Evidence of sustained ferroelectricity in glycine sodium nitrate single crystal

The nonlinear optical single crystals of glycine sodium nitrate were grown by the slow evaporation method. XRD confirmed monoclinic structure. Thermal stability and melting point (225 °C) were investigated. The dielectric behaviour of the crystals in the frequency range 20 Hz–2 MHz at different temperatures is reported in which a ferroelectric to paraelectric phase transition at T_c = 56 °C is observed. The activation energies of GSN were found to be 3.615 eV, 0.593 eV and 0.0733 eV in three temperature regions of conductivity plot due to a hopping conduction mechanism. The crystal has shown high piezoelectric charge coefficient (d₃₃) of 16 pC/N which is nearly double of observed value for γ-glycine single crystal. The spontaneous polarization P_s at room temperature was found to be 1.489 μC/cm² at applied maximum field of 26 kV/cm (1.194 μC/cm² at 12 kV/cm) and the pyroelectric coefficient was determined to be 400 μC/m²/°C. High value of squareness parameter (1.93) makes the GSN crystal suitable for switching applications. Detailed investigations of Ferro-/Piezoelectricity were observed for the first time in glycine sodium nitrate crystals which was found to preserve the ferroelectricity even after applying an electric field much higher than the saturation electric field (12–26 kV/cm). Application of GSN crystals as sensor, high power switch gears and storage memories has been established.     

Potential-induced sonoelectrochemical graphene nanosheets with vacancies as hydrogen peroxide reduction catalysts and sensors

Defective graphene nanosheets (dGN_4V) with 5-9, 5-8-5, and point defects were synthesised by a sonoelectrochemical method, where a potential of 4 V (vs. Ag/AgCl) was applied to drive the rapid intercalation of phosphate ions between the layers of the graphite foil as a working electrode. In addition to these vacancies, double vacancy defects were also created when the applied potential was increased to 8 V (dGN_8V). The defect density of dGN_8V (2406 μm⁻²) was higher than that of dGN_4V (1786 μm⁻²). Additionally, dGN_8V and dGN_4V were applied as catalysts for the hydrogen peroxide reduction reaction (HPRR). The mass activity of dGN_8V (1.31 × 10⁻² mA·μg⁻¹) was greater than that of dGN_4V (1.17 × 10⁻² mA·μg⁻¹) because of its high electrochemical surface area (ECSA, 1250.89 m²·g⁻¹) and defect density (N_D, 2406 μm⁻²), leading to low charge transfer resistance on the electrocatalytic interface. The ECSA and N_D of dGN_4V were 502.7 m²·g⁻¹ and 1786 μm⁻², respectively. Apart from its remarkable HPRR activity, the cost-effective dGN_8V catalyst also showed potential as an amperometric sensor for the determination of H₂O₂.     

Electric field involved transport at elevated temperature in nanocrystalline silicon carbide nitride (nc-SiCN) thin films for harsh environment applications

The present study represents a systematic temperature dependent charge transport and dielectric properties of nanocrystalline silicon carbide nitride (nc-SiCN) thin films grown on Pt/Ti/SiO₂/Si substrate. A large negative temperature coefficient of resistance (TCR) ranging from 6200 to 2300 ppmK^-1 in the temperature range 300–773 K, suggests that the nc-SiCN thin films could be useful for futuristic thermal-based sensors. The current density vs. electric field (J-E) characteristics was measured at different temperatures (300–673 K). Detailed J-E analysis revealed an ohmic conduction at the low applied electric field (<65 kV/cm) within the entire temperature range. However, at high electric field (>65 kV/cm), space charge limited conduction (SCLC) mechanism was found to be dominating in low measurement temperature (300–473K), whereas, a transition from SCLC mechanism to Poole-Frenkel mechanism was observed with further increment in the temperature beyond 473 K. The temperature invariant dielectric tunability (n_r ∼10%) and low zero electric field leakage current density (J ∼10⁻⁷A/cm²) at 673 K temperature, demonstrates the feasibility of nc-SiCN thin films for tunable device applications in the high-temperature and harsh environment.     

Simulation of dark current suppression in p–i–n InGaAs photodetector with In0.66Ga0.34As/InAs superlattice electron barrier

An InGaAs–based photodetector with different periods of inserting strain–compensated In_0.66Ga_0.34As/InAs superlattice (SL) electron barrier in the In_0.83Ga_0.17As absorption layer has been investigated. The band diagram, electron concentration and electric field intensity of the structure were analyzed with numerical simulation. It was found that the period of SL has a remarkable influence on the properties of the photodetectors. With the decrease of the period of In_0.66Ga_0.34As/InAs SL, the dark current density is suppressed significantly, which is reduced to 2.46 × 10⁻³ A/cm² at 300 K and a reverse bias voltage of 1 V when the period is 2.5 nm.     

Engineering of Molecular Bridge on Buried Interface via Ferrocene Carboxylic Acid for High Performance Perovskite Light-Emitting Devices

Quasi-two-dimensional (Quasi2D) perovskite materials gained widespread attention due to whose unique and highly desirable luminescence properties. However, the behavior of perovskite lightemitting diodes (PeLEDs) is prejudiced by inefficient cascading energy transfer of perovskite film and unbalanced charges injection. Here, ferrocene carboxylic acid (FcAd) is employed between hole transport layer (HTL) and perovskite layer as a molecular bridge to solve the current problems of PeLEDs. Ferrocene units can bond with [PbBr₆]⁴⁻, forming one-dimensional (1D) intermediate phases of FcPbBr₃ at the interface, which can manipulate the growth kinetics of perovskite and reconstruct the phase distribution. Therefore, due to the suppression of low dimensional phase content, not only is the cascaded energy transfer of PEA₂(CsPbBr₃)₂PbBr₄ films effectively achieved, but also the quasi-2D perovskite's work function is reduced. Additionally, Pb²⁺ coordinated with the carboxyl group of FcAd, inducing an electric dipole effect that leads to an further upward shift of the perovskite energy level. Eventually, the synergy achieves a significant tailoring between the perovskite and HTL energy exhibits the most excellent external quantum efficiency (EQE) exceeds 27% and optimal brightness exceeds 240000 cd m⁻². Therefore, the preparation method will provide an effective strategy to widen the color gamut of next-generation displays.     

Dielectric,ferroelectric and field-induced strain response of lead-free BaZrO3-modified Bi0.5Na0.5TiO3 ceramics

Lead-free piezoelectric ceramics (1 − x)Bi_0.5Na_0.5TiO₃–xBaZrO₃ (BNT–BZ100x, with x = 0–0.10) were prepared using a conventional solid-state reaction method. The crystal structure, microstructure, dielectric, ferroelectric, and piezoelectric properties of BNT–BZ100x ceramics were studied as functions of different BZ content. X-ray diffraction patterns revealed that the BZ completely diffused in the BNT lattice in the studied composition range. An appropriate amount of BZ addition improved the dielectric, ferroelectric, and piezoelectric properties of BNT ceramics. The remanent polarization (P_r) and piezoelectric constant (d₃₃) increased from 22 μC/cm² and 60 pC/N for pure BNT to 30 μC/cm² and 112 pC/N for x = 0.040, respectively. In addition, electric field-induced strain was enhanced to its maximum value (S_max = 0.40%) with normalized strain (d*₃₃ = S_max/E_max = 500 pm/V) at an applied electric field of 8 kV/mm for x = 0.055. The enhanced strain can be attributed to the coexistence of ferroelectric and relaxor ferroelectric phases.     

The real-time gamma radiation dosimetry with TeO2 thin films

A detailed study of the effect of gamma radiation on the current–voltage characteristics of the TeO₂ thin films of different thicknesses, prepared by thermal evaporation in a vacuum, has been carried out for a much wider range of the gamma radiation doses than made here-to-fore. Subsequently, for the thin films of different thicknesses at different applied voltages, the variations of the current density with dose have been obtained. The current density increases near linearly with the gamma radiation dose up to a critical radiation dose, a dose value higher for the thicker films and decreases thereafter. The sensitivities of these TeO₂ thin films at different applied voltages have been found to be in the range 1.2–37.0 nA/cm²/μGy. Correspondingly, the detection limits have also been estimated and have been found to be in the range 0.22–2.16 mGy. Clearly, the TeO₂ thin films have high potential for their use as real-time gamma radiation dosimeters in monitoring the gamma radiation doses under a variety of practical situations involving low level to high level of the doses.     

Inactivation of extremely halophilic hide-damaging bacteria via low-level direct electric current

The presence of proteolytic and lipolytic extremely halophilic bacteria on brine-cured hides reduces the value of the hide as a raw material for leather manufacturing. Every brine curing raceway that produces hide contains a significant number of extremely halophilic bacteria that contaminate almost every hide. The usual brine raceway treatments used to control bacteria during curing do not control halophilic bacteria. The antibacterial effects of passing 0.5-A low level, direct electric current for 30 min on different species of protease, lipase, both protease and lipase producing extremely halophilic bacteria, as well as a mixed population of extremely halophilic bacteria, were examined in liquid media containing organic substances and 25% NaCl. Although the antibacterial effects varied with different extremely halophilic bacterial species, the application of current demonstrated an antibacterial effect within 20 min of treatment of all species tested. A mixed culture of extremely halophilic bacteria was killed within 10 min. It has been demonstrated that treatment time as short as 5 min is sufficient for the total inactivation of protease producing extremely halophilic bacteria of 10⁷ CFU/mL while lipase or lipase and protease producing extremely halophilic bacteria were inactivated within 20 min. It was also found that the temperature and pH of the test medium increased during treatment. The maximum temperature rise was 9 °C, and the pH increased by 4.     

Highly stable hafnium–tin–zinc oxide thin film transistors with stacked bilayer active layers

Hf–Sn–Zn–O (HTZO) thin films were prepared on SiO₂/SiN_x substrates at room temperature by the direct current (DC) magnetron sputtering of Hf-doped Sn–Zn–O targets. The characteristics of films with different amounts of Hf were analyzed. Amorphous HTZO films were obtained by increasing the Hf content, while polycrystalline films have not shown with Hf doping. With the proper Hf concentration in the HTZO films (∼2.0 atomic % Hf/(Hf + Sn + Zn + O)), HTZO films demonstrated good performance as an oxide semiconductor channel material in thin film transistors (TFTs) with a field effect mobility (μ_FE) of 10.9 cm²V⁻¹ s⁻¹, an on/off current ratio of 10⁹, and a subthreshold voltage swing of 0.71 V/decade.     

Thermoelectric properties in Mn-doped Bi2Se3

Using n-type and p-type Mn-doped Bi₂Se₃ single crystals, a thin-film-type thermoelectric (TE) module was fabricated and the TE characteristics were investigated. The Seebeck coefficient at room temperature was about 100 μV K⁻¹ with different sign for both materials. From the Seebeck coefficient and resistivity values, the electric power of our TE module was evaluated to be 90 μW for a single couple at the temperature difference of 10 K. This value is compared to that (∼21 μW) of commercialized TE device. Nevertheless, the actual power was measured to be quite small around 0.74 μW, which is much higher than other homemade TE power level. This small power is attributed to the high electrical contact resistance between the TE material and the heat source and sink. Assuming the contact resistance level ∼0.1 Ω similar to that of commercialized TE devices, the electric power should be about 41 μW, which is almost 2 times higher than that in commercialized TE devices. These results propose that the Mn-doped Bi₂Se₃ system is another promising TE material, which can be replaced with the commercialized Bi₂Te₃ system.     

The lightning striking distance—Revisited

First return stroke current waveforms measured by Berger [Methods and results of lightning records at Monte San Salvatore from 1963–1971 (in German), Bull. Schweiz. Elektrotech. ver. 63 (1972) 21403—21422] and Berger and Vogelsanger [Measurement and results of lightning records at Monte San Salvatore from 1955–1963 (in German), Bull. Schweiz. Elektrotech. ver. 56 (1965) 2–22] are used to estimate the charge stored in the lightning stepped leader channel. As opposed to previous charge estimates based on the entire current waveform, only the initial portion of measured current waveforms (100 μs in duration) was used in order to avoid the inclusion of any charges not involved in the effective neutralization of charges originally stored on the leader channel. The charge brought to ground by the return stroke within the first 100 μs, Q_f,100 μs (in C) is related to the first return stroke peak current, I_pf (in kA), as Q_f,100 μs=0.61 I_pf. From this equation the charge distribution of the stepped leader as a function of the corresponding peak return stroke current is estimated. This distribution (along with the assumed average electric field of 500 kV/m in the final gap) is used to estimate the lightning striking distance S (in meters) to a flat ground as a function of the prospective return stroke peak current I (in kA): S=1.9 I_pf^0.90. For the median first stroke peak current of 30 kA one obtains S=41 m, while the traditional equation, S=10 I_pf^0.65, gives S=91 m. In our view, the new equation for striking distance provides a more physically realistic basis for the electro-geometric approach widely used in estimating lightning incidence to power lines and other structures.     

Feasibility study of power engineering secondary equipment protection methods from static electricity

The paper presents feasibility study of power engineering secondary equipment protection methods from static electricity basing on calculation and experimental procedure. Method was applied for newly constructed objects and modernized objects as well. The procedure includes calculation of expected electrostatic potential at human body considering environment characteristics (relative humidity, dimensions and electrophysical characteristics of flooring and footwear). Calculated potential was compared to acceptable value. Acceptable value represents immunity test level of secondary equipment (relay protection and automation, communication equipment, PCs) presented in standards [1], [2], [3], [4], [5]. In calculations electrostatic charging current density j₀ = 10 μA/m² was taken as in domestic applications. Calculation result analysis showed optimal methods to limit human electrostatic charge accumulation for designed objects and objects in operation.     

Combination of therapeutic ultrasound with antibiotics interfere with the growth of bacterial culture that colonizes skin ulcers: An in-vitro study

Staphylococcus aureus and Escherichia coli are among the major bacterial species that colonize skin ulcers. Therapeutic ultrasound (TUS) produces biophysical effects that are relevant to wound healing; however, its application over a contaminated injury is not evidence-based. The objective of this research was to analyze the effect of TUS on in vitro-isolated S. aureus and E. coli, including the combination of ultrasound and antibiotics, in order to assess their antibiotic action on bacterial susceptibility. For the experiments, the bacterial strains were suspended in saline, then diluted (10⁴ CFU/mL) for irradiation (at 1 and 3 MHz, 0.5 and 0.8 W/cm² for 0 and 15 min) and the combination treatment of ultrasonication and antibiotics was administered by adding nalidixic acid (S. aureus) and tetracycline (E. coli) at concentrations equivalent to 50% of the minimum inhibitory concentration (MIC). The experiments were carried out in duplicate with six repetitions. The suspensions were inoculated on to Petri plates and incubated at 37 °C and the colony forming units (CFUs) were counted after 24 h. The results were subjected to the Shapiro–Wilk normality test, followed by parametric ANOVA and Tukey’s post hoc test at a significance level of 1%. The results demonstrated that the action of TUS at 1 MHz inhibited bacterial growth while at 3 MHz, bacterial growth was observed in both species. However, the synergistic combination of ultrasound and antibiotics was able to inhibit the growth of both bacteria completely after 15 min of ultrasonication. The results suggest that the action of ultrasound on S. aureus and E. coli are dependent on the oscillation frequency as well as the intensity and time of application. The combination of ultrasound with antibiotics was able to inhibit bacterial growth fully at all frequencies and doses in both species.     

Analytical modeling and ATLAS simulation of N+-InP/n0-In0.53Ga0.47As/p+-In0.53Ga0.47As p-i-n photodetector for optical fiber communication

In this paper we report an analytical modeling of N⁺-InP/n⁰-In_0.53Ga_0.47As/p⁺-In_0.53Ga_0.47As p-i-n photodetector for optical fiber communication. The results obtained on the basis of our model have been compared and contrasted with the simulated results using ATLAS? and experimental results reported by others. The photodetector has been studied in respect of energy band diagram, electric field profile, doping profile, dark current, resistance area-product, quantum efficiency, spectral response, responsivity and detectivity by analytical method using closed form equations and also been simulated by using device simulation software ATLAS? from SILVACO® international. The photodetector exhibits a high quantum efficiency ～90%, responsivity ～1.152–1.2 A/W in the same order as reported experimentally by others, specific detectivity ～5 × 10⁹ cm Hz^1/2 W^?1at wavelength 1.55–1.65 μm, dark current of the order of 10^?11 A at reverse bias of 1.5 V and 10^?13–10^?12 A near zero bias. These values are comparable to those obtained for practical p-i-n detectors. The estimated noise equivalent power (NEP) is of the order of 2.5 × 10^?14 W.     

Study the impact of ultra-sonication and pulsed electric field on the quality of wheat plantlet juice through FTIR and SERS

Pulsed electric field (PEF) and Ultrasound (US) are commonly used in food processing. We investigated the combined impact of pulsed electric field (PEF) and ultrasound (US) on the wheat plantlet juice. When compared with the individual treatments, the highest values of total phenolics, total flavonoids, chlorophyll, ORAC assay, and DPPH activities were obtained using the combined (US + PEF) methods. The US + PEF significantly decreased the peroxidase and polyphenol oxidase activities from 0.87 to 0.27 Abs min⁻¹ and 0.031–0.016 Abs min⁻¹. Also, the synergistic application significantly lowered the yeast and mold (3.92 to 2.11 log CFU/mL), E. coli/Coliform (1.95 to 0.96 log CFU/mL), and aerobics (4.41 to 2.01 log CFU/mL). Furthermore, Fourier Transform Infrared (FT-IR) and surface-enhanced Raman spectroscopy (SERS) was used to analyzing juice quality. Gold nanoparticles (AuNPs) were used as the SERS substrates, which provided stronger Raman peaks for the samples treated with US + PEF methods. The FT-IR analysis showed significant enhancement of the nutritional molecules. The enhanced quality of wheat plantlet juice combined with lower yeast and mold suggests the suitability of integrated methods for further research and applications.     

Ho:LaF3 single crystal as potential material for 2 μm and 2.9 μm lasers

Optical properties of a Ho-doped LaF₃ single crystal have been detailed investigated as a promising material for 2 μm and 2.9 μm lasers for the first time. Judd–Ofelt theory was applied to analyze the absorption spectrum to determine the J–O intensity parameters Ω_t(t=2,4,6), based on which the emission probabilities, branching ratio and radiative lifetime for the as-grown crystal were all calculated. The stimulated emission cross-sections of the ⁵I₇ → ⁵I₈ and ⁵I₆ → ⁵I₇ transitions were obtained by using the Fuchtbauer–Ladenburg method. The gain cross-section for 2 μm emission becomes positive once the population inversion level reaches 30%. The Ho:LaF₃ crystal shows long fluorescence lifetime of ⁵I₇ manifold (25.81 ms) as well as ⁵I₆ manifold (10.37 ms) compared with other Ho³⁺-doped crystals. It can be proposed that the Ho:LaF₃ crystal may be a promising material for 2 μm and 2.9 μm laser applications.     

Influence of YSZ electrolyte thickness on the characteristics of plasma-sprayed cermet supported tubular SOFC

Novel Ni–Al₂O₃ cermet-supported tubular SOFC cell was fabricated by thermal spraying. Flame-sprayed Al₂O₃–Ni cermet coating played dual roles of a support tube and an anode current collector. Y₂O₃-stabilized ZrO₂ (YSZ) electrolyte was deposited by atmospheric plasma spraying (APS) to aim at reducing manufacturing cost. The gas tightness of APS YSZ coating was achieved by post-densification process. The influence of YSZ coating thickness on the performance of SOFC test cell was investigated in order to optimize YSZ thickness in terms of open circuit voltage of the cell and YSZ ohmic loss. It was found that the reduction of YSZ thickness from 100 μm to 40 μm led to the increase of the maximum output power density from 0.47 W/cm² to 0.76 W/cm² at 1000 °C. Using an APS 4.5YSZ coating of about 40 μm as the electrolyte, the test cell presented a maximum power output density of over 0.88 W/cm² at 1030 °C. The results indicate that SOFCs with thin YSZ electrolyte require more effective cathode and anode to improve performance.     

The effects of sintering temperatures on dielectric,ferroelectric and electric field-induced strain of lead-free Bi0.5(Na0.78K0.22)0.5TiO3 piezoelectric ceramics synthesized by the sol–gel technique

Lead-free Bi_0.5(Na_0.78K_0.22)_0.5TiO₃ (BNKT) piezoelectric ceramics were synthesized by the sol–gel technique. The effects of sintering temperatures on the crystal structure, microstructure, densification, dielectric, ferroelectric and electric field-induced strain behaviors of the BNKT ceramics were investigated. X-ray diffraction patterns exhibited a pure perovskite structure from 1075 to 1150 °C. A scanning electron microscopy study revealed an increase in grain size with increasing sintering temperature. The density of the ceramics sintered at 1150 °C reaches a maximum value of 5.55 g/cm³, which is 96% of the theoretical density. BNKT ceramics sintered at an optimum temperature of 1150 °C exhibited a high remnant polarization of 18.5 μC/cm², a high electric field-induced strain of 0.20% and dynamic piezoelectric coefficient d₃₃¹ = (S_max/E_max) of 247 pm/V.     

Transverse piezoelectric properties of Mn-doped Bi0.5Na0.5TiO3 thin films

Lead-free (Bi_0.5Na_0.5)(Ti_1-xMn_x)O₃ (BNTMn-x; x = 0, 0.0025, 0.0050, 0.0100) thin films were fabricated using a chemical solution deposition method on Pt/TiO₂/SiO₂/Si substrate. The effect of Mn substitution on crystal structures, surface morphologies, and ferroelectric and transverse piezoelectric properties of BNTMn-x thin films was investigated. The 0.5 mol% Mn-doped (Bi_0.5Na_0.5)(Ti_0.995Mn_0.005)O₃ thin film exhibited a well-saturated ferroelectric P-E hysteresis loop at room temperature. A remnant polarization (P_r) of 16 μC/cm² was obtained for the BNTMn-0.0050 film at an applied electric field of 400 kV/cm. In addition, a 1.12-μm-thick BNTMn-0.0050 film was applied as a cantilever. The Pt/BNTMn-0.0050/Pt/TiO₂/SiO₂/Si unimorph cantilever exhibited a high transverse piezoelectric coefficient ($e_{31}^1$) of 2.43 C/m².     

The preservable effects of ultrasound-assisted alginate oligosaccharide soaking on cooked crayfish subjected to Freeze-Thaw cycles

To improve the quality of cooked and frozen crayfish after repeated freeze–thaw cycles, the effects of alginate oligosaccharide (1 %, w/v) with ultrasound-assisted (40 W, 3 min) soaking (AUS) on the physicochemical properties were investigated. The AUS samples improved water-holding capacity with 19.47 % higher than the untreated samples. Low-field nuclear magnetic resonance confirmed that mobile water (T₂₂) in the samples after 5 times of freeze–thaw cycles was reduced by 13.02 % and 29.34 % with AUS and without treatment, correspondingly; and with AUS and without treatment, average size of the ice crystals was around 90.26 μm² and 113.73 μm², and average diameter of the ice crystals was 5.83 μm and 8.14 μm, respectively; furthermore, it enhanced the solubility and zeta potential, lowered the surface hydrophobicity, reduced the particle size, and maintained the secondary and tertiary structures of myofibrillar protein (MP) after repeated freeze-thawing. Gel electrophoresis revealed that the AUS treatment mitigated the denaturation of MPs. Scanning electron microscopy revealed that the AUS treatment preserved the structure of the tissue. These findings demonstrated that the AUS treatment could enhance the water retention and physicochemical properties of protein within aquatic meat products during temperature fluctuations..