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Tellurium Oxide, Tellurium Dioxide, Telluric Anhydride, 7446-07-3

Tellurium Oxide, Tellurium Dioxide, Telluric Anhydride, 7446-07-3

TELLURIUM DIOXIDE (TeO₂)

Tellurium(IV) Oxide / Telluric Anhydride

CAS Number: 7446-07-3

EC Number: 231-193-3

 

Tellurium Oxides – CAS Numbers

  • Tellurium monoxide (TeO) – CAS 12033‑34‑0

  • Tellurium dioxide (TeO₂) – CAS 7446‑07‑3

  • Tellurium trioxide (TeO₃) – CAS 13451‑18‑8

  • Tellurium pentoxide (Te₂O₅) – CAS 13598‑59‑5

1. IDENTIFICATION

Property Information
Chemical Name Tellurium Dioxide
Synonyms Tellurium(IV) oxide, Telluric anhydride, Tellurium oxide
Chemical Formula TeO₂
Molecular Weight 159.60 g/mol
CAS Number 7446-07-3
EC Number (EINECS) 231-193-3
Appearance White crystalline powder
Odor Odorless

2. PHYSICAL PROPERTIES

Property Value
Physical State (20°C) Solid (crystalline powder)
Appearance White to off-white crystalline powder
Odor Odorless
Molecular Weight 159.60 g/mol
Melting Point 733 °C (1,351 °F)
Boiling Point 1,245 °C (2,273 °F)
Density (20°C) 5.67 g/cm³
Solubility in Water Insoluble
Solubility in Alkalis Soluble (forms tellurites)
Solubility in Acids Slightly soluble in strong acids
pH (1% solution) Amphoteric behavior
Crystal Structure Tetragonal (paratellurite) or orthorhombic (tellurite)
Refractive Index 2.24 – 2.35
Vapor Pressure Negligible

3. CHEMICAL PROPERTIES

Property Information
Chemical Formula TeO₂
Molecular Weight 159.60 g/mol
Tellurium Content 79.9% Te
Oxygen Content 20.1% O
Oxidation State Te(IV) – can be oxidized to Te(VI) or reduced to Te(0)
Chemical Class Metal oxide (amphoteric)
Amphoteric Behavior Reacts with both acids and bases
Stability Stable under normal conditions
Reaction with Alkalis TeO₂ + 2 NaOH → Na₂TeO₃ + H₂O (sodium tellurite)
Reaction with Acids TeO₂ + 4 HCl → TeCl₄ + 2 H₂O (tellurium tetrachloride)
Incompatible Materials Strong reducing agents, strong acids (forms TeCl₄), strong oxidizers

Key Chemical Features:

  • Amphoteric oxide (behaves as both acid and base)

  • Forms tellurite salts (TeO₃²⁻) with alkalis

  • Can be reduced to elemental tellurium with reducing agents

4. CRYSTAL STRUCTURES

Form Crystal System Density Stability Optical Properties
Paratellurite Tetragonal 5.67 g/cm³ Stable at room temperature Birefringent (optical applications)
Tellurite Orthorhombic 5.67 g/cm³ Metastable Different optical properties

5. APPLICATIONS

5.1. Electronics & Optics (Primary Use)

Application Function
Acousto-optic Devices Bragg cells, modulators, deflectors (paratellurite form)
Optical Modulators High-performance optical switching
Semiconductor Components Substrates and thin films
Infrared Optics IR windows and lenses
Non-linear Optical Materials Frequency doubling and mixing

5.2. Glass & Ceramics Industry

Application Function
Glass Coloring Produces yellow to amber colors in glass
Glass Stabilization Improves chemical durability
Ceramic Glazes Yellow pigment for glazes and enamels
Specialty Glass Tellurite glasses for IR transmission

5.3. Catalysis

Application Function
Oxidation Catalysts Catalyzes selective oxidation reactions
Organic Synthesis Catalyst for various organic transformations
Ammoxidation Catalyst for propylene to acrylonitrile
Dehydrogenation Catalyst for dehydrogenation reactions

5.4. Metallurgy & Alloys

Application Function
Special Alloys Additive in copper, lead, and steel alloys
Tellurium Metal Production Precursor for reduction to elemental tellurium
Cast Iron Improves machinability of cast iron

5.5. Other Applications

Application Function
Glass Polishing Fine abrasive for optical glass
Chemical Reagent Laboratory analytical reagent
Surface Treatment Conversion coatings for metals

6. QUALITY SPECIFICATIONS

Parameter Technical Grade High Purity Grade
Purity (TeO₂) ≥ 99.0% ≥ 99.99%
Tellurium (Te) Content ~79.9% ~79.9%
Appearance White to off-white powder White powder
Insoluble in HCl ≤ 0.1% ≤ 0.01%
Chloride (Cl) ≤ 0.01% ≤ 0.001%
Sulfate (SO₄) ≤ 0.01% ≤ 0.001%
Iron (Fe) ≤ 0.005% ≤ 0.0005%
Heavy Metals (Pb) ≤ 0.005% ≤ 0.0005%
Loss on Ignition ≤ 0.5% ≤ 0.1%

7. STORAGE & HANDLING

Parameter Information
Storage Conditions Cool, dry, well-ventilated area
Container Requirements Tightly closed, moisture-proof containers (HDPE, fiber drums with liner)
Protect From Moisture, strong reducing agents, strong acids
Shelf Life 24-36 months (when stored properly in unopened packaging)
Hygroscopicity Low (insoluble in water, but may absorb surface moisture)
Incompatible Materials Strong reducing agents, strong acids
Packaging Options 25 kg fiber drums (with plastic liner), 100 kg drums, 500 kg FIBC (big bags)

8. SAFETY & HEALTH INFORMATION

GHS Classification

Hazard Class Category
Acute Toxicity (Oral) Category 4 (H302)
Acute Toxicity (Inhalation) Category 4 (H332)
Specific Target Organ Toxicity (Single exposure) Category 3 (H335)
Chronic Aquatic Toxicity Category 2 (H411)

Hazard Statements (H-Codes)

Code Statement
H302 Harmful if swallowed
H332 Harmful if inhaled
H335 May cause respiratory irritation
H411 Toxic to aquatic life with long-lasting effects

Precautionary Statements (P-Codes)

Code Statement
P261 Avoid breathing dust
P264 Wash thoroughly after handling
P270 Do not eat, drink or smoke when using this product
P271 Use only outdoors or in a well-ventilated area
P280 Wear protective gloves and eye protection
P301+P312 IF SWALLOWED: Call a POISON CENTER if you feel unwell
P302+P352 IF ON SKIN: Wash with plenty of water
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes

Toxicological Information

Parameter Value
Oral LD50 (rat) ~1,000 – 2,000 mg/kg (moderate toxicity)
Inhalation LC50 (rat) Not established
Skin Irritation Mild irritant
Eye Irritation Mild to moderate irritant
Chronic Effects May cause tellurium breath (garlic-like odor)

Health Effects:

  • Acute (Inhalation): Respiratory tract irritation, garlic-like breath odor (tellurium breath)

  • Acute (Ingestion): Nausea, vomiting, abdominal pain

  • Chronic: Garlic breath is characteristic; possible kidney and liver effects with prolonged exposure

First Aid Measures

Exposure Route Action
Inhalation Remove to fresh air. Seek medical attention if respiratory irritation occurs.
Skin Contact Wash with plenty of water and soap. Remove contaminated clothing.
Eye Contact Rinse immediately with plenty of water for at least 15 minutes. Seek medical attention.
Ingestion Rinse mouth. Do NOT induce vomiting. Drink water. Seek immediate medical attention.

Personal Protective Equipment (PPE)

Equipment Recommendation
Respiratory Protection Dust mask (N95) when handling powder
Hand Protection Chemical-resistant gloves (nitrile, neoprene)
Eye Protection Safety glasses with side shields
Body Protection Lab coat or protective clothing

9. FIRE FIGHTING MEASURES

Parameter Information
Fire Hazard Non-flammable
Extinguishing Media Use appropriate media for surrounding fire (water, CO₂, dry chemical)
Special Hazards Decomposes when heated to high temperatures, releasing toxic tellurium fumes
Protective Equipment Self-contained breathing apparatus (SCBA), full protective clothing

10. ENVIRONMENTAL INFORMATION

Parameter Information
Aquatic Toxicity Toxic to aquatic life with long-lasting effects (H411)
Biodegradability Not applicable (inorganic)
Bioaccumulation Moderate potential
Persistence Inorganic – does not degrade
Waste Disposal Dispose according to local regulations. Do not discharge into natural water bodies.

11. TRANSPORT INFORMATION

Parameter Information
UN Number 3288 (Toxic solid, inorganic, n.o.s.)
Hazard Class 6.1 (Toxic substance)
Packing Group III
Proper Shipping Name TOXIC SOLID, INORGANIC, N.O.S. (Tellurium dioxide)
Marine Pollutant Yes
ADR/RID Label 6.1

12. REGULATORY INFORMATION

Region Status
EU REACH registered
Turkey (KKDIK) Mandatory compliance; requires registration
USA (TSCA) Listed
Canada (DSL) Listed
Australia (AICS) Listed

13. SYNONYMS & OTHER NAMES

Turkish Name English Name
Tellür Dioksit Tellurium Dioxide
Tellür(IV) Oksit Tellurium(IV) Oxide
Tellürik Anhidrit Telluric Anhydride
TeO₂ TeO₂

Database Identifiers:

  • CAS: 7446-07-3

  • EC: 231-193-3

  • MDL: MFCD00011263

  • PubChem CID: 62638

  • RTECS: WY2675000

14. SUMMARY

Tellurium Dioxide (TeO₂, CAS 7446-07-3) is a white crystalline powder with amphoteric properties. It is the most common oxide of tellurium and is used primarily in electronics (acousto-optic devices), optics (paratellurite crystals), glass and ceramics (colorant, stabilizer), catalysis, and specialty alloys.

Key Features:

Feature Value
Appearance White crystalline powder
Molecular Weight 159.60 g/mol
Melting Point 733°C
Density 5.67 g/cm³
Tellurium Content 79.9%
Solubility Insoluble in water; soluble in alkalis

Main Application Areas:

Sector Applications
Electronics & Optics Acousto-optic devices, modulators, IR optics
Glass & Ceramics Colorant (yellow-amber), stabilizer
Catalysis Oxidation catalysts
Metallurgy Specialty alloys, tellurium metal precursor

Key Safety Points:

  • TOXIC – Harmful if swallowed or inhaled

  • ENVIRONMENTAL HAZARD – Toxic to aquatic life

  • GARLIC BREATH – Characteristic tellurium breath upon exposure

  • NON-FLAMMABLE – Stable solid

  • HANDLE WITH PPE – Use gloves, dust mask, goggles

15. IMPORTANT NOTES

  1. Amphoteric Nature: Tellurium dioxide exhibits amphoteric behavior – it reacts with both acids (forming tellurium salts) and bases (forming tellurites). This property is important for its dissolution in various media.

  2. Paratellurite Form: The tetragonal crystal form (paratellurite) is birefringent and has excellent acousto-optic properties, making it valuable for optical modulators, deflectors, and signal processing devices.

  3. Tellurium Breath: One of the characteristic signs of tellurium exposure is a garlic-like odor on the breath (tellurium breath). This is not harmful itself but indicates systemic absorption.

  4. Glass Coloring: TeO₂ produces yellow to amber colors in glass. Unlike cadmium-based pigments, tellurium does not contain heavy metals of the same regulatory concern, but it is still toxic.

  5. Handling Precautions: Although TeO₂ has low solubility in water, fine dust can be inhaled. Use adequate ventilation or dust masks when handling powder.

  6. Thermal Decomposition: At very high temperatures (>1,000°C), TeO₂ can sublime or decompose, releasing toxic tellurium fumes. Avoid excessive heating.

  7. Comparable to SeO₂: Tellurium dioxide is similar to selenium dioxide (SeO₂) but with higher thermal stability. It is often used in similar applications where higher stability is required.

  8. Optical Applications: High-purity TeO₂ (≥ 99.99%) is required for optical and acousto-optic applications. Lower purity grades are acceptable for glass and ceramic applications.

  9. Biological Effects: Tellurium compounds are toxic. Chronic exposure can cause tellurium breath, dry mouth, metallic taste, and in severe cases, neurological symptoms.

  10. Environmental Considerations: Tellurium is a rare element and its compounds should be recycled when possible. Spent materials may be processed to recover tellurium metal.

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS) provided by the manufacturer/supplier.

 

Oxide Formula Appearance Melting Point Properties Main Uses CAS No.
Tellurium monoxide TeO Gray‑black solid Basic oxide Rare, precursor in synthesis 12033‑34‑0
Tellurium dioxide TeO₂ White crystalline solid 733 °C Amphoteric, insoluble in water, soluble in NaOH Semiconductors, ceramics, glass colorant, catalysts 7446‑07‑3
Tellurium trioxide TeO₃ Yellow‑orange crystals Acidic oxide, strong oxidant Specialty chemical synthesis 13451‑18‑8
Tellurium pentoxide Te₂O₅ Acidic oxide Limited, research‑grade applications 13598‑59‑5

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