Semiconductor published two-dimensional transition metal chalcogenide material phonons and Raman scattering

Semiconductors publish two-dimensional transition metal chalcogenide materials phonon and Raman scattering review article

Comparison of single-layer and double-layer molybdenum disulfide Raman spectra

Invited by Chemical Society Reviews, a review article of the Royal Society of Chemicals, and authored by the Institute of Semiconductors, Chinese Academy of Sciences, Tan Pingheng and PhD student Zhang Wei, etc., on the phonons and pulls of two-dimensional transition metal chalcogenides. A review paper on the Man scattering is recently published online in the journal (Xin Zhang, Xiao-Fen Qiao, Wei Shi, Jiang-Bin Wu, De-Sheng Jiang and Ping-Heng Tan, Phonon and Raman scattering of two-dimensional transition metal dichalcogenides. From monolayer, multilayer to bulk material, Chem. Soc. Rev., 2015, Doi: 10.1039/c4cs00282b). The Review of the Chemical Society is an important academic journal published by the Royal Society of Chemistry. It is one of the most authoritative academic journals in the field of chemistry.

A two-dimensional transition metal chalcogenide represented by a single layer of molybdenum disulfide (1L-MoS2), molybdenum diselenide (1L-MoSe2), tungsten disulfide (1L-WS2), and tungsten selenide (1L-MoS2). Compounds (TMDs) have been found to possess unique electrical and optical properties.

These materials, as well as the corresponding multi-layer materials, can be obtained by mechanical stripping or chemical vapor deposition. Each layer of material is bonded together by van der Waals interactions. The two-dimensional crystal properties of these materials, the band gap in the visible range, the valley polarization characteristics, the large spin-orbit coupling, and the pronounced exciton properties make them highly promising in nanoelectronics and optoelectronics. The lattice vibrations (phonons) are the basic properties of the material. The two-dimensional material has a unique phononic structure, and these phonons will change significantly with the number of layers, especially in the low-frequency region that characterizes interlayer vibration. As the most common tool for detecting lattice vibration properties and phonon physics, Raman spectroscopy plays an important role in the study of two-dimensional materials such as graphene, TMDs, and boron nitride.

In this review article, the author systematically introduced the lattice vibration and phonon dispersion of MX2 type TMDs, revealing their commonalities from the point of view of symmetry; then introduced the Raman process and its selection rules, elaborated first-order, Second-order Raman scattering, resonance and non-resonant Raman scattering and polarization Raman scattering; then the progress of Raman spectroscopy in the study of TMDs materials is reviewed from both resonant and non-resonant Raman scattering; and the introduction of TMDs under extrinsic interference is described. Raman Spectroscopic Study Results. This article not only systematically introduces the results achieved by the research group in the study of Raman spectroscopy of two-dimensional materials, but also uses the inter-layer vibration mode to characterize the number or thickness of two-dimensional materials on any substrate and studies two-dimensional. The latest research progress in the inter-layer coupling of material heterojunctions is introduced. Finally, the paper also reviews the application prospects of Raman spectroscopy in the study of other two-dimensional materials and heterojunctions. This review has important reference value for researchers who want to engage in or are engaged in two-dimensional materials.

In recent years, the research group has carried out relatively systematic research on the optical properties of two-dimensional materials such as graphene and transition metal sulfides, and has achieved certain results. It has been published in Nat. Mater., Nat. Commun. , Phys. Rev. Lett., Phys. Rev. B, J. Am. Chem. Soc., Nano Lett., ACS Nano and Nanocale.

POM plastics,lalso named Acetals(paraformaldehyde) (semel - Stirling),

English name: Polyoxymethylene (Polyformaldehyde),POM mainly has antistatic POM, conductive POM,POM+PTFE SHEET.

 

POM  plastics (polyformaldehyde resin) definition: polyformaldehyde is a linear polymer with no side chain, high density and high crystallographic properties.

According to the different chemical structures in the molecular chain, there are two kinds of homoformaldehyde and copolymerization.

One of the synthetic resin, also known as polyformaldehyde resin, POM plastic, and steel, etc.

POM/Acetals Plastic is a kind of white or black plastic granule with high hardness, high steel and high abrasion resistance.

Mainly used for gears, bearings, auto parts, machine tools, instruments, etc.


 

Advantages:

1. Excellent abrasion and creep resistance property;

2. High dimensional and shape stability;

3. Retains toughness under low temperature (-40°C);

4. Resistant to organic solvents; Insoluble under normal temperature;

5. Thermal deformation temperature is close to that of PC plastic, PTFE plastic and nylon plastic;

6. High compressive strength, second only to Glass Fiber;

7. Good sliding property; wear resistant; non-water absorbent;

 

Disadvantages:

1. Not resistant to acids, especially to mineral acids;

2. Not resistant to UV;

3. Not self-extinguishing, and thus must be kept away from fire;

4. Not resistant to impact. 

 

Applications:

1. Sliding parts: bearing and lining, roller, conveyor chain;

2. Precision mechanical components: gear, cam, coupler, idler roller;

3. Waterproof components: impeller, pump case, gasket;

4. Electrical parts: guide pulley, spring lock;

5. Fixture, lever, handle, knob and other jig materials.


 

Modified POM/Acetals Plastic

 

reinforced POM/Acetals Plastic

Main reinforced material such as glass fiber, glass or carbon fiber, and glass fiber is the most commonly used, the enhanced mechanical performance can be improved 2 ~ 3 times, heat distortion temperature increased by more than 50 ℃.

 

 

High lubrication POM POM/Acetals Plastic

In POM, graphite, F4, molybdenum disulfide, lubricating oil and low molecular weight PE are added to improve the lubrication performance

Combustion characteristics: easy to burn, continue to burn after fire, the upper end of the flame is yellow, the lower end is blue, and the melting drop, the strong irritating formaldehyde flavor, the fish smell

Specification: the thickness of sheet material can be produced from 0.3mm to 1.9mm, the normal width is 600mm, the width cannot exceed 1200mm, the length is not limited.
The thickness of plate can be produced from 2mm to 180mm, the usual specification of 2-10mm is 1000mm* 2000mm, and the commonly used specification of 10-180mm is 600*1200mm.

POM/Acetals Plastic can also be customized according to requirements, and the width cannot exceed 1200mm, and the length is not limited.and The diameter of the rod can be produced from 2mm to 250mm, the length is 1 meter, and POM/Acetals Plastic can be ordered to be more than 3 meters in length.
Color: Black ,white beige and brown, can also be made another color, and the color order is 500KG.


Modified varieties: can be added to the glass fiber, copper powder, and molybdenum disulfide enhancement plate according to customer's requirements.
Add antistatic agent to the permanent plate, the volume resistance value of 10 to the 6 to 9 power.
Add flame retardant to the flame retardant board from UL 94v-0 to HB combustion grade, and other modification requirements are required to customize various additional properties according to the actual use of the customer.
Product certification: most environmental certification reports and safety reports for raw materials, such as SGS report, CTI report, UL report, MSDS safety information, etc.
 

 

POM/Acetals/Derlin Plastic Sheet

POM Plastic Sheet,Copolymer Acetal Sheet,Acetal Plastic Rod,Extruded Antistatic POM Sheet

Dongguan Noegem Plastic Products Co.,Ltd , http://www.noegempLastic.com