What Scientists Must Prepare Before Ordering Custom Crystals
Ordering custom-grown crystals is fundamentally different from purchasing off-the-shelf materials. Research-grade single crystals require precise technical specifications to ensure manufacturability, performance, and experimental reproducibility.
This article provides a researcher-ready technical checklist for scientists and engineers planning to order custom-grown single crystals for scientific and industrial R&D applications.
Overview: Key Parameters That Must Be Defined
- Growth method
- Crystallographic orientation
- Dopant type and concentration
- Raw material purity
- Dimensions and geometry
- Surface finish and optical quality
- Mechanical and dimensional tolerances
SECTION A — 1. Crystal Material & Growth Method
✔ Crystal Type
Clearly specify the crystal material required for your application. Typical examples include:
- Scintillators: LYSO, YSO, BGO, CsI:Tl, NaI:Tl, GAGG:Ce
- Laser crystals: YAG, Nd:YAG, Er:YAG, Ti:Sapphire
- Optical crystals: Sapphire, Quartz, CaF₂, MgF₂
- Semiconductors: Ga₂O₃, ZnO, CdZnTe
- Functional materials: LiNbO₃, LiTaO₃
✔ Growth Method
If known, specify the preferred growth technique:
- Czochralski (CZ)
- Bridgman / Vertical Gradient Freeze (VGF)
- Hydrothermal growth
- Flux growth
- Floating-zone
SECTION B — 2. Size & Geometry (Dimensions)
This information is mandatory for every order.
✔ Specify:
- Length × width × thickness
- Diameter (for wafers or rods)
- Rod vs. plate geometry
- Cutting requirements
- Edge bevel or chamfer
SECTION C — 3. Crystallographic Orientation
✔ Orientation specification
Common orientation formats include:
- (100), (110), (111)
- c-plane, a-plane, r-plane (sapphire)
- X-cut, Y-cut, Z-cut (quartz, LiNbO₃)
✔ Orientation tolerance
- ±0.5° — standard
- ±0.2° — laser / scintillator grade
- ±0.1° — high-end optical applications
If not specified, ±0.5° is typically applied by default.
SECTION D — 4. Doping Level & Uniformity
✔ Mandatory for doped crystals
- Dopant element (Ce, Nd, Pr, Ti, Mg, etc.)
- Concentration (mol%, at.%, wt%, or ppm)
- Uniformity requirements
- Axial or radial gradient limits (if applicable)
Typical examples:
- Nd:YAG — 1.0 at.% Nd
- Ce:GAGG — 0.5–1 mol%
- Ti:Sapphire — 0.15–0.25 wt%
SECTION E — 5. Raw Material Purity
Specify the required starting material purity:
- 4N — 99.99%
- 5N — 99.999%
- 6N — 99.9999% (semiconductor / scintillator grade)
Additional requirements may include:
- Low α-radiation raw materials
- Low Fe or transition-metal contamination
- UV-grade or laser-grade purity
SECTION F — 6. Surface Finish & Optical Quality
✔ Polishing options
- Fine-ground (non-optical)
- Optical polish, single-side
- Optical polish, double-side
✔ Scratch–dig specification
- 80-50 — general
- 60-40 — standard optics
- 40-20 / 20-10 — scientific and laser-grade
✔ Flatness
- λ/2 — general optical
- λ/4 — research-grade optics
- λ/10 — laser resonator grade
✔ Optional coatings
- Anti-reflection (AR) coatings
- High-reflection (HR) mirror coatings
- Protective coatings for scintillators
SECTION G — 7. Mechanical & Dimensional Tolerances
✔ Typical dimensional tolerances
- Length / width: ±0.05–0.10 mm (standard), ±0.02 mm (precision)
- Thickness: ±0.05 mm (standard), ±0.01–0.02 mm (precision)
- Diameter (wafers): ±0.05 mm (standard), ±0.02 mm (precision)
- Parallelism: <10–20 µm (standard), <5 µm (high precision)
✔ Edge specifications
- Chamfer size (typically 0.1–0.3 mm)
- Edge radius
- Safety bevel for brittle crystals
Conclusion
Clear and complete specification of these parameters enables crystal growers and fabrication partners to deliver higher yield, shorter lead times, and more consistent performance.
This checklist is intended to support researchers in communicating technical requirements accurately, improving experimental reproducibility and reducing costly redesign or reprocessing.
