Auswahl der wissenschaftlichen Literatur zum Thema „Composites ME 0-3“

0-3 type magnetoelectric(ME) composites of PbTiO3(PT) and CoFe2O4(CFO) were prepared by a conventional solid-state reaction method with different volume fraction. The composites exhibited ferroelectric phase and ferromagnetic phase coexisting. The ferroelectric and magnetic properties of as-sintered samples were measured. The magnetic properties change regularly with the test frequency. But the dielectric permittivity shows the anomalies, which can be attributed to constraints and dilutions from the ferromagnetic phase and the element diffusion.

Multiferroic composites consisting of a single-phase multiferroic [0.6(PbZr0.53Ti0.47O3)-0.4(PbFe0.5Ta0.5)O3] as a matrix and a magnetostrictive phase (Co0.6Zn0.4Fe1.7Mn0.3O4) dispersed in the matrix are fabricated via hybrid synthesis technique. The structure and surface morphology studies using x-ray diffraction and field emission scanning electron microscopy techniques indicate the formation of 3-0 type particulate composites. Coexistence of soft-magnetic behavior and ferroelectric characteristics are confirmed for composites from magnetization vs magnetic field (M–H) and polarization vs electric field (P–E) measurements, respectively. Magneto-dielectric (MD) measurement shows significant changes in the dielectric properties with the application of a magnetic field, indicating the existence of strong MD behavior. The biquadratic nature of magneto-electric (ME) coupling is described by the Landau free energy equation arising from the strain transfer at the interfaces between the constituent phases. The direct magneto-electric voltage coefficient measurement also confirms very strong coupling between ferroelectricity and magnetism and supports the strain-mediated magneto-electric effect in composites. The Φ = 0.3 composite exhibits the maximum ME coefficient of 20.72 mV/cm Oe with MS = 24.62 emu/g, HC = 59.66 Oe, and piezoelectric coefficient value d33 = 19 pC/N. The strong magneto-electric effect along with low dielectric loss at room temperature in these composites suggests their suitability for multifunctional magneto-electric device applications such as magnetic sensors, etc.

In this study, magnetostrictive powders of CoFe2O4 (CFO) and Zn-substituted CoFe2O4 (CZFO, Zn = 0.1, 0.2) were synthesized in order to decrease the optimal dc magnetic field (Hopt.), which is required to obtain a reliable magnetoelectric (ME) voltage in a 3-0 type particulate composite system. The CFO powders were prepared as a reference via a typical solid solution process. In particular, two types of heterogeneous CZFO powders were prepared via a stepwise solid solution process. Porous-CFO and dense-CFO powders were synthesized by calcination in a box furnace without and with pelletizing, respectively. Then, heterogeneous structures of pCZFO and dCZFO powders were prepared by Zn-substitution on calcined powders of porous-CFO and dense-CFO, respectively. Compared to the CFO powders, the heterogeneous pCZFO and dCZFO powders exhibited maximal magnetic susceptibilities (χmax) at lower Hdc values below ±50 Oe and ±10 Oe, respectively. The Zn substitution effect on the Hdc shift was more dominant in dCZFO than in pCZFO. This might be because the Zn ion could not diffuse into the dense-CFO powder, resulting in a more heterogeneous structure inducing an effective exchange-spring effect. As a result, ME composites consisting of 0.948Na0.5K0.5NbO3–0.052LiSbO3 (NKNLS) with CFO, pCZFO, and dCZFO were found to exhibit Hopt. = 966 Oe (NKNLS-CFO), Hopt. = 689–828 Oe (NKNLS-pCZFO), and Hopt. = 458–481 Oe (NKNLS-dCZFO), respectively. The low values of Hopt. below 500 Oe indicate that the structure of magnetostrictive materials should be considered in order to obtain a minimal Hopt. for high feasibility of ME composites.

AbstractRecent studies have examined moist entropy (ME) as a proxy for moist static energy (MSE) and the relative role of the underlying processes responsible for changes in ME that potentially affect MJO propagation. This study presents an analysis of the intraseasonally varying (ISV) ME anomalies throughout the lifetime of observed MJO events. A climatology of continuing and terminating MJO events is created from an event identification algorithm using common tracking indices including the OLR-based MJO index (OMI), filtered OMI (FMO), real-time multivariate MJO (RMM), and velocity potential MJO (VPM) index. ME composites for all indices show a statistically significant break in the wavenumber-1 oscillation at day 0 for terminating events in nearly all domains except RMM phase 6 and phase 7. The ME tendency is decomposed into horizontal and vertical advection, sensible and latent heat fluxes, and shortwave and longwave radiative fluxes using ERA-Interim data. The relative role of each processes toward the eastward propagation is discussed as well as their effects on MJO stabilization. Statistically significant differences occur for all terms by day −10. A domain sensitivity test is performed where eastward propagation is favored for vertical advection given a larger, asymmetric domain for continuing events. A reduced eastward propagation from vertical advection is evident 2–3 days before similar differences in horizontal advection for terminating events. The importance of horizontal advection for the eastward propagation of the MJO is discussed in addition to the relative destabilization from vertical advection in the convectively suppressed region downstream of future terminating MJOs.

AbstractMotivated by the fast-developing spin dynamics in ferromagnetic/piezoelectric structures, this study attempts to manipulate magnons (spin-wave excitations) by the converse magnetoelectric (ME) coupling. Herein, electric field (E-field) tuning magnetism, especially the surface spin wave, is accomplished in Ni/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) multiferroic heterostructures. The Kerr signal (directly proportional to magnetization) changes of Ni film are observed when direct current (DC) or alternative current (AC) voltage is applied to PMN-PT substrate, where the signal can be modulated breezily even without extra magnetic field (H-field) in AC-mode measurement. Deserved to be mentioned, a surface spin wave switch of “1” (i.e., “on”) and “0” (i.e., “off”) has been created at room temperature upon applying an E-field. In addition, the magnetic anisotropy of heterostructures has been investigated by E-field-induced ferromagnetic resonance (FMR) shift, and a large 490 Oe shift of FMR is determined at the angle of 45° between H-field and heterostructure plane.

This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.

This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.

We investigated the opportunities for obtaining hexaferrites Pb1−xLaxFe12−xZnxO19 (x = 0–1) from citrate–glycerin gel and showed that synthesis occurs via the formation of the Fe3O4 phase; products with a small amount of hematite impurity Fe2O3 can be obtained after firing at 800 to 900 °C with 0 ≤ x ≤ 0.5. If x > 0.5, perovskite-like LaFeO3 is formed in samples, so that if x = 0.9–1, the synthesis products virtually do not contain phases with hexaferrite structures and represent a mixture of LaFeO3, Fe2O3, and Fe3O4. Within the range of 0 ≤ x ≤ 0.5, the electrical and magnetic characteristics of hexaferrites Pb1−xLaxFe12−xZnxO19 are slightly dependent on x and have the following average values: A relative permittivity ε/ε0 ~ 45, a dielectric loss tangent tan δ ~ 0.6, an electrical resistivity R ~ 109 Ohm cm, coercivity Hc ~ 3 kOe, saturation magnetization Ms ~ 50 emu/g, and remanent magnetization Mr ~ 25 emu/g. The magnetoelectric (ME) ceramics 50 wt.% PZTNB-1 + 50 wt.% Pb1−xLaxFe12−xZnxO19 (PZTNB-1 is an industrial piezoelectric material based on lead titanate zirconate (PZT) do not contain impurity phases and have the following characteristics: Piezoelectric coefficients d33 = 10–60 and −d31 = 2–30 pC/N, piezoelectric voltage coefficients g33 = 2–13 and −g31 = 1–5 mV m/N, an electromechanical coupling coefficient Kp = 0.03–0.13, magnetic parameters Hc = 3–1 kOe, Ms = 50–30, and Mr = 25–12 emu/g. The maximum ME coupling coefficient ΔE/ΔH ~ 1.75 mV/(cm Oe) was achieved with x = 0.5.

Abstract Background Superior treatment outcomes were observed with the β-lactam/β-lactamase inhibitor combination of cefepime-enmetazobactam (FPE) compared to piperacillin-tazobactam (PTZ) in the primary efficacy population (m-MITT) of the ALLIUM phase 3 study of adult patients with cUTI/AP. We present here the outcomes in the microbiologically evaluable (ME) and ME+Resistant (ME+R) populations. Methods 1034 cUTI/AP patients randomized 1:1 in a double-blind, multicenter trial received either 2 g cefepime/0.5 g enmetazobactam or 4 g piperacillin/0.5 g tazobactam q8h by 2h infusion for 7 to 14 days. Patients in m-MITT had a Gram-negative urinary baseline pathogen (BP) at >105 CFU/ml with FPE MIC ≤8 µg/ml and PTZ MIC ≤64 µg/ml. ME included patients in m-MITT who received ≥15 consecutive doses of study drug or were classified as clinical failures after receiving ≥9 doses; had a clinical assessment at test-of-cure (TOC) unless clinical failure occurred earlier; did not receive concomitant antibiotics with a non-study agent; and did not have any other protocol violation. ME+R included patients in ME along with those who had BP resistant to either FPE (MIC >8 µg/ml) or PTZ (MIC >64 µg/ml), or a missing MIC value. Overall success was the composite of clinical cure and microbiological eradication (< 103 CFU/ml in urine). Two-sided 95% confidence interval (CI) were computed using the stratified Newcombe method. Results In the ME population, superiority in overall success of FPE (87.0%; 268/308) compared to PTZ (65.4%; 195/298) was demonstrated as the lower bound of the CI (16.6%) of the treatment difference (TD; 23.3%) was greater than 0 (Table). Higher rates of microbiological eradication with FPE contributed to the superior treatment outcomes. In the ME+R population in which BP susceptibility was not an exclusion criterion, favorable outcomes with FPE in overall success (TD 21.6%; 95% CI [15.3, 27.8]) and microbiological eradication (TD 21.0%; 95% CI [14.8, 27.0]) were also observed. Conclusion The confirmation of superior treatment outcomes with FPE in the ME and ME+R populations supports the robustness of the corresponding superiority observed in adult cUTI/AP patients in m-MITT. Disclosures Adam Belley, PhD, Allecra Therapeutics SAS (Consultant) Philip Barth, MD, Allecra Therapeutics SAS (Consultant) Omar Lahlou, PhD, Allecra Therapeutics SAS (Employee) Patrick Velicitat, MD, Allecra Therapeutics SAS (Employee)

Dans la recherche de matériaux magnétoélectriques (ME) présentant des performances ME élevées, nous étudions dans cette thèse certains mécanismes fondamentaux qui conduit au renforcement du couplage magnéto-élastique dans les composites MEs. Notre étude porte sur les composites particulaires 0-3 composés de phase magnétostrictive (MS) de CFO imbibée dans des matrices ferroélectriques (FE) suivantes : à base de Pb PZT, PMNPT et leur alternative sans plomb KNN et BTO. Nous démontrons que la technique Laser Heated Pedestal Growth (LHPG) peut être utilisé pour synthétiser des échantillons massives avec une microstructure texturée prononcée entre les phases FE et MS. Scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) et X-ray diffraction (XRD) sont utilisés pour caractériser systématiquement l’orientation des grains, la taille des grains and la qualité d’interface entre les différentes phases citées ci-avant. Une étude systématique par le biais de la spectroscopie Raman, les mesures de magnétisation M (H,T) et de chaleur spécifique C(T,H) nous ont permis de sonder le couplage magnéto-élastique directement dans les échantillons MEs. En combinant les analyses des données structurales et thermodynamiques précédentes, cela montre que la structure avec une texture prononcée dans les échantillons synthétisés par LHPG conduit à une forte augmentation de la réponse magnéto-élastique. Nous soutenons que ce résultat est très prometteur pour la conception des matériaux ME. Enfin, nous suggérons que l'étude de la chaleur spécifique précédent offre une sonde sans contact pour étudier le couplage spin-réseau de manière intrinsèque dans une large gamme de matériaux ME y compris les multiférroiques
In the search for magnetoelectric (ME) materials with enhanced ME performances, in the present thesis we investigate some fundamental mechanisms leading to an enhanced magnetoelastic coupling in artificial ME composites. We focus on 0-3 particulate composites made of a magnetostrictive (MS) phase CFO embedded in the following ferroelectric (FE) matrices: Pb-based PZT, PMNPT and alternative lead-free KNN and BTO. We demonstrate that the laser heated pedestal growth (LHPG) technique can be successfully used to grow high-quality bulk samples exhibiting a pronounced textured microstructure between the FE and MS phases. Scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterise systematically grain orientation, grain size and quality of the interface between the FE and MS phases. A systematic study by means of Raman spectroscopy, magnetisation M(T,H) and field-dependent specific heat C(T,H) measurements enabled us to probe directly the magnetoelastic coupling in the ME samples. The combined analysis of the above structural and thermodynamic data consistently shows that the pronounced textured structure of the LHPG samples leads to an impressive enhancement of the magnetoelastic response. We argue that this result is very promising for ME material design. We finally propose that the above specific heat study offers a contactless probe to investigate the intrinsic spin-lattice coupling in a wide range of ME materials including multiferroics