Ferroelectric materials Research Papers - Academia.edu (original) (raw)

2025

Ferroelectric bulk material devices have been in existence for over 2 years. '/tx'U V'* L.I TABLE OF CONTENTS I. I would also like to thank James Deal, Norman Abt, Steve Bernacki, Ron Phelps and Dave Rigmaiden for the wealth of information and help that they provided. Last, but certainly not least, I want to thank my lovely wife Lisa. Without her encouragement, understanding and confidence all of this would not have been possible.

2025, Optical Materials

The relationships of the wavelength dependence of both the electro-optic and second harmonic generation coefficients are established within the same model applied to nonlinear optical materials. It is demonstrated that the dispersion of these coefficients can be obtained from the own dependence of the refractive indices only, without any fitted parameter. Solely the measurement of the coefficient at one wavelength is required within this approach. A very good agreement in the k-dependence of electrooptic and second harmonic generation coefficients is achieved between calculated values and experimental data in SBN, DAST, KTP and KNbO 3 crystals.

2025, Journal of Physics: Condensed Matter

The ferroelastic phase transition and shape memory effect in La-modified lead zirconate titanate ferroelectric ceramics are demonstrated directly through the temperature-dependent macroscopic recoverable strain measured in a three-point bending configuration. X-ray diffraction measurements reveal that non-180 • domain switching occurs in the mechanically poled sample in two different ways at the bottom and top of the sample which have been under tensile and compressive stresses, respectively. The calculated fraction of non-180 • switched domains in the poled sample increases nonlinearly with the applied force and shows a saturation trend, which is consistent with the nonlinear behavior of the remnant strain. This study confirms that the mechanical stress applied upon cooling ferroelectric ceramics from the paraelectric to the ferroelectric phase can easily activate ferroelastic domain switching and give rise to preferred domain orientation and consequent macroscopic remnant strain which results in a history effect and shape memory effect via the ferroelastic phase transition.

2025

Nanocomposites of linear chain of ferroelectric-ferromagnetic crystal structure is considered. It is analyzed theoretically in the motion equation method on the pursuit of magnonic excitations,lattice vibration excitations and their interactions leading to a new collective mode of excitations,the electormagnons. In this particular work, it is observed that the magnetizations and polarizations are tunable in a given temperature ranges for some specific values of the coupling order parameter.

2025

Metal oxides are well-known high-k dielectric materials since the early solid state electronics age. However, they were rarely used in modern IC chips except as charge storage layers in MOS capacitors. Recently, due to the performance and reliability issues of the nm thick SiO2 in the gate dielectric application, metal oxide high-k dielectrics become popular alternatives. For the most advanced MOSFET, the sub nm EOT metal oxide is the preferred choice for the gate dielectric for its low leakage current and high reliability. Separately, metal oxides, such as IGZO or ZnO, are popular semiconductor materials in thin film transistors (TFTs) because of its high field effect mobility, e.g., 10 to 100 times that of the a-Si:H TFT. For above applications, the crystalline structure is preferable. For example, for the same metal oxide dielectric, the k value of the crystalline film can be several times higher than that of the amorphous film. TFTs made of the crystalline ZnO semiconductor film...

2025, SSRN

Ferroelectric thin films exhibit unique nanoscale structural and dynamic properties that are crucial for their applications in microelectronics, memory devices, and energy storage systems. This study explores the interplay between film thickness, domain structures, and polarization dynamics in ferroelectric materials. Using advanced characterization techniques such as atomic force microscopy (AFM) and piezoresponse force microscopy (PFM), we analyze the domain morphology, switching kinetics, and local polarization behaviors at the nanoscale. Additionally, theoretical modeling and phase-field simulations provide insight into the influence of strain, defects, and interface effects on the stability and mobility of ferroelectric domains. Our findings highlight the critical role of film-substrate interactions and external electric fields in tuning the dynamic response of ferroelectric films, offering pathways for optimizing their performance in next-generation electronic devices.

2025, Bulletin of the American Physical Society

at Riverside -Relaxor ferroelectric crystals (or simply relaxors) show high dielectric constants and low dielectric losses over a broad range of temperatures. There is consensus that the dielectric properties of the relaxors are due to the formation of polar nanoregions (PNR) below the Burns temperature. Each PNR possesses a net polarization that has many equivalent orientations. The gradient in the polarization leads to charge accumulation on the PNR surfaces. Such charge accumulation produces electric fields, which in turn affect the direction of the polarizations themselves. Knowledge of the electric field and of the polarization distributions is critical to understand the dielectric properties of these systems. Here, we present results on the calculated probability distribution of the electric fields and of the polarizations in the relaxors. Comparison to results obtained from neutron scattering experiments is provided.

2025, J. Eur. Ceram. Soc. 45 (2025) 117567

Lix(Sr0.5Ba0.5)1-x/2Nb2O6 ceramics were prepared by a solid state synthesis and sintered at 1300 • C. XRD investigations reveal single phase samples up to a substitution limit of x = 0.275. For higher lithium contents, the appearance of LiNbO3 as secondary phase was observed. The density of the ceramics increases with lithium content. The microstructures show globular grains which turns to pillar-like grains with rising lithium substitution. Dielectric investigations confirm relaxor ferroelectric behavior and the diffuse phase transition is shifted towards higher temperatures with increasing lithium content from 129 • C (x = 0) to 221 • C (x = 0.275). The diffuseness coefficient increases with the lithium content. From high-temperature XRD measurements the length of the tetragonal cell parameter c decreases with increasing temperature, reaches a minimum at about 150-230 • C (depending on x) and afterward increases with increasing temperature. Additionally, a significant shift of the Nb(2) position with temperature can be observed.

2025

tout au long de la réalisation de ce mémoire. Dans ce travail nous avons proposé plusieurs modèles de ligne microruban avec substrat multicouche chiral -chiroferrite -ferrite, afin de pouvoir étudier les différents effets hybrides de la chiralité et la gyrotropie sur les caractéristiques de propagation de ces structures. Pour cette raison nous avons utilisé la technique de la matrice exponentielle généralisée (GEMT) dans le domaine spectral et l'approche de Galerkin. L e s r é s u l t a t s n u mé r i q u e s o n t mo n t r é q u ' en plus des paramètres de chiralité, les variations de la constante de propagation et la permittivité effective sont en fonction de plusieurs autres facteurs tels que la fréquence de fonctionnement, la magnétisation et l ' o r i e n t a t i o ndu champ de polarisation, les dimensions géométriques de la structure, la largeur et la position du ruban.

2025

In this paper we report the preliminary experimental data of the third order non-linearity in a liquid crystal 5HCB sample doped with methyl-red using Z-scan technique. We observe a negative nonlinearity in the sample, which is great optical nonlinearity ten times more than other results previously reported in liquid crystals. This phenomena is obtained in the nematic phase regime. For

2025, The Japan Society of Applied Physics

For the development of high performance graphene field effect transistors (GFETs), it is essential to form a high quality gate dielectric layer without degrading the pristine properties of graphene. Generally, natural oxide layer of Al as well as ALD-grown Al2O3 layer is used as the gate dielectric layer for GFETs. The natural oxide of Al, however, shows substantial leakage current while the ALD requires a surface modification process beforehand to activate the hydrophobic surface of graphene. To overcome these limitations, we investigated a solution-based formation of an Al2O3 (sol-Al2O3) layer combined with a microwave-assisted annealing. In a solution process, a thermal decomposition process is indispensable to remove the solvent and the stabilizer, which mainly determines the dielectric properties of the film. Normally, the thermal decomposition process is carried out at high temperatures (> 600 C) using a furnace annealing and an oven baking. At these high temperatures, hole...

2025, The Japan Society of Applied Physics

Epitaxial graphene (EG) on silicon carbide (SiC) is promising for fabrication of graphene field-effect transistors (GFETs) because it is formed by a direct growth on large size substrates and requires no transfer procedures that can sometimes cause wrinkles and contaminations. For development of high performance GFETs, it is essential to form a high quality gate dielectric layer without degrading the pristine properties of graphene. There are however several critical restrictions in the formation of gate dielectric layers on graphene, due, for instance, to generation of defects by plasma processing, onset of hole doping during high-temperature annealing, and a need for a surface modification before the atomic-layer deposition (ALD) process. To overcome these limitations, we have been investigating a solution-based formation of an Al2O3 layer (sol-Al2O3) [Park et al., JJAP accepted]. In the solution process, a thermal decomposition process is most important. If residual solvent or st...

2025

The China Central Government is determined to promote the use of solar PV in providing electricity to rural areas as well as supplementing power in cities; the installed PV capacity is predicted to be over 4.2GW by year 2015. To attend such a target, the annual expansion rate of PV installations in China and nearby regions has to be over 40%. At the same time, in May 2005, the Hong Kong local government also established its target in alternative energy, which is 1 to 2% by 2012. With such a rapidly expanding market, the capability in accurately predicting the real performance of a PV system to be installed; together with the proper monitoring and evaluation of its performance are thus of crucial importance to designing of these systems. The HKU & HK PolyU PV research teams are collocating together to introduce a methodology in prediction of PV system performance by considering intelligently the local environmental data into an efficiency model of the PV systems for accurate prediction of power output. Other parameters including orientation, tilt angle, shading factor, panel temperature, wiring configuration, and inverter efficiency are also fed into the prediction algorithm for a year-round energy yield.

2025, Bulletin of the American Physical Society

The American Physical Society Sorting Category: 11.1.1 (E)

2025, Bulletin of the American Physical Society

Submitted for the MAR06 Meeting of The American Physical Society Composition dependence of the diffuse scattering in relaxor (1x)Pb(Mg 1/3 Nb 2/3 )O 3 -xPbTiO 3 (0 ≤ x ≤ 0.40) M. MATSUURA, K. HIROTA, ISSP The University of Tokyo, P. M. GEHRING, NIST Center for Neutron Research, ZUO-GUANG YE, W. CHEN, Department of Chemistry Simon Fraser University, G. SHIRANE, Deapartment of Physics Brookhaven National Laboratory -We have studied composition dependence of diffuse scattering in the relaxor sys 10, 20, 30, and 40% by neutron diffraction. The addition of ferroelectric PbTiO 3 (PT) modifies the "butterfly" and "ellipsoidal" diffuse scattering patterns observed in pure PMN (x = 0), which are associated with the presence of randomly oriented, polar nanoregions (PNR). The spatial correlation length ξ derived from the width of the diffuse scattering increases from 12.6 Å for PMN (x = 0) to 350 Å for PMN-20%PT, corresponding to an enlargement of the PNR. The integrated diffuse scattering intensity, which is proportional to χ ′′ , grows and reaches a maximum at x = 20%. Beyond x =30% PT, a concentration very close to the morphotropic phase boundary (MPB), no diffuse scattering is observed below T C , and well-defined critical behavior is observed. By contrast, the diffuse scattering for x ≤ 20% persists to low temperatures, where the system retains an average cubic structure (T C = 0). We can simulate the wave vector dependence of the diffuse scattering by assuming that it arises from the condensation of a soft transverse-optic (TO) phonon.

2025, arXiv (Cornell University)

Recently, a new orthorhombic phase has been discovered in the ferroelectric system (1x)Pb(Zn 1/3 Nb 2/3 )O3-xPbTiO3 (PZN-xPT) for x= 9%, and for x= 8% after the application of an electric field. In the present work, synchrotron x-ray measurements have been extended to higher concentrations, 10% ≤ x ≤15%. The orthorhombic phase was observed for x= 10%, but, surprisingly, for x ≥11% only a tetragonal phase was found down to 20 K. The orthorhombic phase thus exists only in a narrow concentration range with near vertical phase boundaries on both sides. This orthorhombic symmetry (MC-type) is in contrast to the monoclinic MA-type symmetry recently identified at low temperatures in the Pb(Zr1-xTix)O3 (PZT) system over a triangle-shaped region of the phase diagram in the range x= 0.46-0.52. To further characterize this relaxor-type system neutron inelastic scattering measurements have also been performed on a crystal of PZN-xPT with x= 15%. The anomalous soft-phonon behaviour ("waterfall" effect) previously observed for x= 0% and 8% is clearly observed for the 15% crystal, which indicates that the presence of polar nanoregions extends to large values of x.

2025, Bulletin of the American Physical Society

We have performed neutron scattering studies on low energy phonon modes in the multiferroic BiFeO 3 . We show measurements near (100), ( ), (200) Bragg peaks on the TA, LA and lowest energy TO modes in a broad temperature range from 300 K to 700 K. The intensities, dispersion, and life times (inversed energy width) of these phonon modes are plotted vs. temperature, and anomalies related to the AFM order (Neel temperature of 640 K) are discussed. We also will also discuss additional low energy modes observed that may be related to the "electro-magnon" excitations in this material. This work is supported by the Office of Basic Energy Sciences, DOE.

2025, Bulletin of the American Physical Society

The American Physical Society

2025, Bulletin of the American Physical Society

We have performed inelastic neutron scattering studies of the low-energy phonon and spin-wave modes in the multiferroic BiFeO3. The low-energy phonon and spin wave dispersion relations along different directions have been mapped out over a broad temperature range from 100K to 750K. The temperature dependence of the intensities, dispersion relations, and lifetimes (inverse energy width) of these phonon and spin wave modes will be presented. Possible interactions between the lattice and spin dynamics will also be discussed. This work is supported by the Office of Basic Energy Sciences, DOE.

2025, Bulletin of the American Physical Society

2025, arXiv (Cornell University)

2025, Bulletin of the American Physical Society

2025, Scientific Reports

Coupling of order parameters provides a means to tune functionality in advanced materials including multiferroics, superconductors and ionic conductors. We demonstrate that the response of a frustrated ferroelectric state leads to coupling between order parameters under electric field depending on grain orientation. The strain of grains oriented along a specific crystallographic direction, 〈h00〉, is caused by converse piezoelectricity originating from a ferrodistortive tetragonal phase. For 〈hhh〉 oriented grains, the strain results from converse piezoelectricity and rotostriction, as indicated by an antiferrodistortive instability that promotes octahedral tilting in a rhombohedral phase. Both strain mechanisms combined lead to a colossal local strain of (2.4 ± 0.1) % and indicate coupling between oxygen octahedral tilting and polarization, here termed “rotopolarization”. These findings were confirmed with electromechanical experiments, in situ neutron diffraction and in situ transmi...

2025, Journal of Telecommunication, Electronic and Computer Engineering

This paper investigates the grid-connected photovoltaic (GCPV) effects to the Malaysian distribution systems. Increased in distributed generation installations into electricity distribution network co uld have a better impact on the planning and operation of a power system. The scenario discussed in this paper is the solar irradiance level effects on grid-connected photovoltaic (GCPV) system which located in Universiti Teknikal Malaysia Melaka. The research consists of analysis in current and total harmonic distortion performance due to sun irradiance which may give an impact on photovoltaic systems to generate output power. PV generation depends directly to the sun’s radiation. Hence, the intermittent fluctuations may potentially cause problems to the network operation, especially in high penetration levels. In addition, a larger number of distributed GCPV is added into the grid, the effect or impact may become more significant. There are several previous researched regarding the i...

2025, ACS Applied materials and interface

Understanding the dynamics of electrical signals within neuronal assemblies is crucial to unraveling complex brain functions. Despite recent advances in employing optically active nanostructures in transmembrane potential sensing, there remains room for improvement in terms of response time and sensitivity. Here, we report the development of such a nanosensor capable of detecting electric fields with a submillisecond response time at the single-particle level. We achieve this by using ferroelectric nanocrystals doped with rare-earth ions that produce upconversion (UC). When such a nanocrystal experiences a variation of surrounding electric potential, its surface charge density changes, inducing electric polarization modifications that vary, via a converse piezoelectric effect, the crystal field around the ions. The latter variation is finally converted into UC spectral changes, enabling optical detection of the electric potential. To develop such a sensor, we synthesized erbium and ytterbium-doped barium titanate crystals of ≈160 nm in size. We observed distinct changes in the UC spectrum when individual nanocrystals were subjected to an external field via a conductive atomic force microscope tip, with a response time of 100 μs. Furthermore, our sensor exhibits a remarkable sensitivity of 4.8 kV/cm/ Hz , enabling time-resolved detection of a fast-changing electric field of amplitude comparable to that generated during a neuron action potential.

2025

2025, Proceedings of SPIE - The International Society for Optical Engineering

We present a novel ring resonator for second harmonic generation consisting of only two spherical mirrors and a refractive element. In our work we use periodically poled KTP as a nonlinear material for generating the second harmonic using an 808nm tapered grating stabilized external cavity laser as pump source. With 286mW of fundamental 808nm radiation coupled into the resonator, we generate 130mW blue light at 404 nm, resulting in a power conversion efficiency of 45%.

2025, INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019

2025, Physical Review A

Temporal light modulation methods which are of great practical importance in optical technology, are emulated with matter waves. This includes generation and tailoring of matter-wave sidebands, using amplitude and phase modulation of an atomic beam. In the experiments atoms are Bragg diffracted at standing light fields, which are periodically modulated in intensity or frequency. This gives rise to a generalized Bragg situation under which the atomic matter waves are both diffracted and coherently shifted in their de Broglie frequency. In particular, we demonstrate creation of complex and non-Hermitian matter-wave modulations. One interesting case is a potential with a time-dependent complex helicity ͓Vϰexp(it)͔, which produces a purely lopsided energy transfer between the atoms and the photons, and thus violates the usual symmetry between absorption and stimulated emission of energy quanta. Possible applications range from atom cooling over advanced atomic interferometers to a new type of mass spectrometer.

2025, Rare Metals

The structural, morphological and optical properties of single-phase polycrystalline La 2-x Sr x NiMnO 6 (x = 0, 0.3 and 0.5), synthesized by solid state reaction were investigated. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive analysis of X-rays (EDAX), Raman spectroscopy and diffuse reflectance spectroscopy (DRS) to elucidate the role of A-site Sr-doping in double perovskite La 2 NiMnO 6. Rietveld analysis of XRD patterns revealed that all the samples have monoclinic structure with space group P2 1 /n. Positive gradient in the Williamson Hall plots revealed the presence of tensile strain in all the samples. The morphological studies revealed that average grain size increases along with appreciable decrease in porosity with Sr doping. The Ni/Mn antisite disorder was introduced in the La 2 NiMnO 6 by Sr-doping confirmed by an increase in the full width at half maximum (FWHM) and decrease in intensity of the Raman modes at around 540 and 665 cm-1 which correspond to the antisymmetric stretching and symmetric stretching modes, respectively. DRS results reveal that the band gap in La 2 NiMnO 6 can be tuned down by Sr-doping to a value of 1.37 eV (very close to 1.40 eV, considered as optimum value for better efficiency of a solar cell). Thus, Sr-doped La 2 NiMnO 6 may be of prime importance for applications in solar cells.

2025, Journal de Physique

2025, Solid State Communications

2025, Journal of Crystal Growth

In present work, (Pb 0.5 Ba 0.5 )ZrO 3 (PBZ) thin films with a thickness of 840 nm were successfully fabricated on (Sr 0.95 La 0.05 )TiO 3 (SLT) buffer-layered Pt(1 1 1)/TiO 2 /SiO 2 /Si(1 0 0) substrates via the sol-gel technique. The effects of SLT buffer layer on the microstructure and electrical properties of PBZ thin films were investigated systemically. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that PBZ thin films on SLT buffer-layered substrates showed a more uniform structure with a random orientation. Dielectric measurements illustrated that PBZ films with SLT buffer layer displayed larger dielectric constant, improved tunability and enhanced figure of merit (FOM). Moreover, leakage current of PBZ films was also reduced by SLT buffer layer.

2025, Journal of Electroceramics

This paper addresses the rigorous treatment of the tunability effect (dc electric field driven variation of the permittivity) in a high-contrast two dimensional periodic composite (a matrix of a large dielectric constant ferroelectric material with linear dielectric inclusions). The theoretical analysis here shows that the trend established for the case of low linear dielectric concentrations (that the dilution with a low permittivity dielectric does not result in decrease of the tunability of the composite material), can hold for appreciable dielectric concentrations. We have even documented a pronounced increase of the tunability. The results of our simulations are in qualitative agreement with the experimental data on the composite effect in ferroelectric/dielectric binary-phase systems. The result of the numerical analysis gives no support to the "decoupled approximation" in the effective medium approach often used for the description of the dielectric non-linearity of composites.

2025, Thin Solid Films

BST thin films were etched with inductively coupled CF y(Cl qAr) plasmas. The maximum etch rate of the BST thin films 4 2 was 53.6 nmymin for a 10% CF to the Cl yAr gas mixture at RF power of 700 W, DC bias of y150 V, and chamber pressure 4 2 of 2 Pa. Small addition of CF to the Cl yAr mixture increased chemical effect. Consequently, the increased chemical effect 4 2 caused the increase in the etch rate of the BST thin films. To clarify the etching mechanism, the surface reaction of the BST thin films was investigated by X-ray photoelectron spectroscopy.

2025, IEEE Journal of Quantum Electronics

2025, IEEE Photonics Journal

2025, Journal of Electroceramics

Laminated 3D structures made using lowtemperature co-fired ceramic (LTCC) technology are practical for ceramic micro-electro-mechanical systems (C-MEMS). The sensors for mechanical quantities, and/or actuators, are fundamental parts of MEMS. Thick-film resistors can be used to sense the mechanical deformations, and thick-film piezoelectric materials can be used as electro-mechanical transducers in a C-MEMS structure. The integration of these thick-film materials on LTCC substrates is in some cases difficult to realise due to interactions with the rather glassy LTCC substrates. The subject of our work is an investigation of thick-film materials for electro-mechanical transducers (sensors and actuators) and their compatibility with LTCC substrates. Resistors made with commercial thick-film resistor materials for use as sensors on LTCC substrates have been investigated and evaluated. Ferroelectric ceramic materials based on solid solutions of lead zirconate titanate (PZT) with low firing temperatures around 850°C were developed for thick-film technology and evaluated on LTCC substrates.

2025, Ceramics International

Plate-shaped zinc oxide nanoparticles (ZnO-NPs) were successfully synthesized by a modified sol-gel combustion method. Zinc acetate, pure water and isopropanol were used as the starting materials. Acetic acid, diethanolamine and nitric acid were used as the polymerization agent, complexing agent and fuel, respectively. The precursors were formed by mixing aqueous solutions of zinc acetate, acetic acid and diethanolamine. Nitric acid was used to dry the produced gel. The resulting xerogel was annealed at 600 8C, 650 8C and 750 8C for 1 h. The synthesized ZnO-NPs were characterized by X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA) and high-magnification transmission electron microscopy (TEM). The XRD results revealed that the samples produced were crystalline with a hexagonal wurtzite phase. The TEM results showed single-crystal ZnO-NPs with nearly hexagonal plate shapes. The optical properties of the ZnO-NPs were studied by UV-visible and Fourier-transform infrared spectroscopy (FTIR). The UV-vis absorption spectra of the ZnO-NPs indicated absorption peaks in the UV region, which were attributed to the band gap of the ZnO-NPs. The results of the FTIR and UV-vis studies showed that the optical properties of the ZnO-NPs depended on the annealing temperature.

2025, IEEE Journal of Quantum Electronics

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2025, MDPI polymers

Self-polarized energy harvesting materials have seen increasing research interest in recent years owing to their simple fabrication method and versatile application potential. In this study, we systematically investigated self-polarized P(VDF-TrFE)/carbon black (CB) composite thin films synthesized on flexible substrates, with the CB content varying from 0 to 0.6 wt.% in P(VDF-TrFE). The presence of-OH functional groups on carbon black significantly enhances its crystallinity, dipolar orientation, and piezoelectric performance. Multiple characterization techniques were used to investigate the crystalline quality, chemical structure, and morphology of the composite P(VDF-TrFE)/CB films, which indicated no significant changes in these parameters. However, some increase in surface roughness was observed when the CB content increased. With the application of an external force, the piezoelectrically generated voltage was found to systematically increase with higher CB content, reaching a maximum value at 0.6 wt.%, after which the sample exhibited low resistance. The piezoelectric voltage produced by the unpoled 0.6 wt.% CB composite film significantly exceeded the unpoled pure P(VDF-TrFE) film when subjected to the same applied strain. Furthermore, it exhibited exceptional stability in the piezoelectric voltage over time, exceeding the output voltage of the poled pure P(VDF-TrFE) film. Notably, P(VDF_TrFE)/CB composite-based devices can be used in energy harvesting and piezoelectric strain sensing to monitor human motions, which has the potential to positively impact the field of smart wearable devices.

2025

We investigate a novel ultrasonic motor which generates a stator trajectory in the form of a figure-of-eight by superimposing two resonant modes, with one double the frequency of the other. Topology optimization was used to design the stator structure. In contrast to traditional travelling wave ultrasonic motors, which require two modes to be driven 90° out of phase, only one amplifier is required to drive the proposed device. A prototype device was characterised experimentally and was used to drive a linear bearing at 14 mm/s reversibly and a force of 50 mN was developed by the motor.

2025

For intra-cavity laser beam control, a small, low-cost deformable mirror is required. This mirror can be used to correct for time-dependent phase aberrations to the laser beam, such as those caused by thermal expansion of materials. A piezoelectric unimorph design is suitable for this application. The proposed unimorph consists of a copper disc with mirror finish, bonded to a piezoelectric disc. The deformations that the mirror is required to perform are routinely (at least in optical applications) described using Zernike polynomials, which are a complete set of orthogonal functions defined on a unit disc. The challenge is to design a device that can represent selected polynomials as accurately as possible with a specified amplitude. To assist in the design process, numerical modelling is required to predict the deformation shapes that can be achieved by a unimorph mirror with a particular electrode pattern. In this paper a previously proposed axisymmetric Rayleigh-Ritz formulation, is extended to account for non-axisymmetric voltage distributions, and therefore non-axisymmetric displacements. The Rayleigh-Ritz model, which uses the Zernike polynomials directly to describe the displacements, produced a small model (stiffness matrix dimension equal to the number of polynomials used) that predicts the deformations of the piezoelectric mirror with remarkable accuracy. The results using this Rayleigh-Ritz formulation are compared to results from a traditional finite element analysis using a commercial finite element package. Both numerical models were applied to model a prototype deformable mirror and produced good agreement with experimental results.

2025, Archives of Metallurgy and Materials

The results of the microstructural and dielectric measurements of (Ba1-xPbx)(Ti1-xSnx)O3 (BPTSx) (x = 0, 0.05, 0.10, 0.30) polycrystalline samples are presented. The samples were obtained by means of a high temperature synthesis and their expected stoichiometry was confirmed by energy dispersive spectroscopy (EDS) measurements. The dielectric properties of BPTSx were studied with the use of broadband dielectric spectroscopy. The measurements over a wide range of temperature (from 140 K to 600 K) and frequency (from 0.1 Hz to 10 MHz) were performed. The experimental results indicate an influence of Pb ions in a sublattice A and Sn ions in a sublattice B substitution on paraelectric -ferroelectric phase transition parameters. Diffused phase transitions from a paraelectric to ferroelectric state (for x = 0.10 and x = 0.30) were observed. From the electric modulus measurements in the frequency domain the relaxation times and the activation energy were determined.

2025, Advanced Energy Materials

Till date, fabrication of piezoelectric nanogenerator (PNG) with highly durable, high power density, and high energy conversion efficiency is of great concern. Here a flexible, sensitive, cost effective hybrid piezoelectric nanogenerator (HPNG) developed by integrating flexible steel woven fabric electrodes into poly(vinylidene fluoride) (PVDF)/aluminum oxides decorated reduced graphene oxide (AlO‐rGO) nanocomposite film is reported where AlO‐rGO acts as nucleating agent for electroactive β‐phase formation. The HPNG exhibits reliable energy harvesting performance with high output, fast charging capability, and high durability compared with previously reported PVDF based PNGs. This HPNG is capable for harvesting energy from a variety and easy accessible biomechanical and mechanical energy sources such as, body movements (e.g., hand folding, jogging, heel pressing, and foot striking, etc.) and machine vibration. The HPNG exhibits high output power density and energy conversion efficie...

2025, Journal of Applied Physics

Here, we report the effect of A-site substitution of Tb at the expense of Bi on the ferroelectric and magnetic properties in m = 5 layered 2-D Aurivillius Bi6Ti3Fe2O18 thin films. The nominal stoichiometry of the prepared compound is Tb0.40Bi5.6Fe2Ti3O18, Tb0.90Bi5.1Fe2Ti3O18, and Bi6Ti3Fe2O18. Phase examination reveals that only 0.40 mol. % is successfully substituted forming Tb0.40Bi5.6Fe2Ti3O18 thin films. Lateral and vertical piezoresponse switching loops up to 200 °C reveal responses for Bi6Ti3Fe2O18, Tb substituted Tb0.40Bi5.6Fe2Ti3O18, and Tb0.90Bi5.1Fe2Ti3O18 thin films along the in-plane (±42.31 pm/V, 88 pm/V and ±134 pm/V, respectively) compared with the out-of-plane (±6.15 pm/V, 19.83 pm/V and ±37.52 pm/V, respectively). The macroscopic in-plane polarization loops reveal in-plane saturation (Ps) and remanence polarization (Pr) for Bi6Ti3Fe2O18 of ±26.16 μC/cm2 and ±22 μC/cm2, whereas, ±32.75 μC/cm2 and ±22.11 μC/cm2, ±40.30 μC/cm2 and ±28.5 μC/cm2 for Tb0.40Bi5.6Fe2Ti3O18...

2025, Journal of the American Ceramic Society

Multiferroic materials displaying coupled ferroelectric and ferromagnetic order parameters could provide a means for data storage whereby bits could be written electrically and read magnetically, or vice versa. Thin films of Aurivillius phase Bi6Ti2.8Fe1.52Mn0.68O18, previously prepared by a chemical solution deposition (CSD) technique, are multiferroics demonstrating magnetoelectric coupling at room temperature. Here we demonstrate the growth of a similar composition, Bi6Ti2.99Fe1.46Mn0.55O18, via the liquid injection chemical vapor deposition technique. High resolution magnetic measurements reveal a considerably higher in-plane ferromagnetic signature than CSD grown films (MS = 24.25 emu/g (215 emu/cm 3 ), MR = 9.916 emu/g (81.5 emu/cm 3 ), HC = 170 Oe). A statistical analysis of the results from a thorough microstructural examination of the samples, allows us to conclude that the ferromagnetic signature can be attributed to the Aurivillius phase, with a confidence level of 99.95 %. In addition, we report the direct piezoresponse force