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The development of Ge-rich GeSbTe (GGST) alloys significantly enhanced the high-temperature stability required for Phase-Change Memory technology. Previous studies on Ge enrichment in GeSbTe (GST) materials with Sb-over-Te ratio lower than one (Sb / Te < 1) highlighted the segregation into cubic Ge and cubic GST phases. Such a segregated cubic GST phase is metastable and presents a polycrystalline structure with disordered grain boundaries that could lead to structural relaxation and then to drift phenomena. In this work, using resistivity measurements, Raman spectroscopy, and in situ x-ray diffraction analyses, we demonstrate for the first time to our knowledge that GGST with Sb/Te higher than one (Sb / Te > --> 1) upon annealing leads to the direct formation of a GST hexagonal phase featuring a high growth speed, bypassing the cubic metastable phase. Combined with Ge enrichment, the increased value of the activation energy of the nucleation of Sb / Te > --> 1 GGST alloys ensures a high stability of the amorphous phase. Finally, nitrogen introduction further stabilizes the system against the crystallization, without compromising the high crystalline growth speed and the formation of the stable GST hexagonal phase in alloys with Sb / Te > --> 1. These results demonstrate the possibility to tune the crystalline structure of the segregated phases in Ge-rich GeSbTe alloys, combining the stability at high temperature of the amorphous phase with the high crystallization speed and uniformity (with larger grains) of a targeted GST phase. [ABSTRACT FROM AUTHOR]

Aqueous mixtures of deep eutectic solvents (DESs) have emerged as a subject of interest in recent years for their tailored physicochemical properties. However, a comprehensive understanding of water's multifaceted influence on the microscopic dynamics, including its impact on improved transport properties of the DES, remains elusive. Additionally, the diffusion mechanisms within DESs manifest heterogeneous behavior, intricately tied to the formation and dissociation kinetics of complexes and hydrogen bonds. Therefore, it is imperative to explore the intricate interplay between bond kinetics, diffusion mechanism, and dynamical heterogeneity. This work employs water as an agent to explore their relationships by studying various relaxation phenomena in a DES based on acetamide and lithium perchlorate over a wide range of water concentrations. Notably, acetamide exhibits Fickian yet non-Gaussian diffusion across all water concentrations with Fickian ( τ f ) and Gaussian ( τ g ) timescales following a power-law relationship, τ g ∝ τ f γ , γ ∼ 1.4. The strength of coupling between bond kinetics and different diffusion timescales is estimated through various power-law relationships. Notably, acetamide–water hydrogen bond lifetime is linked to diffusive timescales through a single power-law over the entire water concentration studied. However, the relationship between diffusive timescales and the lifetime of acetamide–lithium complexes shows a sharp transition in behavior at 20 wt. % water, reflecting a change from vehicular diffusion below this concentration to structural diffusion above it. Our findings emphasize the critical importance of understanding bond dynamics within DESs, as they closely correlate with and regulate the molecular diffusion processes within these systems. [ABSTRACT FROM AUTHOR]

The interaction between the magnetic moment of an electron and the magnetic field generated by a moving charge is one component of the spin–orbit interaction. The nuclei in a molecule or solid are charged, are generally in vibrational motion, and so contribute to this interaction, but the direct coupling between nuclear momentum and electron spin is normally ignored in discussions of spin-forbidden phenomena such as transitions between states of different spin, even when the nuclei are recognized as playing a fundamental role (spin–vibronic coupling). Here, we investigate the spin–orbit interaction in a Heisenberg model interacting with vibrating point charges representing nearby bridging ligands. To reach the model, we apply second order perturbation theory to the Hubbard model with the spin–orbit interaction. In contrast to the other components of the spin–orbit interaction, the part that directly couples the momentum of the charge and electron spin appears at first order as an effective magnetic field at each site. We find that the inclusion of this nuclear-motion induced spin–orbit coupling can increase the rate of otherwise spin-forbidden transitions between different spin states of the Heisenberg model by many orders of magnitude. This overlooked interaction may, therefore, play a significant role in spin-forbidden phenomena such as spin relaxation in coupled spin-qubits. [ABSTRACT FROM AUTHOR]

The solid-state synthesized dense ceramic composite, consisting of M-type hexaferrite Ba 0.5 Sr 0.5 Fe 12 O 19 and inverse spinel ferrite Ni 0.3 Co 0.2 Zn 0.5 Fe 2 O 4 (NCZFO) with varying concentrations, demonstrates the presence of apparent colossal permittivity along with dielectric relaxation behaviors at the higher frequency regions for all the composites. This phenomenon manifests as a giant dielectric permittivity of approximately 10 5 at 1 kHz, gradually decreasing to around 10 3 at 1 MHz at room temperature. It can be attributed to the Maxwell–Wagner interfacial polarization, which arises from the presence of different conductivity regions within the microstructures of the composite. The dielectric permittivity and the activation energy are also increased with higher NCZFO content, indicating an intricate microstructure influencing the electrical response by impacting charge carrier movement and ion migration. The presence of both Fe and Co cation defects and oxygen vacancies enhanced non-uniformity in the microstructure with different conductivity regions. The appearance of relaxation peaks in the higher frequency region can be attributed to inhomogeneity in the microstructure. In conjunction with the equivalent circuit analysis, the Nyquist plot confirmed that the electrical response at a lower frequency primarily arises from grain boundaries. The departure from ideal Debye-type relaxation behavior in the electrical response is also confirmed by impedance analysis. Furthermore, the step-like increase in AC conductivity with frequency suggests that the electrical response observed at a lower frequency is not intrinsic. Rather, it indicates the depletion of insulating grain boundaries due to diffusive ion motions resulting from defects. This observation reinforces that the high dielectric permittivity observed in the composite is not an inherent characteristic of the constituent materials. Instead, it arises from the microstructure and the influence of defects within the material. [ABSTRACT FROM AUTHOR]

The reactions of VOSO4·3H2O with Na2(cbdc) (cbdc2− – dianion of cyclobutane-1,1-dicarboxylic acid) and lanthanide(III) nitrates taken in a molar ratio of 1 : 2 : 1 were found to yield a series of isostructural heterometallic compounds [NaLn(VO)2(cbdc)4(H2O)10]n (1Ln, Ln = Tb, Dy, Ho, Er, Tm, Yb). These compounds are constructed from trinuclear anionic units [Ln(VO)2(cbdc)4(H2O)8]− ({LnV2}−) linked by Na+ ions into 1D polymeric chains. The crystal structures of 1Dy and 1Er were determined by single-crystal X-ray diffraction (XRD), and their isostructurality with 1Tb, 1Ho, 1Tm, and 1Yb was proved by powder X-ray diffraction (PXRD). According to alternating current (ac) magnetic susceptibility measurements, 1Dy, 1Er, and 1Yb exhibited field-induced slow relaxation of magnetization. Compound 1Er is the first representative of ErIII–VIV single-molecule magnets. Measuring the temperature dependences of the phase memory time (Tm) for 1Dy and 1Yb using pulsed EPR spectroscopy allowed us to observe the phenomenon of phase relaxation enhancement (PRE) at temperatures below 30 K. In future, this phenomenon may contribute to the evaluation of relaxation times of the lanthanide ions. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of magnetohydrodynamics and heat transfer on the peristaltic transport of Prandtl fluid in a vertical endoscopic tube. The reduction of the complexity of the equations governing the flow of Prandtl fluid entails the use of long wavelength and low Reynolds number approximations. These complex equations for the pressure gradient and velocity profile are handled analytically using the perturbation technique with convective boundary conditions, and the temperature and concentration profiles are carefully solved for the exact solution. The frictional forces and pressure rise are also simulated with numerical integration. The resulting formulas for velocity, temperature, concentration, pressure rise, and pressure gradient are graphed using the MATLAB and MATHMATICA software, and the effects of all the different physical parameters are investigated and assessed. The streamlines with five distinct wave types are sketched at the conclusion to show the phenomenon of trapping. It is investigated that the velocity profile rises due to buoyancy forces and falls due to the influence of magnetic forces. [ABSTRACT FROM AUTHOR]

In this study, the dense and fine‐grained zirconia toughened alumina (ZTA) composite ceramics were efficiently prepared by 3D gel printing technology. Zirconia powder, zirconium oxychloride, and zirconium sol were introduced into boehmite gel as zirconium sources, and their effects on rheological properties, drying characteristics, microstructure, and mechanical properties of ceramics were discussed. The results showed that all gels exhibit reversible shear thinning properties. The gel with zirconia powder has a relaxation phenomenon; zirconium sol forms another gel network in the boehmite gel network, and two linear viscoelastic regions are observed. The gel with zirconia powder has the highest solid loading, small drying shrinkage, and fewer drying defects. The grain growth of ZTA ceramics with zirconium sol was inhibited, and the zirconia grains were evenly distributed, with the highest bending strength of 518 ± 103 MPa. The new gel preparation method and gel drying process offer great possibilities for manufacturing optical glasses and functional ceramics with high‐performance geometric structures, which cannot be achieved by traditional manufacturing methods. [ABSTRACT FROM AUTHOR]

The ceramic material Bi2/3Cu3Ti4−xSixO12 (where x = 0.05, and 0.1) with complex perovskite structure was prepared by semi-wet method sintered at 1173 K for 8 h. X-ray diffraction studies proved the single phase pattern of ceramics. The ceramics were further characterized by SEM and EDX for the microstructural properties and elemental analysis, respectively. The average grain sizes of BCTSO-0.05 and BCTSO-0.1 ceramics were found to be 0.32, and 0.47 μm, respectively. The value of dielectric constant for the BCTSO-0.05 and BCTSO-0.1 ceramics were measured as 953 and 1316 at 100 Hz and 503 K. The tangent loss values of BCTSO-0.05 and BCTSO-0.1 ceramics were found 0.08 and 0.06, respectively, at 303 K and 10 kHz. The oxidation states of the constituent elements in the BCTSO-0.1 ceramic, were verified by XPS. The Impedance and Modulus studies illustrate that the Maxwell–Wagner type of relaxation phenomena is exhibited in the ceramics. The variation of conductivity as function of inverse of absolute temperature is governed by the Arrhenius equation, in the temperature region of 303 to 503 K. [ABSTRACT FROM AUTHOR]

The flexion relaxation phenomenon (FRP) is characterized by the reduction of paraspinal muscle activity at maximum trunk flexion. FRP is reported to be altered (persistence of spinal muscle activity) in more than half of nonspecific chronic low back pain (NSCLBP) patients. Little is known about how the multi-segmental spine affects FRP. The aim of this observational study was to investigate the relationship between FRP and kinematic parameters of the multi-segmental spine in NSCLBP patients. Forty NSCLBP patients and thirty-five asymptomatic participants performed a standing maximal trunk flexion task. Surface electromyography was recorded along the erector spinae longissimus. The kinematics of the spine were assessed using a 3D motion analysis system. The investigated spinal segments were upper thoracic, lower thoracic, thoracolumbar, upper lumbar, lower lumbar, and lumbopelvic. Upper lumbar ROM, anterior sagittal inclination of the upper lumbar relative to the lower lumbar in the upright position, and ROM of the upper lumbar relative to the lower lumbar during full trunk flexion were significantly correlated with the flexion relaxation ratio (Rho 0.42 to 0.58, p < 0.006). The relative position and movement of the upper lumbar segment seem to play an important role in the presence or absence of FRP in NSCLBP patients. [ABSTRACT FROM AUTHOR]

This study establishes a comprehensive correlation among structural, electrical, and dielectric analyses of fluorine-doped tin oxide (FTO) nanoparticles. The nanoparticles were synthesized through the modified sol–gel method under ethyl supercritical conditions. The investigation into the electrical transport, influenced by the microstructure and grain size of FTO nanoparticles, prompted an exploration of charge carrier transport mechanisms and the impact of doping on this behavior. Both structural and electrical analyses were performed on the samples. The x-ray diffraction results reveal a tetragonal rutile structure in the nanoparticles, as validated by Raman analysis. Particle size and strain values were determined using the Williamson–Hall method, complemented by morphological observations using transmission electron microscopy images. Electrical studies revealed semiconducting behavior in all samples, with conductivity analyzed using Jonscher's law. The small polaron hopping and correlated barrier hopping process models are appropriate for describing the conduction process in the prepared sample. The observed behaviors of the imaginary components of impedance (Z″) and modulus (M″) signify a dielectric relaxation phenomenon within the sample, with activation energies closely matching those derived from the conductivity study. The results strongly suggest that our samples hold great promise for future electronic device applications. [ABSTRACT FROM AUTHOR]

The Mpemba effect is a fingerprint of the anomalous relaxation phenomenon wherein an initially hotter system equilibrates faster than an initially colder system when both are quenched to the same low temperature. Experiments on a single colloidal particle trapped in a carefully shaped double well potential have demonstrated this effect recently [A. Kumar and J. Bechhoefer, Nature 584, 64 (2020)]. In a similar vein, here, we consider a piece-wise linear double well potential that allows us to demonstrate the Mpemba effect using an exact analysis based on the spectral decomposition of the corresponding Fokker–Planck equation. We elucidate the role of the metastable states in the energy landscape as well as the initial population statistics of the particles in showcasing the Mpemba effect. Crucially, our findings indicate that neither the metastability nor the asymmetry in the potential is a necessary or a sufficient condition for the Mpemba effect to be observed. [ABSTRACT FROM AUTHOR]

Core–shell structured silicon carbide (SiC)/epoxy (EP) composites exhibit superior non–linear DC conductivity. However, the high voltage alternative current dielectric properties of the composites are rarely reported. In this paper, the time–domain measurement was employed to obtain the basic dielectric characteristics, AC conductivity, and relative permittivity of the SiC/EP and SiC@Al2O3/EP composites under less than the breakdown strength of the SiC/EP (i.e. the amplitude of 1–5 kV mm−1). In addition, in the high AC electric field (i.e. the amplitude of 6–20 kV mm−1), the non–linear AC dielectric properties of the SiC@Al2O3/EP composite are also investigated. The experimental results suggest that the SiC@Al2O3/EP composite shows more obvious non–linear AC dielectric properties than the SiC/EP composite. In the high AC electric field, the AC conductivity of the SiC@Al2O3/EP composite presents the relaxation phenomenon, which is attributed to the excitation field and its derivative. This work lays a foundation for further research on the AC steady–state and transient dielectric properties of the field grading materials, which are widely used to homogenize the nonuniform electric field distribution in many electrical and electronic equipment. [ABSTRACT FROM AUTHOR]

This article takes a phenomenological approach to explore the phenomenon of relaxation as a movement skill. The phenomenological perspective takes inspiration primarily from selected works of Edmund Husserl, Maurice Merleau-Ponty, Samuel Todes, and Kym Maclaren. The author explores the phenomenon of relaxation as a movement skill by analysing three situations: 1) the new-born embracing and being embraced in interpersonal relaxation, 2) the "relaxed attack" approach of elite athletes, and 3) the yogi's experience of finding relaxation in shavasana (dead man's pose). The analyses draw on the phenomenological framework of Husserl's concepts of "passivity", Maclaren's idea of "letting oneself be" and Todes' conceptualisation of a spatiotemporal field further illustrates how the body's unity with the world. The conclusion suggests that relaxation is an ambiguous movement skill, simultaneously an intrinsic part of being alive as a human being, a precondition for all movement capability and an achievement in its own right. [ABSTRACT FROM AUTHOR]

We study a nonlocal problem for new types of hyperbolic heat equations, which is obtained by introducing relaxation corrections into the Fourier formula for both heat flux and temperature gradient. The resulting hyperbolic equations contain the third and fourth order (depending on the number of relaxation coefficients) derivatives with respect to the spatial variable and time (mixed derivatives). A new nonlinear mathematical problem of locally nonequilibrium transport processes is investigated, taking into account relaxation phenomena, based on hyperbolic and parabolic equations. A method for establishing a priori estimates of the Schauder type is proposed. The unique solvability of the problem with internal boundary nonlocal boundary conditions is proved. [ABSTRACT FROM AUTHOR]

In this investigation, results of dielectric features of Li2O–Al2O3–SiO2 (LAS) glass doped with 3.0 mol% of Cr2O3, MoO3, and WO3 are presented. The investigation spans broad regions of frequency (ω) 10−2–106 Hz and temperature (T) 20–240 °C. Initial characterization of the samples by means of optical absorption spectra reveals that Cr ions do persist in Cr3+oxidation state, whereas fractions of Mo and W ions do present in Mo5+ and W5+ states in addition to predominant presence Mo6+ and W6 + ions, respectively. Infrared spectra suggest that Mo5+ and W5+ ions involve in modifying the network of the glass and induced structural disorder. Dielectric parameters and also σac are observed to be the largest for 40Li2O–5Al2O3–52SiO2:3.0 MoO3 (LASMo) glass followed by 40Li2O–5Al2O3–52SiO2:3.0 WO3 (LASW) and 40Li2O–5Al2O3–52SiO2:3.0 Cr2O3 (LASCr) glasses. Analysis of dipolar relaxation phenomena are carried out using Cole–Cole plots. Analysis of the results of σac suggests that polaronic conduction due to electron transfer between Mo5+ ↔ Mo6+ and W5+ ↔ W6+ is prevailed in case of LASMo and LASW glasses and these glasses are predicted to be useful as cathodes, whereas in LASCr glass, ionic conductivity is dominant and is suitable for electrolytes in ionic batteries. [ABSTRACT FROM AUTHOR]

Magnetoelectric materials are considered as the most promising materials for multifunctional device application. In this study, we report a polycrystalline 0.9 PbZr0.52Ti0.48O3-0.1 NiFe2O4 (0.9PZT-0.1NFO) particulate composite prepared via cost-effective solid-state reaction route. The detailed structural analysis is done by performing Rietveld refinement technique. Both X-ray diffraction and Scanning Electron Microscopy confirmed the presence of both ferrite and ferroelectric phases without any interdiffusion. The magnetic and AC electrical properties like conductivity, dielectric constant, dissipation factor (dielectric loss), and impedance spectroscopy analysis were studied in detail with different frequencies and temperatures. A relatively high dielectric constant at low frequencies and high temperatures was obtained. The transition temperature is found to be 440 °C, which is greater than that of pure PZT. Complex impedance spectroscopy and modulus spectroscopy showed the occurrence of relaxation phenomena due to both grain and grain boundaries. The ac conductivity was studied to understand the conduction mechanism in the prepared sample. The composite exhibits the NTCR behavior. The PE loop confirms the ferroelectric property of the prepared sample. The MH loop shows a well-saturated curve, in which the experimental value of saturation magnetization is well-matched with the value obtained from fitting of MH loop to Law of Approach to Saturation. [ABSTRACT FROM AUTHOR]

The enantiomerically pure Schiff base ligands H2L‐S and H2L‐R yield chiral heterometallic dodecanuclear complexes of the form [Cu8Ln4(OH)8(OMe)4(O2CBut)8(L‐S or L‐R)4(H2O)4] where LnIII=Gd (1S), Tb (2S), Dy (3S, 3R), Ho (4S, 4R), Er (5S) or Y (6S, 6R) and H2L=(S or R)‐2‐{[(1‐hydroxypropan‐2‐yl)imino]methyl}‐6‐methoxyphenol. The complexes are isomorphous and crystallize in the non‐centrosymmetric polar space group C2 in enantiomeric conformation. The chirality of the Schiff base ligands originates from the respective S‐ or R‐ enantiomer of 2‐aminopropan‐1‐ol, is imparted to the complexes and to the crystals that belong to non‐centrosymmetric space group. The chirality and enantiomeric conformation of all complexes are retained in dmso solutions as confirmed by Circular Dichroism spectra which consist of mirror images, expected for enantiomeric pairs. All complexes consist of four distorted cubane‐like subunits [Cu2Ln2(μ3‐OH)2(μ3‐OMe)(μ3‐OR)], which share the LnIII ions and result in a cyclic distorted tetragonal arrangement; each edge of the {LnIII4} quadrilateral is occupied by two μ‐OH− ions that further bridge to a CuII ion. Magnetic susceptibility measurements revealed ferromagnetic interactions for 3S with LnIII=Dy and antiferromagnetic interactions for all other complexes. AC susceptibility data of 3S under 1 kOe external dc field indicate slow magnetic relaxation phenomena below 2 K. [ABSTRACT FROM AUTHOR]

AbstractThe current study employs the Cattaneo–Christov diffusion law to analyze the thermal tendency of Maxwell nanomaterials flowing over an unsteady stretching sheet. Thermophoretic and Brownian diffusion aspects of nanosolids are incorporated to investigate thermal and nanoparticle’s concentration distribution. Through flow similarities, the governing PDEs (Partial Differential Equations) are articulated into a set of nonlinear ODEs (Ordinary Differential Equations). The homotopy analysis approach, a recognized semi-analytical technique, is implemented to solve these differential equations. Results are presented graphically, revealing that higher magnetic field strengths diminish the flowing field. Temperature and nanosolids concentration distributions escalate with increasing thermal and singular relaxation time phenomena. Furthermore, when nanoparticle concentration decreases and Brownian motion intensifies, the temperature field rises. It is also observed that heightened resistive heating enhances the fluid’s capability to carry thermal energy. Overall, this investigation sheds light on the intricate interplay between several factors influencing the thermal behavior of Maxwell nanomaterials over a stretching board, offering insights into their practical applications. [ABSTRACT FROM AUTHOR]

Chronic nonspecific low back pain (NSLBP) is a prevalent condition with socioeconomic and healthcare challenges. The flexion–relaxation phenomenon (FRP) evaluation is a valid clinical tool for low back pain (LBP) assessment. Yoga, a holistic mind–body practice, has been explored as an LBP intervention. This study aimed to evaluate the impact of yoga asanas on the FRP in women with NSLBP. The study included healthy and chronic NSLBP females who underwent an eight‐session yoga asanas program, with the first session conducted in‐clinic and the rest delivered with tele‐approach. Outcome measures included pain intensity, flexion–relaxation ratio (FRR), and trough surface electromyography collected during trunk maximum voluntary flexion (MVF). The study included 11 healthy and 10 NSLBP women. Repeated measures test in chronic NSLBP group showed a significant decrease in pain intensity after the 4 weeks follow‐up (visual analog scale [VAS]: 6.80 ± 1.48 vs. 3.30 ± 1.25; p < 0.001) and an FRR improvement after the intervention (5.12 ± 0.93 vs. 9.49 ± 0.92; p < 0.001). VAS and FRR effect sizes were 0.77 and 0.47, respectively. Therefore, we performed a Prophet evaluation to assess FRR trends, finding a growth rate (k) of 0.405 ± 0.448, with a forecast 1 month after the end of the intervention approaching the trend line of the control group. The findings suggested that tele‐yoga asana might have a positive impact on pain intensity and the FRP in chronic LBP. Further research is warranted to confirm the long‐term effects of yoga for managing LBP. [ABSTRACT FROM AUTHOR]

We discuss the decomposition of the tensorial relaxation function for isotropic and transversely isotropic (TI) modified quasi-linear viscoelastic (MQLV) models. We show how to formulate the constitutive equation using a convenient decomposition of the relaxation tensor into scalar components and tensorial bases. We show that the bases must be symmetrically additive, i.e., they must sum up to the symmetric fourth-order identity tensor. This is a fundamental property both for isotropic and anisotropic bases that ensures the constitutive equation is consistent with the elastic limit. We provide two robust methods to obtain such bases. Furthermore, we show that, in the TI case, the bases are naturally deformation-dependent for deformation modes that induce rotation or stretching of the fibres. Therefore, the MQLV framework allows to capture the non-linear phenomenon of strain-dependent relaxation, which has always been a criticised limitation of the original quasi-linear viscoelastic theory. We illustrate this intrinsic non-linear feature, unique to the MQLV model, with two examples (uni-axial extension and perpendicular shear). [ABSTRACT FROM AUTHOR]

This article proposes a numerical routine to predict the residual stresses developing in an epoxy component during its curing. The scaling of viscoelastic properties with the temperature and the degree of conversion is modeled, adopting a mathematical formulation that considers the concurrent effects of curing and structural relaxation on the epoxy's viscoelastic relaxation time. The procedure comprises two moduli: at first, the thermal–kinetical problem is solved using the thermal module of Ansys and a homemade routine written in APDL, then the results in terms of temperature and the degree of conversion profiles are used to evaluate the viscoelastic functions, and the structural problem is solved in the mechanical module of Ansys, allowing the residual stresses calculation. The results show that the residual stresses mainly arise during cooling and scale with the logarithm of the Biot number. [ABSTRACT FROM AUTHOR]

High efficiency Li0.5La0.5SrMgWO6:Mn4+,Eu3+ phosphor was synthesized via the solid-state reaction technique. The XRD, excitation, emission spectra, as well as temperature sensing properties were quantitatively measured. Upon excitation by a 395-nm LED source, the emission peaks were observed at 615 nm and 693 ∼ 707 nm. The quantum efficiency was obtained to be 69%, and the slope efficiency was determined to be 21%. We have also observed that the fluorescence intensity can be modulated through two means, namely, the concentration ratio of Eu3+:Mn4+ and the substitution position of Eu3+. The highest intensity ratio between 615 nm and 693 nm occurs when Eu3+: Mn4+ = 20:1. And the sample "0.5Sr 0.5Mg" exhibits the highest intensity ratio between 615 nm and 693 nm. The fluorescence mechanism has been discussed in light of the theory of energy level transitions, which suggests that the phenomenon of cross relaxation ensures high efficiency. Finally, we investigated the temperature sensing properties of "0.1%Mn 1%Eu" and "0.1%Mn 2%Eu" samples, revealing that the samples exhibit a temperature sensing range of 0.2% ∼ 1.3% /K for Eu: Mn = 10 and 0.1% ∼ 0.4% /K for Eu: Mn = 20, indicating the former's superior suitability as a temperature-sensitive material. The material can be utilized not only for plant cultivation but also as a temperature sensor to monitor the environmental temperature during plant growth. In comparison with traditional Mn4+ doping materials, it is more suitable for plant cultivation, particularly in greenhouse facilities. [ABSTRACT FROM AUTHOR]

In this research, the phenomenon of stress relaxation in unreinforced and reinforced sandy soil with geotextile layer has been studied using a large-scale direct shear test. To investigate the effect of shear speed and soil density on the amount of resistance loss due to stress relaxation, two shear speeds of 0.5 and 5 mm/min and two relative densities of 35% and 60%, respectively, loose and medium density, have been used. All samples have been tested in direct shear test under vertical stress of 100 kPa. The results show that the amount of resistance loss due to stress relaxation depends on the shear stress level, soil density, presence of a geotextile layer in the soil and shear speed. In such a way that by increasing the level of shear stress and shear speed and by decreasing the density of sand and also with the presence of a geotextile layer in soil, the amount of resistance loss due to stress relaxation increases. [ABSTRACT FROM AUTHOR]

In the present work, hybrid nanocomposites of an epoxy resin reinforced with ZnTiO3 and BaTiO3 nanoparticles, at various filler contents, were fabricated and studied. The successful integration of ceramic nanofillers and the fine distribution of nanoparticles were confirmed via X-ray Diffraction patterns and Scanning Electron Microscopy images, respectively. Dielectric properties and related relaxation phenomena were investigated via Broadband Dielectric Spectroscopy in a wide range of frequencies and temperatures. Data analysis showed that dielectric permittivity increases with filler content, although optimum performance does not correspond to the maximum ZnTiO3 content. Four relaxation processes were observed and attributed to interfacial polarization (IP) (at low frequencies and high temperatures), glass-to-rubber transition (α-relaxation) of the epoxy matrix (at intermediate frequencies and temperatures), and local rearrangements of polar side groups of the macromolecules (β-relaxation) and small flexible groups of the main polymer chain (γ-relaxation) occurring at low temperatures and high frequencies. The ability of hybrid nanocomposites to store and retrieve energy was studied under dc conditions by employing a charging/discharging sequence. The stored and retrieved energy increases with filler content and charging voltage. The optimum ability of energy recovering, shown by the epoxy/7 phr ZnTiO3/7 phr BaTiO3 nanocomposite, ranges between 30 and 50 times more than the matrix, depending on the time instant. The employed nanoparticles induce piezoelectric properties in the nanocomposites, as found by the increase in the piezoelectric coefficient with filler content. [ABSTRACT FROM AUTHOR]

High efficiency Li0.5La0.5SrMgWO6:Mn4+,Eu3+ phosphor was synthesized via the solid-state reaction technique. The XRD, excitation, emission spectra, as well as temperature sensing properties were quantitatively measured. Upon excitation by a 395-nm LED source, the emission peaks were observed at 615 nm and 693 ∼ 707 nm. The quantum efficiency was obtained to be 69%, and the slope efficiency was determined to be 21%. We have also observed that the fluorescence intensity can be modulated through two means, namely, the concentration ratio of Eu3+:Mn4+ and the substitution position of Eu3+. The highest intensity ratio between 615 nm and 693 nm occurs when Eu3+: Mn4+ = 20:1. And the sample "0.5Sr 0.5Mg" exhibits the highest intensity ratio between 615 nm and 693 nm. The fluorescence mechanism has been discussed in light of the theory of energy level transitions, which suggests that the phenomenon of cross relaxation ensures high efficiency. Finally, we investigated the temperature sensing properties of "0.1%Mn 1%Eu" and "0.1%Mn 2%Eu" samples, revealing that the samples exhibit a temperature sensing range of 0.2% ∼ 1.3% /K for Eu: Mn = 10 and 0.1% ∼ 0.4% /K for Eu: Mn = 20, indicating the former's superior suitability as a temperature-sensitive material. The material can be utilized not only for plant cultivation but also as a temperature sensor to monitor the environmental temperature during plant growth. In comparison with traditional Mn4+ doping materials, it is more suitable for plant cultivation, particularly in greenhouse facilities. [ABSTRACT FROM AUTHOR]

Although the measurements of the lumbar spine and pelvic flexion have shown that subjects with radiculopathy exhibited greater decreases of motion when compared with subjects with low back pain, there is still a lack of evidence regarding the changes in flexion relaxation ratio in patients with radiculopathy. The aims of this study were to investigate the flexion relaxation ratio and flexion of the lumbar spine and pelvis in subjects with low back pain (LBP) and LBP with radiculopathy (LBPR) in comparison with healthy subjects (CG—control group). A total of 146 participants were divided in three groups: LBP patients (54 males; 21 females); LBPR patients (26 males; 11 females); and CG subjects (16 males; 18 females). The lumbar spine and pelvis flexion was recorded using optoelectronic motion capture system. The electrical activity of the erector spinae muscles was assessed by surface electromyography during flexion-extension movements. Comparisons between groups were made using one-way ANOVA tests and Mann–Whithney U test with the level of statistical significance at 0.05. The lumbar and pelvic flexion and electromyography of the erector spinae muscle showed significant differences between LBP and LBPR patients compared to CG. Patients LBPR showed significantly smaller angles of lumbar and pelvic flexion compared to LBP patients and CG. An increase in the erector spinae muscle activity during flexion was also observed in patients with radiculopathy. The increased muscular activity of the erector spinae is related to the reduced flexion of the lumbar spine in order to protect the lumbar spine structure. Measurements of trunk, lumbar spine and pelvic flexion, and the flexion relaxation ratio may allow us to predict better outcomes or responsiveness to treatment of LBPR patients in the future. [ABSTRACT FROM AUTHOR]

This paper analyzes the effect of crosslinking reactions on a thermoset polymer's viscoelastic properties. In particular, a numerical model to predict the evolution of epoxy's mechanical properties during the curing process is proposed and implemented in an Ansys APDL environment. A linear viscoelastic behavior is assumed, and the scaling of viscoelastic properties in terms of the temperature and degree of conversion is modeled using a modified version of the TNM (Tool–Narayanaswamy–Mohynian) model. The effects of the degree of conversion and structural relaxation on epoxy's relaxation times are simultaneously examined for the first time. This formulation is based on the thermo-rheological and chemo-rheological simplicities hypothesis and can predict the evolution of epoxy's relaxation phenomena. The thermal–kinetic reactions of curing are implemented in a homemade routine written in APDL language, and the structural module of Ansys is used to predict the polymer's creep and stress relaxation curves at different temperatures and degrees of conversion. [ABSTRACT FROM AUTHOR]

The evolution of multifunctional materials is an outstanding research area, which aims to improve the versatility of materials according to their broad domains of usage. Focus interest was paid here to the orthophosphate compound, in particular, the olivine NaMnPO4 material. This compound was synthesized by a solid‐state method and investigated using numerous techniques. Primary room‐temperature structural analysis evidences the sample synthesized in the orthorhombic structure and its phase purity. The sample's average grain size was calculated to be around 420 nm. Further, the band gap for our material was found to be (Eg=4.4 eV) by optical analysis of UV‐visible spectroscopy, revealing that our compound is a potential candidate for optoelectronic applications. The electrical behavior study's main results confirm the ferroelectric character of the sample and support the aim of deepening the knowledge of the material according to its thermally stimulated conduction processes through impedance spectroscopy. Electrical studies revealed the dominant transport processes across various temperature and frequency ranges, leading to the NSPT model. The frequency dependency relates to frequency‐dispersive dielectric spectra, conduction mechanisms, and relaxation phenomena. The obtained results show perspective and suggest that the material under study has a wide range of potential electronic applications. [ABSTRACT FROM AUTHOR]

The evolution of multifunctional materials is an outstanding research area, which aims to improve the versatility of materials according to their broad domains of usage. Focus interest was paid here to the orthophosphate compound, in particular, the olivine NaMnPO4 material. This compound was synthesized by a solid‐state method and investigated using numerous techniques. Primary room‐temperature structural analysis evidences the sample synthesized in the orthorhombic structure and its phase purity. The sample's average grain size was calculated to be around 420 nm. Further, the band gap for our material was found to be (Eg=4.4 eV) by optical analysis of UV‐visible spectroscopy, revealing that our compound is a potential candidate for optoelectronic applications. The electrical behavior study's main results confirm the ferroelectric character of the sample and support the aim of deepening the knowledge of the material according to its thermally stimulated conduction processes through impedance spectroscopy. Electrical studies revealed the dominant transport processes across various temperature and frequency ranges, leading to the NSPT model. The frequency dependency relates to frequency‐dispersive dielectric spectra, conduction mechanisms, and relaxation phenomena. The obtained results show perspective and suggest that the material under study has a wide range of potential electronic applications. [ABSTRACT FROM AUTHOR]

Lanthanide ions, as dopants, have evoked widespread research interest owing to the rich optical, magnetic, and electrical properties, but their luminescent intensity is always limited by typical concentration quenching. Herein, a holmium‐based double perovskite of Cs2NaHoCl6 is reported, which surprisingly breaks through this barrier and achieves efficient red‐NIR emission by virtue of the large unit cell, low phonon energy, high content of activators, and cross relaxation phenomenon between Ho3+. The heavy Ho3+ also endows the intriguing half‐metallic nature with a down‐spin conducting band and an up‐spin insulating band. After performing ion doping on crystallographic sites of Na+ and Ho3+, the photoluminescence quantum yield of such red‐NIR emitter under 450 nm excitation is dramatically promoted to 82.3%, benefiting from the improved crystal field environment that alleviates the parity forbidden rule and suppresses non‐radiative recombination loss. Furthermore, the heat‐favorable phonon‐assisted population processes enable the robust photostability against thermal quenching. By combining a 450 nm chip, the red‐NIR light‐emitting diodes are fabricated, in which the wide‐coverage NIR emissions are ideally suited for medical light source, night vision, nondestructive examination, and transmission imaging. It is believed that this work will open an avenue for enhancing the fluorescence of lanthanide ions and developing advanced spintronic materials. [ABSTRACT FROM AUTHOR]

The issues related to microstructure and its effects on functional properties of electroceramics become increasingly prominent with the progressive downscaling of electronics. In this study, temperature-dependent dielectric and impedance data of BaTiO 3 (BT), Sr-doped BT (BST) and layer-structured BaBi 4 Ti 4 O 15 (BBTO) ceramics are systematically investigated to reveal the effects of doping and perovskite layering on the dielectric relaxation and conduction processes at high temperatures. By using complex impedance spectroscopy, it is demonstrated that the ceramics are electrically heterogeneous structures displaying a non-ideal Debye-like behavior at high temperatures. Using a suitable equivalent circuit model, the impedance diagrams at different temperatures are simulated and the refined values of macroscopic resistance and capacitance are used for the identification and characterization of particular microstructural regions (grains, grain boundaries, interfaces, etc.). The approach of combining the impedance, electric modulus and permittivity formalisms is demonstrated to be effective in explaining the peculiarities of the electrical charge transport mechanism and relaxation in the grains, grain boundaries and interface layers of the ceramics. • Electrical response of ferroelectric ceramics is described by the impedance, electric modulus and permittivity formalisms. • Band transport dominates long-range (non-localized) DC conduction in grains and grain boundaries. • Short-range transport occurs predominantly at interfaces through thermally activated hopping. • Sr-doping and perovskite layering reduce activation energies for the band conduction and dielectric relaxation. • Hopping mechanism is responsible for AC conductivity and low-frequency Maxwell-Wagner-type relaxation. [ABSTRACT FROM AUTHOR]

Two samples of ZnxMn1−xFe2O4 (x = 0, sample A; and x = 0.4, sample B) were synthesized by the hydrothermal method. From complex impedance measurements in the range 100 Hz–2 MHz and for temperatures T between 30 and 130 °C, the barrier energy between localized states ΔErelax was determined for the first time in these samples. For sample B, a single value of ΔErelax was highlighted (0.221 eV), whilst, for sample A, two values were obtained (0.012 eV and 0.283 eV, below 85 °C and above 85 °C, respectively), associated with two zones of different conductivities. Using the Mott's VRH model and the CBH model, we determined for the first time both the bandgap energy barrier (Wm) and the hopping (crossover) frequency (ωh), at various temperatures. The results show that, for sample A, Wm has a maximum equal to 0.72 eV at a temperature between 70 and 80 °C, whilst, for sample B, Wm has a minimum equal to 0.28 eV at a temperature of 60 °C, the results being in good agreement with the temperature dependence of the static conductivity σDC(T) of the samples. By evaluating σDC and eliminating the conduction losses, we identified, using a novel approach, a dielectric relaxation phenomenon in the samples, characterized by the activation energy EA,rel. At various temperatures, we determined EA,rel, which ranged from 0.195 eV to 0.77 eV. These results are important, as understanding these electrical properties is crucial to various applications, especially in technologies where temperature variation is significant. [ABSTRACT FROM AUTHOR]

Background: Melting corneal ulcers are a serious condition that affects a great number of animals and people around the world and it is characterised by a progressive weakening of the tissue leading to possible severe ophthalmic complications, such as visual impairment or blindness. This disease is routinely treated with medical therapy and keratoplasty, and recently also with alternative regenerative therapies, such as cross-linking, amniotic membrane transplant, and laser. Plasma medicine is another recent example of regenerative treatment that showed promising results in reducing the microbial load of corneal tissue together with maintaining its cellular vitality. Since the effect of helium plasma application on corneal mechanical viscoelasticity has not yet been investigated, the aim of this study is first to evaluate it on ex vivo porcine corneas for different exposition times and then to compare the results with previous data on cross-linking treatment. Results: 94 ex vivo porcine corneas divided into 16 populations (healthy or injured, fresh or cultured and treated or not with plasma or cross-linking) were analysed. For each population, a biomechanical analysis was performed by uniaxial stress-relaxation tests, and a statistical analysis was carried out considering the characteristic mechanical parameters. In terms of equilibrium normalised stress, no statistically significant difference resulted when the healthy corneas were compared with lesioned plasma-treated ones, independently of treatment time, contrary to what was obtained about the cross-linking treated corneas which exhibited more intense relaxation phenomena. Conclusions: In this study, the influence of the Helium plasma treatment was observed on the viscoelasticity of porcine corneas ex vivo, by restoring in lesioned tissue a degree of relaxation similar to the one of the native tissue, even after only 2 min of application. Therefore, the obtained results suggest that plasma treatment is a promising new regenerative ophthalmic therapy for melting corneal ulcers, laying the groundwork for further studies to correlate the mechanical findings with corneal histology and ultrastructural anatomy after plasma treatment. [ABSTRACT FROM AUTHOR]

Collisions between ions and neutral particles are often ignored in plasma numerical simulations. However, when studying plasma jets, the collision between neutral particles and ions is significant for ion transport, so calculations cannot ignore this. Therefore, this study adopted a two-fluid model and numerically simulated the process of ion emission from the sheath edge in atmospheric pressure plasma. In this study, particle collisions are treated as Maxwellian particle collisions. We analyze the influence of several parameters, such as sheath thickness and potential drop within the sheath. We also discuss the relaxation phenomenon of relative motion between ions and neutral particles. The research results show a transition from a non-equilibrium state to an equilibrium state in the ion migration region. Based on this change process, the ion migration region can be divided into relaxation and equilibrium zones. The relaxation zone is very thin, where the velocity and temperature of ions vary greatly. In the equilibrium zone, ions and neutral particles can be regarded as a single fluid. This study explores the interaction theory between neutral particles and ions in numerical simulations of plasmas. [ABSTRACT FROM AUTHOR]

Chemical relaxation phenomena, including photochemistry and electron transfer processes, form a vigorous area of research in which nonadiabatic dynamics plays a fundamental role. However, for electronic systems with spin degrees of freedom, there are few if any applicable and practical quasiclassical methods. Here, we show that for nonadiabatic dynamics with two electronic states and a complex-valued Hamiltonian that does not obey time-reversal symmetry (as relevant to many coupled nuclear-electronic-spin systems), the optimal semiclassical approach is to generalize Tully's surface hopping dynamics from coordinate space to phase space. In order to generate the relevant phase-space adiabatic surfaces, one isolates a proper set of diabats, applies a phase gauge transformation, and then diagonalizes the total Hamiltonian (which is now parameterized by both R and P). The resulting algorithm is simple and valid in both the adiabatic and nonadiabatic limits, incorporating all Berry curvature effects. Most importantly, the resulting algorithm allows for the study of semiclassical nonadiabatic dynamics in the presence of spin–orbit coupling and/or external magnetic fields. One expects many simulations to follow as far as modeling cutting-edge experiments with entangled nuclear, electronic, and spin degrees of freedom, e.g., experiments displaying chiral-induced spin selectivity. [ABSTRACT FROM AUTHOR]

The intermolecular forces are of great importance to scientists in a wide field of disciplines as the progress of interactions between molecules determines the bulk properties of substances. It is a matter of fact that the approximation of thermodynamic and transport properties of polymers requires a realistic intermolecular potential associated with the topological constraints of the matter, namely the specific one‐to‐one secondary interactions between molecular groups. The out‐of‐equilibrium volume relaxation in glassy polymers remains confined to the phenomenological observation of bulk properties. The Lennard‐Jones (LJ)‐type potentials and the Tait equation are compared in this communication. It is shown that the subtle relaxation responses observed in glassy polymers can be suitably described using both the local (LJ) interactions and the phenomenological Tait equation for bulk behavior. The approach is based on the oversimplified assumption that the volume relaxation phenomena are the isotropic manifestation of random relaxations of local directional interactions of secondary bonds. The results appear surprisingly appealing, given the straightforward approach. [ABSTRACT FROM AUTHOR]

Thermoplastic polymers exhibit relatively limited surface energies and this results in poor adhesion when bonded to other materials. Plasma surface modification offers the potential to overcome this challenge through the functionalisation of the polymer surfaces. In this study, three polymers of differing hydrophobicity (HDPE, PA12, and PA6) were subjected to a novel, atmospheric, μPlasma surface treatment technique, and its effectiveness at increasing the surface energies was evaluated via measurement of the contact angle. To characterise the physical and chemical changes following μPlasma surface modification, the surface morphology was observed using atomic force microscopy (AFM), and the functionalisation of the surface was evaluated using infrared spectroscopy. Immediately after treatment, the contact angle decreased by 47.3° (HDPE), 42.6° (PA12), and 50.1° (PA6), but the effect was not permanent in that there was a pronounced relaxation or ageing phenomenon in operation. The ageing process over five hours was modelled using a modified stretched exponential function Kohlrausch–Williams–Watts (KWW) model, and it was found that the ageing rate was dependent on the hydrophilicity of polymers, with polyamides ageing more rapidly than polyethylene. [ABSTRACT FROM AUTHOR]

Novel Sillenites Bi25Fe(1−x)AlxO40 (x = 0.00, 0.20, and x = 0.50) have been synthesized using the SSR method. In this paper, the effect of Al-substitution on the physicochemical properties was performed. The X-ray diffraction analysis as well as both Raman and FT-IR spectroscopies indicate that all the elaborated materials have a bcc structure with the I23 space group. The increase of the cell parameters, the morphological features, and thus the decrease of the grain size with Aluminum content is also evidenced via the X-ray patterns and SEM microscopy. DSC measurements highlighted the occurrence of various phenomena related to both structural and dielectric features. The temperature dependence of electrical conductivity and the deduced activation energies pointed to the effect of temperature on the conduction process. The impedance analysis on the samples confirms the onset of relaxation phenomenon in the sample with semiconducting behavior. Furthermore, an AFM-Paramagnetic transition for x = 0.00 and 0.20, with Neel temperatures of 268 and 265 K, respectively. Otherwise, paramagnetic behavior is observed for x = 0.50. The optical measurements make these materials suitable candidates for photocatalysis and optoelectronic applications. [ABSTRACT FROM AUTHOR]

This work aims to upgrade the functional properties of ZnMn 2 O 4 via doping with Bi3+. Nano ZnMn 2-x Bi x O 4 (x = 0, 0.03, 0.05, 0.07, 0.1, 0.15, 0.2) samples were prepared by the sol-gel method. The structure, microstructure, and formed phases in ZnMn 2-x Bi x O 4 samples were determined using Rietveld-calculated profile fitting of the experimental x-ray synchrotron radiation diffraction data. The tetragonal spinel ZnMn 2 O 4 phase was formed with a tiny (∼2–4 %) hexagonal ZnO phase. The morphology and different vibration bands in ZnMn 2-x Bi x O 4 samples were investigated using scanning electron microscopy and Fourier transform infrared techniques. The diffused reflectance technique was used to explore the effect of Bi doping on the absorbance and optical band gap of ZnMn 2 O 4. The optical band gap energy decreased from 2.42 to 1.83 eV as the percentage of Bi-doped ZMO increased from 0 to 10 %, then increased again for higher Bi content. The dielectric permittivity is affected by the Bi-doped amounts and temperature. As the amount of Bi and temperature increased, the impedance of the ZMO sample and relaxation time changed. All samples exhibited both metallic and semiconducting behaviors. All samples have a non-Debye relaxation phenomenon. Samples with x = 0.03 and 0.2 exhibited the maximum conductivity among other doped samples. These findings introduce ZnMn 2-x Bi x O 4 samples for new applications in optoelectronics and optical devices. [ABSTRACT FROM AUTHOR]

BaBi4Zr2Sn2O15, a modified ceramic sample belonging to the oxide family of layered ferroelectrics, is synthesized using the mixed oxide process after firing for calcination at 810 °C for 6 hrs. XRD study of the compound exhibits the growth of an orthorhombic single-phase structure at atmospheric temperature. The electrical properties of the sample are investigated in a broad temperature range (30–500 °C) and frequency range (100 Hz - 106 Hz). The dielectric properties recommend the transition from ferro to paraelectric state at 410 °C which is much more than room temperature. The impact of frequency and temperature on complex immittance parameters (impedance and modulus) are analyzed by an impedance analyzer in broad frequencies and temperature ranges. The electrical properties show; (i) the existence of semiconductor-like negative temperature coefficients of resistance behavior, (ii) evidence of electrical relaxation phenomena as a function of temperature, and (iii) the existence of single electrical relaxation ascribed to the existence of grain contribution to the electric properties. [ABSTRACT FROM AUTHOR]

BaBi4Sn4O15, a Sn-modified ceramic sample of layered ferroelectric oxide family, is developed using a high-temperature mixed oxide route after firing for calcination at 810 °C for 6 h in steps of 50 °C starting from 600 °C. An introductory XRD study of the compound displays the development of the new orthorhombic structured single-phase compound at atmospheric conditions. The electrical behaviors of the compound are investigated in a wide temperature span (30–500 °C) and frequencies ranging from 0.1 kHz to 1 MHz using an impedance analyzer. Dielectric behavior informs that the compound has a phase transition from Ferro to Paraelectric at 370 °C, which is well above room temperature. The impact of temperature and frequency on complex immittance parameters (impedance and modulus) is analyzed using an LCR meter in a broad temperature & frequency span. The electrical properties confirm; (a) the existence of semiconductor-like NTCR (negative temperature coefficients of resistance) behavior, (b) the evidence of the electric relaxation process as a function of temperature, (c) the existence of electric relaxation ascribed to the simultaneous contribution of bulk & bulk interfaces to the electrical behavior, and (d) presence of the non-Debye type relaxation phenomena. The frequency-dependent conductivity follows Jonscher's universal power law. [ABSTRACT FROM AUTHOR]

In this paper, detailed studies of effect of small amount of manganese substitution (at the zirconium site) on the structural, micro-structural, and electrical characteristics of lead zirconate titanate of Pb(Zr0.35–xMnxTi0.65)O3;x = 0, 0.02, 0.06, 0.10 (PZMT)) have been reported. The materials were prepared by using standard ceramic technology. The formation of the compounds and their basic crystal data have been studied through X-ray diffraction (XRD) method. The crystallite size and lattice strain of the compounds, evaluated from Scherrer's and Hall Williamson (H-W) equations, is found to be in the range of 40–50 nm and 11 × 10−4 to 50 × 10−4, respectively. Microstructures of different magnifications, revealing the surface nature of the compounds, have been recorded by field emission scanning electron microscope (FESEM). Effect of Mn+4 ions on electrical behavior (electrical impedance (Z*), electrical modulus (M*), conduction and relaxation phenomenon) of PZMT systems, over wide range of temperature and frequency, has been studied. [ABSTRACT FROM AUTHOR]

Low-temperature anomalies of dielectric permittivity of S n 2 P 2 S 6 crystals were investigated. It is shown that these phenomena have a relaxation character and the observed anomalies could be related to the small hole polarons dynamics with donor-acceptor compensation processes in lattice with tin and sulfur vacancies. To confirm it, we measured the dielectric properties of tin-enriched and sulfur-enriched crystals. It is shown that deviation from stoichiometry leads to a significant change in the low-temperature anomalies of dielectric losses. [ABSTRACT FROM AUTHOR]

The fragility parameter is one of the most important material constants that is extensively used in glass science, playing a central role in the enhancement of understanding the glass formation process of disordered systems. Although fragility has been widely used, this concept has never been precisely defined and evaluated in relaxor ferroelectrics. Here, we have filled up this scientific gap. Based on a generalized Vogel–Fulcher–Tammann equation, the fragility parameter is introduced for relaxor ferroelectrics. The new formulation has been quantitatively assessed by combining dielectric spectroscopy and pyroelectric measurements on canonical relaxors. A clear correlation between the fragility and a new local structural heterogeneity-related order parameter elucidates new information about the ferroelectric order of relaxor ferroelectrics. This may open a new pathway to disentangle relaxation phenomena in other relaxor ferroics. [ABSTRACT FROM AUTHOR]

We have demonstrated magnetodielectric (MD) coupling in an Ising-chain magnet Sr2Ca2CoMn2O9 via detailed investigation of ac susceptibility and dielectric constant as a function of temperature, magnetic field, and frequency. Sr2Ca2CoMn2O9 consists of spin-chains made of the regular stacking of one CoO6 trigonal prism with two MnO6 octahedra. The (Co2+–Mn4+–Mn4+) unit stabilizes a (↑↓↑) spin-state along the chains that are distributed on a triangular lattice. This compound undergoes a partially disordered antiferromagnetic transition at TN ∼ 28 K. The dielectric constant exhibits a clear peak at TN only in the presence of an external magnetic field (H ≥ 5 kOe), evidencing the presence of MD coupling, which is further confirmed by field-dependent dielectric measurements. We argue that spatial inversion symmetry can be broken as a result of exchange-striction along each spin chain, inducing uncompensated local dipoles. At low temperatures, a dipolar relaxation phenomenon is observed, bearing strong similarities to the blocking effect typical of spin dynamics in this compound. Such a spin-dipole relationship is referred to as a "multiblocking" effect, in relation to the concept of magnetodielectric "multiglass" previously introduced for related materials. [ABSTRACT FROM AUTHOR]

Dielectric and thermal properties of polyvinyl butyral (PVB) were studied in this work, using dynamic electrical analysis (DEA) at frequencies from 100 Hz to 1 MHz and temperatures from 293 K to 473 K. Two electrical relaxation processes were investigated: glass transition and interfacial polarization. Above the glass transition temperature (~343 K), interfacial polarization dominates conductive behavior in polyvinyl butyral. The framework of the complex electric modulus was used to obtain information about interfacial polarization. The viscoelastic behavior was analyzed through dynamic mechanical analysis (DMA), where only the mechanical manifestation of the glass transition is observed. The experimental results from dielectric measurements were analyzed with fractional calculus, using a fractional Debye model with one cap-resistor. We were successful in applying the complex electric modulus because we had a good correlation between data and theoretical predictions. The fractional order derivative is an indicator of the energy dissipated in terms of molecular mobility, and the calculated values close to 1 suggest a conductive behavior at temperatures above the glass transition temperature of PVB. [ABSTRACT FROM AUTHOR]