Yogoro Kato and Takeshi Takei synthesized the first ferrite magnet compounds in 1930, work that led to the founding of TDK in 1935.
Barium hexaferrite was discovered by accident at the Philips Natuurkundig Laboratorium in 1950 and marketed from 1952 as Ferroxdure; Philips developed the higher-performance strontium hexaferrite in the 1960s.
The hexagonal ceramics deliver about 0.35 tesla at roughly 5 g/cm³ with coercive fields of 30–160 kA/m, and anchor loudspeakers, small motors and magnetic stripe cards.