KDP
KDP (KH2PO4) is a water-soluble nonlinear-optical single crystal grown from aqueous solution as conventional (CONV) and rapid-growth (RG) boules and as 70% deuterated DKDP-70.
Reference datasheet — KDP is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the CONV condition
KDP tempers and conditions
KDP is supplied in 3 conditions, soft to hard. CONV is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Rapid-growth large-aperture KDP | Pick for metre-class ICF laser frequency-conversion and plasma-electrode Pockels-cell plates where aperture and lead time dominate over ultimate homogeneity. | — | 11 | 0 | 170 HV | 1 W/m·K |
Deuterated KD*P, ~70–98 % deuteration | Choose when low 1.06 µm absorption, larger electro-optic coefficient (lower half-wave voltage) or extended IR transmission to ~1.6 µm is required. | — | 11 | 0 | 165 HV | 1 W/m·K |
CONVDefault Conventional slow solution growth, laser/optical grade | Default choice for Pockels cells, SHG/THG plates and small-to-medium apertures where highest optical homogeneity and damage threshold matter. | — | 12 | 0 | 170 HV | 1 W/m·K |
What is KDP?
KDP (KH2PO4) is a water-soluble nonlinear-optical single crystal grown from aqueous solution as conventional (CONV) and rapid-growth (RG) boules and as 70% deuterated DKDP-70. Density is 2.338 g/cm3 and it can be grown in very large apertures, which is why it is used for harmonic generation and Pockels-cell switching in high-power laser systems such as ICF drivers. Limits are water solubility, an 80 °C service ceiling, low hardness and {100}/{101} cleavage: sawing and diamond flycutting are done in oil, and finished parts must be kept dry. BBO or LBO are the alternatives at small aperture. KDP has a density of 2.34 g/cm³ (0.0845 lb/in³), lighter than 80% of glass grades. It melts at 253°C (487 °F). KDP has a tensile strength of 12 MPa (1.74 ksi), weaker than 92% of glass grades. Elongation at break is 0% and the elastic modulus is 44 GPa (6.38 Msi).
What is KDP used for?
- laser frequency doubling/tripling
- Pockels cell electro-optic switches
- high-power laser systems (e.g., ICF)
Advantages
- Lightweight — 2.34 g/cm³ (0.0845 lb/in³), better than 80% of glass grades
Limitations
- Limited service temperature — 80°C (176 °F), worse than 100% of glass grades
- Low fracture toughness — 0.15 MPa·√m (0.137 ksi·√in), worse than 97% of glass grades
- Needs corrosion protection — 8/100, worse than 94% of glass grades
- Low stiffness — 44 GPa (6.38 Msi), worse than 83% of glass grades
KDP properties
Typical room-temperature values for KDP-CONV; bars are the position among glass grades.
Physical5
KDP has a density of 2.34 g/cm³ (0.0845 lb/in³), lighter than 80% of glass grades. It melts at 253°C (487 °F).
Mechanical13
KDP has a tensile strength of 12 MPa (1.74 ksi), weaker than 92% of glass grades. Elongation at break is 0% and the elastic modulus is 44 GPa (6.38 Msi).
Thermal5
KDP is rated for continuous service to 80°C (176 °F). It conducts heat at 1.3 W/m·K (0.751 BTU/hr·ft·°F), worse than 53% of glass grades. Thermal expansion is 33 µm/m·K (18.3 µin/in·°F).
Electrical5
KDP is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10⁸ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (8/100), worse than 94% of glass grades.
Manufacturability2
KDP's machinability is poor (30/100, better than 71% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. KDP is highlighted; hover a dot for its name, or open the interactive family chart.
Working with KDP
Is KDP easy to machine?
Never use water — saw with wire/OD blade in oil or kerosene, then single-point diamond flycut; cleaves on {100}/{101}, so keep cuts light and stress-free.
Can KDP be welded?
Not weldable; elements are optically contacted, edge-bonded with low-stress adhesive, or mounted in oil-filled or dry-N2 hermetic cells.
Can KDP be formed, bent or molded?
Grown only from aqueous solution (temperature-lowering or rapid point-seed supersaturation) over weeks to months; no melt or ceramic forming route.
KDP chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Kstoichiometric KH2PO4, M=136.09 g/mol | 28.6 – 28.8 | 28.73 |
| P | 22.6 – 22.9 | 22.76 |
| Hacidic protons; replaced by D in DKDP variant | 1.4 – 1.55 | 1.48 |
| metallic impurities (Fe, Cr, Al, Si)ppm-level control required for damage threshold | ≤ 0 | 5×10⁻⁴ |
| O | balance | — |
What surface finishes work on KDP?
Diamond flycut to λ/10 flatness and <2 nm rms, then sol-gel or low-temperature e-beam AR coating; store and use below ~40 % RH with desiccant.
Equivalent designations
Standards and trade names that resolve to KDP in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- KH2PO4
How much does KDP cost?
KDP is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
KDP — frequently asked
What is KDP used for?
KDP is typically used for laser frequency doubling/tripling, pockels cell electro-optic switches and high-power laser systems (e.g., ICF). In short: largest-aperture NLO crystal; water-soluble, oil machining only; 80 °C service ceiling.
What is the tensile strength of KDP?
KDP has a typical tensile strength of 12 MPa (1.74 ksi) — weaker than 92% of glass grades. Strength varies by condition: see the 3 listed tempers.
Is KDP easy to machine?
Not especially — machinability is rated poor (30/100, better than 71% of glass grades). Never use water — saw with wire/OD blade in oil or kerosene, then single-point diamond flycut; cleaves on {100}/{101}, so keep cuts light and stress-free.
Can KDP be welded?
Not weldable; elements are optically contacted, edge-bonded with low-stress adhesive, or mounted in oil-filled or dry-N2 hermetic cells.
What surface finishes work on KDP?
Diamond flycut to λ/10 flatness and <2 nm rms, then sol-gel or low-temperature e-beam AR coating; store and use below ~40 % RH with desiccant.
Can KDP be formed, bent or molded?
Grown only from aqueous solution (temperature-lowering or rapid point-seed supersaturation) over weeks to months; no melt or ceramic forming route.
What is the maximum service temperature of KDP?
KDP is rated for continuous use to about 80°C (176 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does KDP cost?
KDP is a high-cost glass ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Properties of Optical and Laser-Related Materials — Wiley (Marvin J. Weber) (1997)
- Nonlinear Optical Crystals: A Complete Survey — Springer (D. N. Nikogosyan) (2005)
- KDP / DKDP nonlinear and electro-optic crystal datasheets — CASTECH / EKSMA Optics / Fuzhou crystal suppliers (2024)
- Landolt-Börnstein: Elastic, Piezoelectric and Dielectric Constants of Crystals (KDP group) — Springer (1993)
- KDP/DKDP KH2PO4 (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.