Role of Ni2+ substituent on the structural,optical and magnetic properties of chromium oxide (Cr2-xNixO3) nanoparticles

Pristine chromium oxide (Cr₂O₃) and nickel ions (Ni²⁺) substituted Cr₂O₃ nanoparticles were synthesized using a simple co-precipitation technique. The main objective of this work is to investigate Ni²⁺ substituent's role at different concentrations on the structural, morphological, optical, and magnetic properties of Cr₂O₃ nanoparticles. Structural analyses based on X-ray diffraction (XRD), Raman and Fourier transform infra-red (FTIR) data confirmed the successful incorporation of Ni²⁺ into Cr₂O₃ nanoparticles up to x = 0.05 of Ni²⁺ content, without affecting the rhombohedral crystal structure of Cr₂O₃ nanoparticles. Rietveld refinement results showed the variation in lattice parameters and cell volumes alongwith the substitution of Ni²⁺ into Cr₂O₃ nanoparticles. Raman and FTIR spectra also depicted a considerable shift in the characteristic vibration modes of Cr₂O₃ nanoparticles due to strain-induced by Ni²⁺ substitution. Beyond x = 0.05, the structural transformation took place from rhombohedral to cubic crystal structure. Subsequently, new peaks (apart from Cr₂O₃ phase modes) have been observed at x = 0.1 of Ni²⁺ content due to the formation of secondary phase i.e., nickel chromate (NiCr₂O₄). Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) illustrated the changes in the morphology of Cr₂O₃ nanoparticles with Ni²⁺ substitution. UV–Vis analysis revealed a narrowing of optical band energy (E_g) of Ni²⁺ substituted Cr₂O₃ nanoparticles from 3 to 1.85 eV as Ni²⁺ content varies from x = 0 to 0.2, respectively. Afterward, there is an increase in optical band gap energy (E_g) when Ni²⁺ content increased from x = 0.3 to 0.5, as NiCr₂O₄ started dominating the Cr₂O₃ phase. Single-phase Ni²⁺ substituted Cr₂O₃ nanoparticles exhibited a superparamagnetic behavior, whereas the multi-phase compound ascribed to both superparamagnetic and paramagnetic. These changes in optical and magnetic properties can lead to novel strategies to render applications in the field of optoelectronics and optomagnetic devices.     

Electrical and Optical Properties of Transparent Conducting p‐Type SrTiO3 Thin Films

We report a systematic study of the electrical and optical properties of epitaxial perovskite p‐type In‐doped SrTiO₃ thin films (SrIn_xTi_1?xO₃, 0 ≤ x ≤ 0.15) grown on single‐crystal (100)‐oriented LaAlO₃ substrates using a hybrid method which combines pulsed laser deposition and molecular beam epitaxy in a range of deposition conditions. X‐ray diffraction analysis confirms the epitaxial growth of high crystal quality films. Four‐point probe and Hall Effect measurements demonstrate that the films are p‐type semiconductors with a low resistivity of ~10^?2 Ω·cm and a high carrier concentration of ~10¹⁹ cm^?3. The optical transmittance spectra reveal that the films are highly transparent (?70%) in the visible region.     

Slight Ti‐Doping‐Induced Strong Time‐Dependent Electrical Transport Behavior in CuCr1−xTixO2

We investigate the effect of slight Ti substitution (≤0.5%) for Cr in CuCr_1?xTi_xO₂ by measuring the structural, magnetic, and electrical transport properties. Upon Ti doping, the antiferromagnetic transition becomes blurred without a change in Néel temperature. Ti⁴⁺ substituting to Cr³⁺ site is found to significantly enhance the resistivity due to the diminishing conducting holes. We find strong time‐dependent electrical transport behavior in CuCr_1?xTi_xO₂ induced by slight Ti doping. The key observation is that a metastable behavior occurs in Ti‐doped CuCr_1?xTi_xO₂. A strong resistive relaxation (RR) behavior occurs in Ti‐doped CuCr_1?xTi_xO₂ with its magnitude remarkably increasing with increasing Ti content, while it is absent in undoped CuCrO₂. The RR is found to be described by the combination of an exponential function and a logarithmic dependence at long time. The relaxation behavior in CuCr_1?xTi_xO₂ is found to show a correlation with the local lattice deformation.     

Synthesis and thermal expansion behaviors of spin-coated Sc2Mo3O12 thin films

Orthorhombic Sc₂Mo₃O₁₂ films have been successfully prepared via spin coating technique followed by annealing at 500–750 °C. The phase composition, microstructure, morphology and negative thermal behavior of the synthesized Sc₂Mo₃O₁₂ films were investigated. XRD and XPS analysis indicate that as-deposited film is amorphous. Orthorhombic Sc₂Mo₃O₁₂ films can be prepared after post-annealing at 500–750 °C for 1 h. The crystallinity of Sc₂Mo₃O₁₂ films gradually improved with the increase of post-annealing temperature. SEM analysis shows as-deposited film is smooth and compact, and the grain size of Sc₂Mo₃O₁₂ film grows up as the post-annealing temperature increases. Variable temperature XRD analysis demonstrates that the synthesized orthorhombic Sc₂Mo₃O₁₂ films show stable thermo-chemical and anisotropic NTE property in 25–700 °C. The corresponding coefficients of thermal expansion (CTEs) of the orthorhombic Sc₂Mo₃O₁₂ film in a, b and c directions are ?6.68 × 10^?6 °C^?1, 5.08 × 10^?6 °C^?1 and ?4.76 × 10^?6 °C^?1, respectively. The whole unit cell of the orthorhombic Sc₂Mo₃O₁₂ film shrinks and the volumetric CTE of the Sc₂Mo₃O₁₂ thin film is ?6.36 × 10^?6 °C^?1, and the linear CTE is about ?2.12 × 10^?6 °C^?1 (α_v = 3α_l).     

Influence of Cr3+ substitution for Mg2+ on the crystal structure and microwave dielectric properties of CaMg1-xCr2x/3Si2O6 ceramics

The CaMg_1-xCr_2x/3Si₂O₆ (0?≤?x?≤?0.1) microwave dielectric ceramics were synthesized via conventional solid state reaction. In this study, the effects of Cr³⁺ substituting for Mg²⁺ on morphology, crystal structure and microwave dielectric properties of CaMg_1-xCr_2x/3Si₂O₆ ceramics were explored. XRD diffraction patterns exhibited that the CaMg_1-xCr_2x/3Si₂O₆ ceramics possessed the pure phase of CaMgSi₂O₆ when x?≤?0.06 and a small amount of secondary phase Ca₃Cr₂(SiO₄)₃ for 0.08?≤?x?≤?0.1. SEM micrographs revealed that the substitution of Mg²⁺ with Cr³⁺ could decrease the grain size. The apparent density was affected by the concentration of Mg vacancies. The correlation between crystal structure and microwave dielectric properties was investigated through the Rietveld refinement and Raman analysis. The microwave dielectric properties were mainly dependent on relative density, ionic polarizabilities, internal strain ?, disordered structure and MgO₆ octahedron distortions. Finally, CaMg_1-xCr_2x/3Si₂O₆ (x?=?0.02) ceramics sintered at 1270?°C for 3?h exhibited excellent microwave dielectric properties of ε_r?=?8.06, Q?×?f?=?89054?GHz, τ_f?=??44.92182?ppm/ºC.     

Fabrication and characterization of MOCVD (In1-xAlx)2O3 (0.1≤x≤0.6) ternary films

A series of (In_1-xAl_x)₂O₃ (0.1 ≤ x ≤ 0.6) films with tunable bandgap were grown on MgO (100) substrates by MOCVD. The influences of chemical compositions and growth temperatures on the film properties were studied systematically. XRD analyses indicated that the film quality degraded from crystalline to amorphous structure as Al concentration (x) increased. The (In_1-xAl_x)₂O₃ films prepared at 700 °C exhibited better film crystallinity than those of the ones grown at 600 °C. The films prepared at 700 °C with x = 0.1–0.3 showed an epitaxial In₂O₃ <111> orientation with the corresponding growth relationship of In₂O₃ (111)∥MgO (100). The film with x = 0.2 exhibited the best crystallinity and the largest grain size of 25.9 nm. The Hall mobilities and resistivities of the films were influenced evidently by Al concentrations. The Hall mobility showed a monotonous decrease from 12 to 1.1 cm²V^?1s^?1 as x increased from 0.1 to 0.6. The lowest resistivity of 9.2 × 10^?3 Ω cm was acquired for the film with x = 0.2. The average transmittances in the visible region for all the films were beyond 83%. The bandgap of the (In_1-xAl_x)₂O₃ films can be regulated in the range of 3.85–4.88 eV by changing Al concentrations from 0.1 to 0.6.     

Characterization of aluminum gallium oxide films grown by pulsed laser deposition

Aluminum gallium oxide (AGO) films were prepared on conventional c-plane sapphire by pulsed laser deposition (PLD). In the current PLD-AGO studies, target composition or growth temperature is usually the main deposition variable, and the other growth conditions are fixed. This would make it difficult to fully understand the theory and characterization of AGO films. In this study, several growth parameters such as target composition, gas atmosphere, laser repetition frequency, growth pressure, and substrate temperature (T_s) were all modulated to realize and optimize the AGO growth. When the (Al_xGa_1-x)₂O₃ target with the Al content larger than 20?at% was used, a serious target poisoning phenomenon occurred, leading to the extremely unstable growth rate. In comparison to the AGO film grown with argon atmosphere, the higher transparency was reached in the film prepared with oxygen atmosphere due to the relative abundance of oxygen. Because of the homogeneous oxygen reduction, the AGO film with the higher crystal quality was obtained at a higher laser repetition frequency. With an increment of growth pressure, the Al content of AGO film was increased. The growth of AGO film at the higher T_s would cause the higher bandgap value, smoother surface, and growth rate degradation. Additionally, the crystal quality of AGO film can be also improved both by increasing the growth pressure and T_s. The better characterization can be reached in the AGO film grown using the (Al_0.05Ga_0.95)₂O₃ target with oxygen atmosphere at the working pressure of 2?×?10^?1 Torr, the laser repetition frequency of 10?Hz, and the T_s of 800?°C. When the metal-semiconductor-metal photodetector fabricated with this AGO active layer, the best performance including the photocurrent of 7.56?×?10^?8 A, dark current of 1.59?×?10^–12 A, and photo/dark current ratio of 4.76?×?10⁴ (@5?V and 240?nm) were achieved.     

Research on the tribological performance of Cr2O3 filled with bronze‐based PTFE composites

Enhancement of the wear resistance of bronze‐filled polytetrafluoroethylene (PTFE) composites has been achieved using various fillers, for example, chromic oxide (Cr₂O₃), molybdenum disulfide (MoS₂), graphite, and nanometer aluminum oxide (n‐Al₂O₃), in the present study. The wear resistance was evaluated by a block‐on‐ring wear tester, and the effects of fillers on the wear resistance as well as the mechanism were investigated. The wear rate for the composite where the recipe containing 59% PTFE + 40% bronze + 1% Cr₂O₃ was 0.5 × 10^?5 mm^?3/N m and for the composite in the recipe containing 60% PTFE + 40% bronze was 4.2 × 10^?5 mm^?3/N m, which meant that that Cr₂O₃ increased the wear resistance by approximately 10 times. The differential scanning calorimetry measure analysis showed that Cr₂O₃ had a positive effect on the crystallization of PTFE; the crystallinity of PTFE composites increased from 45% to 52%, which exhibited improved wear resistance. Wear testing and scanning electron microscope analysis had shown that Cr₂O₃ had a positive effect on the formation of transfer film and keeping it stable to exhibit improved wear resistance. X‐ray photoelectron spectroscopy results also showed that Cr₂O₃ was effective in tribochemical reactions during sliding against stainless ring; these maybe responsible for forming transfer film and lowering wear rate of composite. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41117.     

Effects of Ni2+ substitution on the crystal structure,bond valence,and microwave dielectric properties of BaAl2–2xNi2xSi2O8–x ceramics

BaAl_2?2xNi_2xSi₂O_8?x (x = 0, 0.005, 0.01, 0.02, 0.03) ceramics were prepared using traditional solid phase reaction method. The microwave dielectric properties, including permittivity (ε_r), quality factor (Q × f), and temperature coefficient of resonant frequency (τ_f), were discussed based on the bond valence theory. The first-principle calculation was adopted to determine the site (Ba, Al, and Si) where doping element (Ni²⁺) would be inclined to occupy. The substitution of Ni²⁺ for Al³⁺ contributed to the breaking of Al-O and Si-O bonds and then facilitated the BaAl₂Si₂O₈ (BAS) hexacelsian-celsian transformation. Moreover, this substitution could change the bond strength between cation and oxygen anion due to the variation of the bond valence, which reasonably explained the variation of ε_r, Q × f, and τ_f values. Well-sintered and completely transformed celsian ceramics can be obtained after doping with Ni²⁺. When x = 0.01, compact BaAl_1.98Ni_0.02Si₂O_7.99 ceramic exhibited highly promising microwave dielectric properties: ε_r = 6.89, Q × f = 53, 287 GHz and τ_f = -25.31 × 10^?6 /°C.     

The Formation of CrO2+2 in the Reaction of Cr2+ + O2 in Aqueous Acid Solutions

The reduction rate of Cr³⁺ by e_aq was determined, k₈ = 1.7 × 10¹⁰ M^?1 s^?1. The reaction of Cr²⁺ with O₂ was studied, k₂ = 1.6 × 10⁸ M^?1 s^?1. The spectrum of CrO²⁺₂ was obtained both with the pulse radiolysis method and by mixing Cr²⁺ with excess of O₂. It was shown that CrO²⁺₂ decays slowly to yield HCrO^?₄. The results suggest that the reaction of Cr²⁺ with O₂ is a two electron transfer process.     

Structure and high-temperature tribological properties of Pb-Cr-O composite films prepared by reactive magnetron sputtering

The formation of ternary composite oxides in a high-temperature environment has laid the foundation for the design of high-temperature wear-resistant self-lubricating film. A series of Pb-Cr-O films with different Cr contents were prepared by incorporating different ratios of Pb-Cr into a target in the reactive magnetron sputtering system. The results showed that the hardness of the Pb-Cr-O films is greatly improved compared to the pure Pb-O film. In addition, the Pb₂₉Cr₄O₆₇ film with the highest Cr content forms an amorphous structure due to the accumulation of Cr⁶⁺ at the grain boundary, which improves the H/E and H³/E² of the film. At 600 °C, in contrast with the single PbO lubricating phase formed by pure Pb₃₃O₆₇ film, the Pb₂₉Cr₄O₆₇ film forms a composite lubricating phase of Pb₅CrO₈ and PbO. This leads to a decreased wear rate as low as 7.2 × 10^?6 mm³N^?1m^?1 while maintaining low coefficient of friction comparable to pure Pb₃₃O₆₇ film. At higher temperature of 700 °C, Cr element in Inconel 718 matrix diffuses into the Pb-based oxide film and forms Pb₅CrO₈ phase similar to Pb₂₉Cr₄O₆₇ film, which improves the wear resistance of the Pb₃₃O₆₇ film while maintaining low friction coefficient of 0.15.     

Highly transparent Yb:Y2O3 ceramics obtained by solid-state reaction and combined sintering procedures

(Y_0.87-xLa_0.1Zr_0.03Yb_x)₂O₃ (x?=?0.02, 0.04, 0.05) transparent ceramics were obtained by solid-state reaction and combined sintering procedures with La₂O₃ and ZrO₂ as sintering additives. A method based on two-step intermediate sintering in air followed by vacuum sintering was applied in order to control the densification and grain growth of the samples during the final sintering process. The results indicate that La₂O₃ and ZrO₂ co-additives can improve the microstructure and optical properties of Yb:Y₂O₃ ceramics at relatively low sintering temperature. On the other hand, the addition of Zr⁴⁺ ions leads to the formation of dispersed scattering volumes in the ceramic bodies. Transmittance of 78.8% was measured for the 2.0?at% Yb:Y₂O₃ ceramic sample at the wavelength of 1100?nm. The spectroscopic properties of Yb:Y₂O₃ ceramics were investigated at room temperature. The obtained results show that the absorption cross-section at 978?nm is in the range of 2.08?×?10^–20 to 2.36?×?10^–20 cm², whereas the emission cross-section at 1032?nm is ~1.0?×?10^–20 cm².     

Effect of (Zn,Mn) co-doping on the structure and ferroelectric properties of BiFeO3 thin films

BiFe_1-2xZn_xMn_xO₃ (BFZMO, with x = 0–0.05) thin films were synthesized via sol–gel method. Effects of (Zn, Mn) co-doping on the structure, ferroelectric, dielectric, and optical properties of BiFeO₃ (BFO) films were investigated. BFZMO thin films exhibit rhombohedral structure. Scanning electron microscopy (SEM) images indicate that co-doping leads to a decrease in grain size and number of defects. Leakage current density (4.60 × 10^?6 A/cm²) of BFZMO film with x = 0.02 was found to be two orders of magnitude lower than that of pristine BFO film. Owing to decreased leakage current density, saturated P–E curves were obtained. Maximum double remnant polarization of 413.2 μC/cm² was observed for BFZMO thin film with x = 0.02, while that for the BFO film was found to be 199.68 μC/cm². The reason for improved ferroelectric properties is partial substitution of Fe ions with Zn and Mn ions, which resulted in a reduction in the effect of oxygen vacancy defects. In addition, co-doping was found to decrease optical bandgap of BFO film, opening several possible routes for novel applications of these (Zn, Mn) co-doped BFO thin films.     

Optical and electrical properties of (111)-oriented epitaxial SrVO3 thin films

Perovskite oxide SrVO₃ (SVO) is a transparent conductor with excellent optical and electrical properties. Most of the previous works have focused on (001)-oriented SVO thin films. As an alternative to tin-doped indium oxide (ITO), the other orientations of SVO thin films are important to be considered as well. In the present work, the optical and electrical properties of (111)-oriented SVO epitaxial films have been investigated. Excellent electrical conductivity (2.92?×?10⁴?S?cm^?1) and optical transparency (56.6%) have been demonstrated, which are comparable to those of ITO and expand the applications of epitaxial SVO thin films in other orientations as transparent conducting oxide.     

Ferromagnetic Enhancement in ZnTiO3 films induced by Co doping

ZnTiO₃ is a promising wide band gap semiconductor material due to its actual and potential applications in catalysts, nonlinear optics, luminescent materials, microwave dielectrics, gas sensors, and solar cells. In this report, Co-doped ZnTiO₃ nanocrystal films were prepared on Si wafers using chemical solutions, and their structural, optical, and magnetic properties were investigated. Co²⁺ ion in the films was confirmed via X-ray photoelectron spectroscopy. X-ray diffraction demonstrated that Co-doped ZnTiO₃ films are a hexagonal space group (No. 148), and the lattice constant a increases but c decreases with the increasing Co content. All of the films show weak room temperature ferromagnetic order, and their saturated magnetizations increase slowly with increasing Co composition, which may be related to bound magnetic polarons. The average radius of bound magnetic polaron is approximately 15?Å. The optical parameters of the films were extracted via spectroscopy ellipsometry. At 532?nm, n, defined as the refractive index of the films, gradually increases as the Co increases. With Co content x from 0.00 to 0.10, E_OBG (the optical band gap of the Co-doped ZnTiO₃) decreases from 4.37 to 4.10?eV, S₀ (the average oscillator strength) decreases from 7.90?×?10^?5 to 6.33?×?10^?5?nm^?2, and λ₀ (the average oscillator wavelength) decreases from 0.0156 to 0.0134?nm, but E₀/S₀ (the electro-optical parameter) of the samples increases from 1.01?×?10^?14 to 1.46?×?10^?13 eVm². The present report will be constructive for possible applications of ZnTiO₃ in magnetic-optical devices.     

Effect of Au ion beam on structural,surface, optical and electrical properties of ZnO thin films prepared by RF sputtering

In the present work, ZnO thin films were irradiated with 700?keV Au⁺ ions at different fluence (1?× 10¹³, 1?× 10¹⁴, 2?× 10¹⁴ and 5?× 10¹⁴ ions/cm²). The structural, morphological, optical and electrical properties of pristine and irradiated ZnO thin films were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), spectroscopy ellipsometry (SE) and four point probe technique respectively. XRD results showed that the crystallite size decreased from pristine value at the fluence 1?×?10¹³ ions/cm², with further increase of ion fluence the crystallite size also increased due to which the crystallinity of thin films improved. SEM micrographs showed acicular structures appeared on the ZnO thin film surface at high fluence of 5?×?10¹⁴ ions/cm². FTIR showed absorption band splitting due to the growth of ZnO nanostructures. The optical study revealed that the optical band gap of ZnO thin films changed from 3.08?eV (pristine) to 2.94?eV at the high fluence (5?× 10¹⁴ ions/cm²). The electrical resistivity of ZnO thin film decreases with increasing ion fluence. All the results can be attributed to localized heating effect by ions irradiation of thin films and well correlated with each other.     

New Li solid electrolytes

New Li-ion conductors with several different structure types are reported. Li₄B₇O₁₂(Cl,Br) and LiM₂P₃O₁₂ (MZr, Hf) have framework structures. The others are based on structures with isolated polyhedra in a network of edge-linked Li polyhedra and include Li_2+xC_1?xB_xO₃, Li_3?x B_1?xC_xO₃, Li_4+xSi_1?xSi_1?xAl_xO₄, Li_4?xSi_1?xP_xO₄, Li_4?2xSi_1?xS_xO₄ and Li _5?xAl_1?xSi_xO₄. Li_0.8Zr_1.8 Ta_0.2P₃O₁₂ has the best room temperature conductivity, ～5 × 10^?6 (Ωcm)_?1. At 300°C, the conductivities of Li_3.75Si_0.75P_0.25O₄, Li_3.4Si_0.3O₄ and Li_2.25C_0.75B_0.25O₃ are 1 × 10^?2 (Ωcm)^?1. These compositions resist attack by molten li at 200°C and some can be easily prepared as dense ceramics.     

Tuning the phase transition temperature of Cr2(MoO4)3 by A-site substitution of scandium

A series of Cr_2-xSc_x(MoO₄)₃ solid solutions with tunable monoclinic-to-orthorhombic phase transition temperature have been synthesized via solid-state reaction. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results show that all synthesized Cr_2-xSc_x(MoO₄)₃ (0?< x?≤?1.4) solid solutions are single phased with no impurities identified, which reveals that Cr³⁺ has been substituted by Sc³⁺ in Cr₂(MoO₄)₃. Monoclinic to orthorhombic phase transition temperature of Cr_2-xSc_x(MoO₄)₃ can be effectively tuned from 372?°C to room temperature as the substituted Sc³⁺-content (x) varies from 0 to 1.4. The synthesized Cr_0.6Sc_1.4(MoO₄)₃ crystalizes in an orthorhombic structure at room temperature, exhibiting anisotropic negative thermal expansion throughout the testing temperature range. The coefficient of thermal expansion measured by thermal mechanical analyzer (TMA) for Cr_0.6Sc_1.4(MoO₄)₃ is ?11.17?×?10^?6 °C^?1 in the testing temperature range of 30–600?°C. Moreover, the crystallization, micromorphology, density and coefficient of thermal expansion of Cr_0.6Sc_1.4(MoO₄)₃ are obviously sensitive to the twice sintering temperature, whereas none of such sensitivity is found for the phase transition temperature.     

Effect of Y doping on microstructure and thermophysical properties of yttria stabilized hafnia ceramics

A series of Y₂O₃-doped HfO₂ ceramics (Hf_1-xY_xO_2-0.5×, x?=?0, 0.04, 0.08, 0.12, 0.16 and 0.2) were synthesized by solid-state reaction at 1600?°C. The microstructure, thermophysical properties and phase stability were investigated. Hf_1-xY_xO_2–0.5x ceramics were comprised of monoclinic (M) phase and cubic (C) phase when Y³⁺ ion concentration ranged from 0.04 to 0.16. The thermal conductivity of Hf_1-xY_xO_2–0.5x ceramic decreased as Y³⁺ ion concentration increased and Hf_0.8Y_0.2O_1.9 ceramic revealed the lowest thermal conductivity of ~?1.8?W/m*K at 1200?°C. The average thermal expansion coefficient (TEC) of Hf_1-xY_xO_2–0.5x between 200?°C and 1300?°C increased with the Y³⁺ ion concentration. Hf_0.8Y_0.2O_1.9 yielded the highest TEC of ~?10.4?×?10^?6 K^?1 while keeping good phase stability between room temperature and 1600?°C.