KNN HP (HP/SPS)
Other
Use the hot-pressed or spark-plasma-sintered near-fully-dense route to suppress alkali volatilization and get the best strength, insulation and consistency in thin elements and high-field drive.
Values for the HP condition
Other KNN tempers and conditions
KNN is listed in 5 conditions; see the grade overview at KNN.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Undoped (K0.5Na0.5)NbO3, conventional air sintering | Use the undoped, conventionally air-sintered baseline when the highest Curie temperature (~410 °C) or an academic reference matters; piezoelectric response and density are lower. | — | — | — | 330 HV | 2 W/m·K |
Textured (templated grain growth) <001> KNN | Choose textured <001> material grown from NaNbO3 platelet templates when piezoelectric constants must come closest to soft PZT; cost and process complexity are the highest of the family. | — | — | — | 380 HV | — |
LTSDefault Li/Ta/Sb-modified soft KNN | Choose the Li/Ta/Sb-modified soft composition, with its phase boundary shifted near room temperature, for the highest piezoelectric and dielectric response in buzzers, atomizer discs and sensors. | — | — | — | 400 HV | 3 W/m·K |
CuO/Mn-doped hard KNN for high-power resonators | Pick the acceptor-doped CuO/Mn hard type for high mechanical quality factor Qm and low loss under continuous high-power drive, such as ultrasonic welding horns and cleaning transducers. | — | — | — | 420 HV | — |
HPThis page HP/SPS | Use the hot-pressed or spark-plasma-sintered near-fully-dense route to suppress alkali volatilization and get the best strength, insulation and consistency in thin elements and high-field drive. | — | — | — | 460 HV | 3 W/m·K |
What is KNN HP?
KNN HP is KNN in the HP condition — use the hot-pressed or spark-plasma-sintered near-fully-dense route to suppress alkali volatilization and get the best strength, insulation and consistency in thin elements and high-field drive. The elastic modulus is 118 GPa (17.1 Msi). KNN HP has a density of 4.52 g/cm³ (0.163 lb/in³), lighter than 54% of ceramic grades. It melts at 1,140°C (2,084 °F). LTS is the default condition FabDigit quotes; HP is available on request or by drawing note.
Limitations
- Limited service temperature — 180°C (356 °F), worse than 86% of ceramic grades
- Poor heat conductor — 3 W/m·K (1.73 BTU/hr·ft·°F), worse than 77% of ceramic grades
KNN HP properties
Typical room-temperature values for KNN HP; 14 are specific to this condition. Other listed values are KNN reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical4
KNN HP has a density of 4.52 g/cm³ (0.163 lb/in³), lighter than 54% of ceramic grades. It melts at 1,140°C (2,084 °F).
Mechanical9
The elastic modulus is 118 GPa (17.1 Msi).
Thermal5
KNN HP is rated for continuous service to 180°C (356 °F). It conducts heat at 3 W/m·K (1.73 BTU/hr·ft·°F), worse than 77% of ceramic grades. Thermal expansion is 7 µm/m·K (3.89 µin/in·°F).
Electrical5
KNN HP is an electrical insulator with a dielectric strength of 6 kV/mm (152.4 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (62/100), worse than 70% of ceramic grades.
Sustainability4
Producing a kilogram of KNN HP takes about 160 MJ of energy and emits 11 kg of CO₂ — more than 59% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
KNN HP's machinability is not recommended (8/100, better than 69% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with KNN HP
Is KNN easy to machine?
After firing, only diamond grinding, ultrasonic drilling or laser cutting is possible; machining in the green or bisque state is by far the cheapest route. Anneal after grinding to remove surface residual stress before poling.
Can KNN be welded?
The ceramic is not weldable. Metal connection is made through fired silver-paste electrodes followed by soft soldering below 250 °C to avoid depoling, or by conductive adhesive.
Can KNN be formed, bent or molded?
Dry pressing, cold isostatic pressing and tape casting are all usable. The sintering window is narrow (about ±20 °C), so fire in sealed saggars with excess alkali in the batch to compensate K/Na volatilisation, otherwise second phases and abnormal grain growth appear.
What surface finishes work on KNN?
Screen-print and fire silver electrodes at roughly 700–800 °C, or sputter Cr/Au. Pole at 2–4 kV/mm in silicone oil at 80–120 °C and age 24 h; finished parts need moisture-barrier packaging.
KNN 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 |
|---|---|---|
| Nbadded as Nb2O5; partly replaced by Ta/Sb in modified grades | 50 – 55 | 54 |
| Kfrom K2CO3; volatile in sintering, added in excess to compensate | 10 – 12 | 11.4 |
| Naintroduced as Na2CO3 | 6 – 7.5 | 6.7 |
| LiA-site dopant in modified (LTS) grades, ~3–6 mol% | 0 – 0.5 | 0.15 |
| TaB-site substitution for Nb in modified grades, ~10–20 mol% | 0 – 12 | 6 |
| SbB-site substitution in modified grades, ~3–7 mol% | 0 – 4 | 1.5 |
| Ooxygen site of perovskite ABO3, ~28 wt% | balance | — |
KNN HP — frequently asked
What is KNN HP used for?
KNN HP is typically used for lead-free piezo actuators, lead-free sensors and green electronics components. In short: lead-free PZT alternative; narrow sintering window; lower density than PZT.
Is KNN HP easy to machine?
Not especially — machinability is rated not recommended (8/100, better than 69% of ceramic grades). After firing, only diamond grinding, ultrasonic drilling or laser cutting is possible; machining in the green or bisque state is by far the cheapest route. Anneal after grinding to remove surface residual stress before poling.
Can KNN HP be welded?
The ceramic is not weldable. Metal connection is made through fired silver-paste electrodes followed by soft soldering below 250 °C to avoid depoling, or by conductive adhesive.
What surface finishes work on KNN HP?
Screen-print and fire silver electrodes at roughly 700–800 °C, or sputter Cr/Au. Pole at 2–4 kV/mm in silicone oil at 80–120 °C and age 24 h; finished parts need moisture-barrier packaging.
Can KNN HP be formed, bent or molded?
Dry pressing, cold isostatic pressing and tape casting are all usable. The sintering window is narrow (about ±20 °C), so fire in sealed saggars with excess alkali in the batch to compensate K/Na volatilisation, otherwise second phases and abnormal grain growth appear.
What is the maximum service temperature of KNN HP?
KNN HP is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASM Engineered Materials Handbook Vol.4: Ceramics and Glasses — ASM International (1991)
- IEEE 176 Standard on Piezoelectricity — IEEE (1987)
- Lead-free piezoceramics (KNN) property reviews — Journal of the American Ceramic Society / Journal of Materials Chemistry C (2019)
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.