed using an Agilent E8364B vector network analyzer in the frequency range of 8–12 GHz (

X

-band). Dielectric loss factor of the prepared CB–PU composites was computed in terms of the dielectric loss tangent (tan

δ_{e}

=

𝜀''

/

𝜀')

. Microwave absorbing properties were appraised in terms of the reflection loss (RL) which in turn was calculated for varying thicknesses of the prepared composites from the measured real and imaginary permittivity data. The minimum RL was observed as −20.10 dB for the absorber with a thickness of 2.2 mm and the bandwidth achieved was 1.92 GHz for RL

\leq -

10 dB. Based on the above results these CB–PU composites have potential use as effective microwave absorbers in 8–12-GHz (

X

-band) frequency range.In this study, carbon black (CB) powder-loaded polyurethane (PU) composites (CB–PU composites) were prepared by melt mixing method with different volume percentages (45, 50, 55, 58 and 61 vol.%) of CB in the PU matrix. The prepared CB–PU composites had been further studied for surface morphology using the field-emission scanning electron microscopy (FESEM) technique. Dielectric properties in terms of real permittivity (

𝜀')

and imaginary permittivity (

𝜀'')

of the fabricated composites were computed using an Agilent E8364B vector network analyzer in the frequency range of 8–12 GHz (

X

-band). Dielectric loss factor of the prepared CB–PU composites was computed in terms of the dielectric loss tangent (tan

δ_{e}

=

𝜀''

/

𝜀')

. Microwave absorbing properties were appraised in terms of the reflection loss (RL) which in turn was calculated for varying thicknesses of the prepared composites from the measured real and imaginary permittivity data. The minimum RL was observed as −20.10 dB for the absorber with a thickness of 2.2 mm and the bandwidth achieved was 1.92 GHz for RL

\leq -

10 dB. Based on the above results these CB–PU composites have potential use as effective microwave absorbers in 8–12-GHz (

X

-band) frequency range..

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150001 (2021)

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Synthesis and characterization of strontium-doped barium titanate thin film by dip and dry technique

S. G. Chavan, A. N. Tarale, and D. J. Salunkhe

Thin films of polycrystalline (Ba1−xSrx)TiO3 (x = 0.2 and 0.3) with Perovskite structure were prepared by a dip and dry technique on a platinum-coated silicon substrate. The good quality thin films with uniform microstructure and thickness were successfully produced by dip-coating techniques annealed at 730∘C for 1 h.

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150002 (2021)

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Structural and dielectric properties of sol–gel processed Ce-doped

{BaTi}_{0.97} Y_{0.03} O_{3}

ceramics

Aziz Nfissi, Yahya Ababou, Mounir Belhajji, Salaheddine Sayouri, and Taj-dine Lamcharfi

Structural and dielectric properties of Ce-doped BaTi0.97Y0.03O3 powders, with the chemical formulation (Ba1−xCex)(Ti(0.97−x/4)- Y0.03)O3 such as x = 0%, 1%, 3%, 5%, 7% and 9%, produced by the sol–gel method, have been investigated. X-ray diffraction analysis showed that Ce3+ ions incorporated Ba sites until x= 7% indi Structural and dielectric properties of Ce-doped

{BaTi}_{0.97}

Y_{0.03}

O₃ powders, with the chemical formulation (Ba

{_{1 -}}_{x}

{Ce}_{x})

(Ti(

{_{0.97 -}_{x}}_{/ 4})

-

Y_{0.03})

O₃ such as

x

= 0%, 1%, 3%, 5%, 7% and 9%, produced by the sol–gel method, have been investigated. X-ray diffraction analysis showed that Ce

^{3 +}

ions incorporated Ba sites until

x

= 7% indicating that this concentration represents a solubility limit of Ce

^{3 +}

ions in

{BaTi}_{0.97}

Y_{0.03}

O₃ matrix. Scanning electron microscopy (SEM) analysis showed a decrease in grain size down to the same concentration of 7%. Raman spectroscopy analysis showed the appearance of

A_{1 g}

mode, which we attributed to the effect of incorporation of Ce

^{3 +}

and Y

^{3 +}

in BaTiO₃ matrix. Dielectric measurements revealed that doping with cerium lowers the temperature of permittivity maximum at the ferroelectric-to-paraelectric transition (FPT) of the

{BaTi}_{0.97}

Y_{0.03}

O₃ sample, and reaches a value that should be below

40^{\circ}

C for

x

= 9%. Moreover, the phenomenon of dielectric resonance was observed on all Ce-doped samples, which was not the case with other dopants as reported in the literature.Structural and dielectric properties of Ce-doped

{BaTi}_{0.97}

Y_{0.03}

O₃ powders, with the chemical formulation (Ba

{_{1 -}}_{x}

{Ce}_{x})

(Ti(

{_{0.97 -}_{x}}_{/ 4})

-

Y_{0.03})

O₃ such as

x

= 0%, 1%, 3%, 5%, 7% and 9%, produced by the sol–gel method, have been investigated. X-ray diffraction analysis showed that Ce

^{3 +}

ions incorporated Ba sites until

x

= 7% indicating that this concentration represents a solubility limit of Ce

^{3 +}

ions in

{BaTi}_{0.97}

Y_{0.03}

O₃ matrix. Scanning electron microscopy (SEM) analysis showed a decrease in grain size down to the same concentration of 7%. Raman spectroscopy analysis showed the appearance of

A_{1 g}

mode, which we attributed to the effect of incorporation of Ce

^{3 +}

and Y

^{3 +}

in BaTiO₃ matrix. Dielectric measurements revealed that doping with cerium lowers the temperature of permittivity maximum at the ferroelectric-to-paraelectric transition (FPT) of the

{BaTi}_{0.97}

Y_{0.03}

O₃ sample, and reaches a value that should be below

40^{\circ}

C for

x

= 9%. Moreover, the phenomenon of dielectric resonance was observed on all Ce-doped samples, which was not the case with other dopants as reported in the literature..

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150003 (2021)

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Ultralow switching voltage and power consumption of GeS₂ thin film resistive switching memory

N. Lyapunov, C. H. Suen, C. M. Wong, Xiaodan Tang, Z. L. Ho, K. Zhou, X. X. Chen, H. M. Liu, Xiaoyuan Zhou, and J. Y. Dai

The coming Big Data Era requires progress in storage and computing technologies. As an emerging memory technology, Resistive RAM (RRAM) has shown its potential in the next generation high-density storage and neuromorphic computing applications, which extremely demand low switching voltage and power consumption. In this The coming Big Data Era requires progress in storage and computing technologies. As an emerging memory technology, Resistive RAM (RRAM) has shown its potential in the next generation high-density storage and neuromorphic computing applications, which extremely demand low switching voltage and power consumption. In this work, a 10 nm-thick amorphous GeS₂ thin film was utilized as the functional layer of RRAM in a combination with Ag and Pt electrodes. The structure and memory performance of the GeS₂-based RRAM device was characterized — it presents high on/off ratio, fast switching time, ultralow switching voltage (0.15 V) and power consumption (1.0 pJ and 0.56 pJ for PROGRAM and ERASE operations, respectively). We attribute these competitive memory characteristics to Ag doping phenomena and subsequent formation of Ag nano-islands in the functional layer that occurs due to diffusion of Ag from electrode into the GeS₂ thin film. These properties enable applications of GeS₂ for low energy RRAM device.The coming Big Data Era requires progress in storage and computing technologies. As an emerging memory technology, Resistive RAM (RRAM) has shown its potential in the next generation high-density storage and neuromorphic computing applications, which extremely demand low switching voltage and power consumption. In this work, a 10 nm-thick amorphous GeS₂ thin film was utilized as the functional layer of RRAM in a combination with Ag and Pt electrodes. The structure and memory performance of the GeS₂-based RRAM device was characterized — it presents high on/off ratio, fast switching time, ultralow switching voltage (0.15 V) and power consumption (1.0 pJ and 0.56 pJ for PROGRAM and ERASE operations, respectively). We attribute these competitive memory characteristics to Ag doping phenomena and subsequent formation of Ag nano-islands in the functional layer that occurs due to diffusion of Ag from electrode into the GeS₂ thin film. These properties enable applications of GeS₂ for low energy RRAM device..

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150004 (2021)

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Electrical conductivity and vibrational studies induced phase transition in [N(C₃

H_{7})_{4}

]₂ZnBr₄ compound

Souad Chkoundali, and Abdelhedi Aydi

Bis-Tetrapropylammonium tetrabromozincate was synthesized and characterized by X-ray powder diffraction, as well as vibrational and impedance spectroscopy. Rietveld’s refinement of X-ray diffractogram confirmed the crystallization of the compound through the monoclinic system (space group C2/c). A temperature study of Bis-Tetrapropylammonium tetrabromozincate was synthesized and characterized by X-ray powder diffraction, as well as vibrational and impedance spectroscopy. Rietveld’s refinement of X-ray diffractogram confirmed the crystallization of the compound through the monoclinic system (space group

C_{2 / c})

. A temperature study of Raman scattering revealed two phase transitions at approximately

T_{1}

= 340 K and

T_{2}

= 393 K. The wavenumber and the line width’s evolution as a function of temperature showed some peculiarities associated with these transitions, which suggests that they are governed by the reorientation of the organic part [N(C₃

H_{7})_{4}

]

^{+}

. The complex impedance plotted as a double semicircular arc in the studied temperature range and the centers of these semicircles lie below the real axis, which indicates that the material is an on-Debye type. These semicircular arcs are related to the bulk and the grain boundary effects. Furthermore, the alternating current conductivity of [N(C₃

H_{7})_{4}

]₂ZnBr₄ obeyed Jonscher’s law:

σ_{A C} (ω)

=

σ_{d c} + A ω^{s}

and the conduction could be attributed to the correlated barrier hopping (CBH) model in both region(I) and (II) and the Non-overlapping Small Polaron Tunneling (NSPT) in region (III).Bis-Tetrapropylammonium tetrabromozincate was synthesized and characterized by X-ray powder diffraction, as well as vibrational and impedance spectroscopy. Rietveld’s refinement of X-ray diffractogram confirmed the crystallization of the compound through the monoclinic system (space group

C_{2 / c})

. A temperature study of Raman scattering revealed two phase transitions at approximately

T_{1}

= 340 K and

T_{2}

= 393 K. The wavenumber and the line width’s evolution as a function of temperature showed some peculiarities associated with these transitions, which suggests that they are governed by the reorientation of the organic part [N(C₃

H_{7})_{4}

]

^{+}

. The complex impedance plotted as a double semicircular arc in the studied temperature range and the centers of these semicircles lie below the real axis, which indicates that the material is an on-Debye type. These semicircular arcs are related to the bulk and the grain boundary effects. Furthermore, the alternating current conductivity of [N(C₃

H_{7})_{4}

]₂ZnBr₄ obeyed Jonscher’s law:

σ_{A C} (ω)

=

σ_{d c} + A ω^{s}

and the conduction could be attributed to the correlated barrier hopping (CBH) model in both region(I) and (II) and the Non-overlapping Small Polaron Tunneling (NSPT) in region (III)..

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150005 (2021)

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Critical temperature below the Curie temperature of ferroelectric ceramics PZT

D. V. Kuzenko

The article presents the results of research the pre-transitional features of the behavior of solid solutions based on lead zirconate-titanate. The presence of a “special” critical temperature Td on the temperature dependences of the permittivity 𝜀(T) and the remanent polarization Pr(T), preceding the temperatu

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150006 (2021)

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Dielectric properties and electrical response of yttrium-doped

{Bi}_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics

Longhai Yang, Luwen Song, Qi Li, and Tao Zhang

(YxBi1−x)2/3Cu3Ti4O12 (x= 0.00–0.30) ceramics were successfully prepared via the conventional solid-state method. X-ray powder diffraction confirmed the lattice constant gradually decreases with increasing Y3+ content. SEM images displayed Y3+ substitution for Bi3+ gave rise to the large abnormal grains, and the size o (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

(

x =

0.00–0.30) ceramics were successfully prepared via the conventional solid-state method. X-ray powder diffraction confirmed the lattice constant gradually decreases with increasing Y

{^{3}}^{+}

content. SEM images displayed Y

{^{3}}^{+}

substitution for Bi

{^{3}}^{+}

gave rise to the large abnormal grains, and the size of abnormal grains became larger with the increase of Y

{^{3}}^{+}

substitution. (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics presented the relatively high dielectric constant of 7400 with the dielectric loss of 0.055 when

x =

0.20. The analysis of complex impedance suggested the grains are semiconductive and the grain boundaries are insulating. For pure

{Bi}_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics, the appearance of additional low-frequency peaks in electrical modulus indicated the grain boundaries are heterogeneous. The investigation of modulus peaks fitting with Arrhenius formula implied that the low-frequency permittivity for all (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics was ascribed to the Maxwell–Wagner relaxation at grain boundaries. In addition, a set of clear dielectric peaks above

200^{\circ}

C associated with Maxwell–Wagner relaxation can be found for all (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics in the temperature dependence of dielectric constant. This set of clear dielectric peaks showed a tendency to shift to higher temperatures with the increase of Y

{^{3}}^{+}

substitution. Meanwhile, a tiny dielectric anomaly at room temperature was found in Y-doped

{Bi}_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics.(

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

(

x =

0.00–0.30) ceramics were successfully prepared via the conventional solid-state method. X-ray powder diffraction confirmed the lattice constant gradually decreases with increasing Y

{^{3}}^{+}

content. SEM images displayed Y

{^{3}}^{+}

substitution for Bi

{^{3}}^{+}

gave rise to the large abnormal grains, and the size of abnormal grains became larger with the increase of Y

{^{3}}^{+}

substitution. (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics presented the relatively high dielectric constant of 7400 with the dielectric loss of 0.055 when

x =

0.20. The analysis of complex impedance suggested the grains are semiconductive and the grain boundaries are insulating. For pure

{Bi}_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics, the appearance of additional low-frequency peaks in electrical modulus indicated the grain boundaries are heterogeneous. The investigation of modulus peaks fitting with Arrhenius formula implied that the low-frequency permittivity for all (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics was ascribed to the Maxwell–Wagner relaxation at grain boundaries. In addition, a set of clear dielectric peaks above

200^{\circ}

C associated with Maxwell–Wagner relaxation can be found for all (

Y_{x}

Bi

{_{1 -}}_{x})_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics in the temperature dependence of dielectric constant. This set of clear dielectric peaks showed a tendency to shift to higher temperatures with the increase of Y

{^{3}}^{+}

substitution. Meanwhile, a tiny dielectric anomaly at room temperature was found in Y-doped

{Bi}_{2 / 3}

Cu₃Ti₄

O_{12}

ceramics..

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150007 (2021)

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Synthesis of novel PANI-based Ti(IV) phosphosulphosalicylate composite cation exchanger — structural, electrical, and impedance properties

T. Amutha, and K. Jacinth Mispa

In order to combine the properties of inorganic ion exchanger and conducting organic polymer, a new class of organic–inorganic composite cation exchanger PANI–Ti(IV) phosphosulphosalicylate (PTPSS) was synthesized by intercalating polyaniline (PANI) into Ti(IV) phosphosulphosalicylate (Ti(IV) PSS) using sol–gel chemica In order to combine the properties of inorganic ion exchanger and conducting organic polymer, a new class of organic–inorganic composite cation exchanger PANI–Ti(IV) phosphosulphosalicylate (PTPSS) was synthesized by intercalating polyaniline (PANI) into Ti(IV) phosphosulphosalicylate (Ti(IV) PSS) using sol–gel chemical route with enhanced properties. PTPSS has been characterized by using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDAX), thermo gravimetric analysis (TGA-DTG), and Transmission Electron Microscopy (TEM). Ac electrical conductivity studies were also performed. This material possessed electrical conductivity of

10^{- 3}

–

10^{- 6}

{Scm}^{- 1}

which falls in the semiconducting range. The frequency (2 × 10⁵ – 1 × 10⁶ Hz) dependent Ac conductivity at room temperature suggests the evidence for the transport mechanism for the conductivity in PTPSS. The structure of the composite cation exchanger extremely supports its conducting behavior.In order to combine the properties of inorganic ion exchanger and conducting organic polymer, a new class of organic–inorganic composite cation exchanger PANI–Ti(IV) phosphosulphosalicylate (PTPSS) was synthesized by intercalating polyaniline (PANI) into Ti(IV) phosphosulphosalicylate (Ti(IV) PSS) using sol–gel chemical route with enhanced properties. PTPSS has been characterized by using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDAX), thermo gravimetric analysis (TGA-DTG), and Transmission Electron Microscopy (TEM). Ac electrical conductivity studies were also performed. This material possessed electrical conductivity of

10^{- 3}

–

10^{- 6}

{Scm}^{- 1}

which falls in the semiconducting range. The frequency (2 × 10⁵ – 1 × 10⁶ Hz) dependent Ac conductivity at room temperature suggests the evidence for the transport mechanism for the conductivity in PTPSS. The structure of the composite cation exchanger extremely supports its conducting behavior..

Journal of Advanced Dielectrics

Publication Date: Jan. 01, 1900
Vol. 11, Issue 1, 2150008 (2021)

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