Curie Temperature Tc Research Articles

Mechanism for Improved Curie Temperature and Magnetic Entropy Change in Sm-Doped Fe88Zr8B4 Amorphous Alloys

In the present work, Fe88Zr8−xSmxB4 (x = 2, 4) amorphous alloys (AAs) were successfully synthesized into the shape of 40-micrometer-thick ribbons and their magnetic properties were measured. The Fe88Zr8−xSmxB4 (x = 2, 4) AAs exhibited a rather high maximum magnetic entropy change (−ΔSmpeak): ~3.53 J/(K × kg) near 317 K for x = 2 and ~3.79 J/(K × kg) near 348 K for x = 4 under 5 T. The effects of a Sm substitution for Zr on the Curie temperature (Tc) and −ΔSmpeak were studied and compared to those of Nd and Pr substitutions, for the purpose of revealing the mechanism involved in more detail.

Electrocaloric effects of Ba1-xCaxTi0.9Zr0.1O3 through both direct and indirect measurements

The electrocaloric effect (ECE) of lead-free BaTiO3 based materials has drawn considerable attention for application in next-generation refrigeration, which has been widely investigated through indirect measurement methods; however, this method is sometimes ineffective because negative and positive ECEs coexist in one material. The paradox of ECE phenomena should be clarified; therefore, in this work, the ECEs of modified BaTiO3 were investigated through both direct and indirect measurement methods. The investigated BaTiO3 compositions herein are (Ba1-xCax)(Ti0.9Zr0.1)O3 (0.05 ≤ x ≤ 0.20), abbreviated as BZT-100xCa. Through indirect measurements, the ECE reached its maximum value around the Curie temperature TC, and the coexistence of negative and positive ECEs was observed in BZT-5Ca, BZT-10Ca, and BZT-15Ca. A laboratory-built ECE direct measurement system utilizing a platinum resistor was used to measure the ECE of BZT-100xCa. Through direct measurement, the maximum ECE appears several Kelvins above the TC, which coincides with the ECE through the indirect measurement, but no negative ECE is observed. Meanwhile, the ECE measured through direct measurement was smaller than that measured through indirect measurement. Through direct measurements, BZT-15Ca exhibited the largest ΔT of 0.291 K and ΔT/ΔE of 0.182 × 10−6 K m/V under 16 kV/cm, indicating that BZT-15Ca has a better ECE performance than previously reported modified BaTiO3 ceramics. By comparison, it can be concluded that the ECE through the indirect measurement method can reflect the approximate variation tendency of the actual ECE, and the negative ECE measured indirectly should be certified through direct measurement method, which doesn't influence the reliability of ECE through the indirect measurement.

Giant irreversibility of the inverse magnetocaloric effect in the Ni47Mn40Sn12.5Cu0.5 Heusler alloy

Direct studies of the adiabatic temperature change (ΔTad) in the Ni47Mn40Sn12.5Cu0.5 Heusler alloy in steady magnetic fields up to 8 T by the extraction method and in pulsed magnetic fields up to 50 T were carried out in this paper. The alloy Ni47Mn40Sn12.5Cu0.5 demonstrates a magnetostructural phase transition (MSPT) of the first order in the 254–283 K temperature range as well as a second order phase transition near the Curie temperature TC = 313 K. An inverse magnetocaloric effect (MCE) was found in the region of the MSPT, and it reaches the maximum value ΔTad = −12 K in 20 T at the initial temperature T0 = 275 K. The irreversible part of the MCE reached ΔTir = −10 K when the field is completely removed. We consider the dynamics of the MCE in the vicinity of the MSPT and discuss the mechanisms that cause the giant irreversibility of the MCE as well as the possibilities of its application in hybrid cooling systems.

Magnetic properties of perovskites Pr0.9Sr0.1 Mn[formula omitted]Mn[formula omitted]O3: Monte Carlo simulations and experiments

This work presents the remarkable experimental magnetocaloric properties of the perovskites Pr0.9Sr0.1Mn0.93+ Mn0.14+O3, including the magnetic entropy change |ΔSm| and the Relative Cooling Power (RCP). To understand these striking properties, we elaborate in this paper a model and use Monte Carlo (MC) simulations to study it for comparison. For the model, we take into account nearest-neighbor (NN) interactions between magnetic ions Mn3+ (S=2) and Mn4+ (S=3/2) and the interactions between these Mn ions with the magnetic Pr ions. The crystal is a body-centered tetragonal lattice where the corner sites are occupied by Mn ions and the center sites by Pr and Sr ions in their respective concentrations given in the compound formula. We use an Ising-like spin model describing a strong anisotropy on the z axis. We show that pairwise interactions between ions cannot reproduce the large plateau of the magnetization experimentally observed below the phase-transition temperature. By introducing for the first time a many-spin interaction between Mn ions, we obtain an excellent agreement with experiments. Fitting the experimental Curie temperature TC with the MC transition temperature, we estimate the value of the effective exchange interaction in the system. From this value, we estimate various exchange interactions between ions: the dominant one is that between Mn3+ and Mn4+ which is at the origin of the ferromagnetic ordering below TC. We also studied the applied-field effect on the magnetization in the region below and above TC. The obtained MC results for |ΔSm| are in agreement with experiments performed for applied fields from 1 to 5 T. MC results of RCP are also shown and compared to experimental ones. Various other physical quantities obtained from MC simulations including internal energy and specific heat, versus temperature are also shown and discussed.

Investigation of rare earth lean Sm-(Fe,Co)-Mo alloys for permanent magnets

Bulk magnets with the composition of Sm1Fe10.5−xCoxMo1.5 (where x = 0, 1, and 2) with the tetragonal ThMn12 structure were prepared and their intrinsic magnetic properties were studied. The cast samples were then subjected to high-energy-ball-milling (HEBM), followed by hot-compaction at 650 °C. The compacted samples were annealed at temperatures ranging from 700 °C to 1000 °C to obtain high coercivity. The effects of Co on the magnetic properties, including the Curie temperature TC, saturation magnetization MS, anisotropy field HA, and energy product (BH)max were investigated. It is observed that Co substitution increases the Curie temperature, the saturation magnetization, and the remanence, but decreases the anisotropy field and the coercivity. Among the investigated samples, the isotropic Sm1Fe9.5Co1Mo1.5 showed the highest energy product (21.5 kJ/m3) after annealing at 750 °C for 48 h, marking a 23 % enhancement relative to our specimen without cobalt substitution.

Enhanced electrocaloric effect in KNN-based ceramic via polymorphic phase transition

A large adiabatic temperature change (ΔT) in lead-free ceramics is highly desired to develop eco-friendly and high efficiency solid-state refrigeration device based on electrocaloric effect (ECE). However, a large ΔT is often obtained near high Curie temperature (Tc > 100 °C), which impedes the practical applications for electrocaloric refrigeration technology. Herein, the lead-free (1-x)(K0.48Na0.535)0.03Li0.07(Nb0.99Sb0.01)O3-xBaZrO3 (x = 0, 0.02, 0.04 and 0.06) ceramics were synthesized through a conventional solid-state sintering method. A polymorphic phase transition (PPT) region is constructed by composition engineering to achieve large ECE near the ambient temperature. A ΔT of 0.48 K under 50 kV/cm is obtained at 60 °C by using the direct measurement in KNLNS-0.02BZ ceramic with coexistence of R-O-T phase. This work suggests that building multi-phase coexistence is a feasible design scheme in order to achieve ECE near the room temperature.

Large magnetocaloric effect in a ternary Laves phase compoundHo2Rh3Ge

Structural and magnetic properties of an intermetallic Ho2Rh3Ge compound have been investigated in this paper. We report the observation of large magnetocaloric effect (MCE) in Ho2Rh3Ge from the characterization of magnetism isotherms. The Rietveld refinement of powder X-ray diffraction revealed that Ho2Rh3Ge crystallizes in a rhombohedral Laves phase structure (space group R3̄m, hR18). It exhibits ferromagnetic order below the Curie temperature TC = 13 K. Around TC, maximum value of entropy change −ΔSm = 25.4 J kg−1 K−1 was observed for a change of magnetic field 0−8 T. The obtained refrigeration capacity (relative cooling power) for a change of magnetic field from 0 8 T is 497(664) J.kg−1. The second–order magnetic phase transition in Ho2Rh3Ge is confirmed from Arrott plots, universal scaling plots of magnetic entropy changes, and also from the field dependence of the magnetic entropy change.

Effect of Al3+ substitution on the magnetodielectric properties of the one-dimensional frustrated Ca3Co2O6

Ca3Co2-xAlxO6 (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1) were prepared via the conventional sol-gel method. The structure, magnetic, dielectric and magnetodielectric properties were investigated. The Rietveld structural refinement confirms the rhombohedral structure of the samples. The positive Curie-Weiss temperature θ and magnetic coupling exchange constants J indicate the dominant intrachain ferromagnetic interactions in the spin chains. The obvious inhibition effect to equally spaced magnetization steps demonstrates that Al3+ could release the magnetic frustration. With Al3+ substitution, both the magnetization intensity and the critical field of the ferrimagnetism to ferromagnetism transition decrease. The samples present obvious dielectric anomalies around the Curie temperature Tc and the freezing temperature Tf. Meanwhile, the magnetic field dependence of dielectric permittivity decreases suddenly at critical magnetic fields. These results reveal strong magnetodielectric coupling effect in Ca3Co2-xAlxO6. The same sign of Δεr and Δtanδ suggests that the magnetodielectric coupling effect is intrinsic.

Effects of Si substitution on ferromagnetic order and off-center rattling of Eu ions in the type-I clathrate Eu8Ga16Ge30

In the ferromagnetic type-I clathrate Eu8Ga16Ge30, the divalent Eu ions are known to rattle among off-center positions in the tetrakaidecahedral cage. We have studied effects of Si substitution on the ferromagnetic state and the rattling motion of the Eu ions in Eu8Ga16Ge30 by measuring the magnetization M, electrical resistivity ρ, thermopower, specific heat C, and Eu partial phonon density of states (Eu pDOS) of Eu8Ga16−xGe30+x−y−zSiy□z (□ = vacancy, 0 ≤y≤ 7.3). Upon increasing y from 0 to 7.3, the lattice parameter decreases by 0.7%, which has no effect on the divalent state of Eu. The Curie temperature TC decreases from 36.2 K to 32.6 K, whereas the specific heat jump at TC, ΔC, increases twofold. For y= 0, both ρ (T) and dM(T)/dT exhibit anomalies below TC at T∗∼ 24 K, which are suppressed by applying magnetic field of 1 T. The anomalies at T∗ disappear by Si substitution at a low level, y = 3.7. The measured Eu pDOS indicates that the low-lying phonon energy of the Eu ions decreases with Si substitution. This softening means that the off-center rattling is changed to on-center one with large amplitude in an anharmonic potential. Based on these findings, we discuss relationship between the off-center Eu rattling and their collective magnetic behavior.

High-stability quinary lead-based piezoelectric ceramics with high piezoelectric properties

Piezoceramics with the formula Pb0.93Sr0.06Ba0.01(Mg1/3Nb2/3)0.035(Ni1/3Nb2/3)0.2 (Sb1/2Nb1/2)0.015(ZrxTi1−x)0.75O3 + 0.5 wt. % Li2CO3, where x = 0.51, 0.50, 0.49, 0.48, 0.47, and 0.46, have been made using the one-step solid-state method. The phase structure and electrical properties were systematically investigated in the quinary system. Here, the crystalline structure transformed gradually from the rhombohedral to tetragonal phase with decreasing Zr content. More importantly, the effective piezoelectric coefficient d33* of the ceramics demonstrates an excellent thermal stability below the Curie temperature. Meanwhile, piezoelectric ceramics with x = 0.49 exhibited the extraordinary electrical properties near the morphotropic phase boundary. A huge piezoelectric coefficient d33 = 853 pC/N, high Curie temperature TC = 152 °C, and the electromechanical coupling coefficients kp = 67.4%, kt = 63.5%, and k33 = 67.4% were obtained at the composition of x = 0.49, which may lead a promising future for the transducer applications.

Critical behavior approaches to 3D-Mean field model of GdPdIn

We report the critical behavior of GdPdIn in the vicinity of the magnetic phase transition through dc-magnetization characterization. The magnetic susceptibility indicates a ferromagnetic (FM) like behavior below the Curie temperature TC= 96 K. Curie–Weiss behavior indicates that the 4f-shells of Gd3+ ions are fully contributing toward the magnetic properties. A second–order ferromagnetic phase transition in GdPdIn has been confirmed from the positive slope of Arrott plots. The critical exponents β= 0.538(2) and γ= 1.077(3) were derived from modified Arrott plots method, while Kouvel–Fisher method yielded β= 0.540(2) and γ= 1.090(2). The third critical exponent value of δ= 2.998(3) is estimated from the critical isotherm at 96 K. The calculated critical exponents value are very close to the mean–field model. The observed critical exponents follow the Widom relation’s δ=1+γ/β. The reliability of obtained critical exponents are examined through the scaling hypothesis. This study also illustrates that exchange interaction (J(r)) in the GdPdIn is found to decay as r−4.5.

Locally Reprogrammable Magnetic Micropillars with On‐Demand Reconfiguration and Multi‐Functionality

AbstractMagnetic micropillars have shown great promise in various applications including information storage, fluid manipulation, and soft robotics. But to date, magnetic micropillars with reprogrammable magnetization, multi‐modal deformation and functionality, and on‐demand fast actuation have not been reported yet. Herein, locally reprogrammable ferromagnetic micropillars with on‐demand reconfiguration and multi‐functionality are reported. The magnetic micropillars are fabricated by dispersing CrO2 microparticles (diameter ≈5 µm, Curie temperature Tc = 110 °C) in the Ecoflex matrix. The magnetization of each micropillar can be easily programmed and reprogrammed by simultaneously heating the micropillar above Tc via laser and applying a magnetizing field. The magnetization can be programmed as omnidirectional in three dimensions, thus entire magnetic micropillar arrays show a variety of deformation modes (including both synchronous and asynchronous modes) with on‐demand fast actuation by remotely applying magnetic fields. Four representative functionalities of the magnetic micropillars are demonstrated: information encryption, particle pumping, ink mixing, and underwater crawling robot.

Temperature Dependence of Complex Relative Permeability of the Polycrystalline La0.7Sr0.3MnO3

<p>吾人量測多晶態鑭鍶錳氧變化溫度的電阻率與頻率範圍為 10 kHz 至 10 MHz 的相對複數磁導率特性。樣品室溫電阻率很小，僅為數 m⋅Ωcm。電阻率隨著溫度增加，在相轉變溫度 TP = 361 K 附近顯現金屬到半導體的相轉變。室溫量測到的磁譜顯現與磁壁位移有關的鬆弛特性，色散情況非常明顯。隨著溫度升高，磁導率增加，在居禮溫度 TC前達到最大值，然後迅速下降。當溫度從室溫增加，磁壁位移鬆弛頻率 fr幾乎保持不變。當溫度升高到 TC附近，由於磁導率迅速降低，fr劇烈增加。在 TC以上，磁譜的色散現象消失。量測到的 fr與理論值相當符合，可看出磁壁位移的阻滯來源主要源自於渦電流阻滯。</p> <p> </p><p>The temperature-dependent resistivity and complex relative permeability of the polycrystalline La0.7Sr0.3MnO3 have been investigated in the frequency range 10 kHz -10 MHz. The measured room-temperature resistivity is of the order of mcm. As the temperature increases, the resistivity increases and shows a metal-insulator transition. The transition temperature TP is about 361 K. There are pronounced dispersions of the relaxation in the measured spectra, which are due to the domain-wall displacement. The magnitude of permeability increases with increasing temperature, reaches its maximum value near the Curie temperature TC, and then abruptly drops. As the temperature increases, the relaxation frequency fr almost remains a constant value. However, it rapidly increases around TC due to the suddenly decrease of the permeability. The dispersion phenomena of the permeability spectra disappear above TC. The consistence of the measured and calculated fr value shows that the damping factor of domain-wall displacement mainly comes from the eddy current.</p> <p> </p>

Study of AC Susceptibility of La0.8Sr0.2MnO3 at Different Frequencies

In the present work, the structural and ac magnetic susceptibility as a function of temperature at different frequencies of perovskite type La08Sr0.2MnO3 (LSMO) compound have been discussed. Conventional solid-state route was used to synthesize LSMO compound. Orthorhombic crystal structure with Pnma space group of the compound was witnessed from the analysis of X-ray diffractograms by Rietveld refinement. The real (χꞌ) and imaginary (χꞌꞌ) part of the ac susceptibility of the compound have been studied. The real part of magnetic susceptibility (χꞌ) of La0.8Sr0.2MnO3 sample increases as temperature decrease. This indicates that the paramagnetic-ferromagnetic phase transition occurs. At different frequencies, i.e. 100Hz and 500Hz the Curie temperature Tc are 326K and 336K respectively. Peaks observed in the imaginary part χꞌꞌ) of magnetic susceptibility plot indicate the presence of sample inhomogeneity.

Giant Nonvolatile Electric Field Control of Proximity‐Induced Magnetism in the Spin–Orbit Semimetal SrIrO3

AbstractWith its potential for drastically reduced operation power of information processing devices, electric field control of magnetism has generated huge research interest. Recently, novel perspectives offered by the inherently large spin–orbit coupling of 5d transition metals have emerged. Here, nonvolatile electrical control of the proximity‐induced magnetism in SrIrO3 based back‐gated heterostructures is demonstrated. Up to a 700% variation of the anomalous Hall conductivity (σAHE) and Hall angle (ΘAHE) as function of the applied gate voltage Vg is reported. In contrast, the Curie temperature TC ≈ 100 K and magnetic anisotropy of the system remain essentially unaffected by Vg indicating a robust ferromagnetic state in SrIrO3 which strongly hints to gating‐induced changes of the anomalous Berry curvature. The electric‐field induced ferroelectric‐like state of SrTiO3 enables nonvolatile switching behavior of σAHE and ΘAHE below 60 K. The large tunability of this system, opens new avenues toward efficient electric‐field manipulation of magnetism.

Enhanced Electromechanical Performance in Lead-free (Na,K)NbO3-Based Piezoceramics via the Synergistic Design of Texture Engineering and Sm-Modification.

Next-generation electromechanical conversion devices have a significant demand for high-performance lead-free piezoelectric materials to meet environmentally friendly requirements. However, the low electromechanical properties of lead-free piezoceramics limit their application in high-end transducer applications. In this work, a 0.96K0.48Na0.52Nb0.96Sb0.04O3-0.04(Bi0.5-xSmx)Na0.5ZrO3 (abbreviated as T-NKN-xSm) ceramic was designed through phase regulation and texture engineering, which is expected to solve this difficulty. Through our research, we successfully demonstrated the enhanced electromechanical performance of lead-free textured ceramics with a highly oriented [001]c orientation. Notably, the T-NKN-xSm textured ceramics doped with 0.05 mol % Sm exhibited the optimal electromechanical performance: piezoelectric coefficient d33 ≈ 710 pC N-1, longitudinal electromechanical coupling k33 ≈ 0.88, planar electromechanical coupling kp ≈ 0.80, and Curie temperature Tc ≈ 244 °C. Finally, we conducted a detailed investigation into the phase and domain structures of the T-NKN-Sm ceramics, providing valuable insights for achieving high electromechanical properties in NKN-based ceramics. This research serves as a crucial reference for the development of advanced electromechanical devices by facilitating the utilization of lead-free piezoelectric materials with superior performance and environmental benefits.

Fabrication of grain-oriented PbNb2O6-based high temperature piezoelectric ceramics

Grain-oriented Sr and Ti modified lead metaniobate (Pb0.96Sr0.04)Nb1.96Ti0.05O6 (PSNT) ceramics with 4 mol% excess of Nb2O5 were prepared by templated grain growth method. The needle-like PSNT templates were obtained through the molten salt synthesis method. The effects of the template concentration (5, 10, 20 and 30 wt%) on the texture degree, microstructure, and electrical properties of textured ceramics were investigated. Improved electromechanical properties were found along the direction perpendicular to the sheet in textured PSNT ceramics, which shows the preferential orientation. An excess of templates would seriously deteriorate the properties of textured ceramics. The textured PSNT ceramics with 5 wt% templates exhibit high Curie temperature Tc of 545 °C, and improvement in piezoelectric coefficient d33 by 9% (d33 = 98 pC/N) and g33 by 45% (g33 = 42 × 10−3 Vm/N), as well as electromechanical coupling coefficient k31 by 18% (k31 = 0.26) compared to randomly oriented ceramics. The study demonstrates that grain-orientation controlling in PN-based ceramics is a potential way to improve the piezoelectric properties while maintaining high Curie temperature.

Anomalous Elastic Evolution Induced by Copper Hopping in van der Waals Ferroelectric CuInP2S6

AbstractVan der Waals (vdW) ferroelectric CuInP2S6 (CIPS) has great potential in post‐Moore's law electronics owing to their advantages of weak interlayer interaction, stable surface with free dangling bonds, and robust switchable spontaneous polarization. The flexoelectric effect is demonstrated as an alternative switching method for the design of ferroelectric domains in layered vdW CIPS. However, the investigation of the correlation between the polarization and elastic properties remains indistinct. Here, an elastic evolution is explored experimentally and theoretically in layered vdW CIPS with temperature, of which Young's modulus (EYoung) is determined by analyzing the force‐indentation responses of vdW ferroelectric CIPS. Interestingly, an anomalous leap in EYoung of CIPS from 35 to 65 GPa occurs when the temperature rises across the Curie temperature TC of ≈315 K. Deep potential molecular dynamic (DPMD) simulations identify that this abnormal behavior can be attributed to temperature‐dependent change of copper distribution and the local copper dynamic hopping, intertwined with the order‐disorder ferroelectric phase transition, which is quite different from the typical decrease of EYoung in the lattice constant due to temperature increasing. The exploration provides an important reference for the analysis of coupled mechanical properties and ferroelectricity in CIPS and its applications in flexible electronics.

Proximity-Induced Interfacial Room-Temperature Ferromagnetism in Semiconducting Fe3GeTe2.

The discoveries of two-dimensional ferromagnetism and magnetic semiconductors highly enrich the magnetic material family for constructing spin-based electronic devices, but with an acknowledged challenge that the Curie temperature (Tc) is usually far below room temperature. Many efforts such as voltage control and magnetic ion doping are currently underway to enhance the functional temperature, in which the involvement of additional electrodes or extra magnetic ions limits their application in practical devices. Here we demonstrate that the magnetic proximity, a robust effect but with elusive mechanisms, can induce room-temperature ferromagnetism at the interface between sputtered Pt and semiconducting Fe3GeTe2, both of which do not show ferromagnetism at 300 K. The independent electrical and magnetization measurements, structure analysis, and control samples with Ta highlighting the role of Pt confirm that the ferromagnetism with the Tc of above 400 K arises from the Fe3GeTe2/Pt interfaces, rather than Fe aggregation or other artificial effects. Moreover, contrary to conventional ferromagnet/Pt structures, the spin current generated by the Pt layer is enhanced more than two times at the Fe3GeTe2/Pt interfaces, indicating the potential applications of the unique proximity effect in building highly efficient spintronic devices. These results may pave a new avenue to create room-temperature functional spin devices based on low-Tc materials and provide clear evidence of magnetic proximity effects by using nonferromagnetic materials.

Impact of Sm2O3 doping on PZT-PMI-PZS ternary ceramics: Phase structure, microstructure, and dielectric characteristics

This study aims to comprehensively evaluate the impact of Sm2O3 doping on PZT ceramics, specifically focusing on the phase structure, microstructure, and dielectric characteristics of Pb1-xSmx[(Zr0.52Ti0.48)0.9(Mo1/3In2/3)0.05(Zn1/3Sb2/3)0.05]O3 samples namely PSZT-PSMI-PSZS ceramics. Sm2O3 was doped at site A within the range of 0.00 ≤ x ≤ 0.08 using the solid-state reaction method and sintering at 1150 °C. The examination of the results revealed that the samples exhibited a perovskite structure, along with a secondary phase, with increasing intensity of the said phase as Sm content increased. XRD, Rietveld refinement, and Raman spectroscopy analysis indicate a decrease in the rhombohedral phase ratio (R) and an increase in the tetrahedral phase ratio (T) with higher Sm content. Microscopic examination using SEM demonstrates variations in microstructure, with the highest density and grain size observed at a small increment of Sm content (x ≤ 0.02). Optimal electrical properties were achieved at x = 0.00, including a high dielectric constant (εr = 8578), Curie temperature (Tc) of 303 °C, and dielectric loss (tanδ) value of 0.34. Conductivity studies indicate a negative temperature coefficient of resistance (NTCR) for all samples. Additionally, the relationship between electrical characteristics and Sm2O3 doping is discussed. This research provides valuable insights into the structural, microstructural, and electrical properties of PZT ceramics affected by Sm2O3 doping.