Primary Peak Research Articles

Thermoluminescence properties of nano-alumina with two different particle sizes

This research aims to examine the thermoluminescence (TL) properties of nano-sized alumina, including the relationship between TL intensity and absorbed dose, the identification of individual luminescence peaks, and determining trap parameters for use as a possible dosimeter. The samples were exposed to 530 to 2646 Gy doses from 60Co irradiation. The results show that micro-sized α-Al2O3 had a main dosimetry peak at Tm = 435 K, while nano-α-Al2O3 samples with particle sizes of 40 and 50 nm displayed a TL luminescence glow curve, with the primary dosimetry peak located in the low-temperature range and a complex structure at higher temperatures (above 500 K). The primary dosimetry peak was influenced by nanoparticle size, with a maximum of 460 K for the 40 nm sample and 467 K for the 50 nm sample. The main dosimetry peak was described by the superposition of two peaks

Intraseasonal oscillations of the Andaman Sea thermocline

Variations in the upper ocean thermal structure have significant implications for air-sea interaction and upper-ocean ecosystem processes. Vertical profiles of temperature measured by a moored buoy located at 10.5°N, 94°E in the Andaman Sea and simulation by an Indian Ocean model are used in this study to characterise the intraseasonal variations (ISV) in the Andaman Sea (AndS) thermal structure and identify their sources. The seasonal variations in the upper ocean thermal structure show a strong semi-annual cycle driven by monsoons. The sub-surface temperature shows significant intraseasonal oscillations within a band of 40–110 days, which are de-coupled from that in the mixed layer, which has dominant periodicity in the band of 90–120 days. Thermocline ISV are seasonally modulated with a primary peak during August–September and a secondary peak during February–March, with significant year-to-year variations. A cross-wavelet analysis shows that ISV in the 40–60 days period is in phase with that at the eastern boundary and they are locally forced by the passage of eddies. The 60–110 day band is out of phase with the eastern boundary and is forced by Rossby waves radiated from the equatorially generated intraseasonal coastal Kelvin waves.

The structures, morphologies and intermediate-temperature electrochemical properties of CuO aided sintering Gd3+ and Ho3+ co-doped ceria electrolytes

In this study, a CuO-assisted sintering Ho3+ and Gd3+ co-doped CeO2 (Gd0.1Ho0.1Ce0.8O2-α-CuO, GHDC-CuO) electrolyte has been successfully synthesized using a citric acid and glycine combustion technique. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe and characterize the morphologies and structures of the produced samples. The XRD results showed that the doped samples' primary diffraction peaks were consistent with those of conventional cerium dioxide. The SEM findings demonstrated that adding the right quantity of CuO aided in the densification of the electrolytes. The total resistance was significantly impacted by the addition of CuO in the following order: R (1400-GHDC) > R (1450-GHDC) > R (1450-GHDC-CuO) > R (1400-GHDC-CuO). After being assembled into a thin film fuel cell, the maximum output power densities of 1400-GHDC-CuO (18 µm) using Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) as the cathode were 396 mW·cm-2 and 490 mW·cm-2 at 700 °C and 750 °C, respectively.

Antimicrobial, function, and crystalline analysis on the cellulose fibre extracted from the banana tree trunks

Bioactive substances such as phenolic compounds, antioxidants, and antibacterial agents are found in natural fibres. In this study, banana fibre was extracted from the trunks of banana plants. Antibacterial activity, FTIR, XRD, and SEM analysis were performed to characterize the banana cellulose fibre, and also raw and alkali-treated banana fibre composite was fabricated with an epoxy matrix. Results of the antibacterial analysis indicate that this banana cellulose fibre strongly impedes bacterial growth with elevated inhibitory zones. The primary peaks observed at 1170 cm−1 and 1426 cm−1 by FTIR analysis correspond to C–O stretching, O–H bending, aliphatic ether, secondary alcohol, and carboxylic acid. The morphological analysis reveals the fibre quality, and the EDX analysis confirms the elements present in the banana cellulose fibre. The XRD results demonstrated a more significant proportion (76.8%) of the amorphous region. This study indicates that banana cellulose fibre could be a promising source of antimicrobial compounds. In addition, the mechanical properties of alkali-treated banana fibre composite were preferable to raw fibre composite by an average of 3% for this banana fibre composite. As a result, this composite can be used to manufacture automobile interior components, as it can reduce the sanitizing periods of interior components during winter months.

A Phenomenological Model for Enthalpy Recovery in Polystyrene Using Dynamic Mechanical Spectra.

This paper studies the effects of annealing time on the specific heat enthalpy of polystyrene above the glass transition temperature. We extend the Tool-Narayanaswamy-Moynihan (TNM) model to describe the endothermic overshoot peaks through the dynamic mechanical spectra. In this work, we accept the viewpoint that the enthalpy recovery behavior of glassy polystyrene (PS) has a common structural relaxation mode with linear viscoelastic behavior. As a consequence, the retardation spectrum evaluated from the dynamic mechanical spectra around the primary Tg peak is used as the recovery function of the endothermic overshoot of specific heat. In addition, the sub-Tg shoulder peak around the Tg peak is found to be related to the structural relaxation estimated from light scattering measurements. The enthalpy recovery of annealed PS is quantitatively described using retardation spectra of the primary Tg, as well as the kinetic process of the sub-Tg relaxation process.

Effect of friction stir welding parameters on microstructure and mechanical properties of the dissimilar alloys of AZ91D and AA7075

Friction stir welding is an efficient joining process for light metal alloys, offering benefits such as high joint efficiency and reduced grain sizes. This work is to investigate the process parameters that can improve the welding quality and reduce the brittle intermetallic compounds, including Al3Mg2 (β) and Al12Mg17 (γ) in the welded region. It was perceived that the process parameters influenced the morphological characteristics and input heat, thereby affecting the materialization of intermetallic compounds. The primary diffraction peaks of both Al and Mg were present in all the joints. Two specific intermetallic phases, Al3Mg2 and Al12Mg17, were formed as a result of the diffusion of Al and Mg atoms during welding. These intermetallic compounds were found in all the joints. The Al12Mg17 phase, when mixed with the Mg phase, tended to migrate towards the weld surface where the AZ91D plate was positioned. This migration might lead to constitutional liquation, which refers to the melting of specific phases during solidification, resulting in the materialization of eutectic microstructures. The highest ultimate tensile strength (UTS) value of 116.64 MPa was achieved with a rotational tool speed of 800 r/min and a traverse speed of 20 mm/min. On the other hand, the lowest UTS value of 68.32 MPa was observed with a rotational tool speed of 400 r/min and a traverse speed (TS) of 20 mm/min. It was noted that lower UTS values were associated with the materialization of dense layers of intermetallic compounds (Al12Mg17 and Mg + Al12Mg17) in the stir zone when using lower rotational tool speed and TS. It suggests that improper processing parameters can lead to the materialization of intermetallic compound in the stir zone, which subsequently decreases the mechanical properties of the weldments.

Stochastic resonance in a model of a periodically driven DNA: Multiple transitions, scaling, and sequence dependence.

We numerically study stochastic resonance in the unzipping of a model double-stranded DNA by a periodic force. We observe multiple peaks in stochastic resonance in the output signal as the driving force frequency is varied for different force amplitudes, temperature, chain length, and chain heterogeneity. Multiple peaks point to the existence of multiple stable and metastable states, which correspond to dynamical states of partially zipped and unzipped conformations and transitions between them. We quantify such transitions by looking at the time evolution of the fraction of bound base pairs. We obtain phase diagrams in the force amplitude-temperature plane both in the resonance frequency of the primary peak and the output signal at the peak value. We further obtain an excellent scaling behavior of the output signal for changing lengths of the DNA. Resonance behavior is also affected by chain heterogeneity as it depends strongly on which base pair the periodic forcing is applied.

Piezoelectric Wafer Active Sensor Transducers for Acoustic Emission Applications.

Piezoelectric materials are defined by their ability to display a charge across their surface in response to mechanical strain, making them great for use in sensing applications. Such applications include pressure sensors, medical devices, energy harvesting and structural health monitoring (SHM). SHM describes the process of using a systematic approach to identify damage in engineering infrastructure. A method of SHM that uses piezoelectric wafers connected directly to the structure has become increasingly popular. An investigation of a novel pitch-catch method of determining instrumentation quality of piezoelectric wafer active sensors (PWASs) used in SHM was conducted as well as an investigation into the effects of defects in piezoelectric sensors and sensor bonding on the sensor response. This pitch-catch method was able to verify defect-less instrumentation quality of pristinely bonded PWASs. Additionally, the pitch-catch method was compared with the electromechanical impedance method in determining defects in piezoelectric sensor instrumentation. Using the pitch-catch method, it was found that defective instrumentation resulted in decreasing amplitude of received and transmitted signals as well as changes in the frequency spectrums of the signals, such as the elimination of high frequency peaks in those with defects in the bonding layer and an increased amplitude of around 600 kHz for a broken PWAS. The electromechanical impedance method concluded that bonding layer defects increase the primary frequency peak's amplitude and cause a downward frequency shift in both the primary and secondary frequency peaks in the impedance spectrum, while a broken sensor has the primary peak amplitude reduced while shifting upward and nearly eliminating the secondary peak.

Decoding the compositions of four bright r-process-enhanced stars

ABSTRACT There has been a concerted effort in recent years to identify the astrophysical sites of the r-process that can operate early in the galaxy. The discovery of many r-process-enhanced (RPE) stars (especially by the R-process Alliance collaboration) has significantly accelerated this effort. However, only limited data exist on the detailed elemental abundances covering the primary neutron-capture peaks. Subtle differences in the structure of the r-process pattern, such as the relative abundances of elements in the third peak, in particular, are expected to constrain the r-process sites further. Here, we present a detailed elemental-abundance analysis of four bright RPE stars selected from the HESP–GOMPA survey. Observations were carried out with the 10-m class telescope Gran Telescopio Canarias (GTC), Spain. The high spectral signal-to-noise ratios obtained allow us to derive abundances for 20 neutron-capture elements, including the third r-process peak element osmium (Os). We detect thorium (Th) in two stars, which we use to estimate their ages. We discuss the metallicity evolution of Mg, Sr, Ba, Eu, Os, and Th in r-II and r-I stars, based on a compilation of RPE stars from the literature. The strontium (Sr) abundance trend with respect to europium (Eu) suggests the need for an additional production site for Sr (similar to several earlier studies); this requirement could be milder for yttrium (Y) and zirconium (Zr). We also show that there could be some time delay between r-II and r-I star formation, based on the Mg/Th abundance ratios.

The role of the Kuroshio Current on the diurnal cycle of Meiyu-Baiu rainband in mid-June

This study investigated the mechanism of the strong diurnal cycle of precipitation over the Kuroshio Current (KC) in mid-June when the climatological location of the Meiyu-Baiu (MB) front is aligned with the KC. The diurnal cycle of precipitation exhibits double peaks, with the primary peak in the morning (03–12 LST) and the secondary peak in the afternoon (12–15 LST). It was revealed that the morning peak is induced by convective instability associated with the large temperature difference between the sea surface and the surface air (TDiff), whereas the cross-frontal circulation is responsible for the afternoon peak. In the morning, heating from the KC intensifies as the TDiff maximizes. Intensified convective instability due to the enhanced heating from the KC increases the mean amount of convective precipitation (CP) as well as the probability of stronger CP. The surface wind convergence and the confluence sustaining the convection intensify the frontogenesis, which leads to the maximization of the frontal intensity in the afternoon. The afternoon peak of precipitation is in accordance with the intensified MB front and the associated cross-frontal circulation. However, direct contribution of diabatic heating to the frontogenesis is relatively weak. This study provides a physical understanding of the intensified diurnal cycle of MB rainfall in terms of the interaction between oceanic and atmospheric fronts, the KC and MB, respectively.

Surface analysis insight note: X‐ray photoelectron spectroscopy analysis of battery electrodes—Challenges with nickel–manganese–cobalt and Li examples using an Al Kα x‐ray source

X‐ray photoelectron spectroscopy (XPS) has become a highly important tool for the analysis of battery materials and components. However, both anecdotal and detailed analysis of selected parts of the literature indicate that many reports of XPS on battery electrodes have significant analysis or data flaws. In this paper, we highlight several of the common challenges that analysts face when using XPS for battery materials, pointing to recent literature that addresses many of the critical issues associated with sample preparation as well as data collection and analysis. A common error for battery materials (and other materials) involves ignoring peak overlaps and interferences. Specifically, when a “minor” peak associated with a component in relatively high concentration overlaps or contributes to the primary peak (or one recommended for quantitative analysis) from a different element in the material. Overlap issues apply to many battery electrodes composed of many elements with complex photoelectron peak structures, as well as those involving peaks with seemingly simpler spectral envelopes such as Li and F. Examples of issues associated with battery systems are highlighted by a discussion of challenges associated with XPS analysis of Li and nickel–manganese–cobalt (NMC) electrodes in battery systems. Lithium analysis has challenges associated with the preparation and an often‐unrecognized peak overlap with F. In our laboratory and in the literature, NMC electrodes are often examined and new XPS users do not always recognize interference of the Auger signal from FKLL (in or on the electrode) with Ni 2p photoelectron spectrum when generated with Al Kα X‐rays. The use of simulated spectra involving both F and NiO demonstrates the extent of F Auger contributions to the Ni 2p signal strength as a function of the F/Ni atom ratio in the material and suggests spectra information that can be used to identify how significant effects will be on the resultant spectra. Our analysis demonstrates that in many cases overlap issues are significant for real electrode materials.

Morphological evolution of desiccation cracking in purple soil under the influence of aggregate size distribution

Desiccation cracking in purple soil subjected to rainfall-evaporation cycles is a common natural phenomenon, in the Three Gorges Reservoir area of China, that detrimentally affects the hydraulic and mechanical properties of soils. The significant spatial variability in the aggregate size distribution (ASD) of purple soil in this area leads to variations in crack morphology. In this study, we experimentally investigated the effects of ASD on morphological evolution of cracks and conducted a regression analysis based on the ASD indices of purple soil. The dynamic geometrical, topological, and statistical characteristics of the crack morphology were analysed using digital image processing and morphological algorithms. The results indicated that the process of crack evolution in purple soil mainly contained three stages, two intersection shapes, and three network forms. The crack morphology in soil with a larger initial mean aggregate size was more irregular and discontinuous. We proposed a cracking evolution function that depicts the crack geometry and topology considering the gravimetric water content as a variable, which proved to be a good fit for modeling the dynamic morphological characteristics of desiccation cracks. The distribution of crack length, crack area, and clod area were well described by the ExpDec function, whereas the crack width revealed a bimodal Gaussian distribution, with primary and secondary peaks of 1–1.5 and 2–3.5 mm, respectively. Moreover, Multiple linear regression models between the crack geometric parameters and ASD indices were established, which indicated that the ASD in the micro-aggregate state determines the final morphological characteristics of cracks, with the content of clay-sized aggregates having the most significant effect. The tensile stress of aggregates in the unsaturated state decreases with increasing radius, based on the microscopic mechanical analysis. These results could provides a theoretical basis for predicting the macroscopic cracking behavior of purple soil under various ASD conditions.

Metal-Free Counter Electrodes for DSSCs Based on Nitrogen-Doped Reduced Graphene Oxide Materials

The importance of counter electrodes in Dye Sensitized Solar Cells (DSSCs) cannot be neglected as they enable the transfer of electrons across the outer circuit, thereby facilitating the reduction reaction of the I3−/I− redox electrolyte. However, the dissolution and deposition of the usual platinum layer on the counter electrode has resulted in contamination concerns. To address this issue, metal-free counter electrodes made of reduced graphene oxide (rGO) aerogels were developed and their catalytic performance towards I3− reduction was evaluated. The reduced graphene materials were characterized, and the fitting analysis of XPS revealed the presence of various nitrogen species, with the primary peaks attributed to pyridinic and pyrrolic nitrogen. The hydrothermal treatment of graphene oxide (GO) resulted in a higher graphitic character and the intensification of the contacts between graphene nanosheets, which should entail higher electrical conductivity, both in-plane and between rGO sheets. Additionally, the presence of nitrogen-provided active sites promoted the catalytic reduction of the electrolyte. Encouragingly, good charge transfer rates were observed between the counter electrode and the electrolyte in the assembled DSSCs, resulting in good photocurrents and exceptional stability over the course of nearly 1200 h after cell assembly. The results obtained suggest that these GO-based systems are promising candidates for developing metal-free counter electrodes for DSSC, supporting the interest of further study.

Wave effects on the hydroelastic response of a surface-piercing hydrofoil. Part 2. Cavitating and ventilating flows

The objective of this paper is to understand the effects of waves and vaporous cavitation upon the hydrodynamic and hydroelastic responses of a flexible surface-piercing hydrofoil, adding to the subcavitating results presented in Part 1. In general, the presence of a sufficiently large vaporous cavitation bubble facilitated the formation of a ventilated cavity, substantially reducing the angle of attack or speed required to induce fully ventilated flow, relative to subcavitating conditions. A new co-analysis procedure was used to isolate synchronous hydrodynamic modes and structural operating deflection shapes. Significant dynamic load amplification occurred when the resonant frequencies of the first twisting and second bending modes coalesced in both fully wetted and partially cavitating flows. The presence of waves did not diminish the effect of frequency coalescence, but did encourage intermittent lock-in with both leading edge cavity shedding and trailing edge vortex shedding at certain speeds. Partial cavity shedding typically had a negligible impact on the power spectral densities of structural motions because of incoherent cavity shedding. However, lock-in between the cavity shedding frequency and modal coalescence frequency led to shifting of the primary frequency peak, as well as amplified harmonics and interactions between the cavity shedding frequency and vortex shedding frequency. The transition from partially cavitating to fully ventilated flow caused sudden and large drops in the mean hydrodynamic loads and deformations, as well as substantial reductions in the intensity of the fluctuations.

On definitions of signal duration, evaluated on close-range airgun signals

In impact assessments for underwater noise, the duration of a transient signal is often expressed by the 90%-energy signal duration τ90 %. Consequently, the rms sound pressure is computed over this duration. Using a large set of measurements on marine-seismic airgun signals, it is shown that τ90 % is often very close to the interval between the primary and secondary pulse (the bubble period) or a small integer multiple thereof. In this situation τ90 % is a measure of the duration of the relative silence between primary and secondary peaks, which is not the intended measure. Rarely, τ90 % quantifies the duration of the main peak, leading to a much lower value of τ90 %. Since the number of peaks included in τ90 % is sensitive to the nature of the signal, relatively small differences in the signal lead to large differences in τ90 %, causing instability in any metric based on τ90 %, e.g., the rms sound pressure. Alternative metrics are proposed that do not exhibit these weaknesses. The consequences for the interpretation of sound pressure level of a transient signal, and the benefits of using a more stable metric than τ90 % are demonstrated.

86‐3: Why perovskite quantum dots will be key for LCD‐, OLED‐ and microLED displays

Green perovskite quantum dots are well known to be the best green color conversion material with respect to color purity (FWHM) and conversion efficiency (quantum yield). These two properties are essential for picture quality (color gamut and peak brightness) but also for minimizing the display power consumption which is getting more and more important for ecological reasons but also for regulatory reasons (especially in the EU). Furthermore there is also a development trend for displays equipped with a so‐called low‐ blue‐light function where the blue primary peak emission wavelength is increased in order to minimized the short‐wave blue light intensity which has a negative influence on the human circadian rhythm. However, such blue wavelength change intrinsically reduces the color gamut of the display and increases the power consumption at the same time. These two adverse effects can be mitigated and even improved by replacing the commonly used green B‐Sialon phosphor by green perovskite quantum dots.Over the last 7 years we have intensively worked on our green perovskite quantum dots and achieved a near‐unity quantum efficiency, an FWHM of 22nm and last but not least a sufficient stability against humidity, temperature and blue flux turning our perovsite QDs commercially viable now. In this presentation we give an overview about our technical perovskite solutions for miniLED backlight films (LCD displays) and also QD pixelated color converters for microLED displays and QD‐OLED displays.

Geochemical approach for decoding the paleoenvironmental and depositional evolution of a coastal lacustrine Konservat-Lagerstätte (Early Cretaceous, south-Central Pyrenees)

The lithographic limestone of La Pedrera de Meià (LPM) in south-Central Pyrenees (NE Spain) is considered one of the best preserved lacustrine-coastal successions of the Early Cretaceous in Europe, hosting a taxonomically diverse record of Barremian biota. While this Konservat-Lagerstätte has been extensively surveyed for paleontological purposes, little is known about the paleoenvironmental and depositional conditions prevailing during the formation of this fossil lagerstätte deposit. LPM limestone is made up of a homogeneous, dark gray to pale brown, faintly laminated 50 m-thick succession of micrite-rich intervals. To shed light on the environmental conditions of deposition, 303 rock samples were studied using a multiproxy approach based on different techniques including petrography, SEM-EDX, XRD, ICP-MS, XRF, Rare Earth Element distributions and C and O stable isotope geochemistry. The combination of sedimentological and geochemical data reveals a vertical shift of facies from littoral to profundal environments and then returning to littoral conditions. Profundal facies are made up of filament-rich mudstones originated from in situ precipitation of micrite either through biotically mediated or physico-chemical processes in undisturbed low energy settings, under anoxic conditions, characterized by the presence of transported terrestrial and lacustrine organisms that are exquisitely well-preserved. Littoral areas are characterized by the presence of in situ charophytes, smooth ostracods, and miliolid foraminifera that accumulated in mud-rich facies indicating low/moderate-energy, shallow-water, and relatively oxygenated conditions. Stable isotopic data and elemental geochemistry suggest a hydrologically closed to semi-closed lacustrine system with a restricted water circulation encouraging dysoxic to anoxic conditions in profundal sediments. Paleoproductivity proxies suggest a good correlation between catchment-derived siliciclastic discharge to the lake and primary productivity peaks. Furthermore, a decline in terrigenous input coupled with a reduction of meteoric water entrance to the lake is interpreted based on elemental proxies derived from paleosalinity and paleoredox analysis. Collectively, the strontium/barium (Sr/Ba) ratios, the sparse presence of miliolid foraminifera, and the isotopic signatures indicate an increase in salinity toward the younger intervals of the lake infilling, although their ultimate causes are unclear (i.e., increased evaporation, or a combination of reduced meteoric input and sporadic marine inputs might explain our data). The present work shows the importance of performing detailed multiproxy geochemical-sedimentological studies to better constrain the unique paleoenvironmental and paleohydrological conditions associated with the exceptional preservation of fossil biotas in Konservat-Lagerstätte deposits in analogous depositional settings.

Potential and electric field analysis of field plated AlGaN/GaN HEMT for high voltage applications using 2-D analytical approach

A physics-based 2-D analytical model is developed for field plated AlGaN/GaN high electron mobility transistor (HEMT) and the effect of field plate on potential and electric field is analyzed. The complete generalized theory developed includes the dependence of electric field and electric potential distribution on (i) different dielectric materials and (ii) dielectric thickness below the field plate. An extensive study of the effect of various non-field plate parameters such as doping concentration in the AlGaN layer, drain source voltage, and gate source voltage has also been carried out. It is observed that with the introduction of field plate, primary peak of electric field gets reduced and redistribution of electric field occurs in a better way with the introduction of much smaller secondary electric field peak. This leads to improved breakdown voltage thus making the device suitable for high voltage applications. The analytical results are also compared with the simulated results extracted with ATLAS 2D device simulation. The good agreement validates the analytical approach.

Two-dimensional ZnO/ZrXY (X, Y = Br, Cl and F) van der Waals heterostructures as promising photocatalysts for high efficiency water splitting

In recent years, hydrogen (H2) energy has been attracting extensive research attention as a clean resource as the energy shortage has become increasingly prominent. Two-dimensional (2D) materials exhibit superior physical and chemical properties compared to their conventional counterparts, hence demonstrating considerable advantages in the water-splitting photocatalyst application. Based on first principle calculations, in this work, monolayered ZnO and ZrXY (X, Y = Br, Cl and F) are combined to form vdW heterostructures and investigate their structural, optical and electronic properties for evaluating their ability to split water photocatalytically. Based on our calculations by two different models (model I and II), ZnO/ZrXY vdW heterostructures exhibit indirect band gaps with a type II band alignment, which benefits the effective spatial separation of photogenerated charge carriers. Bader charge, Charge density difference, and Planner-averaged electrostatic potential analysis suggest that photogenerated charges flow from ZrXY to the ZnO layer are effected by the dipole interface, which prevents the recombination of photogenerated charge carrier and promotes their separation and transfer. Moreover, calculations for optical properties in relation to the dielectric constant's imaginary part indicate that all primary excitation peaks are located in the visible light region, and a red-shift is also observed in ZnO/ZrXY vdW heterostructures. In addition, the band edges of ZnO/ZrXY vdW heterostructures span water redox potentials, which satisfy the requirement of overall photocatalytic water splitting.

Thermoluminescence in GdAl3(BO3)4 phosphors: Unusual heating rate dependencies, dose responses and kinetic parameters

The current study focuses on the production of GdAl3(BO3)4 (GAB) phosphors using gel combustion. X-ray diffraction (XRD) and thermoluminescent (TL) methods were used to investigate the structural and thermoluminescence (TL) features of the samples. XRD results revealed that GAB phosphors were crystallized in a rhombohedral crystal system. TL experimental data exhibited an unusual heating rate behaviour, which was explained by the semi-localized transition model, and this provides valuable insight into the properties of the GAB sample. Beta-irradiated GAB hosts exhibit two primary peaks at 106 °C and 277 °C on their TL glow curves. We have employed a variety of heating rates (VHRs), TM-Tstop method, and computerized glow curve deconvolution (CGCD) techniques. By using a combination of these techniques, we can identify the kinetic parameters of the GAB samples more accurately, including peak numbers, activation energy, and frequency factors. Both Tm-Tstop and CGCD techniques produce similar results in terms of trap numbers and trap depths. In the trap centers, electrons were trapped at 1.05 eV, 0.84 eV, 1.12 eV, 1.20 eV, 1.42 eV, 1.63 eV and 1.42 eV. There was a linear behaviour of GAB samples over a dose range of 0.1 Gy–10 Gy. GAB phosphors did not show any significant changes in TL response with repeated irradiation cycles, suggesting that it is a reliable radiation dosimeter. GAB is therefore a potential candidate for radiotherapy dose measurement based on these findings.