Normal Hysteresis Research Articles

Tunable magnetic switching behavior in La0.7Sr0.3MnO3/PbTiO3 multilayers

Tuning magnetic switching behavior and related magnetic configuration of transition metal oxides (TMOs) is critical for realizing multifunctional materials and devices. In this study, we manipulated the magnetic switching behavior through interface engineering by introducing ferroelectric PbTiO3 (PTO) to form La0.7Sr0.3MnO3 (LSMO)/PTO multilayers. Both the normal hysteresis loop (NHL) and the inverted hysteresis loop (IHL) could be tuned by changing the PTO thickness. All multilayers displayed a transition from NHL to IHL with increasing temperature, and the transition temperature increased with the insertion of the PTO layer or increasing thickness of the PTO. In addition, it was found that the increase in the Curie temperature (Tc) and saturation magnetization (Ms), as well as the decrease in the coercive field (Hc) and exchange bias field (Heb) with a reduction in the thickness of the PTO, is possibly related to the interface phase. This study illustrates the influence of the ferroelectric PTO thickness on the magnetic switching behavior and related magnetic configuration in LSMO, which is possibly driven by the unscreened depolarization charge and oxygen octahedral tilting. This finding may benefit the application of TMOs in multifunctional memory devices.

Sintering-induced multiferroicity in 0.93(Na0.5Bi0.5)TiO3–0.07BaTiO3 ceramics

Two 0.93(Na[Formula: see text]Bi[Formula: see text]TiO3–0.07BaTiO3 ceramics were sintered for 2[Formula: see text]h and 3 h, respectively, by a conventional solid reaction method. The ceramic sintered for 2[Formula: see text]h showed a normal ferroelectric hysteresis loop and paramagnetic behavior, while the ceramic sintered for 3[Formula: see text]h showed a pinched ferroelectric hysteresis loop, weak ferromagnetism, and enhanced magnetoelectric coupling. The origins of the sintering time-related multiferroic properties are discussed in detail. The work offers a new way to induce multiferroicity in ceramics by tuning sintering time.

An adhesion model for contact electrification

Contact electrification (CE) is a universal phenomenon that occurs at the contact interface where tribo-charges transfer from one surface to another. These CE-driven charges accumulate at the interface and can significantly affect the soft adhesive contact. So far, only a few analytical and numerical models have been proposed to partially solve the CE-induced electroadhesive contact problem. In this study, we have developed a full self-consistent contact model to study the CE-induced electroadhesion between a dielectric elastic axisymmetric parabolic surface and a dielectric rigid flat. Both surfaces are initially neutralized and undergo only one loading–unloading cycle. The surface interaction is determined by both the Lennard-Jones and the electrostatic interaction laws. The electrostatic problem is numerically solved to accurately calculate the electrostatic traction due to both the tribo-charges and bound charges. The normal traction, interfacial gap, and hysteresis loop of the force curve are thoroughly investigated. The effect of non-uniform tribo-charge density on the force curve and electrostatic traction is explored. The numerical model developed in the present work can serve as the foundation for more complex electroadhesive contact models. It also sheds light on the interfacial design of CE-related devices, e.g., contact-separation triboelectric nanogenerator.

Evaluation of Structural, Magnetic, and Electromagnetic Properties of Co2+-Substituted NiCuZn Ferrites.

We report citrate gel-assisted autocombusted spinel-type Co2+-substituted NiCuZn ferrites and their electromagnetic properties. Several complementary techniques were used to investigate the influence of Co on structural and electromagnetic properties of Ni0.25-xCoxCu0.20Zn0.55Fe2O4 with x = 0.00-0.25 (step of 0.05). XRD analysis confirmed the highly crystalline single-phase cubic spinel structure with a prominent peak of the (311) plane. FE-SEM analysis showed the loss of porous gel structure (colloidal backbone) due to addition of cobalt into the present ferrite system. The EDAX analysis confirmed the presence of Ni, Cu, Zn, Co, and O in accordance with the relative stoichiometry of Co-substituted NiCuZn ferrite. The electrical resistivity of ferrites is observed to decrease when Co2+ ions are substituted, regardless of AC and DC. The dielectric properties (ε' and ε″) of ferrites exhibited a consistent decrease as the frequency increased, and this trend persisted even at higher frequencies. VSM analysis showed the normal magnetic hysteresis of the developed ferrite system. At x = 0.05, the saturation magnetization of the ferrite was obtained to be the highest among the other substitution levels of Co. The Curie temperature fell down when there was a higher concentration of cobalt in the ferrite system (x = 0.20). After reaching a specific temperature, the μi values decreased abruptly, with an increase in the temperature. The steady state may be deduced from the fact that the constant real component of the initial permeability, μ', remained unchanged. However, with decreasing frequency, the values of μ″ decreased dramatically. The present NiCuZn ferrite series displays the enhanced dielectric properties suggesting the capability of potential candidates for microwave absorption applications with enhanced electromagnetic properties.

Effect of electric field frequency on double hysteresis loops and energy storage characteristics of Sm/Mn co-doped PMN-PT ferroelectric ceramics

The generation and control of double hysteresis loops in ferroelectrics are of great significance for understanding the polarization reversal and application of energy storage. For Sm/Mn ions co-doped 0.70PMN-0.30PT ceramics, results indicate that when Sm-doping content is 2.5 mol%, the Mn doping content is higher than 2.5 mol% and the frequency of the electric field is higher than 5 Hz, double hysteresis loops can be obtained. Low-frequency measurement can transform the double hysteresis loops into normal hysteresis loops. This phenomenon is analyzed by the difference in polarization reversal kinetics between spontaneous polarization and defect polarization.

Inverted Hysteresis in n–i–p and p–i–n Perovskite Solar Cells

A combination of experimental studies and drift‐diffusion modeling has been used to investigate the appearance of inverted hysteresis, where the area under the J–V curve for the reverse scan is lower than in the forward scan, in perovskite solar cells. It is found that solar cells in the p–i–n configuration show inverted hysteresis at a sufficiently high scan rate, whereas n–i–p solar cells tend to have normal hysteresis. By examining the influence of the composition of charge transport layers, the perovskite film crystallinity and the preconditioning treatment, the possible causes of the presence of normal and inverted hysteresis are identified. Simulated current–voltage measurements from a coupled electron–hole–ion drift‐diffusion model that replicate the experimental hysteresis trends are presented. It is shown that during current–voltage scans, the accumulation and depletion of ionic charge at the interfaces modifies carrier transport within the perovskite layer and alters the injection and recombination of carriers at the interfaces. Additionally, it is shown that the scan rate dependence of the degree of hysteresis has a universal shape, where the crossover scan rate between normal and inverted hysteresis depends on the ion diffusion coefficient and the nature of the transport layers.

Effects of pH and vanadium concentration during the impregnation of Na-SiO2 supported catalysts for the oxidation of propane

The linear and non-linear effects of the impregnation pH and of the concentration of vanadium in solution over the properties of Na-SiO2 supported catalysts used for the oxidation of propane under light-off/light-out tests at oxidizing conditions were studied. The listed factors had no net effects over the loading of vanadium, the surface area, and the porous structure of the catalysts. Depending on the pH, sodium vanadates of different particle sizes were formed; namely, NaVO3 microcrystals and particles made of α-NaVO3 and β-NaVO3 phases were formed at acidic pH, whereas sodium metavanadate nanoparticles were formed at pH=9.0. For the catalysts synthesized at pH=3.8, i.e., near the point of zero charge of the support, and at pH=9.0, the α-NaVO3 phase prevailed over the β-NaVO3 phase after dehydration and catalytic testing. The catalyst synthesized at pH=9.0 and at the highest concentration of vanadium in the impregnating solution showed normal hysteresis behavior while being the best in terms of the selectivity to propene and the conversions of propane and oxygen which were at the same level as the ones found for a VOx/SiO2 benchmark. The correlation of the catalytic trends with the physicochemical properties of the catalysts allowed concluding that increasing the impregnation pH favors the formation of less reducible and more acidic V4+ species that favor the reactivity and the selectivity to propene over the Na-SiO2 supported sodium vanadate catalysts synthesized herein. the most selective to propane oxidative dehydrogenation at a propane conversion comparable. Kinetic and thermodynamic arguments were discussed to elucidate the origin the catalytic trends.

Spin Induced Quantum Tunneling of the Magnetization

Quantum tunneling of the magnetization (QTM) of the spin-1/2 Vanadium-15 (V[Formula: see text] single molecular magnets (SMMs) is investigated by means of the effective field theory developed by Kaneyoshi. We deal with the two hexagon layers (shell, V[Formula: see text] and one triangular interlayer (core, V[Formula: see text] with the spin-1/2 Ising particles. We find that the V[Formula: see text] has a normal ferromagnetic hysteresis behavior for its all spins are up (parallel). However, V[Formula: see text] has a staircase-like hysteresis behavior that is the signature of the QTM for the spin-down orientation (antiparallel) of the core. QTM appears with the splitting of the magnetizations versus temperature ([Formula: see text]–[Formula: see text] and external field ([Formula: see text]–[Formula: see text] curves. Namely, QTM occurs from [Formula: see text] to [Formula: see text] in the core, from +[Formula: see text] to [Formula: see text] [Formula: see text] in the shell (only [Formula: see text]–[Formula: see text] curves at [Formula: see text] 0.1) and from [Formula: see text] to [Formula: see text] [Formula: see text] in the total V[Formula: see text]. By considering these different splitting behaviors of the magnetizations of the shell, core and total [Formula: see text] at [Formula: see text] and [Formula: see text], we suggest three different kinds of QTM: 1-ferromagnetic QTM (FMQTM) at [Formula: see text] for the shell, 2-antiferromagnetic QTM (AFMQTM) at [Formula: see text] for the core and 3-paramagnetic QTM (PMQTM) at [Formula: see text] for the shell, core and total V[Formula: see text] SMM. Moreover, it is found that there is a relationship between the QTM and type II and surface superconductivity. The EFT results of QTM in V[Formula: see text] are in good agreement with the other theoretical and experimental results of the V[Formula: see text] and other SMMs.

CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

Biomineralization and Magnetism of Uncultured Magnetotactic Coccus Strain THC‐1 With Non‐chained Magnetosomal Magnetite Nanoparticles

AbstractMagnetotactic bacteria (MTB) have long fascinated geologists and biologists because they biomineralize intracellular single domain (SD) magnetite crystals within magnetosomes that are generally organized into single or multiple chains. MTB remains in the geological record (magnetofossils) are ideal magnetic carriers and are used to reconstruct paleomagnetic and paleoenvironmental information. Here we studied the biomineralization and magnetic properties of magnetosomal magnetite produced by uncultured magnetotactic coccus strain THC‐1, isolated from the Tanghe River, China, by combining transmission electron microscope (TEM) and rock magnetic approaches. Our results reveal that THC‐1 produces hexagonal prismatic magnetite single crystals that are elongated along the [111] crystallographic direction. Most of the magnetite crystals within THC‐1 are dispersed without obvious chain assembly. A whole‐cell THC‐1 sample yields a normal SD hysteresis loop and a Verwey transition temperature of ~112 K. In contrast to MTB cells with magnetosome chain(s), THC‐1 cells have a teardrop first‐order reversal curve distribution that is indicative of moderate interparticle interactions. Due to the absence of a magnetosome chain, THC‐1 has relatively high values of the difference between the saturation isothermal remanent magnetization (SIRM) below and above the Verwey transition temperature for field‐cooled and zero field‐cooled SIRM curves (δFC, δZFC) and a low δFC/δZFC value. Together with previous studies, our results demonstrate that some MTB species/strains can form magnetosomal magnetite without linear chain configurations. Magnetite produced by MTB has diverse magnetic properties, which are distinctive but not necessarily unique compared to other magnetite types. Therefore, combining bulk magnetic measurements and TEM observations remains necessary for identifying magnetofossils in the geological record.

Nylon 10-12-based ferroelectric capacitor for energy storage

The energy storage properties of ferroelectric capacitors of nylon 10-12 were investigated. The energy density and the energy efficiency were determined at a high temperature of 90 °C. The normal hysteresis loop of displacement–electric field at room temperature decreased in width at 90 °C. An energy density (U) of 3.92 J cm−3 at 327 MV m−1 was measured for the melt-quenched sample and U of 3.86 J cm−3 at 383 MV m−1 for the annealed-quenched sample. No decrease in the energy efficiency was measured at increased electric fields. An energy efficiency of over 90% was measured for both samples.

An Open Loop Digitally Controlled Hybrid Supply Modulator Achieving High Efficiency for Envelope Tracking With Baseband up to 200-MHz

Envelope tracking (ET) is an effective way to improve the efficiency of power amplifier (PA) for 5G communication systems. To understand the restriction of the hybrid supply modulator (HSM) for ultra-wide band ET applications, an extended power loss model and a Short Time Fourier Transform (STFT) methodology are put forward to be the fundamental guide of the control methodology. An average voltage alignment (AVA) algorithm is proposed, which aligns the current waveforms by using pre-cached envelope signals to reduce the power loss due to the mismatch. Furthermore, a digital low pass filter (LPF) is integrated in the AVA controller, aiming at eliminating the necessity of very high-speed switches in HSM, which reduces the difficulty of hardware facility. The prototype chip is fabricated with a standard 0.18 μm CMOS technology and fulfilled with the discrete components on the PCB to verify the methodology and the system. Measurement results show that the proposed method extends the tracking bandwidth up to 200-MHz, and achieves 20% efficiency increment with the maximum 20 MHz switching frequency decrement comparing to the normal hysteresis comparison logic. A GaAs PA is introduced to measure the system linearity, and the ACPR of ET PA reaches -32 dBc. The proposed strategy successfully push the HSM ET application to hundreds of MHz compared with the previous level of 10-MHz.

Characteristics of inductively coupled plasma (ICP) and helicon plasma in a single-loop antenna

Large area uniform plasma sources, such as high-density magnetized inductively coupled plasma (ICP) and helicon plasma, have broad applications in industry. A comprehensive comparison of ICP and helicon plasma, excited by a single-loop antenna, is presented in this paper from the perspectives of mode transition, hysteresis behavior, and density distribution. The E-H mode transition in ICP and the E-H-W mode transition in helicon plasma are clearly observed in the experiments. Besides, the considerable variation of hysteresis behavior from inverse hysteresis to normal hysteresis by the influence of the magnetic field is explored. The bi-Maxwellian and Maxwellian electron energy distribution functions in each discharge are used to explain this phenomenon, which is essentially related to the transition from a nonlocal kinetic property to a local kinetic property of electrons. In addition, we notice that the plasma density, in the radial direction, is peaked in the center of the tube in ICP, but a complicated distribution is formed in helicon plasma. In the axial direction, the maximum plasma density is still in the center of the antenna in ICP, whereas the highest plasma density is located downstream, far away from the antenna, in helicon plasma. It is believed that the reflected electrons in the sheath and pre-sheath by the upper metallic endplate and downstream propagated helicon wave will be responsible for this plasma density profile in helicon plasma. Due to the constrained electron motion in the magnetic field, an extremely uniform density distribution will be obtained with an appropriate axial magnetic field in the wave discharge mode.

Optical and electrical properties of ferroelectric Bi0.5Na0.5TiO3-NiTiO3 semiconductor ceramics

(1-x)Bi0.5Na0.5TiO3-xNiTiO3 semiconducting ferroelectric ceramics (named (1-x)BNT-xNTO) were successfully prepared by using a solid state reaction method. All samples shows normal polarization-electric field hysteresis loops, and a maximum polarization Pmax is obtained in the x = 0.06 composition. The diffuse factor γ decreases slightly from 1.732 to 1.571 with the addition of NiTiO3. In addition, Ni doping can substantially reduce the band gap of Bi0.5Na0.5TiO3 materials to ~2 eV. In a 0.94BNT–0.06NTO compound, the XPS spectra shows that the chemical formula is accurately [Bi0+, Bi3+]0.5Na0.5[Ti3+, Ti4+]O2.25-0.06Ni[Ti3+, Ti4+]O2.67. Moreover, the short-circuit current (Jsc) in the composition is 1.36 nA/cm2, and the open-circuit voltaic (Voc) is 0.35 V for photovoltaic effects. The novel BNT system, which illustrates three narrow band gaps and relatively high polarization values, has broad application prospects for ferroelectric photovoltaic devices.

The inverted hysteresis loops and exchange bias effects in amorphous/nanocrystalline Fe72Cu1V4Si15B8 ribbons at room temperature

?he influence of thermally induced microstructural transformations on magnetic properties of Fe72Cu1V4Si15B8 ribbon with combined amorphous/nanocrystalline structure is presented. The experiments showed that thermally induced structural changes are in correlation with the appearance of magnetic hysteresis, i.e. with inverted hysteresis loops (IHL) and exchange bias (EB) effects. It was found that the ratio of surface to volume of a ribbon sample have an influence on hysteresis loop appearance. The inverted hysteresis loops were observed for the 1.5 mm wide and 55 ?m thick alloy samples shorter than 10 mm, but for the samples longer than 10 mm hysteresis loops were normal. With an increase of annealing temperature, a shift of the hysteresis loops measured at room temperature was noticed. The highest positive exchange bias field Heb was observed for the sample annealed at 723 K, together with the lowest magnetic field at which the changes from inverted to normal hysteresis loop occurred. Annealing at the temperature of 823 K resulted in negative Heb.

Excellent Fireproof Characteristics and High Thermal Stability of Rice Husk-Filled Polyurethane with Halogen-Free Flame Retardant.

The thermal stabilities, flame retardancies, and physico-mechanical properties of rice husk-reinforced polyurethane (PU–RH) foams with and without flame retardants (FRs) were evaluated. Their flammability performances were studied by UL94, LOI, and cone calorimetry tests. The obtained results combined with FTIR, TGA, SEM, and XPS characterizations were used to evaluate the fire behaviors of the PU–RH samples. The PU–RH samples with a quite low loading (7 wt%) of aluminum diethylphosphinate (OP) and 32 wt% loading of aluminum hydroxide (ATH) had high thermal stabilities, excellent flame retardancies, UL94 V-0 ratings, and LOIs of 22%–23%. PU–RH did not pass the UL94 HB standard test and completely burned to the holder clamp with a low LOI (19%). The cone calorimetry results indicated that the fireproof characteristics of the PU foam composites were considerably improved by the addition of the FRs. The proposed flame retardancy mechanism and cone calorimetry results are consistent. The comprehensive FTIR spectroscopy, TG, SEM, and XPS analyses revealed that the addition of ATH generated white solid particles, which dispersed and covered the residue surface. The pyrolysis products of OP would self-condense or react with other volatiles generated by the decomposition of PU–RH to form stable, continuous, and thick phosphorus/aluminum-rich residual chars inhibiting the transfer of heat and oxygen. The PU–RH samples with and without the FRs exhibited the normal isothermal sorption hysteresis effect at relative humidities higher than 20%. At lower values, during the desorption, this effect was not observed, probably because of the biodegradation of organic components in the RH. The findings of this study not only contribute to the improvement in combustibility of PU–RH composites and reduce the smoke or toxic fume generation, but also solve the problem of RHs, which are abundant waste resources of agriculture materials leading to the waste disposal management problems.

Model Predictive Thrust Force Control of a Linear Flux-Switching Permanent Magnet Machine With Voltage Vectors Selection and Synthesis

To reduce the thrust force ripple of a complementary and modular linear flux-switching permanent magnet machine, a model predictive thrust force control (MPTFC) is developed and implemented in this paper based on the active voltage vectors selection (AVVS) and two-voltage-vector synthesis (TVVS). First, the active voltage vectors are screened and assigned to the specific sector, instead of traversing all the possible vectors, and consequently, significantly decrease prediction workload. Second, for the elimination of the weighting factor in the conventional MPTFC, the control object is transformed from the thrust force and stator flux to the stator flux only by using the load angle. Third, to achieve the steady-state performance improvement, the TVVS approach is applied in each control period, where the optimal TVVS and its dwell time are simultaneously obtained by only one cost function. Both simulated and experimental results verify that the steady-state performance improvement can be realized by the developed MPTFC through comparing with normal hysteresis current control and conventional MPTFC strategies.

Ionic dipolar switching hinders charge collection in perovskite solar cells with normal and inverted hysteresis

Drift-diffusion modeling of the ionic dipole switching from the measurement of fast scanned and long pre-biased electrical response is proposed as a novel protocol for evaluation of limit hysteretic effects in perovskite solar cells. Up to eight systems were measured including CH3NH3PbI3, Cs0.1FA0.74MA0.13PbI2.48Br0.39 and FA0.83MA0.17Pb1.1Br0.22I2.98 3D perovskite absorbers, as well as 2D capping layers towards the selective contacts. We show systematic hysteretic patterns, even among typical hysteresis-free devices, including normal and inverted hysteresis as general dissimilar trend between CH3NH3PbI3 and mixed perovskite cells, respectively. Particularly, strong changes in the short-circuit current density (Jsc) were identified, in addition to different trends affecting the fill factor (FF) and the open-circuit voltage (Voc). The changes in Jsc were analyzed with state-of-the-art numerical drift-diffusion simulations concluding in an important reduction in the charge collection due to ionic distribution switching depending on the pre-biasing protocol and the type of absorbing perovskite. It is shown that mixed perovskites inhibit ionic dipolar switching. In addition, our calculi signal on the required conditions for the occurrence of inverted hysteresis and changes in the Voc. Regarding the FF and Voc patterns a new empirical approach is introduced and corresponding interpretations are proposed.

Influence of non-stoichiometry on the ferroelectric aging properties of Mn-doped BaTiO3 ceramics

In the present work, the effect of the non-stoichiometry on the dielectric and ferroelectric properties especially the aging phenomenon of Bam(Ti0.995Mn0.005)O3 ceramics is studied. With the A/B site stoichiometry ratio m increased from 0.990 to 1.010, the Curie temperature is decreased from 128 to 118 °C monotonically. The non-stoichiometry shows the dramatic effect on the aging phenomenon of the Mn-doped BaTiO3 ceramics. As the aged sample with m 1 samples, it shows the normal hysteresis loop and electro-strain curve as the un-aged samples. The valence state analysis of Mn ions shows that for the m 1 samples Mn2+ and Mn4+ ions co-exist. Moreover, with m decreasing, the amount of Mn2+ ions increases. It is proposed that the non-stoichiometry affects the valence state of Mn ions, which causes the number of oxygen vacancies to change, ultimately affecting the aging effect of the Mn-doped BaTiO3 ceramics.

Tailoring Crystal Structure of FA0.83Cs0.17PbI3 Perovskite Through Guanidinium Doping for Enhanced Performance and Tunable Hysteresis of Planar Perovskite Solar Cells

AbstractCurrent–voltage hysteresis of perovskite solar cells (PSCs) has raised the concern of accurate performance measurement in practice. Although various theories have been proposed to elucidate this phenomenon, the origin of hysteresis is still an open question. Herein, the use of guanidinium cation (Gu+)‐dopant is demonstrated to tailor the crystal structure of mixed‐cation formamidinium‐cesium lead triiodide (FA0.83Cs0.17PbI3) perovskite, resulting in an improved energy conversion efficiency and tunable current–voltage hysteresis characteristic in planar solar cells. Particularly, when the concentration of Gu‐dopant for the perovskite film increases, the normal hysteresis initially observed in the pristine PSC is first suppressed with 2%‐Gu‐dopant, then changed to inverted hysteresis with a higher Gu‐dopant. The hysteresis tunability behavior is attributed to the interplay of charge/ion accumulation and recombination at interfaces in the PSC. Furthermore, compared to the cell without Gu+‐dopant, the optimal content of 2% Gu+‐dopant also increases the device efficiency by 14%, reaching over 17% under one sun illumination.