Bismuth Telluride, Dibismuth Tritelluride, 1304-82-1

Bismuth Telluride, Dibismuth Tritelluride, 1304-82-1

BISMUTH TELLURIDE (Bi₂Te₃)

1. PRODUCT DEFINITION AND CHEMICAL IDENTITY

Note: Bismuth telluride is the benchmark and most widely used thermoelectric material for near-room-temperature applications. It is a narrow-bandgap semiconductor with a unique layered crystal structure, which gives it an exceptionally high thermoelectric figure of merit (ZT) between 200 K and 400 K. It is commercially produced in both n-type (typically doped with selenium or excess tellurium) and p-type (typically doped with antimony) forms to create the n-p couples required for solid-state thermoelectric modules. Its primary use is in Peltier cooling devices and low-grade waste-heat-to-power generation.

2. PHYSICAL AND CHEMICAL PROPERTIES

3. FUNCTIONAL PROPERTIES AND MODE OF ACTION

• Peltier Effect (Solid-State Cooling): When a direct current (DC) is passed through a junction of n-type and p-type Bi₂Te₃, one side absorbs heat and becomes cold, while the other side releases heat and becomes hot. A thermoelectric module, composed of many such couples, acts as a compact, vibration-free, solid-state heat pump.

• Seebeck Effect (Power Generation): When a temperature difference is maintained across a Bi₂Te₃ couple, it generates a DC voltage. Modules can convert waste heat from industrial processes, automotive exhausts, or geothermal sources into usable electrical power.

• Dopant Engineering for Performance: The material's thermoelectric performance is optimized by precisely controlled doping. N-type legs are typically doped with selenium (Bi₂Te₃₋ᵧSeᵧ), while p-type legs are doped with antimony ((Bi₁₋ₓSbₓ)₂Te₃). This maximizes the Seebeck coefficient while minimizing thermal conductivity, resulting in the highest possible ZT value.

4. COMMERCIAL FORMS AND TYPES

5. SECTORAL APPLICATIONS AND USAGE RATES

6. ALTERNATIVE NAMES AND SYNONYMS

7. SAFETY, STORAGE, AND REGULATORY INFORMATION

• GHS Classification (CLP Regulation):

  • Signal Word: Warning

  • Hazard Statements: H302 (Harmful if swallowed), H332 (Harmful if inhaled).

  • Precautionary Statements: P261, P264, P270, P271, P280, P301+P312, P304+P340, P312, P330, P501.

• Toxicity: Harmful if swallowed or if dust is inhaled. May cause irritation. Like other tellurium compounds, exposure can lead to a temporary garlic-like body odour ("tellurium breath").

• Storage:

  • Store in a cool, dry, and well-ventilated area in tightly sealed, labelled containers.

  • Protect from moisture and strong oxidizing acids.

• Personal Protective Equipment (PPE): When handling powder, use nitrile gloves, safety goggles, and a suitable dust mask (N95/FFP2). Ensure adequate local exhaust ventilation.

• Market Note: Bismuth telluride is produced in smaller volumes compared to photovoltaic materials like CdTe. It is a niche, specialty material usually supplied by companies focused on thermoelectric technologies. Sourcing bulk quantities may require contacting specialized suppliers.

8. FREQUENTLY ASKED QUESTIONS

Q1: Why is bismuth telluride the benchmark thermoelectric material?
It possesses a rare combination of physical properties that maximize the thermoelectric figure of merit (ZT) near room temperature: a high Seebeck coefficient, high electrical conductivity (like a good conductor), and very low thermal conductivity (like a good insulator). This "phonon-glass, electron-crystal" behaviour is most pronounced in Bi₂Te₃.

Q2: What is the difference between a Peltier cooler and a thermoelectric generator?
They use the same Bi₂Te₃ module but operate in reverse. A Peltier cooler uses an applied DC current to force a temperature difference. A thermoelectric generator uses an applied temperature difference to generate a DC current. The hardware is essentially the same.

Q3: Can bismuth telluride be used at very high temperatures?
No, its thermoelectric performance peaks below 200 °C and its operational limit is around 250 °C. For high-temperature waste heat recovery (e.g., automotive exhaust), other materials like lead telluride (PbTe) or silicon-germanium (SiGe) alloys are used.

9. QUICK REFERENCE TABLE