Lithium Sodium Potassium Niobates (LNKN) are considered among the most promising piezoceramic materials as lead free alternatives to commonly used PZT (Lead Zirconate Titanate) ceramics.

A water-based, scalable production process for Niobates has been developed and optimized at Taniobis, which does not need organic solvents or ball milling steps. LNKN with specific combination of low primary particle size and phase composition can be produced.

To estimate the CO₂ footprint of Niobium vs. Lead based ceramics it should be noted that results from published LCA (life cycle analysis) differ widely with the data assumption for the calculation. The ecological impact is strongly depending on the type of mining that is used to extract the niobium ores. About 95% of global Niobium mining of more than 100,000t/a are sourced from open pit mining. Taniobis´ Niobate process offers the advantage of using no organic solvents, no energy intense ball milling and can rely on the high utilization rate of Niobium secondary raw materials at Taniobis.

LNKN piezoceramics offer the advantage of high operating temperature. Ceramic LNKN specimen sintered at Taniobis have a density of 4.3 g/cm³ with a Curie temperature at 1kHz of 470°C, which is 120°C higher than for PZT. A clear dependence of the dielectric properties on the storage conditions of the ceramic samples was shown. Small signal measurements gave piezoelectric constants in accordance with the literature data.

In general, LNKN offers further technical advantages over PZT. Current PZT piezoceramics need precious metal electrodes as firing of PZT in reducing atmosphere, where cheaper electrode materials like nickel do not oxidize, would cause the lead oxide in the ceramic turn into metal. LNKN can be sintered in a reducing atmosphere allowing for the usage of cheaper inner electrode material like nickel. Low-cost metal electrodes allow more and thereby thinner layers in actuators without cost increase.

As the piezoelectric elongation of an actuator is proportional to the number of layers at a given voltage, thinner layers could enable a large displacement. The almost 50% lower density of LNKN compared to PZT makes LNKN a promising material for higher frequency transducers. As the frequency is inversely proportional to the square root of the density, low density means that a high frequency transducer can operate at a higher frequency for the same thickness.

Dr. Sven Albrecht