SrBi2Nb2O9 Research Articles

Enhancing SrBi₂Nb₂O₉ Ceramics: The Role of Neodymium Substitution in Structural, Dielectric, and Ferroelectric Properties.

This study investigates the impact of neodymium substitution for bismuth in SrBi2Nb2O9 (SBN) ceramics, a potential lead-free alternative for ferroelectric applications. X-ray diffraction analysis reveals a decrease in lattice parameters and volume with increasing Nd content. Scanning electron microscopy examines the influence of neodymium on grain morphology, showing a transition from characteristic SBN plate-like grains to a mix of plates and micro-spheres. Dielectric properties are evaluated, showing an increase in room-temperature permittivity for Nd-doped samples compared to the undoped counterparts. Additionally, the influence of Nd doping on relaxor ferroelectric behavior is studied. The Curie temperature (Tc) increases with Nd concentration, while the temperature dependence of relaxation time weakens. Ferroelectric properties exhibit significant changes due to Nd doping. Inverse permittivity versus temperature (ϵr-1 vs. T) measurements suggest an unconventional response, potentially due to lattice strain induced by the larger ionic radius of Nd. The potential influence of doping concentration on the order of the ferroelectric transition is also explored. Overall, neodymium substitution in SBN ceramics enhances their ferroelectric properties, making them promising for advanced electronic applications.

Exploring the Multifunctional aspects of SrBi2-X(CoFe2O4)XNb2O9 Nanocomposite Materials Emphasizing the Structural, Elastic, and Optical Properties

Nanocomposites of SrBi(2-X)(CF)XNb2O9 (SBNCF) (CF=CoFe2O4 for X = 0.0 to 0.5 with a step increment of 0.1) were synthesized using the hydrothermal method and characterized for their structural, morphological, elastic, and optical properties. The incorporation of CF into SrBi2Nb2O9 (SBN) resulted in hybrid composites with tailored properties. X-ray Diffraction (XRD) with Rietveld refinement analysis confirmed the formation of orthorhombic SBN and spinel CF phases. Field Emission Gun Scanning Electron Microscopy (FEG-SEM) revealed that SBN exhibits a plate-like morphology, with the incorporation of CF into the SBN matrix resulting in both plate-like and octahedral-shaped grains. The Brunauer–Emmett–Teller (BET) method was used to determine the pore radius and surface area, both of which were found to have increased, indicating an enhancement in photocatalytic performance. The presence of the constituent elements in the prepared compositions was confirmed by Energy Dispersive Spectroscopy (EDS). Fourier Transform Infrared Spectroscopy (FTIR) spectra were used to determine elastic properties, suggesting potential applications in electronic noise filtering. From Diffuse Reflectance Spectroscopy (DRS), a recognizable semiconducting behavior and band gap bowing were noticed in SBNCF nanocomposites on the obtained energy band gap values (2.20 eV - 1.56 eV) compared to the SBN host matrix (3.16 eV). The materials exhibited strong emission peaks at 470 nm, 528 nm, 584 nm, and 703 nm upon the excitation of 425 nm light using Photoluminescence (PL) spectroscopy. The white emission was predominant at room temperature in all the produced samples and the corresponding color temperature values range from 5865.93 K to 7599.05 K from the CIE diagram. The SBNCF materials are promising candidates in photocatalytic reactions and white light-emitting diodes (w-LEDs) based on their enhanced optical properties.

Selective Exposure of Robust Perovskite Layer of Aurivillius-Type Compounds for Stable Photocatalytic Overall Water Splitting.

Aurivillius-type compounds ((Bi2 O2 )2+ (An -1 Bn O3 n +1 )2- ) with alternately stacked layers of bismuth oxide (Bi2 O2 )2+ and perovskite (An -1 Bn O3 n +1 )2- are promising photocatalysts for overall water splitting due to their suitable band structures and adjustable layered characteristics. However, the self-reduction of Bi3+ at the top (Bi2 O2 )2+ layers induced by photogenerated electrons during photocatalytic processes causes inactivation of the compounds as photocatalysts. Here, using Bi3 TiNbO9 as a model photocatalyst, its surface termination is modulated by acid etching, which well suppresses the self-corrosion phenomenon. A combination of comprehensive experimental investigations together with theoretical calculations reveals the transition of the material surface from the self-reduction-sensitive (Bi2 O2 )2+ layer to the robust (BiTiNbO7 )2- perovskite layer, enabling effective electron transfer through surface trapping and effective hole transfer through surface electric field, and also efficient transfer of the electrons to the cocatalyst for greatly enhanced photocatalytic overall water splitting. Moreover, this facile modification strategy can be readily extended to other Aurivillius compounds (e.g., SrBi2 Nb2 O9 , Bi4 Ti3 O12 , and SrBi4 Ti4 O15 ) and therefore justify its usefulness in rationally tailoring surface structures of layered photocatalysts for high photocatalytic overall water-splitting activity and stability.

High electrical properties and good upconversion luminescence in SrBi1.94-xEr0.06YbxNb2O9 lead-free piezoelectric ceramics

SrBi1.94-xEr0.06YbxNb2O9 (x = 0.000, 0.002, 0.004 and 0.006, noted as SBEN-xYb) composites were prepared using traditional solid-phase sintering technology. The influences of (Er, Yb)3+ co-doping on the electrical and luminous properties as well as energy band structure of SrBi2Nb2O9 (SBN) ceramics were systematically investigated. The outstanding comprehensive characteristics with low dielectric loss (tanδ ~ 0.073%), high remnant polarization (2Pr ~ 10.73 μC/cm2), large piezoelectric responses (d33 ~ 15 pC/N) and excellent upconversion photoluminescence (UC-PL) are simultaneously observed by Yb doping with a concentration of x = 0.004. The UC-PL spectrum excited by 980 nm laser shows double bands at 533 nm and 554 nm in the green region, and single band at 672 nm in the red region. A density functional theory (DFT) calculation was performed to reveal the physical origin of electrical conductivity and UC-PL. It is seen that the band gap consistently decreases, while the contribution from f state of (Er, Yb)3+ is intensified with increasing Yb3+, elaborating the variations of electrical conductivity and UC-PL intensity. Related mechanisms for the improvement of UC-PL and electrical properties were discussed.

Multi-functional attributes of rare earth double doped SrBi2Nb2O9 ferroelectric system

The ferroelectric perovskite SrBi2Nb2O9 (SBN) material with a low concentration of double doping at the Bi-site of SBN was studied to understand its influence and usefulness in integrated optoelectronic, soft magnetic memory devices and wear-resistant tribomaterials. The aim of the present study is double doping of SBN with a set of rare earth elements Pr3+/Dy3+ (SBPDN), Pr3+/Gd3+ (SBPGN), Pr3+/Sm3+ (SBPSN), and Pr3+/Y3+ (SBPYN) at the Bi-site of SBN to establish the multifunctional ceramic nature pertaining to diverse applications. XRD with Rietveld refinement analysis acknowledged a single-phase orthorhombic structure with an increase in lattice parameters and unsystematic changes in crystallite size. SEM study indicated that the samples possessed non-uniformly distributed needle-shaped grains. The purity of the material and the detection of functional groups were received from the EDS and FTIR spectroscopy. Structural modifications in SBN have been determined based on a diffuse reflectance spectroscopy (DRS) study and therefore the band gap values decrease from 2.98 eV (SBN) to 2.70 eV (double doping) because of the growth of distortion in the structure and pronounced increase in the density of localized states. Photoluminescence (PL) study on double doped SBN material with an excitation wavelength of 320 nm has yielded a novel red emission at 609 nm, that may be useful for white LEDs. The ferromagnetic signature in the studied materials was confirmed from the room temperature VSM study. Noticed mild wear and a low coefficient of friction in the studied materials of SBPDN and SBPSN compared to other studied ceramic samples from mechanical studies. The simultaneous manifestation of optical, magnetic, and mechanical properties by double-doped SBN ceramics keeps the materials as multi-functional candidates for optoelectronic devices, soft magnetic memory devices, and wear-resistant tribomaterials.

EFFECTS OF La2O3 AND Bi2O3 ADDITIONS ON THE MICROWAVE DIELECTRIC AND ANTENNA PROPERTIES OF SrBi2Nb2O9 CERAMIC MATRIX

This work presents a comparison between the dielectric properties of the SrBi2Nb2O9 (SBN)ceramic matrix and the individual additions of Bi2O3and La2O3, suggesting the material that would be most suitable for microwave applications. The SBN sample was synthesized by solid-state reaction, and the X-ray diffraction method (XRD) was used for the structural characterization of the materials analyzed in this study. The thermal stability of the samples was measured experimentally by studying the temperature coefficient of resonant frequency (τf) the results confirm that the individual additions of 15wt% of Bi2O3or La2O3improved the thermostability of the composites. The Hakki-Coleman method was used to obtain the dielectric properties in the microwave range, and it is possible to observe that the dielectric permittivity of the composites increased, while their loss tangents decreased. The numerical simulation demonstrated the functioning of the materials as dielectric resonating antennas (DRA), with a reflection coefficient below -10 dB in all samples.

Preferential growth characteristics and ferroelectric properties of epitaxial SrBi2Nb2O9 thin films along the a-axis direction due to the misfit strains

Epitaxial SrBi2Nb2O9 (SBN) thin films were grown on single crystal (100) Nb-doped SrTiO3 (Nb:STO) substrates and (100) Rh substrates with different lattice constants, respectively. The Nb:STO substrates have a lattice constant similar to that of SBN and the epitaxial SBN thin films on the Nb:STO substrates were grown along the c-orientation, and the epitaxial SBN thin films on the Rh substrates were grown along a-orientation with a small lattice constant by compressive stress. The epitaxially a-oriented SBN thin films showed excellent ferroelectric properties compared to the epitaxially c-oriented SBN thin films because the SBN as a layered perovskite material has polar axis perpendicular to the c-orientation. It was confirmed that the epitaxially a-oriented SBN thin film having the polar axis parallel to the switching electric field has faster polarization switching speed than the epitaxially c-oriented SBN thin film having the polar axis perpendicular to the switching electric field.

Structural, Mechanical and Magnetic Characterization of Rare Earth Double Doped SrBi2Nb2O9 lead Free Ceramics

Lead free dielectric materials of Strontium Bismuth Niobate SrBi2Nb2O9 (SBN) and rare earth double doped SrBi1.8Pr0.1Gd0.1Nb2O9 (SBPGN), SrBi1.8Pr0.1Y0.1Nb2O9 (SBPYN), SrBi1.8Eu0.1Gd0.1Nb2O9 (SBEGN) and SrBi1.8Eu0.1Y0.1Nb2O9 (SBEYN) were prepared by two-stage solid-state reaction route. The XRD studies have confirmed the formation of single-phase orthorhombic crystal structure. The microstructural analysis showed the formation of plausible needle shaped grains in the prepared ceramics. The FTIR study was used to investigate the effect of preparation and doping processes on the band intensities of the spectra. Mechanical studies showed that SBEGN and SBEYN ceramics exhibited mild wear (<10−6 mm3 Nm−1) compared to others. The low friction coefficient values of SBPYN (0.044), SBEGN (0.058) and SBEYN (0.002) to that of SBN necessitate lattice strain in these materials. The VSM studies on the rare earth double doped SBN ceramic materials confirmed the induction and existence of magnetic order in SBPGN and SBEGN.

Structural properties of Strontium Bismuth Niobate (SrBi2Nb2O9) ferroelectric ceramics

The pure SrBi2Nb2O9 (SBN) ceramic was synthesized by the conventional solid-state reaction method. The sample was then undergoing heat treatment at different calcination temperatures: 800 °C, 850 °C, and 950 °C, and the evolution of phases were studied at these different calcination temperatures, followed by sintering at 1000 °C of temperature to form single-phase SBN. Few secondary phases have been identified along with the desired SBN phase but begin to decrease with the increase in the calcination temperature. The most appropriate calcination and sintering temperature have been successfully investigated with no impurity phase. The structural morphology of the sample sintered at 1000 °C studied under SEM reveals the formation of the highly dense plate-like grains and EDS provides information about the elemental composition. The Raman analysis revealed the formation of the orthorhombic phase of pure SBN.

Dielectric characterisation and numerical investigation of SrBi2Nb2O9–Bi2O3 composites for applications in microwave range

We present a study of the dielectric properties and behaviour of dielectric resonator antennas (DRAs) based on SrBi2Nb2O9 (SBN)-Bi2O3 composites. X-ray diffraction is used for structural characterisation of the samples and it indicates the formation of a new phase after the addition of Bi2O3. The temperature coefficient of resonant frequency (τ f) is measured and the results demonstrate that the increment of Bi2O3 improves the thermal stability of the composites from −345.62 to −235.02 ppm/°C. For the dielectric properties, it is observed that Bi2O3 additions cause the formation of new phases, which present higher dielectric ϵ’ than SBN. Our numerical simulations show that the materials operate as DRAs and that SBN-Bi2O3 composites could be potential candidates for DRAs operating in the S band.

Reversible upconversion modulation in new photochromic SrBi2Nb2O9 based ceramics for optical storage and anti-counterfeiting applications

The manipulation of luminescence properties of upconversion (UC) materials from micro to macro aspects is of vital importance for disclosing new physical phenomena and expanding the range of applications. In this work, a novel class of SrBi2Nb2O9 (SBN)-based inorganic photochromic (PC) phosphors was synthesized, which exhibited intense susceptibility to visible light irradiation. Large reversible UC modulation ability upon PC effect was realized. Besides, the regulation of UC luminescence was discovered to strongly rely on the irradiation time and heating processes. The mechanisms connected to the UC luminescence, PC effect, and UC manipulation were illustrated. These results demonstrated that SBN-based samples owing high reversible manipulation ratio, fast response, low heating temperature, and excellent reproducibility can be employed as a type of ideal optical medium for future information storage device. In addition, based on the reversible behavior of photochromism, the application of the SBN-based ceramic as an anti-counterfeiting agent was also depicted.

Flexoelectric switching characteristics depending on crystallinity of highly c-oriented epitaxial SrBi2Nb2O9 thin film

We demonstrated the formation and reading of flexoelectrically-switched polarization nanobits in c-oriented, epitaxial layered-perovskite thin films. Highly c-oriented epitaxial SrBi2Nb2O9 (SBN) thin films were deposited on Nb-doped single crystal (100) SrTiO3 (Nb:STO) substrates via pulsed laser deposition (PLD) technology. X-ray diffraction (XRD) experiments, ferroelectric hysteresis loops, leakage current curves, and fatigue characteristics revealed that these films preferred in-plane oriented domains. Flexoelectrically switched polarization nanobits with horizontally switched domains were formed within an upwardly switched domain of the c-oriented epitaxial SBN thin film by applying external forces orthogonal to the surface. In particular, flexoelectrically switched polarization nanobits didn't have out-of-plane-oriented domains, reflecting the c-oriented nature of the Aurivillius SBN thin film.

Synthesis, DC conductivity and Dielectric studies on double doped Strontium Bismuth Niobate Ceramics

The Strontium Bismuth Niobate SrBi2Nb2O9 (SBN), K0.025Sr0.95Gd0.025Bi2Nb2O9 (KSGBN1) and K0.05Sr0.9Gd0.05Bi2Nb2O9 (KSGBN2) ceramics were prepared by two stage solid state reaction method. Crystal structure of sintered samples was studied by powder X - ray diffraction technique. XRD patterns well matched with reported data (ICSD #82280).The lattice parameters of the samples were calculated using POWD Software. Pellets of 10mm diameter and thickness about 1mm∼2mm were prepared and final sintered in the temperature range 900°C ∼950°C for four hours. The surface morphology of the samples was studied from Scanning electron Microscope pictures. The Temperature dependence of DC conductivity and dielectric properties were obtained and analyzed. Conclusions arrived at are presented.

Electrical and ferroelectric properties of RF sputtered PZT/SBN on silicon for non-volatile memory applications

We report the integration of multilayer ferroelectric film deposited by RF magnetron sputtering and explore the electrical characteristics for its application as the gate of ferroelectric field effect transistor for non-volatile memories. PZT (Pb[Zr0.35Ti0.65]O3) and SBN (SrBi2Nb2O9) ferroelectric materials were selected for the stack fabrication due to their large polarization and fatigue free properties respectively. Electrical characterization has been carried out to obtain memory window, leakage current density, PUND and endurance characteristics. Fabricated multilayer ferroelectric film capacitor structure shows large memory window of 17.73 V and leakage current density of the order 10−6 A cm−2 for the voltage sweep of −30 to +30 V. This multilayer gate stack of PZT/SBN shows promising endurance property with no degradation in the remnant polarization for the read/write iteration cycles upto 108.

First principles investigation of the strain-mode coupling in SrBi2Nb2O9

ABSTRACTThe Aurivillius compounds SrBi2Nb2O9 (SBN) and SrBi2Ta2O9 (SBT) present at room temperature isomorphous ferroelectric structures that are stabilized by a complex interplay of three order parameters via a trilinear coupling. In this work we examine the influence of the in-plane misfit strain in the strength of the relevant instabilities and the couplings between them. A mixed strain-stress enthalpy compatible with the symmetry of SBN is developed with all the parameters obtained from first principles. We find that the dominant role of the order parameters varies as a function of the strain and, as a consequence, that the value of the polarization can be tuned by choosing the lattice parameter of the substrate. It is also shown that the sequence of phase transitions and the main features of the phase diagram change qualitatively in terms of the strain.

The Effect of (K0.5Bi0.5) Doping on Structural and Dielectric Properties of SrBi2 Nb2O9 Ceramics

The Effect of (K_0.5Bi_0.5) Doping on Structural and Dielectric Properties of SrBi₂ Nb₂O₉ Ceramics

Vibrational analysis on two-layer Aurivillius phase Sr1−xBaxBi2Nb2O9 using Raman spectroscopy

A Raman spectroscopy study at room temperature was carried out on Sr1−xBaxBi2Nb2O9 ferroelectric ceramics (x=0, 15, 30, 50, 70, 85, 100at%). The results were compared to the Raman activity of SrBi2Nb2O9(SBN) and has suggested that the Sr2+/Bi3+/Ba2+ mixing at the A sites of the pseudo-perovskite structure leads to a wavenumber shift with the increasing of the barium content in the structure connected to OAO bending mode, which was observed at 222cm−1, and the OBO bending A1g mode (B=Nb5+), which was observed at 171cm−1 due to the modification environment by the barium substitution. A wavenumber shift was observed for the NbO stretching A1g mode connected to the NbO6 octahedral, which was observed at 843cm−1 in the SBN sample, due to the octahedral distortions. The B2g mode was related to the atoms vibration in the (x, y)-plane and was observed at 568cm−1. This mode was less affected by the barium substitution, which has been attributed to changes in the fluoride layer of the Aurivillius structure. The modes activities were observed to be quite different for x≤30at% and x≥50at%, which has been attributed to a higher concentration of Ba2+ into the A sites for the higher barium contents.

Photoluminescence, enhanced ferroelectric, and dielectric properties of Pr3+-doped SrBi2Nb2O9 multifunctional ceramics

Pr3+-doped SrBi2Nb2O9 (SBN) multifunctional ceramics were synthesized by the conventional solid state method. The photoluminescence (PL) excitation and emission spectra, enhanced ferroelectric and dielectric properties were investigated. The X-ray diffraction (XRD) and FESEM analyses indicated that the samples were simple phase and uniform flake-structure. Under the 250–350nm ultraviolet (UV) excitations, the red emission was obtained and the optimal emission intensity was investigated when Pr doping level was 0.005mol. With the increasing of the Pr3+ ion contents, the ferroelectric properties were enhanced obviously. As a new multifunctional material, the Pr3+-doped SBN ceramics could be used for a wide range of application, such as integrated electro-optical devices.

Structure, Dielectric Relaxor Behavior and Ferroelectric Properties of Sr&lt;sub&gt;1-x&lt;/sub&gt;La&lt;sub&gt;x&lt;/sub&gt;Bi&lt;sub&gt;2&lt;/sub&gt;Nb&lt;sub&gt;2-x/5&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt; Ferroelectric Ceramics

Ferroelectric ceramics, Sr1-xLaxBi2Nb2-x/5O9 (SLBNO), were prepared using the conventional solid-state reaction method. Effect of lanthanum substitution on dielectric and ferroelectric properties of SrBi2Nb2O9 (SBN) ceramics were investigated. X-ray diffraction analyses (XRD) revealed that all the specimens had a single phase with orthorhombic space group A21am. The maximum dielectric permittivity peak broadened gradually with the increase in lanthanum substitution indicated that the phase transition from normal ferroelectrics to relaxor ferroelectrics occurred in SLBNO ceramics. The modified Curie-Weiss (CW) law was used to describe the relaxor behavior of the SLBNO ceramics. The relaxation indication coefficient (γ) was estimated from a quadratic fit of modified CW law and was found to be 1.7 and 2.0 for the SLBN20 and SLBN30 specimens, respectively. Curie temperature (Tc) of the SBN ceramic was decreased gradually with the increase in lanthanum substitution. In addition, the ferroelectric properties of the SBN ceramic were enhanced significantly by the introduction of lanthanum ions and the maximum of remnant polarization (Pr) was found to be 4.35 μC/cm2 for the SLCB20 specimen. Nature of relaxor behavior of the SLBNO ceramic is attributed to the cationic disordering at nanoscale on A site by the introduction of lanthanum ions.

Influence of zirconium doping on structure, microstructure, dielectric and impedance properties of strontium bismuth niobate ceramics

Efforts have been made in this work to enhance the dielectric properties of SrBi2Nb2O9 (SBN) by partial substitution of Zr4+ for Nb5+. Systematic investigations on structure, microstructure, dielectric and impedance properties of the SrBi2(Nb2−(4/5)xZrx)O9 [where, x = 0, 0.1 and 0.2] ceramic samples were carried out to understand the effect of substitution of Zr4+ for Nb5+ in SrBi2Nb2O9. The X-ray diffraction (XRD) investigations indicated that the lattice volume of SrBi2(Nb2− (4/5)xZrx)O9 with x = 0.1 and 0.2 decreases compared to SBN. The SEM investigations revealed an increase in the size of grains and the change on shape of grains to elongated plate shaped structure with the increase of x (x = 0.1 and 0.2) in SrBi2(Nb2−(4/5)xZrx)O9. Higher Curie temperature and enhanced peak dielectric constant at the Curie temperature were observed for both the SrBi2(Nb2−(4/5)xZrx)O9 with x = 0.1 and 0.2 ceramic samples compared to SBN. Among the investigated compositions the higher Curie temperature and enhanced peak dielectric constant at the Curie temperature was observed for SrBi2(Nb2−(4/5)xZrx)O9 with x = 0.1.