Nanocrystalline cores

Nanocrystalline magnetic cores are made of nanocrystalline steel with crystalline structure where the sizes of individual grains do not exceed 70 nm. The nanocrystallization process of the FeCuNbSiB material is performed in thermal T or thermomagnetic T+H field that provide the possibility of producing cores with different magnetic properties. The nanocrystalline steel tapes are the most modern soft magnetic materials with very low magnetic loss level. The material has also very low magnetostriction level and therefore it is very useful in low noise electrical applications working in devices at high frequencies. The nanocrystalline tapes are used for the construction of the following types of magnetic cores: wound cores, wound cut cores and also stacked and block cores. The cores protection is provided by plastics, resins or pressboard covers.

Basic properties of nanocrystalline toroidal cores

Curie Temperature

560   (°C)

Crystallization temperature

510   (°C)


7.2   (g/cm3)


130   (mW × cm)

Saturation induction Bs

1.25   (T)

Coercivity Hc  

< 1.60 (A/m)

Losses P at 50 Hz, 0.2 T

< 0.0025   (W/kg)

Losses P at 20kHz, 0.2T

< 3.4   (W/kg)

Relative magnetic permeability
at 50Hz, 0.4 A/m

> 150 000   (-)

Relative magnetic permeability
at 1kHz, 0.4 A/m

> 35 000   (-)

Relative magnetic permeability
at 2kHz, 0.4 A/m

> 30 000   (-)

Saturation magnetostriction  

0.2 x 10-6   (ppm)

Stack factor 

> 0.75   (-)

Outer diameter

20 – 300   (mm)

Inner diameter

15 – 290   (mm)