Fused Quartz Crucibles: Laboratory, Industrial & CZ Silicon Pulling
Written by Fei X, Engineering Lead, FGQuartz · Reviewed by Fei X, Production/QA Manager, FGQuartz
Published: February 2022 · Last updated: September 2026
Quick Answer: A fused quartz crucible is a high-purity (SiO₂ ≥ 99.99%) containment vessel used for melting, calcining, or growing crystals at temperatures up to 1200°C+ without introducing metallic or carbon contamination. FGQuartz manufactures both clear laboratory crucibles (10 ml–2000 ml) and large CZ/MCZ crucibles for semiconductor and solar silicon pulling (up to 32″/800 mm diameter), in cylindrical, conical, flat-bottom, and fully custom profiles.
Key Takeaways
- Ultra-High Purity: ≥ 99.99% SiO₂ base material with controlled hydroxyl (OH) content and ultra-low alkali metals.
- Two Product Families: Laboratory crucibles (10 ml–2000 ml) and industrial CZ/MCZ crucibles (up to 32″/800 mm) — different construction, same purity standard.
- Five Profile Options: CZ/MCZ double-layer, cylindrical, conical/round-bottom, flat-bottom, and fully custom-machined.
- Thermal Performance: Continuous service to 1200°C, outstanding thermal shock resistance, excellent devitrification resistance.
- No Minimum Order Quantity: Single laboratory prototypes through production CZ volumes, all under one ISO 9001 facility.
- Fabrication Under One Roof: Arc fusion, flame forming, CNC machining, fire polishing, and thermal annealing.
FGQuartz manufactures high-purity fused quartz crucibles for laboratory analysis and industrial crystal growth, supplying customers in 40+ countries since 2005. Browse our full product portfolio.
What Is a Fused Quartz Crucible?
A fused quartz crucible is a vessel made from amorphous silicon dioxide (SiO₂ ≥ 99.99%), used to contain high-temperature melts, chemical reactions, or crystal growth processes. Unlike metal, graphite, or ceramic crucibles, fused quartz is chemically inert, electrically non-conductive, and introduces virtually no carbon or metallic ions into the material it holds — which is why it is the standard containment vessel for Czochralski (CZ) silicon crystal pulling, high-temperature calcination, and trace-element laboratory analysis.
Why quartz instead of other materials? Three properties make it uniquely suited to containment work: (1) near-zero thermal expansion, which prevents cracking during rapid heating/cooling cycles; (2) exceptional chemical inertness, meaning it does not react with or contaminate most melts and reagents; and (3) full transparency to visual inspection, letting operators monitor a melt or reaction without opening the vessel.
FGQuartz crucibles range from 10 ml clear laboratory vessels to 32-inch industrial CZ crucibles, manufactured with strict control of hydroxyl (OH) content and trace metal impurities to support extended high-temperature service.
Quartz Crucible Types & Profiles
FGQuartz engineers five primary crucible architectures, from standard laboratory ware to heavy-duty ingot-pulling vessels. The table below is a quick reference; full detail on each type follows.
| Crucible Type | Best For | Key Feature | Typical Capacity |
|---|---|---|---|
| CZ / MCZ Crucibles | Monocrystalline silicon ingot pulling | Opaque outer shell + bubble-free clear inner layer | Up to 32″ (800 mm) diameter |
| Cylindrical Crucibles | Uniform-wall melts, standard furnace fitments | Consistent wall thickness for even heat distribution | 50 ml – 2000 ml (lab); larger on request |
| Conical / Round-Bottom | Complete melt drainage, pouring applications | Shape minimizes residual material after pouring | 10 ml – 1000 ml |
| Flat-Bottom Laboratory | Ashing, calcination, hot-plate work | Stable footprint on lab benches and hot plates | 10 ml – 2000 ml |
| Custom Machined | Proprietary R&D tooling, OEM equipment | Custom flanges, threaded necks, integrated handles | Any, per drawing |
CZ / MCZ Silicon Pulling Crucibles
Engineered for the Czochralski process in semiconductor and solar PV manufacturing. These are the most demanding crucibles FGQuartz manufactures — a double-layer construction with an opaque, devitrification-resistant outer shell and an ultra-clear, bubble-free inner layer that contacts the molten silicon directly, minimizing melt contamination during the multi-hour pulling process.
Key features:
• Opaque outer layer for thermal insulation and structural stability during sagging
• Ultra-clear, bubble-free inner layer to limit oxygen and metallic contamination in the melt
• Enhanced resistance to high-temperature sagging and devitrification over multi-hour pulls
See Solar PV Quartz and Semiconductor Quartz. Related article: Quartz Crucibles for Czochralski Silicon Growth.
Cylindrical Crucibles
A cylindrical crucible maintains a uniform wall diameter from top to bottom, rather than tapering to a point or curve. This profile is the most common general-purpose format for both laboratory and mid-scale industrial use, because the even wall thickness gives consistent heat transfer across the vessel and a stable seating fit in furnace wells, hot plates, and holder fixtures.
Key features:
• Even wall thickness for uniform heat distribution during heating and cooling
• Stable, flat or slightly rounded base for secure furnace/holder seating
• Available clear (laboratory grade) or with an opaque outer layer (industrial grade)
Commonly specified for calcination, general melting, and as a base format for further custom machining (handles, spouts, lids).
Conical & Round-Bottom Crucibles
Conical and round-bottom profiles taper toward the base, which minimizes residual material clinging to the vessel walls — important for pouring applications and processes where complete material recovery matters (precious metal refining, small-batch chemical synthesis).
Key features:
• Shape encourages complete drainage when pouring molten material
• Reduces localized stress points compared to sharp-cornered geometries
• Frequently paired with a matching pouring spout
Flat-Bottom Laboratory Crucibles
Flat-bottom crucibles are the standard choice for benchtop and hot-plate work where the vessel must sit stably without a holder. Clear fused silica construction lets operators visually monitor color change, boiling, or reaction progress during ashing and calcination.
Key features:
• Stable footprint on lab benches, hot plates, and muffle furnace floors
• High resistance to acids and aggressive chemical reagents
• Matching quartz lids and custom pouring spouts available
Custom Machined Crucibles
Bespoke quartz containment vessels machined to your CAD drawings — custom flanges, threaded necks, integrated handles, or specialized wall profiles for specific heat distribution requirements. Ideal for proprietary R&D tools and OEM equipment where no standard geometry fits. Learn more about custom fabrication.
Typical Specifications of Quartz Crucibles
The following tables reflect baseline specifications of FGQuartz high-purity crucibles. Volumetric capacities, wall thicknesses and edge profiles are fully customizable from your CAD drawings. For complete material data, see our Technical Specifications.
1. Dimensional & Capacity Range
| Parameter | Typical Range | Notes |
|---|---|---|
| Laboratory Capacity | 10 ml – 2000 ml | Clear fused silica, available with lids |
| Industrial / CZ Diameter | Up to 32″ (800 mm)+ | Opaque outer layer, clear inner bubble-free layer |
| Wall Thickness | 1.5 mm – 15 mm+ | Customized for structural integrity |
| Base Profiles | Flat, Round, Conical, Cylindrical | Precision-machined or flame-formed |
2. Material Purity (Base Fused Silica)
| Property | Typical Value |
|---|---|
| SiO₂ Purity | ≥ 99.99% |
| Alkali Metals (Li, Na, K) | Ultra-low (to limit melt contamination) |
| Hydroxyl (OH) Content | < 5 ppm for high-temp applications |
| Inner Surface Quality | Bubble-free, highly vitrified clear layer |
3. Thermal & Physical Performance
| Property | Typical Value |
|---|---|
| Continuous Operating Temp. | Up to 1200°C |
| Devitrification Resistance | Excellent (long thermal cycles) |
| Coefficient of Thermal Expansion | Approx. 5.5 × 10⁻⁷ /°C |
| Thermal Shock Resistance | Outstanding (rapid heating/cooling when properly designed) |
Note: Values are baseline. Dimensional tolerances, corner radii and wall profiles are confirmed during engineering DFM review.
How Quartz Crucibles Are Made
High-purity quartz crucibles require controlled thermal processing and precision cold working. FGQuartz uses arc fusion, flame work and CNC machining under one quality system — from a 50 ml research crucible to production CZ vessels, fabrication stays under one roof.
Arc Fusion — High-purity quartz sand is fused in a rotating mold using electric arc heating, producing large-format CZ crucibles with a robust opaque outer shell (formed from coarser natural quartz sand for insulation and structural strength) and a clear, bubble-free inner layer (formed from higher-purity synthetic or select natural silica) fused in a single continuous process.
Flame Forming & Welding — Oxy-hydrogen torches soften and shape fused silica tubing or sheet stock into laboratory crucibles, pouring spouts, handling rods, and flanges, with flame-welded seams for leak-tight, contamination-free joints.
CNC Precision Machining — Diamond milling and grinding achieve tight dimensional tolerances, flat mounting bases, threaded necks, and interlocking lid seats that flame forming alone cannot produce.
Fire Polishing — A final flame pass seals micro-cracks and machining marks on internal surfaces, reducing particulate shedding risk at high operating temperatures — critical for semiconductor-grade CZ crucibles.
Thermal Annealing — Controlled cool-down in an annealing oven relieves internal stress introduced during forming or machining, improving the crucible’s resistance to thermal shock in service.
Full process detail: Quartz Custom Fabrication Process Guide.
Quartz Crucibles vs. Alternative Crucible Materials
Fused quartz is one of several crucible materials used across industry — the right choice depends on melt temperature, chemical compatibility, and contamination tolerance.
| Material | Max Temp | Contamination Risk | Typical Use |
|---|---|---|---|
| Fused Quartz | ~1200°C (short-term higher) | Very low (chemically inert) | CZ silicon pulling, lab analysis, acid digestion |
| Graphite | ~3000°C (inert atmosphere) | Carbon pickup risk | Metal casting, vacuum furnaces |
| Platinum | ~1700°C | Extremely low | Precision analytical chemistry, glass melting |
| Alumina Ceramic | ~1750°C | Low, but reacts with some fluxes | Metal melting, high-temp sintering |
Fused quartz remains the standard choice wherever chemical purity and non-conductivity outweigh the need for extreme temperature ceilings — particularly in semiconductor-grade crystal growth, where even trace carbon or metallic contamination affects device yield. For melts requiring temperatures above quartz’s practical service range, graphite or ceramic crucibles are typically better suited.
Applications of Quartz Crucibles
Semiconductor & Solar PV
Crystal growth and related thermal processes:
• Czochralski (CZ) monocrystalline silicon pulling
• Directional solidification (DS) for multicrystalline silicon
• Specialized melting for advanced compound semiconductors
See our full Semiconductor and Solar PV Quartz application pages for the related component range.
Laboratory & Analytical Chemistry
High-purity research and sample prep:
• Sample ashing and high-temperature calcination
• Trace element analysis requiring low-leaching vessels
• Acid digestion and precious metal refining
Explore Laboratory Quartz and the Laboratory Quartz Glassware Guide.
Advanced Materials & Phosphors
Industrial thermal processing:
• Calcining LED phosphors and luminescent materials
• Sintering battery powder materials
• High-temperature ceramic preparation
Supported by our high-temperature process expertise across furnace and thermal treatment applications.
Equipment OEMs
Tool and furnace partners:
• Replacement crucibles for legacy furnaces
• Custom geometries for specialized thermal equipment
• Repeat / blanket order programs for OEMs
Full OEM / ODM custom fabrication programs available — see our custom fabrication capabilities above.
How to Choose the Right Crucible for Your Application
Use this three-step framework to specify the right crucible before requesting a quote:
- Identify your process type. Crystal growth (CZ/MCZ) requires the double-layer opaque/clear construction; general lab melting or ashing works with a standard single-layer clear crucible; pouring-heavy processes favor a conical or round-bottom profile for full drainage.
- Confirm thermal and chemical exposure. Continuous operation above 1150°C for extended periods increases devitrification risk — specify low-OH, high-purity material and plan for proper surface cleaning between cycles. Confirm your process doesn’t involve hydrofluoric acid or high-temperature concentrated alkalis, which will etch quartz.
- Decide standard vs. custom. If your furnace, holder, or process interface requires a specific diameter, flange, spout, or handle not covered by standard sizes, plan for a custom-machined crucible — FGQuartz accepts single-piece prototype orders with no MOQ.
Not sure which profile fits your process? Send your application details to our engineering team for a free feasibility review.
Quartz Crucible Pricing: What Drives the Cost?
Quartz crucible pricing depends on four main factors:
- Size and capacity — a 50 ml laboratory crucible costs a fraction of a 32-inch CZ crucible.
- Wall construction — CZ crucibles with an opaque outer shell plus bubble-free clear inner layer require more processing than a single-layer laboratory crucible.
- Geometry complexity — standard cylindrical or conical shapes are more economical than custom-machined flanges, threaded necks, or integrated handles.
- Order volume — unit pricing improves at higher volumes, though FGQuartz accepts single-piece prototype orders with no MOQ.
For an accurate quote, send your capacity requirement, base profile, and any drawings to our engineering team — quotations are typically returned within 24 business hours.
Quality Assurance & Handling Guidance
Every FGQuartz crucible is inspected before shipment for dimensional accuracy (coordinate measuring machine verification), surface quality (micro-scratch and inclusion check), and residual stress (polarizing microscope inspection) under our ISO 9001 quality system.
In-service handling tip: Clean crucibles with an acid bath or alcohol wipe before high-temperature use to remove surface contaminants such as alkali salts and fingerprints — these act as catalysts for devitrification (surface crystallization) above ~1150°C, which can shorten service life and introduce particulates into sensitive processes.
Why Choose FGQuartz for Crucibles
• Experience since 2005: Thermal and fused silica process expertise for laboratory and industrial crucibles.
• High-purity base material: SiO₂ selected to limit contamination and support high-temperature service.
• Integrated manufacturing: Arc fusion, CNC machining, flame work, fire polishing and annealing under ISO 9001.
• Flexible volume: Single laboratory prototypes through production and OEM supply, no minimum order quantity.
• Metrology and QC: Wall thickness, geometry and surface quality checked against approved drawings.
• Global reach: Export experience to 40+ countries with full compliance documentation and custom export packaging.
• Full related range: Process tubes, wafer boats, rods and tanks.
More about the company: About FGQuartz.
Frequently Asked Questions
Send capacity or key dimensions, bottom type, lid requirement, process temperature and chemistry, quantity, and a drawing or sketch (DXF, STEP, IGES or PDF preferred). State clearly whether the use is laboratory or CZ silicon pulling.
The minimum order quantity is one prototype. Typical lead time is about 3–6 weeks after drawing approval, depending on size and complexity.
Yes. Matching lids and flat, round, conical or cylindrical profiles are available. Pouring spouts, flanges and custom wall thickness are made to customer drawings.
A laboratory crucible is usually clear fused silica, smaller volume (about 10 ml–2000 ml), used for ashing, calcination and chemical analysis. A CZ or MCZ crucible is a large industrial vessel (diameters up to about 32 inches / 800 mm class) with an opaque outer layer and a clear, bubble-free inner layer for monocrystalline silicon growth. Specify laboratory or CZ use on the RFQ.
Yes. We supply CZ crucibles for semiconductor and solar monocrystalline growth, and DS crucibles for polysilicon casting
Crucible purity directly limits impurity transfer into the molten silicon, which affects crystal quality, oxygen content and device or cell performance.
FGQuartz supplies laboratory crucibles typically from about 10 ml to 2000 ml, and industrial CZ-type crucibles with diameters up to about 32 inches (800 mm) class. Bottom profiles can be flat, round, conical or cylindrical. Lids, wall thickness and custom shapes are made to the customer drawing.
Czochralski (CZ) and Magnetic Czochralski (MCZ) silicon single-crystal growth, solar polysilicon casting, and FZ/VGF on request.
Ready to Source High-Purity Quartz Crucibles?
Whether you need standard clear lab crucibles, flat-bottom calcination vessels, cylindrical profiles or heavy-wall CZ silicon pulling crucibles, FGQuartz manufactures to your drawings and capacity requirements.
Send CAD files or key dimensions for a feasibility review and quotation — typically within 24 business hours.