N-LaK9 HT (High-transmittance melt)
Heat-treated state
Pick where long glass paths or blue/near-UV throughput matter (projection, scanners, multi-element objectives).
Values for the HT condition
What is N-LaK9 HT?
N-LaK9 HT is N-LaK9 heat treated to HT — pick where long glass paths or blue/near-UV throughput matter (projection, scanners, multi-element objectives). N-LaK9 HT has a tensile strength of 55 MPa (7.98 ksi), stronger than 71% of glass grades. The elastic modulus is 110 GPa (16 Msi). N-LaK9 HT has a density of 3.51 g/cm³ (0.127 lb/in³), heavier than 67% of glass grades.
Advantages
- Stiff — 110 GPa (16 Msi), better than 83% of glass grades
Limitations
- Poor heat conductor — 0.9 W/m·K (0.52 BTU/hr·ft·°F), worse than 84% of glass grades
N-LaK9 HT properties
Typical room-temperature values for N-LaK9 HT; 3 are specific to this condition. Other listed values are N-LaK9 reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
N-LaK9 HT has a density of 3.51 g/cm³ (0.127 lb/in³), heavier than 67% of glass grades.
Mechanical11
N-LaK9 HT has a tensile strength of 55 MPa (7.98 ksi), stronger than 71% of glass grades. The elastic modulus is 110 GPa (16 Msi).
Thermal5
N-LaK9 HT is rated for continuous service to 500°C (932 °F). It conducts heat at 0.9 W/m·K (0.52 BTU/hr·ft·°F), worse than 84% of glass grades. Thermal expansion is 6.3 µm/m·K (3.5 µin/in·°F).
Electrical2
Chemical & Environmental2
Corrosion resistance is good (62/100), worse than 65% of glass grades.
Sustainability4
Producing a kilogram of N-LaK9 HT takes about 60 MJ of energy and emits 4.5 kg of CO₂ — more than 58% of glass grades. Typical recycled content is 20%.
Manufacturability2
N-LaK9 HT's machinability is not recommended (12/100, worse than 68% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with N-LaK9 HT
Is N-LaK9 easy to machine?
No conventional machining — diamond core drilling, curve generating, loose-abrasive lapping then CeO2 polishing; grinds faster than N-BK7 but chips more at edges.
Can N-LaK9 be welded?
Not weldable; joining is by optical contact, UV/epoxy cementing or low-stress mounting.
Can N-LaK9 be formed, bent or molded?
Hot forming by reheat pressing of gobs above ~700 °C; Tg ≈ 640 °C is too high for standard low-Tg precision glass molding, and slow fine annealing is mandatory to control index and birefringence.
What surface finishes work on N-LaK9?
Polished surfaces should be AR-coated promptly; the La-crown surface is stain-sensitive, so avoid alkaline cleaners and long humid storage.
N-LaK9 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 |
|---|---|---|
| La2O3Typical of the lead-free lanthanum-borate crown family; exact batch is proprietary to the melter. | 25 – 45 | 35 |
| B2O3Network former, approximate family value | 15 – 30 | 22 |
| SiO2Approximate family value | 3 – 15 | 8 |
| ZnOApproximate family value | 3 – 15 | 8 |
| ZrO2Index/chemical-durability booster, approximate | 2 – 8 | 5 |
| CaO + BaO + other modifiersN-series is lead- and arsenic-free | balance |
N-LaK9 HT — frequently asked
What is N-LaK9 HT used for?
N-LaK9 HT is typically used for camera lenses, microscope objectives and telescope optics. In short: high index, low dispersion; grinds faster than N-BK7.
What is the tensile strength of N-LaK9 HT?
N-LaK9 HT has a typical tensile strength of 55 MPa (7.98 ksi) — stronger than 71% of glass grades.
Is N-LaK9 HT easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 68% of glass grades). No conventional machining — diamond core drilling, curve generating, loose-abrasive lapping then CeO2 polishing; grinds faster than N-BK7 but chips more at edges.
Can N-LaK9 HT be welded?
Not weldable; joining is by optical contact, UV/epoxy cementing or low-stress mounting.
What surface finishes work on N-LaK9 HT?
Polished surfaces should be AR-coated promptly; the La-crown surface is stain-sensitive, so avoid alkaline cleaners and long humid storage.
Can N-LaK9 HT be formed, bent or molded?
Hot forming by reheat pressing of gobs above ~700 °C; Tg ≈ 640 °C is too high for standard low-Tg precision glass molding, and slow fine annealing is mandatory to control index and birefringence.
What is the maximum service temperature of N-LaK9 HT?
N-LaK9 HT is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- N-LaK9 optical glass datasheet / Optical Glass Data Sheets — SCHOTT AG (2023)
- TIE-19/TIE-33 Technical Information (stress birefringence, annealing) — SCHOTT AG (2020)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.