Structure-property correlations in molybdenum trioxide thin films and nanoparticles

Bhatia, Shally; Khanna, Atul; Jain, Rahul; Hirdesh,

doi:10.1088/2053-1591/ab1855

Cited by 11 publications

(7 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates structural damage and the photo-oxidation of MoS 2 to MoO 3 . , The absence of the Raman mode is the result of the amorphous nature of the oxide. MoO 3 is a wide band gap semiconductor (3.2 eV) . Therefore, no PL is observed because the band gap is larger than the excitation energy.…”

Section: Resultsmentioning

confidence: 99%

“…MoO 3 is a wide band gap semiconductor (3.2 eV). 47 Therefore, no PL is observed because the band gap is larger than the excitation energy. In the center of the flake (Figure S5h), the intensity of the Raman modes and PL is reduced by the structural damage and photo-oxidation, but the PL peak appears at the same position as compared to the as-prepared flake.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Real-Time Observation of Photo-oxidation of Single MoS₂ Flakes Using Stochastic Optical Reconstruction Microscopy

Jelken,

Lambin,

Avilés

et al. 2023

J. Phys. Chem. C

View full text Add to dashboard Cite

We report on molybdenum disulfide (MoS 2 ) flakes grown by chemical vapor deposition (CVD), which exhibit an increased photoluminescence (PL) intensity at the edge of the flake under moderate irradiation. The photo-induced chemisorption of O 2 and H 2 O to sulfur vacancies in the edge regions is the origin of the modulated PL intensity. The MoS 2 flakes were analyzed utilizing correlated multispectral wide-field microscopy with stochastic optical reconstruction microscopy (STORM). The advantage of the wide-field approach compared to conventional point scanning microscopy is a faster acquisition over a larger field of view without exposing the sample to high irradiance conditions. This enables in situ and realtime measurements of the PL intensity fluctuations and the identification of defects within the flake. The STORM postprocessing reveals fine structures within the flake and enhances the contrast, which cannot be revealed by point scanning microscopy. In particular, by increasing the intensity over the nondestructive threshold, the stochastic optical reconstruction enables the study of the kinetics of defect domain generation with reduced PL and Raman intensity caused by lattice defects or photo-oxidation of MoS 2 to MoO 3 . Additional measurements of the work function by Kelvin force microscopy, the topography, and the friction force by AFM reveal that the defect domains start to form at the edge of the flake, with a larger interlayer height and work function but reduced friction force compared to MoS 2 . The stochastic optical reconstruction microscopy postprocessing is a powerful technique to understand the layer-by-layer photo-oxidation of MoS 2 flakes and gives new insights in the design of, for example, MoS 2 /MoO 3 heterostructures.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Real-Time Observation of Photo-oxidation of Single MoS₂ Flakes Using Stochastic Optical Reconstruction Microscopy

Jelken,

Lambin,

Avilés

et al. 2023

J. Phys. Chem. C

View full text Add to dashboard Cite

show abstract

“…It forms a layered structure by zigzag chains of [MoO 6 ] octahedral units shared at edges and corners so that layers are linked together by weak Van der Waals bindings. [MoO 6 ] octahedral units determine the lattice type and hence the phase stability of molybdenum trioxide [10,20,21]. The metastable monoclinic phase occurs in cubic ReO 3 type structures, and it is created by [MoO 6 ] octahedral units joined together only at corners [5,22].…”

Section: Introductionmentioning

confidence: 99%

Room-temperature growth optimization and PL characteristic of polytype h/α-MoO₃ thin films by chemical precipitation method

Ghaleghafi¹,

Rahmani²

2022

Phys. Scr.

View full text Add to dashboard Cite

In this study, MoO3 thin films were coated using a simple chemical precipitation technique at room temperature, without using an autoclave or other complex equipment. Films were deposited on precoated MoO3 seed layers prepared by spray pyrolysis on glass substrates. The effects of the seed layer growth conditions and pH value of the precipitation method’s solution on the characteristics of MoO3 films were investigated. The Raman and X-ray diffraction techniques showed that MoO3 films have grown in mixed hexagonal (h) and orthorhombic (α) crystal structures and the scanning electron microscope verified that the samples’ surface was covered of both hexagonal micro rods and lamellar micro belts. The XRD patterns indicated that the crystallinity was significantly improved using a seed layer sprayed under lower carrier gas pressure, and lower pH value of the precipitation method’s solution. The UV–Visible spectra showed that using seed layers prepared at higher carrier gas pressure decreases the bandgap of the films prepared by precipitation, due to the incorporation of more oxygen vacancies. The photoluminescence studies showed that the film deposited at a higher solution’s pH value has higher PL intensity, which indicates that this sample is a suitable candidate for optoelectronic applications.

show abstract

“…In addition, PXRD obtains broader reflections and lower absolute intensities for smaller average crystallite size and for decreased crystal quality. , Although spectroscopic methods, such as IR , and Raman, , can obtain raw material crystalline and polymorph identification in a non-destructive manner, these methods are more conducive to investigate crystallinity on the surface, with little studies have being done in the bulk. For example, although Bhatia et al were able to use high-resolution low-frequency Raman in order to analyze the crystal structure on the surface for both amorphous and crystalline films of molybdenum trioxide, Raman was unable to analyze the bulk nanocrystal structure without implementation of XRD as well . In addition, even though the new spectroscopic improvements concerning ssNMR improved sensitivity in order to give unique insights into the microscopic and macroscopic structure of APIs, these studies have been mainly applied to microcrystalline solids from ground commercial tablets, leading to average ensemble measurements .…”

Section: Introductionmentioning

confidence: 99%

“…For example, although Bhatia et al were able to use high-resolution low-frequency Raman in order to analyze the crystal structure on the surface for both amorphous and crystalline films of molybdenum trioxide, Raman was unable to analyze the bulk nanocrystal structure without implementation of XRD as well. 21 In addition, even though the new spectroscopic improvements concerning ssNMR improved sensitivity in order to give unique insights into the microscopic and macroscopic structure of APIs, these studies have been mainly applied to microcrystalline solids from ground commercial tablets, leading to average ensemble measurements. 22 Similar to the techniques discussed, most other benchtop methods do not have great penetration or high enough sensitivity to measure trace crystallinity within a bulk sample.…”

Section: ■ Introductionmentioning

confidence: 99%

Disparities of Single-Particle Growth Rates in Buried Versus Exposed Ritonavir Crystals within Amorphous Solid Dispersions

et al. 2020

View full text Add to dashboard Cite

Seeded growth rates of ritonavir in copovidone at 75% relative humidity (RH) and 50 °C were evaluated by single-particle tracking second harmonic generation (SHG) microscopy and found to be ∼3-fold slower for crystallites at the surface compared to the bulk. The shelf lives of final dosage forms containing amorphous solid dispersions (ASDs) are often dictated by the rates of active pharmaceutical ingredient crystallization. Upon exposure to elevated RH, the higher anticipated water content near the surfaces of ASDs has the potential to substantially impact nucleation and growth kinetics relative to the bulk. However, quantitative assessment of these differences in growth rates is complicated by challenges associated with discrimination of the two contributions (supersaturation and molecular mobility) in ensemble-averaged measurements. In the present study, "sandwich" materials were prepared, in which sparse populations of ritonavir single-crystalline seeds were pressed between two similar ASD films to assess bulk crystallization rates. These sandwich materials were compared and contrasted with analogously prepared "open-faced" samples, without the capping film, to assess the surface crystallization rates. Single-particle analysis by SHG microscopy time-series during in situ crystallization produced average growth rates of 3.8 μm/h for bulk columnar crystals with a particle-to-particle standard deviation of 0.9 μm/h. In addition, columnar crystal growth rates for surface particles were measured to be 1.3 μm/h and radiating crystal growth rates for surface particles were measured to be 1.0 μm/h, both with a particle-to-particle deviation of 0.4 μm/h. The observed appearance of radiating crystals upon surface seeding is attributed to reduced ritonavir solubility upon water adsorption at the interface, leading to higher defect densities in crystal growth. Despite substantial differences in crystal habit, correction of the surface growth rates by a factor of 4 from geometric effects resulted in relatively minor but statistically significant differences in the growth kinetics for the two local environments. These results are consistent, with viscosity being a relatively weak function of water absorption coupled with primarily diffusion-limited growth kinetics.

show abstract

Structure-property correlations in molybdenum trioxide thin films and nanoparticles

Cited by 11 publications

References 42 publications

Real-Time Observation of Photo-oxidation of Single MoS₂ Flakes Using Stochastic Optical Reconstruction Microscopy

Real-Time Observation of Photo-oxidation of Single MoS₂ Flakes Using Stochastic Optical Reconstruction Microscopy

Room-temperature growth optimization and PL characteristic of polytype h/α-MoO₃ thin films by chemical precipitation method

Disparities of Single-Particle Growth Rates in Buried Versus Exposed Ritonavir Crystals within Amorphous Solid Dispersions

Contact Info

Product

Resources

About

Structure-property correlations in molybdenum trioxide thin films and nanoparticles

Cited by 11 publications

References 42 publications

Real-Time Observation of Photo-oxidation of Single MoS2 Flakes Using Stochastic Optical Reconstruction Microscopy

Real-Time Observation of Photo-oxidation of Single MoS2 Flakes Using Stochastic Optical Reconstruction Microscopy

Room-temperature growth optimization and PL characteristic of polytype h/α-MoO3 thin films by chemical precipitation method

Disparities of Single-Particle Growth Rates in Buried Versus Exposed Ritonavir Crystals within Amorphous Solid Dispersions

Contact Info

Product

Resources

About

Real-Time Observation of Photo-oxidation of Single MoS₂ Flakes Using Stochastic Optical Reconstruction Microscopy

Real-Time Observation of Photo-oxidation of Single MoS₂ Flakes Using Stochastic Optical Reconstruction Microscopy

Room-temperature growth optimization and PL characteristic of polytype h/α-MoO₃ thin films by chemical precipitation method