 The potassium sodium niobate, KNN, a lead-free material, is a promising candidate for replacing PZT in applications such as sensors and actuators due to its environmental friendliness and high efficiency. However, producing pure KNN ceramic with a high density and a uniform, fine-grained microstructure is challenging. Various methods have been developed to address these issues, including solid-state synthesis, centering, and special centering techniques. Solid-state synthesis produces KNN powders with low densities and large grain sizes, while centering requires careful control over the temperature and atmosphere to avoid coarsening and achieve densification. Pressure-assisted centering and spark plasma centering have proven successful in achieving higher densities than conventional centering. This article was authored by Barbara Malik, Jurij Karuza, Jika Hreskak, and others.