BNT-BT-KNN
Grade
Relaxor composition (e.g. 0.92BNT–0.06BT–0.02KNN) giving giant field-induced strain (>0.3 %) for lead-free actuators, at the cost of large hysteresis, high driving field and near-zero small-signal d33.
Values for the BNT-BT-KNN condition
Other BNT tempers and conditions
BNT is listed in 4 conditions; see the grade overview at BNT.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
1-x)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3 (x ≈ 0.16–0.20 | Rhombohedral–tetragonal MPB with a higher depolarization temperature than BNT-BT; choose when the device must run warmer than ~100 °C. | — | 42 | 0.05 | 500 HV | 2 W/m·K |
BNT-BT-KNNThis page ternary relaxor (incipient piezoelectric) actuator composition | Relaxor composition (e.g. 0.92BNT–0.06BT–0.02KNN) giving giant field-induced strain (>0.3 %) for lead-free actuators, at the cost of large hysteresis, high driving field and near-zero small-signal d33. | — | 42 | 0.05 | 510 HV | 2 W/m·K |
0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3, MPB composition | The workhorse commercial BNT solid solution at the rhombohedral/tetragonal MPB — best d33 and easiest poling, but depolarizes near 100 °C so keep operating temperature low. | — | — | — | 520 HV | — |
BNTDefault Pure Bi0.5Na0.5TiO3, pressureless sintered | Baseline pure composition: highest Curie point and depolarization temperature of the family, but hard to pole (Ec ≈ 7 kV/mm) and modest d33 — pick for research and higher-temperature ferroelectric use. | — | — | — | 550 HV | — |
What is BNT-BT-KNN?
BNT-BT-KNN is BNT in the BNT-BT-KNN grade — relaxor composition (e.g. 0.92BNT–0.06BT–0.02KNN) giving giant field-induced strain (>0.3 %) for lead-free actuators, at the cost of large hysteresis, high driving field and near-zero small-signal d33. The elastic modulus is 100 GPa (14.5 Msi). BNT-BT-KNN has a density of 5.8 g/cm³ (0.21 lb/in³), heavier than 61% of ceramic grades. It melts at 1,300°C (2,372 °F). BNT is the default condition FabDigit quotes; BNT-BT-KNN is available on request or by drawing note.
Limitations
- Limited service temperature — 90°C (194 °F), worse than 97% of ceramic grades
- Poor heat conductor — 1.5 W/m·K (0.867 BTU/hr·ft·°F), worse than 92% of ceramic grades
BNT-BT-KNN properties
Typical room-temperature values for BNT-BT-KNN; 17 are specific to this condition. Other listed values are BNT reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical4
BNT-BT-KNN has a density of 5.8 g/cm³ (0.21 lb/in³), heavier than 61% of ceramic grades. It melts at 1,300°C (2,372 °F).
Mechanical9
The elastic modulus is 100 GPa (14.5 Msi).
Thermal5
BNT-BT-KNN is rated for continuous service to 90°C (194 °F). It conducts heat at 1.5 W/m·K (0.867 BTU/hr·ft·°F), worse than 92% of ceramic grades. Thermal expansion is 9 µm/m·K (5 µin/in·°F).
Electrical5
BNT-BT-KNN is an electrical insulator with a dielectric strength of 7 kV/mm (177.8 V/mil) and a resistivity of 3×10⁸ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (80/100), better than 56% of ceramic grades.
Sustainability4
Producing a kilogram of BNT-BT-KNN takes about 95 MJ of energy and emits 8.5 kg of CO₂ — less than 57% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
BNT-BT-KNN's machinability is not recommended (5/100, worse than 59% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with BNT-BT-KNN
Is BNT easy to machine?
Green machining or tape casting before firing; fired parts only by diamond grinding, lapping and ultrasonic/laser drilling — brittle and prone to edge chipping.
Can BNT be welded?
Not weldable; join by silver/epoxy electroding, glass frit or active-metal brazing to metallized surfaces.
Can BNT be formed, bent or molded?
Solid-state calcination of Bi2O3/Na2CO3/TiO2 then uniaxial or CIP pressing, tape casting or screen printing; sinter 1100–1200 °C in sealed sagger with a Bi/Na-rich atmosphere powder to curb volatilization.
What surface finishes work on BNT?
Lap to thickness, fire-on silver or sputtered Cr/Au electrodes, then pole in silicone oil at 4–8 kV/mm (higher field than PZT) and age before test.
BNT 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 |
|---|---|---|
| Bias Bi2O3 in the A-site (0.5 formula units) | 48.5 – 50 | 49.3 |
| Naas Na2CO3 precursor; volatile above ~1150 °C | 5.2 – 5.6 | 5.43 |
| TiB-site, from TiO2 | 22.2 – 23 | 22.6 |
| Operovskite ABO3 lattice oxygen | balance | — |
BNT-BT-KNN — frequently asked
What is BNT-BT-KNN used for?
BNT-BT-KNN is typically used for lead-free actuators, lead-free sensors and energy harvesting devices. In short: lead-free PZT alternative; relaxor ferroelectric ceramic; 150 °C service ceiling.
Is BNT-BT-KNN easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 59% of ceramic grades). Green machining or tape casting before firing; fired parts only by diamond grinding, lapping and ultrasonic/laser drilling — brittle and prone to edge chipping.
Can BNT-BT-KNN be welded?
Not weldable; join by silver/epoxy electroding, glass frit or active-metal brazing to metallized surfaces.
What surface finishes work on BNT-BT-KNN?
Lap to thickness, fire-on silver or sputtered Cr/Au electrodes, then pole in silicone oil at 4–8 kV/mm (higher field than PZT) and age before test.
Can BNT-BT-KNN be formed, bent or molded?
Solid-state calcination of Bi2O3/Na2CO3/TiO2 then uniaxial or CIP pressing, tape casting or screen printing; sinter 1100–1200 °C in sealed sagger with a Bi/Na-rich atmosphere powder to curb volatilization.
What is the maximum service temperature of BNT-BT-KNN?
BNT-BT-KNN is rated for continuous use to about 90°C (194 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Perovskite lead-free piezoelectric ceramics — review of BNT-based systems — Journal of the American Ceramic Society / J. Electroceram. (2019)
- PIC700 lead-free bismuth-sodium-titanate piezoceramic data — PI Ceramic GmbH (2023)
- IEC 60483 / IEEE 176 Standard on Piezoelectricity — IEC / IEEE (1987)
- Lead-free piezoceramic property compilations (BNT, BNT-BT, BNT-BKT) — Materials Project / MatWeb-class aggregators (2024)
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.