NaI (Tl) (Thallium-doped Sodium Iodide)
Keywords:
Scintillation Crystals
- Product Introduction
- Key advantages
- Application areas
- Product Features
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- Commodity name: NaI (Tl) (Thallium-doped Sodium Iodide)
Sodium iodide is one of the most widely used materials in scintillator applications, and it can be employed both as a single crystal and as a polycrystal.Thallium-doped sodium iodide (NaI(Tl)) crystals are high-performance scintillation crystals.
Product Introduction
Sodium iodide is one of the most widely used materials in scintillator applications, and it can be employed both as a single crystal and as a polycrystal.
Thallium-doped sodium iodide (NaI(Tl)) crystals are high-performance scintillation crystals. These crystals are grown by adding an appropriate concentration of the activator thallium (Tl) to a sodium iodide (NaI) matrix material. They exhibit a peak emission wavelength of 415 nm, which perfectly matches the photocathode of commonly used photomultiplier tubes.
Single-crystal NaI(Tl) exhibits planar cleavage under similar shock conditions. In detector components made from single-crystal materials, even tiny cracks can propagate throughout the entire crystal, potentially disrupting light collection and degrading pulse height resolution.
The polycrystalline structure originates from a unique manufacturing process: a single-crystal ingot undergoes recrystallization under heat and pressure. The resulting material is characterized as a polycrystalline (thermally forged crystalline) material, featuring an interwoven microstructure of randomly oriented crystalline grains. Notably, the density of NaI remains unchanged throughout this process. While this property significantly enhances mechanical strength, it has no impact on scintillation performance, as polycrystalline NaI(Tl) material is optically identical to its single-crystal counterpart. Moreover, any fractures caused by thermal or mechanical shocks are typically confined—or at least limited—to small, localized grain volumes. Because the cleavage planes of these grains are randomly oriented, minor cracks are highly unlikely to propagate across grain boundaries. This makes polycrystalline NaI(Tl) the material of choice for applications where robustness is critical, such as well logging, measurement while drilling (MWD), and aerospace applications.
Key Advantages
- High light output
- Available in single crystal and polycrystalline forms
- Minimal self-absorption of scintillation light
- The emission spectrum well-matched to the sensitivity curve of alkali Photocathode photomultiplier tube (PMT).
- High detection efficiencyApplication Areas
-In γ cameras, positron emission tomography (PET) scanners, and tther radiation detection systems
- Nuclear medicine, nuclear physics, radiation detection
- Aerial surveying, environmental monitoring
- Well logging and scientific researchProduct Features
Material Properties
Density
3.67 g/cm³
Thermal Expansion Coefficient (K⁻¹)
47.4 × 10 -6
Mohs Hardness
2.1 Mohs
Cleavage Plane
(100)
Deliquescence
Yes
Decay Time
250 ns
Emission Peak Wavelength
415 nm
Refractive Index (at the maximum emission wavelength)
1.85
Afterglow
0.3–0.5% @ 6 mm
Temperature Coefficient
0.3% C-1
Light Output
38000 Photon/Mev
Melting Point
651°C
Product Processing Indicators
Effective Aperture
>90%
Dimensions
Customized to Customer Specifications
Diameter Tolerance
+0/-0.05 mm
Length Tolerance
±0.2 mm
Chamfer
≤0.2×45°
Surface Quality
40-20 S-D
Flatness
≤λ/6 @ 632.8 nm
Parallelism
<20"
Perpendicularity
≤15′
Chipped edge
<0.1 mm
Coating
Customized to Customer Specifications
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- Luminescent properties
- Radiation resistance
- Short decay time
- Fine energy resolution
- Non-hygroscopic -
- High-energy physics experiments
- Nuclear Medicine
- Environmental Monitoring
- Space Science
- Large Electron-Positron Collider
- Dark Matter Detection -
Material Properties Molecular formula Bi4Ge3O12 Crystal structure Cubic crystal system Lattice constant a = 1.0518 Å Production method Tiraf Method Density 7.12g/cm3 Mohs Hardness 5Mohs Radiation Length 1.1cm Transmittance range 350 nm ~ 5500 nm Relative Light Output (%) 10-14 Nal (Tl) Fluorescence spectrum peak 480–510 nm Recession time 300ns Energy resolution 20 (511 keV, %) Refractive index 2.098 @ 632.8 nm Melting point 1050°C Product Processing Metrics Directional <001> +/- 0.5° Effective Aperture >90% Dimensions Customized to customer specifications Diameter Tolerance +0 / -0.05 mm Length Tolerance ±0.2mm Protective Chamfer ≤0.2 × 45° Surface finish 10-5 S-D Flatness ≤λ/10 @ 632.8 nm Analyzing wavefront distortion ≤λ/8 @ 632.8 nm Parallelism <20" Verticality ≤15′ Chipped edge < 0.1 mm Coating Customized to customer specifications
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