scholarly journals Nanocrystalline Antiferromagnetic High-κ Dielectric Sr2NiMO6 (M = Te, W) with Double Perovskite Structure Type

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3996
Author(s):  
Jelena Bijelić ◽  
Dalibor Tatar ◽  
Sugato Hajra ◽  
Manisha Sahu ◽  
Sang Jae Kim ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Sol Gel ◽  
Double Perovskite ◽  
Structure Type ◽  
Nyquist Plot ◽  
Dielectric Constants ◽  
Nanocrystalline Powders ◽  
Double Perovskites ◽  
Magnetic Studies ◽  
Magnetic Ground State

Double perovskites have been extensively studied in materials chemistry due to their excellent properties and novel features attributed to the coexistence of ferro/ferri/antiferro-magnetic ground state and semiconductor band gap within the same material. Double perovskites with Sr2NiMO6 (M = Te, W) structure type have been synthesized using simple, non-toxic and costless aqueous citrate sol-gel route. The reaction yielded phase-pure nanocrystalline powders of two compounds: Sr2NiWO6 (SNWO) and Sr2NiTeO6 (SNTO). According to the Rietveld refinement of powder X-ray diffraction data at room temperature, Sr2NiWO6 is tetragonal (I4/m) and Sr2NiTeO6 is monoclinic (C12/m1), with average crystallite sizes of 49 and 77 nm, respectively. Structural studies have been additionally performed by Raman spectroscopy revealing optical phonons typical for vibrations of Te6+/W6+O6 octahedra. Both SNTO and SNWO possess high values of dielectric constants (341 and 308, respectively) with low dielectric loss (0.06 for SNWO) at a frequency of 1 kHz. These values decrease exponentially with the increase of frequency to 1000 kHz, with the dielectric constant being around 260 for both compounds and dielectric loss being 0.01 for SNWO and 0.04 for SNTO. The Nyquist plot for both samples confirms the non-Debye type of relaxation behavior and the dominance of shorter-range movement of charge carriers. Magnetic studies of both compounds revealed antiferromagnetic behavior, with Néel temperature (TN) being 57 K for SNWO and 35 K for SNTO.

Improved Electrical Properties of BaTiO3 – coated CaCu3Ti4O12 Dielectrics

2012 ◽  
Vol 1454 ◽  
pp. 75-80
Author(s):  
Hui Eun Kim ◽  
Sung Yun Lee ◽  
Sang-Im Yoo
Keyword(s):  
Solid State ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Leakage Current ◽  
Sol Gel ◽  
Dielectric Constants ◽  
Order Of Magnitude ◽  
Ccto Sample ◽  
State Mixing ◽  
Large Improvement

ABSTRACTWe report a significant improvement in the electrical properties of CaCu3Ti4O12 (CCTO) dielectrics by the BaTiO3 (BTO) additive. The addition of BTO to CCTO was performed using two different methods of a solid-state mixing and a sol-gel coating. Compared with pure CCTO ceramics (εr ∼ 52,000 and tanδ ∼ 0.38 at 100 kHz), BTO-added CCTO samples commonly showed a large improvement in the dielectric loss property although their dielectric constants were depressed around one order of magnitude; εr ∼ 5900 and tanδ ∼0.05 for 5 mol% BTO-coated CCTO sample and εr ∼ 4,075 and tanδ ∼ 0.02 for 5 mol% BTO-mixed CCTO sample. In addition, BTO-coated CCTO samples showed relatively lower leakage current than those of BTO-mixed CCTO samples, implying that the sol-gel coating is more effective for improving the electrical properties of CCTO.

Preparation of Double-Perovskites Sr2Fe1-xScxMoO6-δ Powders for the Cathode of SOEC by Sol-Gel Citrate Method

2010 ◽  
Vol 105-106 ◽  
pp. 657-659 ◽  
Author(s):  
Ben Ge ◽  
Jing Tao Ma ◽  
De Sheng Ai ◽  
Xu Ping Lin ◽  
Chang Sheng Deng
Keyword(s):  
Perovskite Structure ◽  
Ph Value ◽  
Sol Gel ◽  
Double Perovskite ◽  
Double Perovskites ◽  
Pure Perovskite Structure ◽  
Sintering Atmosphere ◽  
Citrate Method ◽  
X Ray ◽  
Air Atmosphere

Double-perovskite Sr2Fe1-xScxMoO6- (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4) powders have been synthesized by sol-gel citrate method. Initial powders were calcined in different temperature and atmosphere (air, H2(4vol%)/Ar), then analyzed by using the methods of X-ray, scanning electron microscopy (SEM), as well as thermal analysis. It is found that the formation of perovskite structure is related to the content of Sc, pH value, calcination temperature and sintering atmosphere. Especially, a pure perovskite structure almost completely formed after three hours sintering in atmosphere of H2(4vol%)/Ar. Although the formation of perovskite structure also happened in the air atmosphere, at the same time the SrMoO4 structure formed undesirably as a result of oxidization of Mo.

(C3H9NI)4AgBiI8: a direct-bandgap layered double perovskite based on a short-chain spacer cation for light absorption

2020 ◽  
Vol 56 (21) ◽  
pp. 3206-3209 ◽  
Author(s):  
Yunpeng Yao ◽  
Bo Kou ◽  
Yu Peng ◽  
Zhenyue Wu ◽  
Lina Li ◽  
...  
Keyword(s):  
Light Absorption ◽  
Double Perovskite ◽  
Structure Type ◽  
Short Chain ◽  
Double Perovskites ◽  
Direct Bandgap

A new iodide layered double perovskite (C3H9NI)4AgBiI8 (IPAB) has been developed based on a short-chain spacer cation, which is the first homologous compound in iodide double perovskites that adopt the Ruddlesden–Popper structure type.

Piezoelectricity in 0-3 PZT-PVDF Nano Composites Prepared via a Modified Solution Casting Process

2012 ◽  
Vol 510-511 ◽  
pp. 520-526 ◽  
Author(s):  
S. Aftab ◽  
H. Nawaz ◽  
M.S. Mirza ◽  
M. Shoaib ◽  
M. Siddiq
Keyword(s):  
Dielectric Loss ◽  
Piezoelectric Properties ◽  
Sol Gel ◽  
Casting Process ◽  
Dielectric Constants ◽  
Solution Casting ◽  
Hot Press ◽  
Volume Percent ◽  
Conventional Solution ◽  
Piezoelectric Charge

0-3 nanocomposites of PVDF with varying volume percents of strontium doped PZT have been synthesized using a combination of a modified solution casting process and the hot press technique. The nanocrystalline PZT used prepared from the sol gel route and was in the calcined state. An increase in the volume percent of PZT caused an increase in the dielectric constant, dielectric loss and piezoelectric charge coefficients. The experimental dielectric constants gave a perfect fit to the theoretical Furukawa model. However, no significant trend is perceived for the dielectric loss. SEM and XRD aided in determining the morphology and the crystalline phases in PVDF, PZT and PVDF/PZT composite. TG/DSC was done to confirm the percentage crystallinity of PVDF. A comparison with samples prepared from the conventional solution casting process has also been given. Composites prepared from the modified solution casting process using nanocrystalline strontium doped PZT give better piezoelectric properties as compared to earlier works.

scholarly journals Sol gel and ceramic synthesis of Sr2FeMo1−xWxO6 (0 ≤ x ≤ 1) double perovskites series

RSC Advances ◽  
2016 ◽  
Vol 6 (48) ◽  
pp. 42069-42075 ◽  
Author(s):  
M. Iranmanesh ◽  
M. Lingg ◽  
M. Stir ◽  
J. Hulliger
Keyword(s):  
Sol Gel ◽  
Double Perovskite ◽  
Double Perovskites ◽  
Ceramic Synthesis ◽  
Pure Phase

Optimization of pure phase double perovskite series via sol–gel methods.

Dielectric Properties of Sol-Gel Prepared Ni-Doped CaCu3Ti4O12 Ceramics

2012 ◽  
Vol 204-208 ◽  
pp. 4193-4196
Author(s):  
Lei Jiao ◽  
Hui Li ◽  
Yan Wei Yang ◽  
Tian Ping Wang
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sol Gel ◽  
Low Frequency ◽  
Frequency Region ◽  
Dielectric Constants ◽  
High Frequency Region ◽  
Xrd Pattern ◽  
Calcium Copper Titanate ◽  
Titanate Ceramics

Dielectric properties of sol–gel prepared Ni-doped calcium copper titanate Ceramics (CCNTO) are investigated. For the x of CaCu3NixTi4O12+x is 0, 0.1, 0.2, 0.3 respectively. The XRD pattern shows that crystal structure of the sample without Ni is basically single-phase. The dielectric properties of CCNTO were analyzed by Agilent 4294A. The experimental results show that the sample has a better dielectric properties when x=0.2. The maximum dielectric constants is found when x=0.2. The dielectric loss decreased with the increases of Ni in the low frequency region, the high frequency region is just the opposite, the sample has lower dielectric loss in the low frequency region when x=0.2.

scholarly journals Lattice Vibrational Characteristics and Structures-Properties Relationships of Non-Stoichiometric Nd[Mg0.5Sn0.5(1+x)]O3 Ceramics

2020 ◽  
Author(s):  
Feng Shi ◽  
en-cai xiao ◽  
Wen Lei ◽  
Guohua Chen ◽  
Ying Chen
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Low Frequency ◽  
Double Perovskite ◽  
Dielectric Constants ◽  
Quantum Model ◽  
Sintering Process ◽  
Main Crystalline Phase ◽  
Vibrational Characteristics ◽  
Degree Of Order

Abstract Non-stoichiometric Nd[Mg0.5Sn0.5(1+x)]O3 (-0.04 ≤ x ≤ +0.04) - type samples were prepared using a traditional two-step solid-state sintering process. Their crystal structures, phase compositions, dielectric properties and lattice vibrational characteristics were identified in detail. Double perovskite Nd(Mg0.5Sn0.5)O3 with a monoclinic structure was distinguished as the main crystalline phase, pure phase was obtained when x < 0, and the sample [Nd(Mg0.5Sn0.49)O3] at x = -0.02 shows the excellent dielectric properties: εr = 18.74, Q × f = 47,979 GHz. Lattice vibrational characteristics were clarified with Raman and infrared active modes assigned and illuminated, accurately. The intrinsic properties were fitted by four-parameter semi-quantum model, which show that the low-frequency infrared modes yield a more significant contribution to permittivity and dielectric loss. Raman shifts of modes F2g(A) and F2g(B) correlate with dielectric constants negatively, which implies that the bond length has a positive correlation with permittivity. Full widths at half maximum of vibritional modes A1g(O) correlate with dielectric loss values positively and correlate with the degree of order (S) negatively.

scholarly journals Influence of A-site Cation on Structure and Dielectric Properties in A2DyBiO6 (A=Mg, Ca, Sr, Ba) Double Perovskites

2014 ◽  
Vol 67 (2) ◽  
pp. 250 ◽  
Author(s):  
Simona Feraru ◽  
Adrian I. Borhan ◽  
Petrisor Samoila ◽  
Gigel G. Nedelcu ◽  
Alexandra R. Iordan ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Sol Gel ◽  
Double Perovskite ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Double Perovskites ◽  
Structural Characterisation ◽  
Auto Combustion ◽  
Xrd Patterns ◽  
A Site

Double perovskite metal oxides with formula A2DyBiO6 (A = Mg, Ca, Sr, Ba) were synthesised by a sol–gel auto-combustion method, using citric acid as the combustion agent. The effects of A-site cation on the structure, morphology, and dielectric properties were examined. The synthesis was monitored using Fourier transform infrared spectroscopy (FTIR) to indicate the absence of organic phase. X-ray diffraction (XRD) analysis showed that the compounds have three different perovskite structures. Structural characterisation of the samples was evaluated using XRD patterns. Scanning electron microscopy showed that all samples are formed by agglomerated particles. Dielectric properties were evaluated using dielectric permittivity and dielectric losses. Cole–Cole plots show a single semicircle for all materials, indicating that the double perovskites obtained are composed of well conducting grain boundaries and poorly conducting grains.

Electron microscopy studies of PZT ferroelectric film capacitor structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1364-1365
Author(s):  
V. Kaushik ◽  
P. Maniar ◽  
J. Olowolafe ◽  
R. Jones ◽  
A. Campbell ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sol Gel ◽  
Ferroelectric Material ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Lead Zirconium Titanate ◽  
Si Substrate ◽  
Film Capacitor ◽  
Pzt Films ◽  
High Dielectric

Lead zirconium titanate films (Pb (Zr,Ti) O3 or PZT) are being considered for potential application as dielectric films in memory technology due to their high dielectric constants. PZT is a ferroelectric material which shows spontaneous polarizability, reversible under applied electric fields. We report herein some results of TEM studies on thin film capacitor structures containing PZT films with platinum-titanium electrodes.The wafers had a stacked structure consisting of PZT/Pt/Ti/SiO2/Si substrate as shown in Figure 1. Platinum acts as electrode material and titanium is used to overcome the problem of platinum adhesion to the oxide layer. The PZT (0/20/80) films were deposited using a sol-gel method and the structure was annealed at 650°C and 800°C for 30 min in an oxygen ambient. XTEM imaging was done at 200KV with the electron beam parallel to <110> zone axis of silicon.Figure 2 shows the PZT and Pt layers only, since the structure had a tendency to peel off at the Ti-Pt interface during TEM sample preparation.

scholarly journals Synthesis and characterization of Mg–Zn ferrite based flexible microwave composites and its application as SNG metamaterial

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Md Atiqur Rahman ◽  
Mohammad Tariqul Islam ◽  
Mandeep Singh Jit Singh ◽  
Md Samsuzzaman ◽  
Muhammad E. H. Chowdhury
Keyword(s):  
Low Cost ◽  
Sol Gel ◽  
Microwave Frequency ◽  
Dielectric Substrate ◽  
Dielectric Constants ◽  
Potential Candidate ◽  
Flexible Composites ◽  
Average Grain Size ◽  
Zn Ferrite ◽  
High Flexibility

AbstractIn this article, we propose SNG (single negative) metamaterial fabricated on Mg–Zn ferrite-based flexible microwave composites. Firstly, the flexible composites are synthesized by the sol-gel method having four different molecular compositions of MgxZn(1−x)Fe2O4, which are denoted as Mg20, Mg40, Mg60, and Mg80. The structural, morphological, and microwave properties of the synthesized flexible composites are analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and conventional dielectric assessment kit (DAK) to justify their possible application as dielectric substrate at microwave frequency regime. Thus the average grain size is found from 20 to 24 nm, and the dielectric constants are 6.01, 5.10, 4.19, and 3.28, as well as loss tangents, are 0.002, 0.004, 0.006, and 0.008 for the prepared Mg–Zn ferrites, i.e., Mg20, Mg40, Mg60, and Mg80 respectively. Besides, the prepared low-cost Mg–Zn ferrite composites exhibit high flexibility and lightweight, which makes them a potential candidate as a metamaterial substrate. Furthermore, a single negative (SNG) metamaterial unit cell is fabricated on the prepared, flexible microwave composites, and their essential electromagnetic behaviors are observed. Very good effective medium ratios (EMR) vales are obtained from 14.65 to 18.47, which ensure the compactness of the fabricated prototypes with a physical dimension of 8 × 6.5 mm2. Also, the proposed materials have shown better performances comparing with conventional FR4 and RO4533 materials, and they have covered S-, C-, X-, Ku-, and K-band of microwave frequency region. Thus, the prepared, flexible SNG metamaterials on MgxZn(1−x)Fe2O4 composites are suitable for microwave and flexible technologies.

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