Annealing In Atmosphere Research Articles

Bandgap Reduction and Enhanced Photoelectrochemical Water Electrolysis of Sulfur-doped CuBi2O4 Photocathode

As interest in hydrogen energy grows, eco-friendly methods of producing hydrogen are being explored. CuBi2O4 is one of the p-type semiconductor cathode materials that can be used for photoelectrochemical hydrogen production via environment-friendly water electrolysis. CuBi2O4 has a bandgap of 1.5 – 1.8 eV which allows it to photogenerate electrons and holes from the absorption of visible light. This study investigated the effect of sulfur doping on the bandgap and photoelectrochemical water reduction properties of CuBi2O4. Sulfur-doped CuBi2O4 thin films were electrochemically synthesized using a nitrate-based precursor solution with thiourea. This was followed by two-step annealing in an Ar atmosphere, which effectively prevented the oxidation of sulfur. Sulfur doping up to 0.1 at% led to the expansion of the lattice volume of the CuBi2O4. The bandgap was reduced from 1.9 eV to 1.5 eV with increasing doping concentration, which resulted in the enhancement of photoelectrochemical current density by ~240%. X-ray photoelectron spectroscopy showed that sulfur-doping reduced oxygen vacancies with increasing doping concentration, confirming that the enhanced photoelectrochemical properties resulted from the reduction in bandgap, not from any extrinsic factor such as oxygen vacancies. Further studies of sulfur-doped CuBi2O4 to improve surface coverage are expected to lead to a more promising photoelectrochemical cathode material.

Orbital polarization change and magnetic enhancement in rutile MnO2-δ epitaxial films

Effectively manipulating the orbital configuration is an emerging method to design quantum functional materials with novel electronic ground states. Here, we report the realization of orbital polarization change in rutile MnO2-δ epitaxial thin films by reductive treatments such as CaH2 coating annealing and hydrogen atmosphere annealing. These treated samples show significant lattice expansion due to the generation of oxygen vacancies and incorporation of H, and the mixed valence states of Mn2+ and Mn3+ are formed with the decrease in the Mn valence state. The X-ray linear dichroism results show that the electron occupied state of Mn in the treated film samples changes from 3d3z2-r2 to 3dx2-y2, which means that the deprivation of oxygen atoms in the oxygen octahedron of MnO6 causes a change of orbital polarization. The resulting high spin state in the treated MnO2-δ films greatly enhances the magnetic properties of the films. This work not only demonstrates how the oxygen atoms in the edge-shared oxygen octahedron of rutile structures are replaced by reduction but also extends the study of orbital polarization and magnetic ground state control in oxide epitaxial films.

Effective substrate for the growth of multilayer h-BN on sapphire—substrate off-cut, pre-growth, and post-growth conditions in metal-organic vapor phase epitaxy

The substrate is one of the key components that determines the quality of the epitaxial layers. However, the implications of growing two-dimensional layers on three-dimensional bulk substrates have not yet been fully understood, and these implications need to be studied for different combinations of materials and substrates. Here, we present a study that addresses the influence of the sapphire substrate off-cut angle on the final growth of two-dimensional layers of hexagonal boron nitride (h-BN) by metal-organic vapor phase epitaxy (MOVPE). A two-step wafer-scale process was used in one epitaxial MOVPE procedure. The main process starts with a self-limiting continuous growth of a BN buffer followed by flow-modulated epitaxy in the second step, and is used to study substrates with different off-cuts angles, pre-growth nitridation steps, and post-growth annealing. An initial nitridation step at the growth temperature allowed for the growth of an AlN sublayer. This layer is shown to smooth out the underlying sapphire and establishes an ‘effective’ sapphire/AlN substrate. This step is also responsible for enforcing a specific growth of the BN layer in a crystallographic orientation, which is shown to strongly deviate from the substrate for off-cut angles larger than 0.3°. A substrate with off-cut angle of 1° clearly yields the highest quality of h-BN layers as evidenced by the lowest amount of debris on the surface, most intense x-ray diffraction signal, minimal Raman phonon line width and thinnest amorphous BN (a-BN) at the interface with the effective substrate. Our study shows that the off-cut angles of sapphire substrates strongly influence the final epitaxial h-BN, clearly indicating the importance of optimal substrate preparation for the growth of two-dimensional BN layers. Post-growth annealing in N2 atmosphere at 800 °C improves the top surface morphology of the final stack, as well as suppresses further the presence of a-BN.

Synthesis of V2O5 Nanoribbon–Reduced Graphene Oxide Hybrids as Stable Aqueous Zinc-Ion Battery Cathodes via Divalent Transition Metal Cation-Mediated Coprecipitation

Aqueous zinc-ion batteries (AZIBs) are an emerging sustainable and safer technology for large-scale electrical energy storage. Here, we report the synthesis of hybrid materials consisting of V2O5 nanoribbons (NRs) and reduced graphene oxide (rGO) nanosheets as AZIB cathode materials by divalent metal cation-mediated coprecipitation. The divalent metal ions M2+ (Zn2+ and Mn2+) effectively neutralize the negative charges on the surface of microwave-exfoliated crystalline V2O5 NRs and graphene oxide (GO) nanosheets to form a strongly bound assembly. After thermal annealing in a nitrogen atmosphere, GO is converted into rGO with higher electrical conductivity while the layers in V2O5 NRs are expanded by M2+ intercalation. When only Zn2+ ions are used during coprecipitation, the produced Zn-V2O5 NR/rGO hybrid shows a very high reversible specific capacity of ∼395 mAh g–1 at 0.50 A g–1 but suffers from poor stability. This is improved by mixing Mn2+ with Zn2+ ions during coprecipitation. The (Mn + Zn)-V2O5 NR/rGO hybrid shows a slightly lower specific capacity of ∼291 mAh g–1 at 0.5 A g–1 but a substantially improved long-cycling stability and better rate performance due to the stronger binding of Mn atoms in the V2O5 host that serve as stable pillars to support the expanded V2O5 layers.

Large-Area Perovskite Film Prepared by New FFASE Method for Stable Solar Modules Having High Efficiency under Both Outdoor and Indoor Light Harvesting.

High-quality perovskite film is deposited on a 30cm× 40cm LiCoO2 -coated ITO/glass via newly developed freely falling anti-solvent extraction (FFASE) method followed by post watervapor annealing in an ambient atmosphere. Perovskite solar modules (PSMs, active area of 25.2cm2 with mask) based on this high-quality film achieve the highest efficiency of 16.04 and 30.76% under 1sun (100mW cm-2 ) and 945 lux fluorescent light illumination, respectively. The encapsulated PSMs are stable at -20 to 80°C thermal cycling and keep high efficiency at temperature as low as -20°C and as high as 80°C. When the encapsulated PSM is heated at 85°C and 85% relative humidity under room lighting or heated at 60°C under AM1.5 (100mW cm-2 ) illumination for 1000h, loses only ≈8% of its original efficiency. The high stability of PSMs is due to very high quality perovskite absorber being used. The underlying concept of the FFASE method for extracting the solvent from the large-area perovskite precursor film is that the whole precursor film contacts with the fresh anti-solvent during the crystallization stage.

Magnetorheological properties of Fe–Co nanoparticles with high saturation magnetization and low coercivity

Fe–Co alloys exhibit an excellent saturation magnetization, which makes them become a potential candidate for the high property magnetic particles in magnetorheological fluids (MRFs). How to decrease their coercivity and residual magnetization without sacrificing the saturation magnetization is a crucial problem to be solved. In this study, Fe–Co nanoparticles were prepared by DC arc discharge and further disposed through low temperature annealing in Ar atmosphere. The successful synthesis of Fe–Co nanoparticles was proved by x-ray diffraction and EDS. The vibrating sample magnetometer results revealed that the prepared Fe–Co nanoparticles had a saturation magnetization of 208 emu g−1, while the coercivity and remanent magnetization were 58 Oe and 5.8 emu g−1, respectively. The MR properties of Fe–Co nanoparticles based MRFs (FeCoNP-MRFs) with 10% particles by volume fraction were systematically investigated. The FeCoNP-MRFs showed up to 4.61 kPa dynamic shear stress at 436 kA m−1 magnetic field and an excellent reversibility. The MR properties of FeCoNP-MRFs were fitted well by Bingham and power law model, and described by Seo-Seo and Casson fluid model. Meanwhile, the sedimentation ratio of FeCoNP-MRFs was still 87.3% after 72 h, indicating an excellent sedimentation stability.

Understanding the Effect of Oxygen Content on Ferroelectric Properties of Al-Doped HfO Thin Films

To satisfy the demand of high-speed and low-power memory in the field of integrated circuits, different elements doped HfO2 ferroelectric tunnel junctions have been developed. In this work, we investigate the annealing atmosphere effects on the ferroelectric property of the Al-doped HfO2 (HfAlO) ferroelectric tunnel junctions based on first-principles calculation and experiments. The ferroelectric layer/electrode interface has the obvious effect on ferroelectric property of the devices under different oxygen content annealing atmosphere, including 0%, 50% and 100% O2. The first-principle analysis verified that stable o-phase proportion in HfAlO film owing to the co-existence of the Al and oxygen vacancy is the key element to stable ferroelectric performance of device. This work could promote the development of HfAlO ferroelectric tunnel junctions for next-generation in-memory computing applications.

Electrospun single-phase spinel magnetic high entropy oxide nanoparticles via low-temperature ambient annealing.

High entropy oxide nanoparticles (HEO NPs) with multiple component elements possess improved stability and multiple uses for functional applications, including catalysis, data memory, and energy storage. However, the synthesis of homogenous HEO NPs containing five or more immiscible elements with a single-phase structure is still a great challenge due to the strict synthetic conditions. In particular, several synthesis methods of HEO NPs require extremely high temperatures. In this study, we demonstrate a low cost, facile, and effective method to synthesize three- to eight-element HEO nanoparticles by a combination of electrospinning and low-temperature ambient annealing. HEO NPs were generated by annealing nanofibers at 330 °C for 30 minutes under air conditions. The average size of the HEO nanoparticles was ∼30 nm and homogenous element distribution was obtained from post-electrospinning thermal decomposition. The synthesized HEO NPs exhibited magnetic properties with the highest saturation magnetization at 9.588 emu g-1 and the highest coercivity at 147.175 Oe for HEO NPs with four magnetic elements while integrating more nonmagnetic elements will suppress the magnetic response. This electrospun and low-temperature annealing method provides an easy and flexible design for nanoparticle composition and economic processing pathway, which offers a cost- and energy-effective, and high throughput entropy nanoparticle synthesis on a large scale.

In English

We report the synthesis of β-SiC/por-Si/mono-Si heterostructure by a hybrid method, consisting of the electrochemical etching of the single-crystal silicon surface with a subsequent carbidization by a thermal annealing in a methane atmosphere. This method has a number of advantages over the known ones, because it is cheap enough and allows one to form the silicon carbide layers of high- quality. The formed structure was studied by means of SEM, EDX and XRD methods. As a result, the dense β-SiC layer, consisting of an array of the spherical islands with diameters of 2–6 μm, coated with the small pores, was formed on the por-Si/mono-Si surface. The geometric dimensions of the islands were studied by calibrating the sample image in the ImageJ software package. The maximum value of the linear size (diameter) of the island dmax = 5.95 μm and the minimum value dmin = 2.11 μm were found in the studied area. In general, the average diameter of the islands is d = 3.72 μm. The distribution has the left-sided asymmetry, that is, the smaller islets predominate. Roundness (the ratio of the area to the square of the larger axis) R = 0.86. According to the results of EDX analysis, it was found that the synthesized structure surface consists exclusively of the carbon and silicon atoms, indicating the high quality of the formed structures. It was found that the SiC film crystallizes in the cubic phase. The formation of the islands is explained by means of the layer-plus-island growth model according to Stranski-Krastanow mechanism, which is characterized by the formation of the dense wetting layer with the massive island complex on the surface. It should be also noted that the porous SiC layers of island type can, in turn, show the perspective as the buffers with the heteroepitaxy of the silicon substrate materials.

Nanofluidic electrolyte based on nitrogen doped reduced graphene oxide as an electrocatalyst for VO2+/VO2+ in vanadium redox flow battery

Vanadium Redox Flow Battery (VRFB) have garnered significant attention in recent years as a stationary energy storage system, yet its prevalence is hindered by sluggish electron transfer kinetics. Herein, we demonstrate the prospects of nanofluidic electrolyte based on nitrogen doped reduced graphene oxide (N-rGO) as an electrocatalyst for positive half-cell in VRFB. N-rGO with rich nitrogen functional group and structural defect is synthesized through improved Hummers' method, followed by thermal annealing in an inert atmosphere using an eco-friendly nitrogen precursor. The electrochemical kinetics of positive redox pair VO2+/VO2+is found to be improved significantly with nanofluidic electrolyte and were in proportion to the concentration of N-rGO. On comparison with base electrolyte, N-rGO (0.1 wt%) based nanofluidic electrolyte exhibited better electrochemical reversibility, 35 % improvement in peak current density, reduced overpotential and charge transfer resistance by 23 % and 58 % respectively. The enhanced electrochemical performance may be attributed to the enhanced electrochemical surface area and electrical conductivity of N-rGO along with improved hydrophilicity of nanofluid. The present study proposes N-rGO based nanofluidic electrolyte as a potential candidate for effective electrocatalysis in VRFB.

Microstructure and mechanical properties of open-cell Ni-foams with hollow struts and NiO oxide layers

Based on electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS), open-cell Ni foams fabricated by electroplating on a removable template were investigated. Hollow struts or cavities inside the Ni foams were observed, implying traces of a removable template. The crystallographic orientations and grain structures of the Ni foam struts were also examined. Individual grains of Ni foams covered the struts completely through the thickness direction. The crystallographic orientations of the Ni foam struts display a random distribution. Σ3 twinning boundaries were also observed in the Ni matrix. During a two-hour heat treatment at 1273 K under atmospheric condition, refined NiO layers clearly formed on the surface of the Ni matrix. The overall grain sizes of the NiO are smaller than those of the Ni matrix. The obvious crystallographic relationship between the Ni matrix and the NiO layers was observed at the high misorientation angles. Ni foams with high porosity revealed a stress drop and NiO layers that formed during atmospheric annealing caused a predominant stress drop. Young’s modulus and the hardness of the Ni matrix and NiO layers were measured from a Ni foam cell structure consisting of nodes, by means of nano-indentation tests.

Effects of High-Temperature Annealing Atmosphere on the Secondary Recrystallization Behavior and Magnetic Properties of Fe-3.2%Si-0.055%Nb Grain-Oriented Silicon Steel.

High-temperature annealing is a key step for the secondary recrystallization of grain-oriented silicon steel, which has an important effect on the final sharp Goss texture. In this work, the effects of three different annealing atmospheres during high-temperature annealing (100%H2, 25%N2 + 75%H2 and 50%N2 + 50%H2) on the secondary recrystallization microstructure and texture of Fe-3.2%Si-0.055%Nb low temperature grain-oriented silicon steel were analyzed by optical microscopy (OM) and electron back-scattered diffraction (EBSD) techniques, and the magnetic properties of the samples were compared. The results show that when the high-temperature annealing atmosphere is 100%H2, the texture of the grains with secondary recrystallization is mainly <110>//ND orientation, but the grains without secondary recrystallization have a disordered orientation. When the high-temperature annealing atmosphere is 50%H2 + 50%N2, the secondary recrystallization grains present a Goss texture and brass texture. After high-temperature annealing in the 25%N2 + 75%H2 atmosphere, the sample can be fully recrystallized to obtain secondary recrystallization grains; the grain size is relatively uniform and the texture is mainly a Goss texture with a sharp edge. The content of this reaches 93.1%, the magnetic induction B800 is the highest, reaching 1.89 T, and the iron loss P1.7/50 is the lowest, reaching 1.33 W/kg.

Influence of Annealing Temperature on the Magnetic Properties of One-dimensional Diluted Magnetic Semiconductor Zn0.95Mn0.05O Tuning with Vacuum Atmospheric Annealing

Influence of Annealing Temperature on the Magnetic Properties of One-dimensional Diluted Magnetic Semiconductor Zn0.95Mn0.05O Tuning with Vacuum Atmospheric Annealing

Enhancement of electrical conductivity of hydrazine-reduced graphene oxide under thermal annealing in hydrogen atmosphere

The effect of further thermal annealing in a hydrogen atmosphere on the electrical properties of hydrazine-reduced graphene oxide (RGO) was investigated. It was found that heat treatment significantly improves the conductivity of RGO and reduces the room temperature resistivity by ten times. The changes become even more significant at the temperature decrease to 4.2 K and can exceed five orders. The variable range hopping conduction mechanism is the major charge transfer in the RGO at low temperatures for all annealing temperatures in the hydrogen of 100–800 °C. It is shown that the characteristic temperature T0 of the hopping transport exhibits an exponential decrease with an increase in the annealing temperature. Low-temperature studies of electric charge transfer reveal that the unified activation energy accompanying the improvement in conductivity is 0.3 eV.

Selective High-Resistance Zones Formed by Oxygen Annealing for -GaO Schottky Diode Applications

Selective area doping technique is essential for diversifying semiconductor device structures. In this letter, selective high-resistance zones on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 wafers were successfully achieved by a high-temperature oxygen annealing process. Polysilicon, which proved to have an ideal blocking capability against oxygen annealing ambient, was employed as an annealing cap layer to prevent local carrier concentration changes during annealing. Based on this unique process approach, we further demonstrate a high-resistance anode edge termination of Schottky barrier diodes, which can considerably reduce the leakage current and increase the breakdown voltage of the devices. This research broadens the device manufacturing method and promotes the development of Ga2O3 devices.

2D-Antimonene-assisted hetero-epitaxial growth of perovskite films for efficient solar cells

There are many grain boundaries and defects in polycrystalline perovskite films, resulting in sacrificed efficiency and instability for perovskite solar cells (PSCs). By regulating the growth of perovskite grains along the vertical direction through epitaxial growth, one may expect fewer grain-boundaries, effective charge transport, improved crystalline quality, and reduced defect density. However, there is still no suitable epitaxial growth substrate for perovskite. Here, we developed an electrochemical lithiation intercalation and ultrasonication method to prepare high-quality antimonene nanosheets (ANs). It is found that the perovskite film grows preferentially along the (012) planes of the ANs that have perfect lattice match with the (001) planes of the perovskite, leading to a high-quality perovskite film with a preferential orientation along the [001] direction and greatly enlarged grain size. Consequently, the oriented perovskite-based PSC achieves a remarkable PCE of 24.54% and shows an enhanced stability under ambient conditions, thermal annealing or light illumination. This work opens an effective avenue to effectively control the oriented growth of perovskite film for high-performance perovskite optoelectrical devices.

Equivalent circuits of FeCoZr-alloy nanoparticles deposited into Al2O3 and PZT dielectric matrices nanogranular composite films

The paper presents equivalent substitution circuits (ESCs) describing nanogranular composite films (Fe0.45Cо0.45Zr0.10)x(Al2O3)1 – x and (Fe0.45Cо0.45Zr0.10)x(PZT)1 – x with a concentration of metal-containing granules in the range 0.3 &lt; х &lt; 0.8. Films of 2–7 μm thick were obtained by ion-beam sputtering of composite targets in pure argon or in Ar – O2 mixture, followed by stepwise (with a step of 25 K) isochronous (15 min) annealing in air in the temperature range of 398 – 873 K. Deposition of nanocomposites in an oxygen-containing atmosphere or subsequent annealing in air led to the formation of nanoparticles with a core – shell structure consisting of Fe0.45Cо0.45Zr0.10 metallic alloy cores coated with shells of native iron and cobalt oxides (FeO, Fe3O4, Fe2O3, CoO). It has been established that when such shells contain semiconductor-type iron oxides (like FeO and Fe3O4) the frequency dependences of the total impedance Z (f, T) of nanocomposites can be described using ESCs containing two resonant RCL-circuits, that is accompanied by a positive phase shift of the current relative to the applied bias voltage (the so-called negative capacitance effect). The prevailing of dielectric-like oxides (Fe2O3) in shells around metallic cores leads to ESCs either with one resonant RCL-circuit or without it at all. This results in disappearing of the negative capacitance effect when usual capacitive-like behaviour of nanocomposite behaviour is observed. It is shown that if we construct ESCs for nanocomposites with different ratios of the metallic (FeCoZr) and dielectric (Al2O3, PZT) components, it is possible to describe the Z (f, T) dependences for every circuit elements (R, C, L) corresponding both to individual phase components in nanocomposites including intrinsic semiconductor- or dielectric-like iron and cobalt oxides in shells around metallic cores.

ZnO/Ti3C2 composite with oxygen vacancies and Schottky barrier for effective detection of ppb-level NO2 at room temperature

Room-temperature detection of low concentrations of toxic and harmful gases is of great significance for the health and life of human being and contributes to long-term stability and low power consumption of gas sensors. In this work, we firstly prepared a ZnO1-x/Ti3C2 composite with rich oxygen vacancies by a hydrothermal process and subsequent annealing in hydrogen atmosphere. The experimental results reveal that the ZnO1-x/Ti3C2 composite exhibits very high responses (ΔR/Ra) of 0.03, 0.21 and 2.28 to 0.01, 1 and 10 ppm NO2 at room temperature, among which the response to 10 ppm NO2 is 2.3 and 14.2 times higher than those of ZnO/Ti3C2 composite and pristine Ti3C2, respectively. Moreover, the ZnO1-x/Ti3C2 composite presents good linear response (R2 = 0.99509), reproducibility and long-term stability to NO2. The outstanding NO2 sensing properties of ZnO1-x/Ti3C2 composite are mainly attributed to the presence of abundant oxygen vacancies and the formation of ZnO1-x/Ti3C2 Schottky barrier. Both the gas responses and calculated adsorption energies of ZnO1-x/Ti3C2 and ZnO/Ti3C2 composites to NO2, NH3, CO, HCHO and acetone demonstrate the high selectivity of the ZnO1-x/Ti3C2 composite to NO2. This work provides a new perspective on enhancing the room-temperature gas sensitivity of MOS-containing composites by constructing oxygen vacancies and heterojunction.

Improving the Sensing Properties of Graphene MEMS Pressure Sensor by Low-Temperature Annealing in Atmosphere.

The high demand for pressure devices with miniaturization and a wide bearing range has encouraged researchers to explore new high-performance sensors from different approaches. In this study, a sensitive element based on graphene in-plane compression properties for realizing pressure sensing is experimentally prepared using microelectromechanical systems (MEMS) fabrication technology; it consists of a 50 µm thick, 1400 µm wide square multilayer component membrane and a graphene monolayer with a meander pattern. The prepared sample is extensively characterized and analyzed by using various techniques, including atomic force microscopy, Raman spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, COMSOL finite element method, and density functional theory. The sensing performance of the new pressure sensor based on the sensitive element are obtained by theoretical analysis for electromechanical measurements of the sensitive element before and after low-temperature annealing in atmosphere. Results demonstrate that atmospheric annealing at 300 °C enhances the pressure sensing sensitivity by 4 times compared to pristine graphene without annealing, which benefits from the desorption of hydroxyl groups on the graphene surface during annealing. The sensitivity is comparable and even better than that of previous sensors based on graphene in-plane properties. Our results provide new insights into realizing high-performance MEMS devices based on 2D sensitive materials.

B-Site Fe/Re Cation-Ordering Control and Its Influence on the Magnetic Properties of Sr2FeReO6 Oxide Powders.

Double-perovskite oxide Sr2FeReO6 (SFRO) powders have promising applications in spintronics due to their half-metallicity and high Curie temperature. However, their magnetic properties suffer from the existence of anti-site defects (ASDs). Here, we report on the synthesis of SFRO powders by the sol–gel process. The B-site cationic ordering degree (η) and its influence on magnetic properties are investigated. The results demonstrate that the η value is well controlled by the annealing temperature, which is as high as 85% when annealing at 1100 °C. However, the annealing atmospheres (e.g., N2 or Ar) have little effect on the η value. At room temperature, the SFRO powders crystallize in a tetragonal crystal structure (space group I4/m). They have a relatively uniform morphology and the molar ratios of Sr, Fe, and Re elements are close to 2:1:1. XPS spectra identified that Sr, Fe, and Re elements presented as Sr2+, Fe3+, and Re5+ ions, respectively, and the O element presented as O2-. The SFRO samples annealed at 1100 °C in N2, exhibiting the highest saturation magnetization (MS = 2.61 μB/f.u. at 2 K), which was ascribed to their smallest ASD content (7.45%) with an anti-phase boundary-like morphology compared to those annealed at 1000 °C (ASDs = 10.7%) or 1200 °C (ASDs = 10.95%).