A Deep Dive into Advanced Materials: Properties, Applications, and Comparisons

Posted on Sep 2, 2024 in Chemistry

What are High Entropy Alloys?

High-entropy alloys (HEAs) are substances constructed with equal or nearly equal quantities of five or more metals. These alloys are currently the focus of significant attention in materials science and engineering because they have potentially desirable properties.

Furthermore, research indicates that some HEAs have considerably better strength-to-weight ratios, with a higher degree of fracture resistance, tensile strength, as well as corrosion and oxidation resistance than conventional alloys.

Graphene vs. Silicene: Key Differences

While both are single-layer materials, graphene and silicene exhibit distinct properties:

Structural Differences:

  • Graphene: Flat, two-dimensional structure.
  • Silicene: Periodically buckled topology.

Bonding and Stacking:

  • Silicene: Stronger interlayer coupling compared to multilayered graphene.
  • Graphene: Exhibits pi-stacking, leading to graphite-like forms, while silicene does not.

Chemical Properties:

  • Oxidized silicene (2D silica) has a different chemical structure than graphene oxide.
  • Silicene’s hydrogenation reaction is more exothermic than graphene’s.

Advantages of Silicene:

  1. Stronger spin-orbit coupling, potentially enabling the quantum spin Hall effect at accessible temperatures.
  2. Better band gap tunability, crucial for room-temperature field-effect transistors (FETs).
  3. Easier valley polarization, making it suitable for valleytronics research.

Exploring Graphene-Like Materials

Examples of Graphene-Like Materials:

  • Layered van der Waals (vdW) materials: h-BN, MoS2, α-MoO3, and V2O5
  • Graphitic-like ZnO
  • MXenes (metal carbides or carbonitrides)
  • Theoretical materials: B2C, SiC2, BSi3, arsenene, and antimonene
  • Single-layer coordination polymers: [Cu2Br(IN)2]n (IN = isonicotinato), Fe-phthalocyanine, and nickel bis(dithiolene)

Major Applications of Graphene-Like Materials:

  • Solar energy cells
  • Electrical batteries
  • Medical applications (corporal scanning, bionics)
  • LEDs
  • Electronics industry

Understanding Biodegradable Materials

Properties of Biodegradable Materials:

  • Stable and durable for intended use.
  • Easily broken down upon disposal.
  • Non-toxic.
  • Maintain good mechanical integrity until degraded.
  • Controlled degradation rates.

Factors Controlling Degradation Rate:

  • Percent crystallinity
  • Molecular weight
  • Hydrophobicity

Chemical Reactions During Biodegradation:

  • Oxidation-based reactions
  • Hydrolysis-based reactions

Composting vs. Biodegradation:

Biodegradation may take longer than composting.

Types of Thermal-Based Biodegradable Films:

  • Biodegradable polyethylene film
  • Starch-based or biobased (hydrodegradable) film
  • Additive-based film
  • Oxodegradable film
  • Films with enhanced hydrophilicity

Unveiling the Properties of Graphene

Structure of Graphene:

  • Two-dimensional, crystalline allotrope of carbon
  • Single layer of graphite
  • Honeycomb (hexagonal) lattice

Allotropic Forms of Carbon:

  • Diamond
  • Graphite
  • Graphene
  • Nanotubes
  • Fullerenes

Properties of Graphene:

Electrical Properties:

  • Electrical conductivity 200 times faster than silicon
  • Dissipates heat 10 times better than copper

Mechanical Properties:

  • Strongest material ever discovered
  • Ultimate tensile strength of 130 GPa (compared to 400 MPa for structural steel)
  • Highly flexible

Optical Properties:

  • Can transform light into electricity with 82% greater efficiency than current industrial technology
  • Absorbs only 2.3% of white light, making it very transparent

Strength Comparison:

Graphene is hundreds of times stronger than most steels by weight.

Metallic Glasses: A Unique Class of Materials

Distinctive Feature:

Unlike most metals that are crystalline in their solid state, amorphous metals are non-crystalline and have a glass-like structure.

Advantages of Metallic Glasses:

  • Good electrical conductivity
  • Low shrinkage during cooling
  • Resistance to plastic deformation
  • Better resistance to wear and corrosion due to the absence of grain boundaries

Types of Metallic Glasses:

  1. Metal-metal metallic glasses
  2. Metal-metalloid metallic glasses

Industrial Applications of Metallic Glasses:

  • High-efficiency transformers (amorphous metal transformers) at line frequency and higher frequencies
  • Electronic article surveillance (e.g., theft control passive ID tags)
  • Thermoplastic forming, utilizing their unique softening behavior above their glass transition temperature