BNT
Grade · default condition
BNT = 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.
Values for the BNT 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 |
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 | — |
BNTDefaultThis page 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?
BNT is BNT in the BNT grade — 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. The elastic modulus is 110 GPa (16 Msi). BNT has a density of 5.85 g/cm³ (0.211 lb/in³), heavier than 61% of ceramic grades. It melts at 1,300°C (2,372 °F).
Limitations
- Limited service temperature — 150°C (302 °F), worse than 90% of ceramic grades
- Poor heat conductor — 1.8 W/m·K (1.04 BTU/hr·ft·°F), worse than 89% of ceramic grades
BNT properties
Typical room-temperature values for BNT; 10 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 has a density of 5.85 g/cm³ (0.211 lb/in³), heavier than 61% of ceramic grades. It melts at 1,300°C (2,372 °F).
Mechanical9
The elastic modulus is 110 GPa (16 Msi).
Thermal5
BNT is rated for continuous service to 150°C (302 °F). It conducts heat at 1.8 W/m·K (1.04 BTU/hr·ft·°F), worse than 89% of ceramic grades. Thermal expansion is 9 µm/m·K (5 µin/in·°F).
Electrical5
BNT is an electrical insulator with a dielectric strength of 7 kV/mm (177.8 V/mil) and a resistivity of 1×10⁹ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (82/100), better than 61% of ceramic grades.
Sustainability4
Producing a kilogram of BNT 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's machinability is not recommended (5/100, worse than 59% of ceramic grades).
Common Calculations2
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with BNT
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 — frequently asked
What is BNT used for?
BNT 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 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 be welded?
Not weldable; join by silver/epoxy electroding, glass frit or active-metal brazing to metallized surfaces.
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.
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 is the maximum service temperature of BNT?
BNT is rated for continuous use to about 150°C (302 °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.