Ce-Ti Co-Doped Quartz Tubes: Applications, Color, Solarization
This page brings together several articles explaining how Ce-Ti co-doped quartz tubes behave in real applications, including their blue-purple color, UV performance, and resistance to solarization.
It is intended for readers working with UV, medical, or radiation-sensitive systems who need a clearer understanding of material behavior and selection.
Table of Contents
The Role of Cerium (Ce) in Quartz Tubes
Introduction: Why Add Cerium to Quartz Glass?
Doping quartz tubes with cerium (Ce) is a highly important technical approach, and its primary purpose is very clear:
Core function: significantly enhance the radiation-resistance against UV-induced darkening of quartz glass.
In other words, cerium doping is used to prevent the quartz tube from darkening and aging under strong ultraviolet irradiation, thereby maintaining long-term and stable UV transmittance.
Detailed Mechanism: How Cerium Works
The working principle behind this is a clever “sacrificial protection” mechanism.
Root Cause of the Problem
When high-purity quartz tubes are exposed to high-energy short-wave UV (especially <250 nm), the internal micro-defects (such as oxygen-deficient centers and impurity ions) become activated and form light-absorbing “color centers,” causing the quartz to darken and the UV transmittance to decline.
This process is known as radiation-induced darkening.
Introduction of Cerium
During the manufacturing of quartz glass, small amounts of cerium (usually Ce³⁺ and Ce⁴⁺ ions) are added in the form of cerium oxide (CeO₂) or other compounds, allowing the ions to distribute uniformly throughout the glass network.
Working Mechanism
Cerium ions act as “energy traps” or “sacrificial agents” inside the glass.
When high-energy UV photons strike the material, their energy would normally break the Si–O–Si bonds in the quartz network and form color centers.
However, the presence of cerium ions provides an energy level that is easier to excite.
The high-energy photons are preferentially absorbed by cerium ions, causing valence-state transitions (Ce³⁺ ⇌ Ce⁴⁺), and the absorbed energy is dissipated by releasing lower-energy photons (such as visible light) or heat.
Simple Analogy
Cerium acts like a “lightning rod,” actively absorbing the “energy lightning” that would have damaged the quartz glass structure. Through its own sacrifice it protects the quartz from forming color centers.
Main Properties and Advantages of Cerium-Doped Quartz Tubes
Exceptional Radiation Resistance
This is the most essential advantage. Under long-term exposure to deep UV sources (such as mercury lamps, xenon lamps, excimer lamps), cerium-doped quartz tubes experience minimal UV transmittance decay, greatly extending service life.
Maintained UV Transmittance
Although cerium doping introduces mild intrinsic absorption below 350 nm (compared with ultra-high-purity synthetic quartz), it sacrifices a small initial portion of transmittance in exchange for extreme long-term stability.
For applications requiring long service life and stable output, this is a critical trade-off.
Appearance Characteristics
Cerium-doped quartz tubes usually exhibit a slight yellowish tint (due to UV absorption by cerium ions), which distinguishes them from colorless high-purity quartz tubes.
Primary Application Fields
Cerium-doped quartz tubes are the preferred material for the following high-intensity UV applications:
- High-intensity UV lamps: such as UV curing lamps (printing, coatings, adhesives) and UV sterilization lamps (especially for high-power water treatment and air purification systems)
- Excimer lamps: emitting specific wavelengths (e.g., 172 nm, 222 nm, 308 nm) of rare-gas discharge light, with extremely short wavelengths and high photon energy, requiring very high radiation-resistant materials
- Semiconductor lithography tools: used in certain UV-related auxiliary equipment or illumination systems
- Scientific research light sources: experimental systems requiring long-term stable UV output
Conclusion
Cerium functions as a stabilizer in quartz tubes, absorbing high-energy radiation through a sacrificial mechanism. This effectively suppresses radiation-induced darkening and ensures long-term, stable performance of quartz tubes operating in harsh UV environments.
Industries That Require Ce-Ti Co-Doped Quartz Tubes
Ce-Ti co-doped quartz tubes are essential materials in industries that demand extremely high stability and spectral purity from ultraviolet light sources due to their outstanding anti–radiation darkening performance and unique deep-blue filtering characteristics.
Their main application fields are as follows:
1. UV Curing
This is the core and most widespread application of Ce-Ti co-doped quartz tubes.
Function:
Used for manufacturing lamp tubes for high-intensity UV curing mercury lamps and metal halide lamps.
Why They Are Essential:
- Anti-aging:
UV curing lamps operate at extremely high power and contain abundant short-wave UV (UVC, UVV). Ordinary quartz tubes quickly undergo “radiation darkening,” causing a rapid drop in UV output and reduced curing efficiency. Ce-Ti co-doped tubes maintain long-term stable output and extend lamp life. - Optical filtering:
Their deep-blue characteristic absorbs most visible and infrared light, resulting in a more “pure” UV output. This reduces unnecessary heating (thermal effect) on cured workpieces—critical for heat-sensitive materials such as plastics, films, and electronics—while improving curing efficiency.
2. High-End UV Sterilization (Disinfection)
Mainly used in high-power, long-life sterilization systems.
Function:
Used in high-intensity mercury lamps or excimer lamps for water treatment, air purification, and surface disinfection.
Why They Are Essential:
- Long lifetime & stability:
Industrial and municipal disinfection systems often operate 24/7. Lamp tubes must maintain stable UV intensity to ensure sterilization performance. The anti-aging capability of Ce-Ti co-doped tubes ensures reliable sterilization efficiency and longer maintenance intervals. - High-power tolerance:
These systems use extremely high-power lamps, requiring exceptional radiation-resistance from the quartz material.
3. Printing and Plate Making
Function:
Used as exposure light sources in PS plate exposure machines and CTP plate-making systems.
Why They Are Essential:
High-intensity UV is required for rapid exposure. Stability of lamp output directly affects plate quality and consistency. Ce-Ti co-doped tubes ensure that exposure energy remains consistent throughout the lamp’s lifetime.
4. Semiconductor Lithography
Although not used for the most advanced EUV lithography, they are applied in auxiliary processes.
Function:
Used in mask inspection, alignment illumination systems, and some older-generation lithography light sources.
Why They Are Essential:
Semiconductor manufacturing demands extreme process stability and controllability. Any light source fluctuation must be eliminated. Ce-Ti co-doped quartz tubes ensure absolute stability of auxiliary light sources over long operational periods.
5. Scientific Research & Special Lighting
Function:
Used in scientific experimental devices requiring stable UV sources, excitation sources for spectrometers, and fluorescence detection systems.
Why They Are Essential:
Scientific research requires reproducible conditions and reliable data. A degrading light source introduces variables and compromises experimental accuracy. Ce-Ti co-doped tubes provide a “constant” UV baseline for research.
6. Medical Phototherapy
Function:
Used in UV phototherapy equipment for treating skin diseases such as psoriasis and vitiligo.
Why They Are Essential:
Medical treatment requires strict dose control. Physicians must set precise UV radiation doses according to patient condition. This requires highly stable and predictable light output. Ce-Ti co-doped tubes ensure treatment safety and effectiveness.
Summary: Why These Industries Choose It
| Industry | Core Requirement | Value Provided by Ce-Ti Co-Doped Quartz Tubes |
|---|---|---|
| UV Curing | Efficiency, stability, low heat load | Anti-aging, filtering (removing IR & visible light) |
| High-End Sterilization | Long-term stability, high power, reliability | Exceptional radiation resistance, long lifetime |
| Printing & Plate Making | Consistent exposure quality | Stable output power |
| Semiconductor | Process control, absolute stability | Extreme reliability, eliminating light-source variables |
| Scientific & Medical | Accurate data, precise dosage | Stable and predictable UV output |
Conclusion
Ce-Ti co-doped quartz tubes are not general-purpose materials—they are high-end specialty materials developed to solve the specific challenge of long-term stability and spectral purification in high-intensity UV light sources.
They are primarily used in industrial sectors where production efficiency and process reliability are treated as mission-critical.
Although the material cost is higher, the significantly extended lifetime, stable production quality, and reduced downtime fully offset the expense.
Which Medical and Phototherapy Devices Require Ce-Ti Co-Doped Quartz Tubes
In the field of medical phototherapy, Ce-Ti co-doped quartz tubes are not used in all devices. Instead, they are applied specifically in high-end equipment that demands extremely high stability and long service life of the light source.
These devices primarily utilize the biological effects of ultraviolet radiation for treatment, and Ce-Ti quartz tubes serve as one of the core components ensuring accurate therapeutic dosage and safe, effective performance.
Below are the main categories of medical and phototherapy devices that require this special type of quartz tube:
1. Ultraviolet Phototherapy Devices
This is the most widely used field, involving devices that use high-intensity UV radiation to treat various skin conditions.
Full-Body UV Phototherapy Chambers
Description:
A large chamber that allows a patient to stand inside, with its inner walls lined with high-intensity UV lamps.
Why Ce-Ti Quartz Tubes Are Needed:
Treatments for conditions such as psoriasis and vitiligo usually require multiple sessions. Physicians calculate the precise radiation dosage for each session (often measured in joules per square centimeter). If the lamp output decays due to irradiation darkening, the patient may receive an insufficient dose (poor therapeutic effect), or unintentionally extend exposure time to compensate (increasing burn risk).
Ce-Ti tubes ensure stable and predictable UV output throughout the lamp’s lifespan, forming the foundation for both treatment safety and efficacy.
Handheld / Local UV Phototherapy Devices
Description:
Small devices used for treating localized skin lesions.
Why Ce-Ti Quartz Tubes Are Needed:
Similar to full-body chambers, accurate dosage is essential. This is especially important for home-use phototherapy devices, where stable device performance is critical for patient self-operation.
UV Vitiligo Treatment Systems
Description:
Often based on 308 nm excimer light (or laser), one of the most effective modern treatments for vitiligo.
Why Ce-Ti Quartz Tubes Are Needed:
The excitation lamp of a 308 nm excimer device is its core component. It must operate at extremely high power to generate strong UV radiation for gas excitation. The quartz tube here is subjected to an extremely harsh irradiation environment.
Only Ce-Ti materials with outstanding anti-radiation capability can ensure long-term stable output and service life. Ordinary quartz tubes will quickly age and fail under such conditions.
2. Medical-Grade UV Sterilization Devices
Although standard sterilization lamps can use conventional fused quartz, medical-grade applications require higher stability — a scenario where Ce-Ti tubes become essential.
Hospital Air / Surface Disinfection Systems
Description:
Used in operating rooms, patient rooms, and biosafety laboratories within fixed disinfection systems or circulating air sterilization units.
Why Ce-Ti Quartz Tubes Are Needed:
Such systems often require 24/7 continuous operation or very high usage frequency.
Ce-Ti quartz tubes maintain sterilizing UV intensity above the designed dosage for extended periods, ensuring reliable disinfection performance while significantly reducing maintenance and replacement frequency — lowering hospital operating costs and safety risks.
Water Disinfection Systems
Description:
Applied in wastewater treatment in hospitals, clinics, and laboratories to inactivate pathogens before discharge.
Why Ce-Ti Quartz Tubes Are Needed:
Again, long-term stability and reliability are critical requirements.
3. Blood Treatment and Pathogen Inactivation Equipment
This is a highly specialized application area.
Description:
Specific wavelengths of UV light (such as UVC) are used to irradiate blood products (such as plasma and platelets), inactivating viruses (HIV, hepatitis viruses, etc.) and bacteria without damaging functional blood components.
Why Ce-Ti Quartz Tubes Are Needed:
This process requires extremely precise radiation dosage
- Too little: pathogens are not effectively inactivated.
- Too much: blood components may be damaged.
Therefore, the light source must maintain exceptionally stable output without degradation over time.
Ce-Ti co-doped quartz tubes are ideal for producing UV light sources for such equipment.
Summary: Common Characteristics of Devices Using Ce-Ti Co-Doped Quartz Tubes
Medical equipment that requires Ce-Ti quartz tubes usually meets one or more of the following criteria:
- Dosage-critical applications:
Therapeutic or sterilization effectiveness is directly linked to the received UV dose. Any inaccuracy may lead to treatment failure or safety risks. - High-intensity output requirements:
Devices operate with extremely high UV lamp power, placing great demands on the quartz material’s anti-aging ability. - Long-term reliability:
Used in continuous-operation or long-term stability scenarios where lamp replacement is difficult or costly. - Professional, high-end applications:
Usually found in hospitals, professional clinics, or biological laboratories rather than in consumer-grade home products.
Therefore, Ce-Ti co-doped quartz tubes are chosen for high-end professional medical phototherapy devices to achieve precise dosage control and reliable service life. Behind this choice is a strong commitment to patient safety and treatment effectiveness.
What Is Solarization (Radiation-Induced Darkening)?
Let us take a closer look at a very important and unique phenomenon in quartz glass—radiation-induced darkening.
Core Definition
Radiation-induced darkening, also known as solarization, refers to the formation of defect centers inside quartz glass when exposed to high-energy radiation such as short-wave ultraviolet, X-rays, or gamma rays. These defects cause a significant and irreversible decrease in transmittance in the UV and visible regions, especially within the 200–300 nm band. In simple terms, the glass becomes “darker” or “discolored” after irradiation.
You can think of it as the glass undergoing “photo-aging” or being “sun-burned.”
Why Does Radiation-Induced Darkening Occur?
The fundamental reason is that microscopic structural defects in quartz glass are activated by high-energy photons.
Intrinsic Defects
Ideal high-purity quartz glass consists solely of a SiO₂ network. However, during actual manufacturing, certain subtle defects are inevitably introduced. The most common types are:
- Oxygen-deficient defects:
In a perfect structure, two oxygen atoms should connect one silicon atom. When one oxygen atom is missing, a dangling bond is formed. - Impurity ions:
Even in highly pure quartz, trace amounts of impurities may exist, such as aluminum (Al³⁺) or germanium (Ge⁴⁺). To maintain charge balance, these impurities can capture a hydrogen ion (H⁺) or an alkali metal ion (Na⁺), forming structures such as [AlO₄/H⁺].
Activation by High-Energy Radiation
When quartz glass is irradiated by high-energy photons such as short-wave UV, the energy is sufficient to break these weak chemical bonds.
- For oxygen-deficient defects: Si–Si bonds are broken.
- For impurity-related defects: The H⁺ in [AlO₄/H⁺] is ejected.
Formation of Color Centers
These processes generate highly active and unstable “color centers.” They act as electron traps and introduce new energy levels within the band gap of the glass.
These new levels absorb specific wavelengths of light—especially UV and violet light.
The glass may appear slightly yellow or brown, yet its UV transmittance drops sharply because ultraviolet photons are absorbed by these color centers.
What Factors Influence Radiation-Induced Darkening?
Radiation Source and Dose
Shorter wavelength (higher energy), stronger intensity, and longer exposure all increase the severity of solarization. Deep UV (DUV) and vacuum UV (VUV) are the main contributors.
Purity and Type of Quartz Glass (Most Critical Factor)
- Standard quartz tubes:
Higher impurity and defect content results in poor radiation resistance—darkening occurs easily. - High-purity quartz tubes:
Lower impurity levels improve radiation resistance. - Synthetic quartz tubes:
The best choice for anti-solarization performance.
Manufactured by CVD (chemical vapor deposition), synthetic quartz glass contains extremely low intrinsic defects and metal impurities. Therefore, it remains very stable under high-energy radiation, and transmittance decay is minimal.
Dopant Elements
Certain dopants can suppress radiation-induced darkening. For example, doping quartz glass with cerium (Ce).
Ce³⁺/Ce⁴⁺ can act as a “sacrificial agent,” absorbing energy through valence-state changes when exposed to high-energy radiation. This protects the glass network from damage and prevents the formation of light-absorbing color centers. Such glass is known as radiation-resistant quartz glass.
Operating Temperature
At high temperatures (typically above 300°C), color centers become unstable and may undergo partial annealing, leading to some degree of transmission recovery.
However, at room temperature, the darkening effect is essentially permanent.
How to Prevent or Reduce Radiation-Induced Darkening?
Proper Material Selection
For applications operating under long-term UV exposure—such as UV germicidal lamps, UV curing lamps, and excimer lamps—one must choose radiation-resistant synthetic quartz tubes or cerium-doped quartz tubes.
Although more expensive, they ensure long-term stable light output and longer service life.
Environmental Control
Avoid exposing quartz tubes to unnecessary strong radiation sources.
Regular Replacement
For standard quartz tubes, treat them as consumables and replace them according to the transmittance decay.
Therefore, when your application involves high-energy UV sources, radiation-induced darkening becomes one of the most critical factors in quartz material selection.
Why Are Cerium-Doped Quartz Tubes on the Market Blue-Purple Instead of Light Yellow?
Pure Ce³⁺-Doped Quartz Tubes Are Light Yellow
Pure cerium (Ce³⁺)–doped quartz tubes are light yellow. However, the so-called “cerium-doped quartz tubes” commonly seen on the market show a deep blue color, which is actually because another element—titanium (Ti)—is introduced either simultaneously or afterward.
A more accurate name for this deep-blue material should be “Ce-Ti co-doped quartz glass.”
Core Reason: Interaction Between the Valence States of Cerium and Titanium
Pure Cerium Doping (Ce³⁺): Light Yellow
When quartz glass contains only cerium and cerium exists in the trivalent state (Ce³⁺), its absorption band is mainly in the ultraviolet range (strong absorption of light <350 nm). It has only very weak absorption in the visible region, so the glass appears light yellow.
Key Step: Introduction and Oxidation of Titanium (Ti)
In actual industrial production, trace amounts of titanium (Ti) may be introduced from raw materials or processes.
More commonly, manufacturers intentionally dope both cerium (Ce) and titanium (Ti) to adjust and optimize material properties.
In the high-temperature oxidizing atmosphere used for melting quartz glass (such as oxygen-containing conditions), titanium is easily oxidized to the tetravalent state (Ti⁴⁺).
Color Reaction: Charge-Transfer Transition
The root cause of the deep blue color is not Ce³⁺ or Ti⁴⁺ themselves, but a strong interaction between them called heterovalent charge-transfer transition.
Specific Process
An electron transfers from Ce³⁺ to an adjacent Ti⁴⁺, causing an instantaneous change in valence state:
Ce³⁺ + Ti⁴⁺ → Ce⁴⁺ + Ti³⁺
The energy absorbed during this electron transition corresponds to photons in the lower-energy part of the visible spectrum (orange-red to yellow light, around 500–600 nm).
When white light passes through this glass, the orange-red light is strongly absorbed, and the transmitted light becomes a mixture of blue and purple, so the glass appears deep blue-purple.
Why Do Manufacturers Do This? Advantages of Ce-Ti Co-Doping
Stronger Radiation Resistance
The combination of cerium and titanium creates a synergistic effect, and its resistance to radiation-induced darkening (solarization) is usually more excellent and stable than that of quartz doped with cerium alone or titanium alone.
Wider Spectral Adaptability
This deep-blue glass is itself an efficient optical filter. It not only resists its own aging but also:
- absorbs unnecessary infrared radiation, reducing heat effects
- absorbs visible light, making the output light more concentrated in the ultraviolet band and “purifying” the UV light
This is beneficial for applications requiring specific UV wavelengths while avoiding visible-light interference (such as UV curing and photolithography).
Process and Cost
Sometimes titanium is an inherent impurity in raw materials. Rather than spending great effort to remove it, it is better to utilize its synergy with cerium to produce a material with better performance.
Summary Comparison
| Property | Pure Ce-Doped Quartz Tube | Ce-Ti Co-Doped Quartz Tube |
|---|---|---|
| Appearance | Light yellow | Deep blue / blue-purple |
| Cause of Coloring | Intrinsic absorption from Ce³⁺ | Charge-transfer transition between Ce³⁺ and Ti⁴⁺ |
| Main Absorption Region | Ultraviolet (<350 nm) | Ultraviolet + visible (orange-yellow light) |
| Radiation Resistance | Excellent | Usually better |
| Additional Function | Radiation resistance | Radiation resistance + infrared and visible-light filtering |
Conclusion
The deep-blue “cerium-doped quartz tubes” you see are actually performance-optimized Ce-Ti co-doped quartz tubes. Their color does not come from cerium alone but from the unique spectral absorption characteristics caused by charge-transfer reactions between cerium and titanium under high-temperature oxidizing conditions. This is a material engineered to deliver top-level anti-aging performance and specific filtering functions.
Request Quartz Glass Solution
We supply Ce-Ti co-doped quartz tubes for applications where UV stability and resistance to radiation-induced darkening are important.
If you are evaluating material options or need a solution for a specific application, you may contact us to discuss your requirements.
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