Phase Composition Research Articles

Low temperature fabrication of Ba0.9Cs0.3Cr2.1Ti5.9O16 ceramic waste form for cesium immobilization using Bi2O3 as sintering aid

In this paper, we present a productive low-temperature fabrication of Cs-hollandite ceramics by adding Bi2O3 as a sintering aid to achieve high cesium retention. The effects of Bi2O3 addition on the phase composition, crystal structure and aqueous stability of the stoichiometric Ba0.9Cs0.3Cr2.1Ti5.9O16 ceramic waste form were investigated. It was found that adding Bi2O3 can effectively reduce the sintering temperature and promote densification of Cs-containing hollandite products. The Cs-hollandite ceramic with 2 wt% Bi2O3 sintered at 1000 °C showed a single phase with > 98 % cesium retention, which was ∼ 200 °C lower and ∼ 11 % retention rate higher than those of reported Cs-bearing hollandite. Moreover, the leached sample remained stable tetragonal structure, the LRCs was in the order of 10-3 g·m−2·d-1 after 28 days and the leaching indexes > 8, exhibiting good aqueous stability. This route can be considered as a promising solution to prevent cesium loss for incorporating the cesium waste in ceramic hosts.

Corrosion property investigation of laser-cladding copper coating in the simulated nuclear waste disposal solution

To explore the efficient corrosion protection for the nuclear waste storage containers, pure copper coatings were successfully prepared on the 20# steel pipe surface using an infrared laser system under different laser powers. The study was conducted on the copper coatings, encompassing the surface quality, defects, microstructure, elemental distribution, phase composition, and corrosion products. The electrochemical and immersion corrosion behavior of the copper coatings in simulated nuclear waste disposal solutions was analyzed. The pure copper coating prepared by 2800 W laser power has fewer amounts and smaller sizes of defects inside the coating with only a slight fusion of Cu and Fe elements at the interface, which exhibits the highest corrosion potential and the smallest self-corrosion current density. During the immersion corrosion process, pores and unfused defects inside the coating, as well as the pits formed by galvanic coupling corrosion, lead to enhanced acidity inside these defects, resulting in a higher corrosion rate. As the immersion time proceeds, the corrosion rate slows down gradually and the content of Cu2+ corrosion product increases significantly.

A novel Gd2O3–Al2O3–SiO2 glass-ceramics substrate material with comprehensive performance

A novel Gd2O3–Al2O3–SiO2 glass-ceramics (GAS GCS) for substrate application was prepared using the melt-quenching method. The present study pay attention to investigate the crystallization and sintering behaviors, phase compositions, micromorphology, dielectric and mechanical properties of GAS glass-ceramics. An appropriate amount of Gd2O3 diminished the glass viscosity while enhancing structural stability, thereby reducing the activation energy for crystallization and sintering. This contributed to the GAS GCS achieve dense microstructure and high crystallinity. X-ray diffraction (XRD) and Raman spectroscopy analyses confirmed the presence of high-density crystal phases, namely Gd2SiO5 and Gd2Si2O7, which significantly contribute to the enhanced density of the samples. Moreover, a positive correlation was observed between the dielectric constant and crystallinity. Notably, the GAS GCS composition of 41 wt% Gd2O3-21.3 wt% Al2O3-37.7 wt% SiO2 exhibited optimal properties, including a flexural strength of 243.4 MPa, Vickers hardness of 7.77 GPa, elastic modulus of 154.02 GPa, coefficient of thermal expansion of 5.9 × 10−6/°C, dielectric constant of 7.43, and dielectric loss of 4.05 × 10−3. These outstanding characteristics position it as a promising candidate for substrate materials.

The Effect of W, Cr, Mo Content on the Microstructure and Mechanical Properties of the Weld Interface of TiC Cermet and Low-Carbon Steel

In this study, the influence of W, Cr, and Mo on the microstructure and mechanical properties of the arc-welded interface of TiC cermet and low-carbon steel was investigated. MIG arc welding was employed to deposit muti-alloyed low-carbon steel flux-cored wire onto the surface of the TiC cermet to create the arc-welded interface. Analysis of the microstructure, phase composition, and shear fracture of the interface were conducted by OM (optical microscopy), SEM (scanning electron microscope), EMPA (Electron Probe X-ray Micro-Analyzer), and XRD (X-ray diffraction) methods. The results indicate that the order of influence on the performance of the welded interface is perceived as Cr > W > Mo. The preferred ratio of element content is W at 1.0 wt.%, Cr at 0.5 wt.%, and Mo at 2.0 wt.%. During the arc-welding process, W and Mo formed a rim structure of TiC particles to inhibit the dissolution of TiC particles, while Cr formed dispersed carbides in the bonding phase. The synergistic impact of these components resulted in the simultaneous enhancement of both the TiC particles and the bonding phase. This led to a significant increase in the shear strength of the TiC cermet welded interface to 787 MPa, marking an 83% improvement compared to the welded interface without reinforcement, which exhibited a shear strength of 430 MPa.

Investigation on phase composition and microwave dielectric properties of MgO-SiO2-TiO2 system

Investigation on phase composition and microwave dielectric properties of MgO-SiO2-TiO2 system

Phase composition, crystal structures and enhanced microwave dielectric properties of Mg2+/Zr4+ co-doped Al2Mo3O12 ceramics

In this work, the substitution of Al3+ by Zr/Mg in Al2Mo3O12 was designed to enhance the quality factor while simultaneously adjusting the thermal stability of the resonant frequency. The Al2-2x(Zr0.5Mg0.5)2xMo3O12 (AMZM) (0.1 ≤ x ≤ 0.5) ceramics were synthesized using a simple solid-state method, resulting in all components exhibiting single-phase crystallinity and a dense structure. A phase transition temperature below room temperature was observed when x ≥ 0.4. Furthermore, the quality factor of the synthesized samples, compared to pure-phase Al2Mo3O12 (εr = 6.79, Q×f = 28471GHz, τf = -48.77 ppm/℃), increased by nearly threefold. A detailed investigation of the crystal structure of the samples was conducted through Rietveld refinement. The composition with x = 0.3 (monoclinic phase) exhibited optimal dielectric performance after sintering at 800 ℃ for 6h: εr = 7.84, Q×f = 86511GHz, τf = -42.08 ppm/℃. By forming a composite ceramic with (Li1/2Sm1/2)MoO4, the negative τf value was further adjusted to near zero.

Role of carbide grit size and in-flight particle parameters on the microstructure, phases, and nanoscale properties of HVOF sprayed WC-12Co coatings

Effects of particle temperature and velocity on crystallinity and phase composition of WC-Co coating are successfully decoupled. The effect of grit size on the dissolution and decarburization process is established analytically. The nanostructured coatings were found to be less crystalline than their conventional counterpart for similar in-flight parameters. The cooling rate and the degree of carbide dissolution in the binder phase govern the crystallinity of the as-sprayed coatings. An increase in either of these factors results in a higher degree of amorphization of as-sprayed coatings. The phases present in the coating were quantified, and correlated with particle temperature and velocity independently. The degree of decarburization increased with an increase in particle temperature. The calculated change in Gibbs free energy justified these observations. The effect of particle velocity on crystallinity or phase composition was not significant. The nano hardness of the carbide grits was increased with particle temperature owing to the formation of a hard W2C phase. Similarly, the dissolution of carbides in the binder and the formation of the Co3W9C4 phase increased the binder hardness. The energy analysis revealed brittleness of the binder matrix increased significantly with deposition temperature owing to the formation of the Co3W9C4 phase.

Electromagnetic wave-absorbing of polymer derived rod-like ZrB2 ultrahigh-temperature ceramic composites

Ultra-high temperature ceramics (UHTCs) are candidates that can be used in extremely high temperature environments relative to the Si-based ceramic due to their excellent high-temperature performance. However, there are few researches on the electromagnetic wave absorption of the UHTCs themselves. In this work, rod-like ZrB2 and its composites were prepared by polymer derived method at a lower temperature. The phase composition and electromagnetic wave absorption properties of the ceramics at different pyrolyzed temperatures were analyzed. The rod-like ZrB2 pyrolyzed at 1500 °C shows a RLmin of -54.77dB at a thickness of 4.7mm. The rod-like ZrB2/SiC has an absorption bandwidth of 5.68GHz (RL <-10 dB, 7.6-13.28GHz) at a thickness of 4.25mm, exceeding the X-band. An absorption bandwidth of 2.24GHz for RL <-20 dB (99% absorbed) was obtained by the fabricated composites. The strong absorption of rod-like ZrB2/SiC composites is due to the strong conductive loss and multiple scattering of electromagnetic wave by the rod-like network structure. The formation of core-shell ZrB2/SiC increases the polarization and enhance the electromagnetic wave absorbing properties of the ceramics. The results of this study show that the polymer derived UHTCs have the strong ability to absorb electromagnetic wave.

Bioactivity of radiopaque 45S5 bioactive glass with progressive additions of Bi2O3: A dissolution study under static conditions

The integration of bioactive glasses (BGs) into hard tissues in in-vivo models can be evaluated through X-ray radiographs. The image contrast plays an important role and should be enhanced to improve accurate minimal invasive diagnostics of the performance of BGs containing implants after surgery. The present work shows the effect of the progressive addition of Bi2O3 (up to 12.2 wt%) on the structure, thermal properties, radiopacity, and bioactivity of 45S5-like BG obtained by quenching of the melt prepared from oxide precursors. The BG chemical composition, phase composition, structure, chemical state, thermal properties, and radiopacity were respectively investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and radiopacity analysis according to the ISO13116:2014 norm. The bioactivity of the glasses was monitored by immersing them in a simulated body fluid (SBF) under static conditions. The apatite formation ability and ion concentration in SBF after 3, 7, 14, and 21 days were investigated by XRD, scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and ICP mass spectrometry (ICP-MS). All samples were found to be X-ray amorphous. Simultaneous formation of [BiO3] and [BiO6] units is noted in the BG. The glass radiopacity increased up to 1.8 and 4.2 times compared to the reference glasses without Bi2O3. Bi2O3 additions in the glass slow down the formation of apatite-like structures as a result of the network forming role of [BiO3] and [BiO6] units in the BG. Nevertheless, the BGs with the 12.2 wt % Bi2O3 still shows the ability to form apatite deposits after 7 days of immersion in simulated body fluid (SBF).

Influence of temperature on the nanomechanical characteristics and wear performance of FeCrMoNiBCuSiC coating

This paper introduced a metallic glass coating, Fe50.5Cr20Mo15Ni5B4.5Cu2.5Si1.8C0.6 (wt.%), deposited via high velocity oxygen-fuel (HVOF) spraying. The phase composition, thermodynamic stability, microstructure, nanomechanical characteristics, and wear performance at different temperatures were investigated. The coating exhibited an amorphous/nanocrystalline structure and a crystallization temperature of 632 ℃. The hardness and creep displacements were (11.01±1.24) GPa and 23nm, respectively. After annealing at 300 ℃ and 600 ℃, the corresponding hardness increased to (15.12±1.20) GPa and (17.24±1.49) GPa, while the creep displacements decreased to 7nm and 5nm. The wear rate showed a positive correlation with temperature (T1/2), while the friction coefficient displayed a negative correlation. This study provided new insights into the elevated-temperature wear characteristics of Fe-based metallic glass coatings.

Multiparameter optimization of non-thermal plasma-driven synthesis of carbohydrate-stabilized rhenium nanoparticles towards enhancement of their catalytical activity for reduction of nitroaromatic compounds

This study aims to optimize the synthesis of carbohydrate-stabilized rhenium nanoparticles (ReNPs) utilizing cold atmospheric pressure plasma (CAPP), specifically direct current atmospheric pressure glow discharge (dc-APGD), hypothesizing that controlling synthesis parameters will enhance catalytic efficiency in the reduction of nitroaromatic compounds (NACs). The dc-APGD system operated in flowing liquid cathode (FLC-dc-APGD) and flowing liquid anode (FLA-dc-APGD) modes. Design of experiments (DOE) and response surface methodology (RSM) were employed for the first time to optimize ReNPs synthesis. This included optimizing the concentration of ReO4- in ReNPs precursor solution, solution flow rate as well as discharge current. ReNPs were characterized using high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), and X-Ray photoelectron spectroscopy (XPS). In turn, optical emission spectroscopy (OES) was employed for the identification of reactive species generated in plasma phase that contributed to the synthesis of ReNPs. The resultant sizes, surface charges, and phase compositions were linked with synthesis parameters and then with catalytic activities revealed by the variety of ReNPs. HRTEM photomicrographs revealed spherical and spherical-like morphologies of obtained ReNPs synthesized using FLC-dc-dc-APGD and FLA-dc-APGD modes with the actual sizes of 7.28 ± 2.90nm and 3.24 ± 0.57nm, respectively. Optimized conditions yielded ReNPs with exceptional catalytic activity, reducing 94.9% (FLC-dc-APGD) and 90.5% (FLA-dc-APGD) of 4-nitrophenol (4-NP) with the apparent rate constants (k1) 0.269 and 0.107min-1, respectively. Further, the conversions of 90% were achieved over FLC-dc-APGD-based ReNPs for nitrobenzene (NB), 2,4,6-trinitrophenol (2,4,6-TNP), 2,4-dinitrophenol (2,4-DNP), and 4-nitroaniline (4-NA). In these cases, the k1 values were 0.235, 0.174, 0.070, 0.001min-1 for, respectively. The results allowed to find a correlation between ReNP size distribution, oxidation state, and catalytic activity that suggested a potential for tailored Re nanocatalysts in environmental remediation.

Research on the application of phosphogypsum in magnesium oxysulfate cement: A comparison with sand

Phosphogypsum (PG), as an industrial by-product, has historically suffered from challenges in achieving efficient utilization, resulting in enormous accumulation and environmental contamination. In this study, a certain proportion of PG was employed as a substitute for sand in magnesium oxysulfate cement (MOSC). The effects of PG on the properties, pores distribution, phase composition and microstructure of MOSC were investigated. The results showed that the introduction of PG yielded several beneficial effects, including enhanced volume stability and water resistance, alongside reduced apparent density. However, it also entailed several drawbacks, such as decreased paste flowability, prolonged setting time and increased water absorption rate of the specimens. PG incorporation induced no new crystalline phase, but moderate PG could promote nucleation and development of 5Mg(OH)2∙MgSO4∙7H2O (5∙1∙7 phase) and the group at 10% PG substitution has the highest compressive strength of 68.2 MPa. PG demonstrated the capability to hinder precipitation of Mg(OH)2, thereby enhancing the mechanical properties of MOSC. Due to the affordability and favorable environmental sustainability, PG-MOSC displayed considerable potential for various applications. This study elucidates the mechanism by which PG influences MOSC, providing reference and approach for the recycling of PG.

Effects of Ti on the solidification and crystallization behavior of nanocomposite permanent material under different cooling rates

Effects of Ti on the crystallization behavior, phase composition, microstructure and magnetic properties of Nd2Fe14B/α-Fe dual-phase nanocomposite permanent magnet materials in different states were studied, respectively. The results show that Ti could affect the solidification and crystallization behavior of dual-phase nanocomposite materials by regulating the cooling rate during the rapid solidification process. When the cooling rate is slow, part of Ti atoms enters the soft magnetic phase α-Fe, and part forms the TiFe2 phase around the hard magnetic phase. Exchange coupling is enhanced. The maximum energy product and the remanence of the alloy are 10.54 MGOe and 8.34 kGs, respectively. When the cooling rate faster, Ti can stabilize another ferromagnetic ThMn12-type phase with a low coercivity and maximum energy product, which should be avoided. When the cooling rate is fast enough to form amorphous, Ti and Fe preferentially combine to form the TiFe2 phase during crystallization, which selectively inhibits the growth of the hard magnetic phase and the precipitation of the soft magnetic phase, resulting in a significant enhancement of coercivity to 12.82 kOe. By regulating the mechanism of Ti in the solidification and crystallization process, nanocomposite permanent magnet materials with varying magnetic characteristics can be obtained, offering a flexible approach to tailoring their performance according to specific application requirements.

Studying the formation of nodules in a Ni-Fe-Cr based superalloy used in fireside corrosion under the impact of creep stress

Creep rupture tests on a Ni-Fe-Cr based superalloy were conducted in a custom-built rig at 750 ℃ under simulated fireside corrosion environment. The impact of creep stress on corrosion was investigated by controlling load level (without loading, loads of 120~195MPa). The phase composition, microstructure, and morphology of surface corrosion products and corrosion-affected area were studied. The mechanism responsible for the production of surface nodules and the observed uniform oxide scale during fireside corrosion are discussed. Results show that the presence of creep stress promotes the development of surface nodules and increases the corrosion-affected area.

Analysis of the wear behavior and corrosion resistance of CoCrFeNiMn-2% CNTs laser cladding composite coating

Carbon nanotubes (CNTs), as a kind of nanopowder, can be used as reinforcing powder to improve various properties of coatings because of their good self-lubricating properties and three-dimensional structure. However, CNTs are difficult to mix uniformly with other powders due to their easily disrupted microstructure and extremely low density. Therefore, CoCrFeNiMn HEA and 2 wt.% CNTs were mixed by a new mixing method—alcohol stirring and ball-less ball mill mixing methods. CoCrFeNiMn /2 wt.% CNTs coatings prepared by laser cladding (LC). The phase composition, microstructure, wear resistance, and corrosion resistance of the HEA/CNTs coating were analyzed by various characterization techniques. The results showed that grain refinement occurred in the coatings after adding CNTs, generating fine carbides. It was calculated that the densification percentage of the HEA/CNTs coating increased and the porosity decreased. Compared with the HEA coating, the microhardness of the HEA/CNTs coating increased by 101.66%, and the friction coefficient and wear rate of the HEA/CNTs coating were only 63.30% and 6.22% of the HEA coating. The more positive Ecorr and smaller Icorr indicated that the HEA/CNTs coating has better corrosion resistance.

Surface aspects of novel Bio-HEAs MAO-treated in a Ca-, P-, and Mg-rich electrolyte

This study evaluated the effect of alloying elements, applied voltage, and bioactive species (Ca, P, and Mg) enrichment during the micro-arc oxidation (MAO) treatment of novel high entropy alloys (HEAs) targeted for biomedical applications. The non-equiatomic TiZrNbTaMo (TaMo), TiZrNbTaMn (TaMn), and TiZrNbFeMo (FeMo) samples were submitted to MAO treatment at distinct voltages (100, 200, and 300 V), then their chemical, phase, and morphological aspects were evaluated by x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM). Finally, the preliminary physicochemical behavior regarding contact angle and surface energy in distilled water at room temperature was evaluated. The results indicated that the alloying elements played a global role in the bulk’s phase composition, possessing distinct proportions of BCC and HCP phases. The MAO-treated surfaces depicted different mechanisms of anodic oxide growth and dielectric breakdown, forming the typical porous surface at distinct applied voltages. The bioactive species (Ca, P, and Mg) were gradually enriched in the oxide layer, composed of distinct nano-crystalline and amorphous layers that are typical of MAO-treated surfaces. As a result, roughness, contact angle and surface energy values of the MAO-treated samples were affected by the applied voltage and the bulk’s chemical composition, indicating potential for use in the biomedical field, especially as long-term implants and bone fixation devices.

Preparation of wide bandgap CuGaSe2 absorbers and solar cells by sputtering a selenium-rich ceramic target and annealing in a selenium-free atmosphere

CuGaSe2 (CGSe) material possesses a wide bandgap of approximately 1.7 eV, making it a promising prospect for top cells in tandem solar cells. Depositing CGSe precursor films by magnetron sputtering of a selenium-rich ceramic target is easy to operate and control. After annealing the precursor films at different temperatures in a selenium-free argon atmosphere, avoiding the use of toxic H2Se. To achieve an absorber exhibiting appropriate performance, the morphologies, phase composition, absorption characteristics, roughness, lattice structure, and work function of CGSe absorbers annealed at different temperatures were investigated. The CGSe absorber annealed at 550 °C showed uniform grain, a single-phase composition, high absorbance, flat surface, and compact crystal structure. The absorber annealed at excessive temperature led to the formation of Cu2-xSe, inducing defects and carrier recombination. The work function of CGSe absorber annealed at 590 °C increases, resulting in the misalignment of its band with the Mo back contact. The enhancement of absorber contributes positively to solar cell device performance. CGSe solar cells prepared using the absorber annealed at 550 °C exhibited excellent photoelectric properties. The increase in minority carrier lifetime and recombination resistance improves the transport characteristics of carriers.

Effect of hexagonal boron nitride content on the anisotropy of hot-press-sintered AlN/BN composite ceramics

The AlN/BN composite ceramic, fabricated via hot-press sintering, exhibits obvious anisotropy due to the establishment of directional alignment of h-BN. However, the variation and influence mechanisms of bending strength (σ) and thermal conductivity (λ) are remain unclear in different directions, which greatly limit the application of AlN/BN composite ceramics. In this paper, the effects of h-BN content on phase composition, microstructure and anisotropy of AlN/BN composite ceramics are discussed in detail. The results reveal that AlN/BN composite ceramics have three directions: perpendicular (⊥), longitudinal parallel (∥), and lateral parallel (≡) to the hot-pressing direction. The content of h-BN is a crucial factor affecting the anisotropy of AlN/BN composite ceramics. h-BN enhances the thermal conductivity in the ∥ and hinders the thermal conductivity in the ⊥. With the increase in h-BN amount, λ∥ rises gradually, while λ⊥ gradually falls. When the mass percentage of h-BN and AlN is 25% (AB25), the λ∥ is as high as 90 W·m−1·K−1, which is about 2.25 times that of λ⊥. In terms of mechanical properties, σ≡ and σ⊥ first increase and then decrease, while σ∥ only decreases. This is attributable to h-BN being effective in enhancing mechanical properties by inhibiting crack propagation in the ⊥ and ≡ direction, while the promotion of crack propagation leads to a decrease in mechanical properties in the ∥ direction. σ≡ reaches the highest values (σ≡ = 460.2 MPa) at an h-BN amount of 10% (AB10), which is about 1.19 and 2.04 times that of σ⊥ and σ∥, respectively, and 22.1% higher than that of AB0.

Effects of Cr2O3 doping on crystallization behavior and electrochemical properties of Li2O–Al2O3–TiO2–P2O5–SiO2 glass-ceramics

Bulk glass-ceramic solid electrolytes of the Li2O–Al2O3–TiO2–P2O5–SiO2 system were prepared by melt-quenching and one-step heat treatment method in this work. The effects of the gradual substitution of Al3+ by Cr3+ and the elevation of the heat treatment temperature on the phase composition, microstructure, and ionic conductivity of the solid electrolytes were systematically investigated. The results show that the major crystalline phase is LiTi2(PO4)3, and the conductivity of the glass-ceramics initially enhances and then decreases as the Cr2O3 content increases from 0 mol% to 3 mol%. The highest conductivity is obtained when the Cr2O3 content is 2 mol%, measuring 4.45 × 10−4 S/cm at 25 °C. Additionally, the mechanism of the surface exfoliation of the glass-ceramics and the enhancement achieved by doping with Cr3+ are explained according to microstructure analysis. This work provides a simple method to enhance the electrical conductivity and physical properties of LATP glass-ceramic solid electrolytes, which is of great significance for the design of lithium-ion solid electrolytes.

Sintering behavior and densification mechanism of MoOx targets obtained by hot pressing

MoOx targets for magnetron sputtering Mo–O films were obtained by vacuum hot pressing sintering. MoOx powder was obtained by hydrogen reduction of MoO3, and the O/Mo atomic ratio was determined by the k-value method. The sintering behavior and densification mechanism of the MoOx target were analyzed by exploring the influence of hot pressing sintering pressure, temperature, and holding time on the target's density, phase composition, and morphology. MoOx targets with different oxygen content were sintered using MoOx powder with O/Mo of 2.838, 2.679, and 2.494, respectively. The results reveal that complex reactions occur in the shrinkage stage of sintering. The content of Mo4O11 increases, the content of Mo9O26 and MoO2 decreases, and the oxygen content of the targets is positively correlated with the content of MoO2 in MoOx powder. Subsequently, Mo4O11 grain growth densifies the targets. Excessive sintering temperature and pressure will cause the decomposition of Mo4O11, resulting in a decrease in density. Finally, the MoO2.623 target with a density of 97.85 % was obtained by hot pressing sintering with MoO2.494 as raw material at 973 K, 40 MPa, and holding temperature for 60 min. Raman mapping shows the MoO2.623 target with 16.9 wt% MoO2 and 83.1 wt% Mo4O11, and the phase distribution was uniform.