Abstract: Soft ferrites have excellent a.c.permeability, but it is reduced under stress.It has a hyperbolic re- lationship between permeability μ and stress σ or a linear increase of 1/μ with σ.It is also found that the stress sensitive factor α depends on sample porosity p.For fully densified Mn-Zn ferrites α is only 10~(-7)～10~(-8) MPa~(-1),but it increases to 6× 10~(-6) MPa~(-1) for samples containing closed porosity 6%.Such materials could be used as a sensor for measuring pressure。

Key words: ferrite, permeability, hydrostatic stress