STRUCTURAL AND DIELECTRIC PROPERTIES OF Ba0.5Sr0.5TiO3 THIN FILMS GROWN ON LAO WITH HOMO-EPITAXIAL LAYER FOR TUNABLE APPLICATIONS

2004 ◽  
Vol 18 (15) ◽  
pp. 2153-2168 ◽  
Author(s):  
M. CHANDRA SEKHAR
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Interfacial Layer ◽  
Ferroelectric Properties ◽  
Buffer Layers ◽  
High Tunability ◽  
Low Leakage ◽  
Structural Growth ◽  
Bst Films ◽  
Dielectric Devices

The epitaxial, single phase (100) Ba 0.5 Sr 0.5 TiO 3 (BST) films with thin interfacial layer of BST (x=0.4) were deposited on LAO (100) substrates using Pulse Laser Deposition (PLD). These films were characterized in terms of their phase formation and structural growth characteristics using X-ray diffraction and Atomic Force Microscopy respectively. The dielectric properties are strongly affected by the substrate type, post deposition annealing time, and temperature. In order to verify all these properties, thin interfacial-buffer layers of BST (10, 20, 50 nm) were introduced to relieve the stress induced between the film and the substrate. The variations of dielectric constant and ferroelectric properties of as deposited films are discussed in detail. The high tunability, low dielectric loss and low leakage current of these films make them attractive candidates for fabricating tunable dielectric devices. The observed dielectric properties of the BST-films are attributed to homo-epitaxial interfacial layer, which is responsible for the increase in the dielectric constant and tunability.

Pulsed Laser Deposition of BaxSr1−xTiO3 Films on MgO, LaAlO3 and SrTiO3 for Tunable Microwave Applications

1998 ◽  
Vol 541 ◽  
Author(s):  
Wontae Chang ◽  
James S. Horwitz ◽  
Won-Jeong Kim ◽  
Jeffrey M. Pond ◽  
Steven W. Kirchoefer ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electric Field ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Dielectric Constants ◽  
Laser Deposition ◽  
Film Stress ◽  
Donor Acceptor ◽  
Bst Films

AbstractSingle phase BaxSr1−xTiO3 (BST) films (∼0.5-7 μm thick) have been deposited onto single crystal substrates (MgO, LaAlO3, SrTiO3) by pulsed laser deposition. Silver interdigitated electrodes were deposited on top of the ferroelectric film. The room temperature capacitance and dielectric Q (1/tanδ) of the film have been measured as a function of electric field (≤80 kV/cm) at 1 - 20 GHz. The dielectric properties of the film are observed to strongly depend on substrate type and post-deposition processing. After annealing (≤1000° C), it was observed that the dielectric constant and % tuning decreased and the dielectric Q increased for films deposited onto MgO, and the opposite effect was observed for films deposited onto LaA1O3. Presumably, this change in dielectric properties is due to the changes in film stress. Very thin (∼50 Å) amorphous BST films were successfully used as a stress-relief layer for the subsequently deposited crystalline BST (∼5000 Å) films to maximize % tuning and dielectric Q. Films have been deposited from stoichiometric targets and targets that have excess Ba and Sr. The additional Ba and Sr has been added to the target to compensate for deficiencies in Ba and Sr observed in the deposited BST (x=0.5) films. Films deposited from compensated targets have higher dielectric constants than films deposited from stoichiometric targets. Donor/acceptor dopants have also been added to the BST target (Mn, W, Fe ≤4 mol.%) to further improve the dielectric properties. The relationship between the dielectric constant, the dielectric Q, the change in dielectric constant with electric field is discussed.

Tunability in Ba1–xSrxTiO3-based Ferroelectrics

2000 ◽  
Vol 656 ◽  
Author(s):  
Daniel M. Potrepka ◽  
Steven C. Tidrow ◽  
Arthur Tauber
Keyword(s):  
Dielectric Constant ◽  
Phase Shifters ◽  
Low Loss ◽  
Low Dielectric ◽  
High Tunability ◽  
Low Leakage ◽  
Low Leakage Current ◽  
True Time ◽  
The Impact ◽  
Improve Device

ABSTRACTFerroelectrics are presently of interest for phase shifters, filters, and true time delay devices. Voltage tunable paraelectrics have the potential to lower device cost and reduce power consumption compared with presently available devices. In order to improve device performance to acceptable levels, materials must have high tunability, low dielectric constant, low loss tangent, and low leakage current. Using existing predictive techniques, compositions of Ba0.6Sr0.4TiO3-based ferroelectrics with charge-compensated substitutions for Ti4+ were synthesized. Results of capacitance measurements are used to obtain dielectric constant and tunability in the paraelectric (T > TC) regime. The relevance to device requirements is discussed. Results for substituted samples are compared to those for (unsubstituted) Ba0.6Sr0.4TiO3. Discussion of the impact of the results on predictive techniques for tunability is addressed.

ELECTRICAL PROPERTIES OF HETEROLAYERED BaTiO3/(Bi1/2Na1/2)TiO3 THICK FILMS

2009 ◽  
Vol 23 (31n32) ◽  
pp. 3785-3791
Author(s):  
SUNG-PILL NAM ◽  
HYUN-JI NOH ◽  
SUNG-GAP LEE ◽  
SEON-GI BAE ◽  
YOUNG-HIE LEE
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Screen Printing ◽  
Remanent Polarization ◽  
Ferroelectric Properties ◽  
Thick Films ◽  
Rhombohedral Structure ◽  
Structural And Electrical Properties ◽  
Printing Techniques

The heterolayered BT/BNT thick films were fabricated by screen printing techniques on alumina substrates electrodes with Pt . Their structure and ferroelectric properties were investigated with the heterolayered tetragonal/rhombohedral structure composed of the BT and the BNT thick films. The structural and electrical properties of the heterolayered BT/BNT thick films were studied. The dielectric properties such as dielectric constant, loss and remanent polarization of the heterolayered BT/BNT thick films were superior to those of single composition BNT, and those values for the heterolayered BT/BNT thick films were 1455, 0.025 and 12.63 µC/cm2.

scholarly journals Enhanced dielectric and ferroelectric properties of surface hydroxylated Na0.5Bi0.5TiO3 (NBT)-poly(vinylidene fluoride) (PVDF) composites

2018 ◽  
Vol 08 (03) ◽  
pp. 1850017 ◽  
Author(s):  
Srikanta Moharana ◽  
Shraddhakara Sai ◽  
Ram Naresh Mahaling
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Ferroelectric Properties ◽  
Material Surface ◽  
Hydroxyl Groups ◽  
Energy Storage Devices ◽  
Surface Hydroxylation ◽  
High Dielectric

The surface hydroxylation treatment has been carried out by using hydrogen peroxide (H2O2) to modify the surface of Na[Formula: see text]Bi[Formula: see text]TiO3 (NBT) particles in a ferroelectric polymer (PVDF) via solution casting technique. The FTIR study confirms the presence of hydroxyl groups on the surface of NBT. The FE-SEM analysis reveals that h-NBT particles are dispersed homogeneously within the polymer matrix. The surface hydroxylation treatment plays an important role in high dielectric constant and also reduced loss by conducting the material surface with [Formula: see text]OH functional groups. The prepared composite with 40[Formula: see text]wt.% of h-NBT showed enhanced dielectric constant ([Formula: see text]114), negligible loss (0.22) and high AC conductivity as compared to that of the unmodified NBT. Such significant enhancement in dielectric properties may be due to the strong interaction between h-NBT particles and PVDF matrix at the interface. The percolation theory is used to explain the dielectric properties of h-NBT-PVDF composite. Furthermore, the remnant polarization of the un-poled h-NBT-PVDF composites (2[Formula: see text]Pr–1.19[Formula: see text][Formula: see text]C/cm2 for 40[Formula: see text]wt.% of h-NBT) is also improved. The present findings give an idea of high dielectric constant and relatively low loss composite materials as a promising candidate for electronic and energy storage devices.

Effects of (Li, Ce) Co-Doping on Microstructure, Dielectric and Ferroelectric Properties of Strontium Niobate Ceramics

2014 ◽  
Vol 787 ◽  
pp. 236-241 ◽  
Author(s):  
Gang Chen ◽  
Jie Hao Wei ◽  
Xiao Dong Peng ◽  
Chun Lin Fu ◽  
Wei Cai
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Solid State ◽  
Remnant Polarization ◽  
Ferroelectric Properties ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Co Doping ◽  
Maximum Value ◽  
Coercive Electric Field

Sr2-x(Li2/3, Ce1/3)x Nb2O7 (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5) (SLCN) ceramics were prepared by solid-state reaction method. The microstructure, dielectric and ferroelectric properties were investigated. The results show that all ceramics have high relative densities. Li+ and Ce4+ co-doping can promote the grains growing, and improve the dielectric and ferroelectric properties of strontium niobate ceramics. The dielectric constant decreases firstly, and then increases with the increasing of x in Sr2-x(Li2/3, Ce1/3)x Nb2O7, and the sample with x = 0.5 exhibits enhanced dielectric properties (εr ≈ 250, tanδ ≈ 0.02). The remnant polarization (Pr) and coercive electric field (Ec) of SLCN ceramics increase firstly, and then decrease with the increasing of Li+ and Ce4+ content, finally reach the maximum value of remnant polarization (Pr ≈ 0.058μC/cm2, Ec ≈ 6.87 kV/cm ) for x = 0.2.

Surface Morphologies of PVDF-TrFE/MgO Nanocomposite Thin Films and its Effect on the Ferroelectric Properties

2015 ◽  
Vol 1134 ◽  
pp. 6-11 ◽  
Author(s):  
Mohamad Hafiz Mohd Wahid ◽  
Rozana Mohd Dahan ◽  
Siti Zaleha Sa'ad ◽  
Adillah Nurashikin Arshad ◽  
Muhamad Naiman Sarip ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Magnesium Oxide ◽  
Ferroelectric Properties ◽  
Filler Loading ◽  
Nanocomposite Thin Film ◽  
Nanocomposite Thin Films ◽  
Surface Morphologies

The enhancement of ferroelectric and dielectric properties of PVDF-TrFE by incorporating various percentages of Magnesium Oxide (1 – 7%) for spin coated nanocomposite thin film was demonstrated. Observations showed uniform distribution and low agglomeration of MgO in the PVDF-TrFE nanocomposite thin film, especially for 3% MgO. Additionally, the 3% MgO incorporated into PVDF-TrFE had generated the highest Pr (88 mC/m2) and dielectric constant (13.6) in comparison other percentage compositions. However, the addition of more than 3% MgO filler loading caused a reduction in the ferroelectric and dielectric properties of the nanocomposite thin films.

Dielectric Properties of (Bi1/2Na1/2)TiO3-SrTiO3 Ferroelectric Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 49-50
Author(s):  
Chao Liu ◽  
Yuan Fang Qu ◽  
Feng Long Han ◽  
Yuan Liang Li ◽  
Xiao Yan Li
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Ferroelectric Properties ◽  
Dielectric Constants ◽  
Ferroelectric Ceramics

Ferroelectric properties of (Bi1/2Na1/2) TiO3-SrTiO3 were studied. The dielectric properties were measured at 1KHz. It was found that the dielectric constants are improved with the increase of additive amount of BNT. If the amount continues increasing, the properties become worse, the optimum dielectric constant of the samples can reach 4300. When the proportion of (Bi1/2Na1/2)TiO3: SrTiO3 is 65:35, with the increase of additive amount of MnCO3, the Curie temperature descends obviously. The dielectric constant increased at beginning and dropped sharply when the amount of MnCO3 exceeds 1.1wt%.

Effects of LSCO Buffer Layer on the Microstructure and Dielectric Properties of Ba0.6Sr0.4TiO3 Films Prepared by Sol-gel Methods

2009 ◽  
Vol 1199 ◽  
Author(s):  
Songwei Han ◽  
Shengwen Yu ◽  
Jinrong Cheng
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Random Orientation ◽  
X Ray ◽  
Bst Thin Films ◽  
Structure And Morphology ◽  
Bst Films

AbstractIn this work, Ba0.6Sr0.4TiO3(BST) thin films were deposited on Ti substrates using conductive La0.5Sr0.5CoO3 (LCSO) as buffer layers. Both BST and LSCO films were prepared by sol-gel methods. The structure and morphology of BST and LSCO films were analyzed by X-ray diffraction (XRD). XRD results show that both BST and LSCO films have perovskite structure with random orientation. The dielectric properties of BST films were dependent on the thickness of LSCO buffer layers. Upon using LSCO buffer layers, the dielectric properties of BST films were significantly improved. The dielectric constant, tunability, and dielectric loss of BST thin films for LSCO of 150 nm achieved about 453, 0.032 and 31.26% respectively.

Dielectric properties of plasma-spray-deposited BaTiO3 and Ba0.68Sr0.32TiO3 thick films

2003 ◽  
Vol 18 (5) ◽  
pp. 1227-1231 ◽  
Author(s):  
K. Ahn ◽  
B. W. Wessels ◽  
S. Sampath
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Plasma Spray ◽  
Interfacial Layer ◽  
Thick Films ◽  
Low Dielectric Constant ◽  
Second Phase ◽  
Spray Process ◽  
Low Dielectric ◽  
Deposited Films

The dielectric properties of high-k dielectric BaTiO3 and Ba0.68Sr0.32TiO3 thick films deposited on alumina substrates using a plasma-spray process were investigated. The as-deposited films were predominantly crystalline but contained an amorphous second phase, the amount of which depended on spray conditions. The effect of the spray conditions on crystallinity was studied and related to the dielectric properties of the films. The presence of a low dielectric constant interfacial layer in plasma-spray-deposited films was determined from the dependence of the dielectric constant on film thickness. After annealing at 500 °C for 20 h in air, the crystallinity and dielectric constant increased. Annealing was also found to affect the interfacial layer properties.

scholarly journals Study of Ferroelectric Properties of Hydrogen Bonded Rubidium Dihydrogen Arsenate (RdA) Crystal

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Pawan Singh ◽  
Trilok Chandra Upadhya ◽  
Muzaffar Iqbal Khan ◽  
Sidharth Kashyap
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Response Function ◽  
Ferroelectric Properties ◽  
Mode Frequency ◽  
Experimental Results ◽  
Ferroelectric Crystal ◽  
Coupled Mode ◽  
Theoretical Results ◽  
Hydrogen Bonded

A simple pseudospin lattice coupled mode model with addition of third and fourth-order phonon anharmonic interactions terms, direct spin-spin interactions terms and external electric field term has been considered for investigation of transition phenomena and dielectric properties of hydrogen bonded ferroelectric crystal Rubidium dihydrogen arsenate (RDA). A double-time thermal dependent Green’s function method has been used for derivation of response function. From response function shift, width and soft mode frequency have been derived for RDA crystal. Response function is also related to dielectric constant which has been obtained in present paper. By fitting model values of different parameters in obtained expressions, the temperature variations of normal mode frequency, dielectric constant, and loss tangent have been calculated numerically for RDA crystal. Our theoretical results are compared with experimental results. It is observed that our theoretical results agree with experimental results. Therefore, it can be concluded that the modified pseudo-spin lattice coupled mode model with the simplest approximation is quite suitable to explain the transition and dielectric properties of RDA crystal.

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