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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Selective CW Laser Synthesis of MoS2 and Mixture of MoS2 and MoO2 from (NH4)2MoS4 Film

Very recently, the synthesis of 2D MoS2 and WS2 through pulsed laser-directed thermolysis can achieve wafer-scale and large-area structures, in ambient conditions. In this paper, we report the synthesis of MoS2 and MoS2 oxides from (NH4)2MoS4 film using a visible continuous-wave (CW) laser at 532 nm, instead of the infrared pulsed laser for the laser-directed thermolysis. The (NH4)2MoS4 film is prepared by dissolving its crystal powder in DI water, sonicating the solution, and dip-coating onto a glass slide. We observed a laser intensity threshold for the laser synthesis of MoS2, however, it occurred in a narrow laser intensity range. Above that range, a mixture of MoS2 and MoO2 is formed, which can be used for a memristor device, as demonstrated by other research groups. We did not observe a mixture of MoS2 and MoO3 in the laser thermolysis of (NH4)2MoS4. The laser synthesis of MoS2 in a line pattern is also achieved through laser scanning. Due to of the ease of CW beam steering and the fine control of laser intensities, this study can lead toward the CW laser-directed thermolysis of (NH4)2MoS4 film for the fast, non-vacuum, patternable, and wafer-scale synthesis of 2D MoS2.

(NH4)2MoS4↗
DOE OSTI2025

From Pollutant Removal to Renewable Energy: MoS2-Enhanced P25-Graphene Photocatalysts for Malathion Degradation and H2 Evolution

The widespread presence of pesticides—especially malathion—in aquatic environments presents a major obstacle to conventional remediation strategies, while the ongoing global energy crisis underscores the urgency of developing renewable energy sources such as hydrogen. In this context, photocatalytic water splitting emerges as a promising approach, though its practical application remains limited by poor charge carrier dynamics and insufficient visible-light utilization. Herein, we report the design and evaluation of a series of TiO2-based ternary nanocomposites comprising commercial P25 TiO2, reduced graphene oxide (rGO), and molybdenum disulfide (MoS2), with MoS2 loadings ranging from 1% to 10% by weight. The photocatalysts were fabricated via a two-step method: hydrothermal integration of rGO into P25 followed by solution-phase self-assembly of exfoliated MoS2 nanosheets. The composites were systematically characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Photocatalytic activity was assessed through two key applications: the degradation of malathion (20 mg/L) under simulated solar irradiation and hydrogen evolution from water in the presence of sacrificial agents. Quantification was performed using UV-Vis spectroscopy, gas chromatography–mass spectrometry (GC-MS), and thermal conductivity detection (GC-TCD). Results showed that the integration of rGO significantly enhanced surface area and charge mobility, while MoS2 served as an effective co-catalyst, promoting interfacial charge separation and acting as an active site for hydrogen evolution. Nearly complete malathion degradation (~100%) was achieved within two hours, and hydrogen production reached up to 6000 µmol g−1 h−1 under optimal MoS2 loading. Notably, photocatalytic performance declined with higher MoS2 content due to recombination effects. Overall, this work demonstrates the synergistic enhancement provided by rGO and MoS2 in a stable P25-based system and underscores the viability of such ternary nanocomposites for addressing both environmental remediation and sustainable energy conversion challenges.

Chemistry↗
DOE OSTI2024

Hydrogen Production and Li-Ion Battery Performance with MoS2-SiNWs-SWNTs@ZnONPs Nanocomposites

This study explores the hydrogen generation potential via water-splitting reactions under UV-vis radiation by using a synergistic assembly of ZnO nanoparticles integrated with MoS2, single-walled carbon nanotubes (SWNTs), and crystalline silicon nanowires (SiNWs) to create the MoS2-SiNWs-SWNTs@ZnONPs nanocomposites. A comparative analysis of MoS2 synthesized through chemical and physical exfoliation methods revealed that the chemically exfoliated MoS2 exhibited superior performance, thereby being selected for all subsequent measurements. The nanostructured materials demonstrated exceptional surface characteristics, with specific surface areas exceeding 300 m2 g−1. Notably, the hydrogen production rate achieved by a composite comprising 5% MoS2, 1.7% SiNWs, and 13.3% SWNTs at an 80% ZnONPs base was approximately 3909 µmol h−1g−1 under 500 nm wavelength radiation, marking a significant improvement of over 40-fold relative to pristine ZnONPs. This enhancement underscores the remarkable photocatalytic efficiency of the composites, maintaining high hydrogen production rates above 1500 µmol h−1g−1 even under radiation wavelengths exceeding 600 nm. Furthermore, the potential of these composites for energy storage and conversion applications, specifically within rechargeable lithium-ion batteries, was investigated. Composites, similar to those utilized for hydrogen production but excluding ZnONPs to address its limited theoretical capacity and electrical conductivity, were developed. The focus was on utilizing MoS2, SiNWs, and SWNTs as anode materials for Li-ion batteries. This strategic combination significantly improved the electronic conductivity and mechanical stability of the composite. Specifically, the composite with 56% MoS2, 24% SiNWs, and 20% SWNTs offered remarkable cyclic performance with high specific capacity values, achieving a complete stability of 1000 mA h g−1 after 100 cycles at 1 A g−1. These results illuminate the dual utility of the composites, not only as innovative catalysts for hydrogen production but also as advanced materials for energy storage technologies, showcasing their potential in contributing to sustainable energy solutions.

Chemistry↗
DOE OSTI2019

Defect Healing in Layered Materials: A Machine Learning-Assisted Characterization of MoS2 Crystal Phases

Monolayer MoS2 is an outstanding candidate for a next-generation semiconducting material because of its exceptional physical, chemical, and mechanical properties. To make this promising layered material applicable to nanostructured electronic applications, synthesis of a highly crystalline MoS2 monolayer is vitally important. Among different types of synthesis methods, chemical vapor deposition (CVD) is the most practical way to synthesize few- or mono-layer MoS2 on the target substrate owing to its simplicity and scalability. However, synthesis of a highly crystalline MoS2 layer remains elusive. This is because of the number of grains and defects unavoidably generated during CVD synthesis. Here, we perform multimillion-atom reactive molecular dynamics (RMD) simulations to identify an origin of the grain growth, migration, and defect healing process on a CVD-grown MoS2 monolayer. RMD results reveal that grain boundaries could be successfully repaired by multiple heat treatments. Our work proposes a new way of controlling the grain growth and migration on a CVD-grown MoS2 monolayer.

Hong, Sungwook↗
DOE OSTI2019

Measuring nanoscale thermal gradients in suspended MoS2 with STEM-EELS

Transition metal dichalcogenides such as molybdenum disulfide (MoS2) may see service in the heart of next-generation nanoelectronic devices, where highly localized power dissipation can produce nontrivial temperature gradients over nanometer-scale distances. Here, we demonstrate that MoS2 is a promising target for plasmon energy expansion thermometry (PEET), a high-spatial resolution temperature mapping technique employed in a scanning transmission electron microscope (STEM) equipped with electron energy loss spectroscopy (EELS). We first use a calibrated, commercial MEMS-style TEM sample heater chip to measure the temperature dependence of the MoS2 bulk plasmon. We corroborate the chip's temperature calibration with Raman thermometry and determine the bulk thermal expansion coefficient (TEC) of MoS2 in the temperature range of 300–1100 K. Applying this TEC value to PEET measurements on a suspended MoS2 flake, we map 70–90 K/μm temperature gradients with a submicrometer spatial resolution.

Shen, Lang (ORCID:0000000297554821)↗
DOE OSTI2024

Intercalation of quaternary ammonium cations as a key factor of electron storage in MoS2 thin films

Electrochemical intercalation of cations within two-dimensional transition metal dichalcogenides presents a promising route for tailoring their optoelectronic properties. We have now succeeded in modulating the optical properties of MoS2 thin films through electrochemical intercalation of quaternary ammonium cations. The spectroelectrochemical experiments conducted with varying sizes of the intercalant revealed the size-dependent stability of the intercalated MoS2 nanosheets. The observed absorption change of the exciton bands is reversible and arises from the storage of electrons in MoS2 nanosheets and the subsequent weakening of interlayer van der Waals interactions following cation intercalation. This structural change is evidenced by the emergence of A*1g out-of-plane Raman mode. Additionally, the photoelectron spectroscopy reveals the emergence of a lower binding energy component of Mo 3d and the shift in Fermi level to higher energies, confirming the presence of stored electrons in cation intercalated-MoS2. The underlying mechanism of intercalation-induced property modifications in MoS2 discussed in the present study is useful in developing strategies for energy conversion devices.

Physics↗
DOE OSTI2026

Temperature-Dependent Transport Characteristics of 2D MoS2 Channel FETs Grown Using Salt-Based Precursors

D Transition Metal Dichalcogenides (TMDs), particularly MoS2, are promising candidates for sub-10 nm Gate All Around (GAA) CMOS FETs. Salt-assisted Chemical Vapor Deposition (CVD) enable lateral MoS2 growth at atmospheric pressure and low temperatures. This work analyzes salt-based precursor-driven CVD-grown MoS2 FETs at various temperatures. MoS2 was grown using Ammonium Molybdate salt, sulfurized at 750∘C, and transferred onto p−Si3/SiO2 substrates. At room temperature, threshold voltage (VT) ranged from -35 V to -25 V, with a peak drain current of 1.2μA/μm. As temperature increased above 325K, VT shifted exponentially, and carrier mobility dropped significantly. At 400 K, the gate lost channel control, though gate leakage current remained low. These results are compared with non-salt-based MoS2 growth to assess salt precursor effects.Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (https://www.energy.gov/doe-public-access-plan).

Jones, Andrew [ORNL] (ORCID:0009000233849687)↗
DOE OSTI2020

Materials Data on Sb(MoS2)6 by Materials Project

(MoS2)6Sb crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one antimony molecule and four MoS2 clusters. In two of the MoS2 clusters, Mo+4.50+ is bonded in a 2-coordinate geometry to two S2- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) Mo–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+4.50+ and one S2- atom. The S–S bond length is 2.08 Å. In the second S2- site, S2- is bonded in a 2-coordinate geometry to one Mo+4.50+ and one S2- atom. In two of the MoS2 clusters, there are two inequivalent Mo+4.50+ sites. In the first Mo+4.50+ site, Mo+4.50+ is bonded in a 1-coordinate geometry to two S2- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) Mo–S bond lengths. In the second Mo+4.50+ site, Mo+4.50+ is bonded in a 1-coordinate geometry to two S2- atoms. There are one shorter (2.32 Å) and one longer (2.33 Å) Mo–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to one Mo+4.50+ and one S2- atom. The S–S bond length is 2.09 Å. In the second S2- site, S2- is bonded in a 1-coordinate geometry to one Mo+4.50+ and one S2- atom. The S–S bond length is 2.09 Å. In the third S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+4.50+ and two S2- atoms. The S–S bond length is 3.75 Å. In the fourth S2- site, S2- is bonded in a 1-coordinate geometry to one Mo+4.50+ and two S2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg(MoS2)6 by Materials Project

Hg(MoS2)6 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one mercury molecule and four MoS2 clusters. In two of the MoS2 clusters, Mo+3.67+ is bonded in a 1-coordinate geometry to two S2- atoms. Both Mo–S bond lengths are 2.32 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+3.67+ and one S2- atom. The S–S bond length is 2.08 Å. In the second S2- site, S2- is bonded in a 1-coordinate geometry to one Mo+3.67+ and one S2- atom. In two of the MoS2 clusters, there are two inequivalent Mo+3.67+ sites. In the first Mo+3.67+ site, Mo+3.67+ is bonded in a 1-coordinate geometry to two S2- atoms. Both Mo–S bond lengths are 2.32 Å. In the second Mo+3.67+ site, Mo+3.67+ is bonded in a 1-coordinate geometry to two S2- atoms. There are one shorter (2.31 Å) and one longer (2.32 Å) Mo–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to one Mo+3.67+ and one S2- atom. The S–S bond length is 2.08 Å. In the second S2- site, S2- is bonded in a 1-coordinate geometry to one Mo+3.67+ and one S2- atom. The S–S bond length is 2.08 Å. In the third S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+3.67+ and two S2- atoms. The S–S bond length is 4.07 Å. In the fourth S2- site, S2- is bonded in a distorted single-bond geometry to one Mo+3.67+ and two S2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Pressure‐Induced Metallization and Isostructural Transitions in 3R‐MoS2

At ambient conditions 3R-polytypes of transition metal dichalcogenides (TMDs) demonstrate fascinating properties because of their unique layer stacking. Understanding the structure-property relationship is essential for the realization of their use in spintronic, valleytronic, and optoelectronic applications. Herein, after the high pressure-temperature synthesis of 3R-MoS2 in a large volume cubic press, a concomitant experimental and theoretical high-pressure study of 3R-MoS2 is reported, leading to the discovery of pressure-induced reversible isostructural phase transitions without symmetry breaking. Concurrent with the isostructural transitions, a semiconductor-to-metal transition is observed, owing to strong interlayer interaction and charge redistribution across the van der Waals gap under pressure. The pressure-induced enhancement of interlayer interactions together with the robust intrinsic layer stacking in 3R-MoS2 prevent the layers from sliding under pressure and hinder a corresponding volume collapse. This study on continuous pressure-tuning of crystal and electronic structure in 3R-MoS2 will play a vital role in developing the next-generation devices involving coupling of structural, optical, and electrical properties of 3R-polytypes of TMDs and other layered materials.

Ahmad, Azkar Saeed↗
DOE OSTI2026

Irradiation-Induced Structural Disorder and Its Influence on the Mechanical Response of Polycrystalline MoS2

Molybdenum disulfide (MoS2) thin films are widely used as dry-film lubricants and protective coatings in aerospace and other radiation-exposed environments. Conventional synthesis routes produce polycrystalline films whose grain boundaries and other native defects cause their mechanical and tribological behavior to differ substantially from that of ideal single crystals. Under irradiation, these films progressively evolve from polycrystalline structures, composed of layered MoS2 grains, into highly disordered and eventually amorphous structures, altering both their tribological performance and mechanical integrity. Here, we employ reactive atomistic simulations to investigate irradiation-driven structural evolution in bulk polycrystalline MoS2. Using controlled primary knock-on atom (PKA) events, we characterize the progressive transition from a polycrystalline microstructure to an amorphous network by tracking defect accumulation and structural disorder. We then establish how this transition modifies the dominant deformation mechanisms and the temperature-dependent tensile response. Specifically, irradiation suppresses interlayer sliding and delamination, mechanisms which facilitate the deformation of the pristine polycrystal, resulting in defect-induced hardening. Broadly, our results establish direct process–structure–property relationships linking irradiation-induced defect accumulation, microstructural evolution, deformation mechanisms, and mechanical behavior, providing an atomistic framework for understanding the structural integrity and long-term reliability of irradiated MoS2 coatings.

Moore, Daniel [Sandia National Laboratories (SNL)]↗
DOE OSTI2020

Site-dependent reactivity of MoS2 nanoparticles in hydrodesulfurization of thiophene

The catalytically active site for the removal of S from organosulfur compounds in catalytic hydrodesulfurization has been attributed to a generic site at an S-vacancy on the edge of MoS2 particles. However, steric constraints in adsorption and variations in S-coordination means that not all S-vacancy sites should be considered equally active. Here, we use a combination of atom-resolved scanning probe microscopy and density functional theory to reveal how the generation of S-vacancies within MoS2 nanoparticles and the subsequent adsorption of thiophene (C4H4S) depends strongly on the location on the edge of MoS2. Thiophene adsorbs directly at open corner vacancy sites, however, we find that its adsorption at S-vacancy sites away from the MoS2 particle corners leads to an activated and concerted displacement of neighboring edge S. This mechanism allows the reactant to self-generate a double CUS site that reduces steric effects in more constrained sites along the edge.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Interconnected Vertically Stacked 2D-MoS2 for Ultrastable Cycling of Rechargeable Li-Ion Battery

2D layer structured material is often high-capacity ionic storage material with fast ionic transport within the layers. This appears to be the case for non-conversion layer structure, such as graphite. However, this is not the case for conversion-type layered structure such as transition metal sulfide, in which localized congestion of ionic species adjacent to the surface will induce localized conversion, leading to the blocking of the fast diffusion channels and fast capacity fading, which therefore constitutes one of the critical barriers for the application of transition metal sulfide layered structure. In this work, we report the tackling of this critical barrier through nanoscale engineering. We discover that vertically-stacked 2D-MoS2 can dramatically enhance the cycling stability. Atomic level in-situ TEM observation reveals that the MoS2 nanocakes assembled with tangling (100)-terminated nanosheets offer abundant open channels for Li+ insertion through the (100) surface, featuring an enhanced cyclability performance for over 200 cycle with a capacity retention of 90%. In contrast, (001)-terminated MoS2 nanoflowers only retains 10% of original capacity after 50 cycles. The present work demonstrates a general principle and opens a new route of crystallographic design to enhance electrochemical performance for assembling 2D materials for energy storage.

Sun, Congli↗
DOE OSTI2021

Electronic structure modulation of MoS2 by substitutional Se incorporation and interfacial MoO3 hybridization: Implications of Fermi engineering for electrocatalytic hydrogen evolution and oxygen evolution

The design of earth-abundant electrocatalysts that can facilitate water splitting at low overpotentials, provide high current densities, and enable prolonged operational lifetimes is central to the production of sustainable fuels. The distinctive atomistic and electronic structure characteristics of the edges of MoS2 imbue high reactivity toward the hydrogen evolution reaction. MoS2 is nevertheless characterized by significantly high overpotentials as compared to platinum. Here, we demonstrate that modulation of the electronic structure of MoS2 through interfacial hybridization with MoO3 and alloying of selenium on the anion sublattice allows for systematic lowering of the conduction band edge and raising of the valence band edge, respectively. The former promotes enhanced electrocatalytic activity toward hydrogen evolution, whereas the latter promotes enhanced activity toward the oxygen evolution reaction. Such alloyed heterostructures prepared by sol-gel reactions and hydrothermal selenization expose a high density of edge sites. The alloyed heterostructures exhibit low overpotential, high current density, high turnover frequency, and prolonged operational lifetime. The mechanistic origins of catalytic activity have been established based on electronic structure calculations and x-ray absorption and emission spectroscopy probes of electronic structure, which suggest that interfacial hybridization at the MoO3 interface yields low-lying conduction band states that facilitate hydrogen adsorption. In contrast, shallow Se 4p-derived states give rise to a raised effective valence band maximum, which facilitates adsorption of oxygen intermediates and engenders a low overpotential for the oxygen evolution reaction. The findings illustrate the use of electronic structure modulation through interfacial hybridization and alloying to systematically improve electrocatalytic activity.

Parija, Abhishek↗
DOE OSTI2020

Materials Data on MoS2 by Materials Project

MoS2 is Molybdenite-like structured and crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three MoS2 sheets oriented in the (0, 0, 1) direction. Mo4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. All Mo–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoS2 by Materials Project

MoS2 is Molybdenite structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two MoS2 sheets oriented in the (0, 0, 1) direction. Mo4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. All Mo–S bond lengths are 2.42 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MoS2 by Materials Project

MoS2 is trigonal omega-like structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one MoS2 sheet oriented in the (0, 0, 1) direction. Mo4+ is bonded to six equivalent S2- atoms to form edge-sharing MoS6 octahedra. All Mo–S bond lengths are 2.44 Å. S2- is bonded in a 3-coordinate geometry to three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Materials Data on MoS2 by Materials Project

MoS2 crystallizes in the orthorhombic Pmmn space group. The structure is one-dimensional and consists of two MoS2 ribbons oriented in the (1, 0, 0) direction. there are eight inequivalent Mo4+ sites. In the first Mo4+ site, Mo4+ is bonded to six equivalent S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.41 Å) and two longer (2.42 Å) Mo–S bond lengths. In the second Mo4+ site, Mo4+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.41 Å) and two longer (2.42 Å) Mo–S bond lengths. In the third Mo4+ site, Mo4+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.41 Å) and two longer (2.42 Å) Mo–S bond lengths. In the fourth Mo4+ site, Mo4+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.41 Å) and two longer (2.42 Å) Mo–S bond lengths. In the fifth Mo4+ site, Mo4+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.41 Å) and two longer (2.42 Å) Mo–S bond lengths. In the sixth Mo4+ site, Mo4+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.42 Å) and two longer (2.47 Å) Mo–S bond lengths. In the seventh Mo4+ site, Mo4+ is bonded in a distorted square co-planar geometry to four equivalent S2- atoms. All Mo–S bond lengths are 2.39 Å. In the eighth Mo4+ site, Mo4+ is bonded to six S2- atoms to form distorted edge-sharing MoS6 pentagonal pyramids. There are four shorter (2.39 Å) and two longer (2.42 Å) Mo–S bond lengths. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. The S–Mo bond length is 2.42 Å. In the third S2- site, S2- is bonded in an L-shaped geometry to two equivalent Mo4+ atoms. In the fourth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the fifth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the sixth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the seventh S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms. In the eighth S2- site, S2- is bonded in a 3-coordinate geometry to three Mo4+ atoms.

36 MATERIALS SCIENCE↗