Authors:S. K. Sinha, S. Kumari, R. K. Chaudhary Abstract: Journal of Advanced Dielectrics, Volume 09, Issue 02, April 2019. Incorporation of Te and Gd were done based on the stoicheometric formula PbTi[math] Te[math]GdxO3 (PTTeG). TG characterization of green powder revealed the completion of solid state reaction at temperature 450∘ C. XRD of modified PTTeG powders milled for 10[math]h was found most suitable as it gives pure single-phase tetragonal structure. Dielectric constant was found as 2543 at curie temperature of 480∘C in the case of 5[math]wt.% of Gd in PTTeG. Piezoelectric Coefficient was found as 241 [math] 10 [math] C/N at 39[math]Kv/cm of poling field. The results obtained were comparable and even better than so far reported in similar kind of materials. Citation: Journal of Advanced Dielectrics PubDate: 2019-05-16T06:04:19Z DOI: 10.1142/S2010135X19500176

Authors:Poonam Kumari, Madan Lal, Sunil Kumar, Radheshyam Rai, Anupinder Singh, D. V. Karpinsky, Igor Bdikin Abstract: Journal of Advanced Dielectrics, Volume 09, Issue 02, April 2019. In this research paper, we utilized the traditional high-temperature solid-state reaction method to fabricate the K[math]Na[math]NbO3, K[math]Na[math]NbO3 and K[math]Na[math]NbO3 (abbreviated as KNN-1, KNN-2, and KNN-3, respectively) lead-free ion deficient ceramics for understanding the influence of ionic deficiency on the crystalline structure and dielectric/piezoelectric properties of the samples. X-ray diffraction patterns of these samples exhibited a perovskite tetragonal phase. Dielectric anomalies around 287∘C and 471∘C were identified as ferroelectric to ferroelectric and ferroelectric to paraelectric-transition temperatures for KNN-2 at 1[math]kHz. It was found that the composition KNN-2 exhibit relatively high Curie temperature i.e., 471∘C. The conductivity plots confirm that the activation energies are frequency-dependent. The impedance behavior in our ceramic samples can be analyzed with the bulk/grain effect. The slope of [math] with temperature shows negative temperature coefficient of resistance (NTCR) type behavior in proposed KNN ceramics material. Citation: Journal of Advanced Dielectrics PubDate: 2019-05-16T06:03:40Z DOI: 10.1142/S2010135X19500164

Authors:Ravindra V. Shinde, Avadhut R. Deshmukh, Shital A. Ingole, Ashok C. Kumbharkhane Abstract: Journal of Advanced Dielectrics, Volume 09, Issue 02, April 2019. The time-domain reflectometry technique was exercised to assess the complex permittivities of 1-chloropropane and ethanol along with their binary mixture in the frequency range of 10[math]MHz–50[math]GHz and in the temperature range of 10–[math]C. Dielectric parameters like static dielectric permittivity ([math] and relaxation time ([math] have been acquired by the least-square-fit method. The obtained assessments of static permittivity and relaxation time were used to compute various dielectric parameters like excess dielectric constant, excess relaxation time, Kirkwood correlation factor and thermodynamic parameters. The experimental outcome illustrates the nonlinear variations in dielectric permittivity, relaxation time and authenticates the structural formation due to intermolecular interaction between 1-chloropropane and ethanol. Molecular rotary motion and dipole reorientation movements of these complex systems are presented in agreement with the molar entropy and enthalpy. Citation: Journal of Advanced Dielectrics PubDate: 2019-05-16T06:03:28Z DOI: 10.1142/S2010135X19500188

Authors:Mohammad Sajjad Hossain, Yeasmin Akter, Mohammad Shahjahan, Muhammad Shahriar Bashar, Most. Hosney Ara Begum, Md. Moazzem Hossain, Suravi Islam, Nazia Khatun, Md. Al-Mamun Abstract: Journal of Advanced Dielectrics, Volume 09, Issue 02, April 2019. Polycrystalline NiCuZn ferrite (NixCu[math]Zn[math]Fe2O4; [math], 0.3, 0.4 and 0.5) were prepared through sol–gel auto combustion method applying double sintering technique. Structural, morphological, elemental analyses (EDS), Fourier-transform infrared spectroscopy (FTIR), Direct Current (DC) electrical resistivity, dielectric, magnetic and optical properties of prepared samples were analyzed. XRD profiles reveal the formation of simple cubic spinel structure without any traceable impurity. The average crystallite size lies within the range of 22–29[math]nm. Lattice parameter decreases with increasing Ni concentration. Room temperature DC resistivity was recorded from [math] to [math][math][math][math]cm. Both dielectric constant ([math]) and loss factor (tan[math]) were decreased with increase of frequency while AC conductivity increases. FTIR absorption peak occurred at three different frequency ranges at 570–577[math]cm[math], 1635–1662[math]cm[math] and 3439–3448[math]cm[math]. Magnetic properties were investigated by using vibrating sample magnetometer (VSM). Decreasing trends were observed for saturation magnetization ([math]), magnetic coercivity ([math]) and remanant magnetization ([math]) with the increase of Ni content. Optical band gap ([math]2.70–2.79[math]eV) were calculated from diffuse reflectance data by using Kubelka–Munk function. Citation: Journal of Advanced Dielectrics PubDate: 2019-05-16T06:02:57Z DOI: 10.1142/S2010135X19500206

Authors:Zhi-Hao Zhao, Rui-Fang Ge, Yejing Dai Abstract: Journal of Advanced Dielectrics, Ahead of Print. This paper investigates a system of 0.93Bi[math]Na[math]TiO3–0.06BaTiO3–0.01K[math]Na[math]NbO3–[math]CuO (BNT–BT–KNN–[math]CuO, [math][math]mol.%) ceramics, which were fabricated by the conventional solid-state process through the granulation of vacuum freeze drier. The results show that the CuO doping made a significant enhancement on the piezoelectric properties of the BNT–BT–KNN ceramics. With the doping of CuO, the transition temperature between ferroelectric phase and ergodic relaxor state is reduced to near room temperature, resulting in pinched [math]–[math] loops and “sprout” shape [math]–[math] curves. For the composition with [math], a high unipolar strain of 0.39% under 5[math]kV/mm contributes a large [math][math]pm/V at room temperature, which is competitive with the other BNT-based ceramics. Citation: Journal of Advanced Dielectrics PubDate: 2019-05-23T08:49:09Z DOI: 10.1142/S2010135X1950022X

Authors:C. L. Wang Abstract: Journal of Advanced Dielectrics, Ahead of Print. Two sets of experimental data of piezo-catalytic degradations are adapted to fit with three-parameter Mittag–Leffler functions. One set is degradation on methyl orange (MO) using catalysis of nano-sized barium titanates, and another set is on Rhodamine-B (RhB) using molybdenum disulfide nano-flowers as catalysts. The fitting results suggest that these piezo-catalytic degradations can be described either as Davidson–Cole type response function or Havriliak–Negami type of dielectric relaxation. This work confirms completely the universality in chemical reaction kinetics, which can be described by fractional differential equations with Mittag–Leffler functions as their solutions. Citation: Journal of Advanced Dielectrics PubDate: 2019-05-21T10:32:50Z DOI: 10.1142/S2010135X19500218

Authors:Anshi Yan, Yangjie Liu, Wenfeng Wang Abstract: Journal of Advanced Dielectrics, Ahead of Print. In this paper, we revisit the simple problem of reflection from a dielectric sphere for light rays and define a form of optical inverse problem in the sense of geometrical optics (GO). A general analytic formula is derived to obtain the refraction index of the sphere for any incidence light to emerge in a deflected angle. Numerical wave simulation and ray tracing are performed to verify the inverse formulae derived. Citation: Journal of Advanced Dielectrics PubDate: 2019-04-11T08:52:00Z DOI: 10.1142/S2010135X1950019X

Authors:Shilong Zhang, Ruicheng Xu, Zhendong Li, Qianwei Zhang, Li Cheng, Zhenhua Wang, Chunlin Fu Abstract: Journal of Advanced Dielectrics, Ahead of Print. Organic–inorganic hybrid perovskites with 3D perovskite structure have gained much attention as light harvesting materials in thin-film photovoltaics. This is because of their outstanding light-absorption characteristics, charge-transport dynamics and their simple processability using lab-scale solution and vapor phase deposition techniques. However, the inherent instability and lead toxicity of lead-based PSCs are the major problems at present. Recent studies have shown that the (CH3NH[math]Bi2I9 (MBI) 0D bismuth-based compound can be used as an optical absorption layer in solar cells. In this paper, the (CH3NH[math]Bi2I9 was doped with Cl− and a series of (CH3NH[math]Bi2I[math]Clx films were prepared. The effects of different doping amounts on the microstructure, photovoltaic properties and ferroelectric properties were systematically investigated. Scanning electron microscope (SEM) and Atomic force microscope (AFM) analysis showed that with the increase of doping content, the density of the films increased and the roughness decreased. The photoelectric conversion efficiency of (CH3NH[math]Bi2I[math]Clx raises with the increase of doping content. For example, the photoelectric conversion efficiency of (CH3NH[math]Bi2I3Cl6 is 0.473%. We find that the leakage current descends into the increase in doping content, which may be due to the increase in the film density and the decrease of porosity. These research results have a positive effect on the development of Bi-based lead-free perovskite. Citation: Journal of Advanced Dielectrics PubDate: 2019-03-25T02:08:25Z DOI: 10.1142/S2010135X19500139

Authors:Anand Yadav, Pankaj Choudhary, P. Saxena, V. N. Rai, A. Mishra Abstract: Journal of Advanced Dielectrics, Ahead of Print. In the present work, series of Zn ion-doped Ni[math]ZnxFe2O4 ([math]) ceramics were prepared by the double sintered solid-state reaction route to find out the influence of Zn[math] ions on the crystal structure, lattice structure and dielectric behavior of parent NiFe2O4. X-ray diffraction (XRD) study favors that all the prepared compounds belong to the cubic spinel structure. Lattice parameters found to have increasing value with increased Zn[math] ion substitution. The Raman scattering measurement discerns optical-active modes with blue shift as the doping increases. The dielectric constant ([math] and dielectric tangent loss (tan [math] decrease with an increase in frequency and at higher frequency, both become constant. Dielectric parameters observe nonlinear behavior with increasing Zn[math] ion substitution. Room temperature dielectric constant of 10% Zn ion-doped NiFe2O4 [Ni[math]Zn[math]Fe2O4] is much higher as compared to other prepared ceramics. The room temperature ac conductivity is found to increase with increase in frequency and temperature-dependent ac conductivity increases with increase in temperature. Citation: Journal of Advanced Dielectrics PubDate: 2019-03-25T02:08:24Z DOI: 10.1142/S2010135X19500140

Authors:Ji Zhang, Rui-Xue Wang, Ling Li, Lei Sun, Zheng-Bin Gu, Haibo Zhang, Shan-Tao Zhang Abstract: Journal of Advanced Dielectrics, Ahead of Print. Charge nonstoichiometric 0.94Bi[math]Na[math]TiO3–0.06BaTiO3 (BNT-BT) ([math]) ceramics were prepared and investigated. The depolarization temperature was dependent on composition and the ferroelectric property of [math] was suppressed more significantly than the [math], indicating the composition-sensitive electrical properties. Furthermore, the [math] was close to the insulator/conductor composition boundary while the [math] was close to the ferroelectrics/relaxor boundary. These results were attributed to the complex effect of donor doping and acceptor doping on depolarization field. This work provides robust clues to tune and/or design electrical property and conductivity of Bi[math]Na[math]TiO3-based materials. Citation: Journal of Advanced Dielectrics PubDate: 2019-03-19T01:44:45Z DOI: 10.1142/S2010135X19500127

Authors:Sarah L. Rasheed, Emad K. Al-Shakarchi Abstract: Journal of Advanced Dielectrics, Ahead of Print. The dielectric ceramic of barium dititanate compound BaTi2O5 had been prepared through the hydrothermal process by applying different parameters, such as pH-value, reaction time, temperature and pressure. The prepared powders were examined by X-ray diffraction (XRD). The predominant phase was a monoclinic phase with lattice constants ([math], [math], [math] Å), ([math], [math]), and the unit cell volume (527 Å3). The surface morphology was demonstrated by Scanning Electron Microscopy (SEM). It exhibited the grains in spherical and elliptical shapes with high homogeneity. The shapes of nanostructure were analyzed by Transmission Electron Microscopy (TEM). The appearance of nanostructures like the nanoparticles and nano rods were found. The size of nanoparticles was in the range of 9–31[math]nm, and size of nanorods was 32–37[math]nm. The dielectric measurements were done by using LCR meter at different temperature and frequencies (10, 50 and 100[math]kHz). It was clear that the Curie temperature had a high value up to (485∘C). The relative permittivity was partially changed for two prepared samples regarding high pressure and long reaction time, which were the main preparation conditions of hydrothermal method. Citation: Journal of Advanced Dielectrics PubDate: 2019-03-04T04:20:08Z DOI: 10.1142/S2010135X19500115

Authors:Maheswar Panda Abstract: Journal of Advanced Dielectrics, Ahead of Print. The frequency-dependent percolation and scaling behavior of a variety of polymer/metal composites (PMC), based on polyvinylidene fluoride (PVDF) matrix and various types of fillers such as; metal/alloy particles of different sizes, prepared through cold/hot pressing process conditions have undergone investigation. The universal percolation behavior in the vicinity of percolation threshold ([math]), i.e., [math] and [math] is well satisfied, which suggests [math] to be independent of frequency, where [math] and [math] are the effective ac conductivity and effective dielectric constants of the composite and [math] is the frequency of applied ac signal. The obtained experimental values of the exponents are consistent with the inter-cluster polarization model ([math] and [math]), satisfying [math]. The widely used percolative equations are well fitted with the experimental results of all PMC at all values of the frequency. The value of [math] is found to be independent of frequency of the applied signal, suggesting the studied PMC are real percolating systems. The critical exponents ([math] and [math]) which characterize the divergence of [math] and [math] in the vicinity of [math] are found to decrease with the increase of frequency. The rate of decrease of ‘[math]’ and ‘[math]’ with increase of frequency is attributed to the method of preparation, size of the fillers, adhesiveness of polymer/filler and the rate of decrease of [math] with frequency (due to the absence of different extents of contributions of various types of conventional polarizations). Citation: Journal of Advanced Dielectrics PubDate: 2019-02-26T02:58:10Z DOI: 10.1142/S2010135X19500103