Development and application of ferrite materials for low temperature co-fired ceramic （LTCC） technology are dis- cussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 ℃. These ferrite materials are research focuses and are applied in many ways in electronics.
Ni0.3Cu0.07Zn0.63Fe2-xLaxO4 ferrites were prepared by solid phase method and sintered at 1,150 ℃ for 6 h.The phase formation,microstructure,and magnetic properties of samples were investigated.With doping of La3＋,the samples contain two phases：LaFeO3 and NiCuZn ferrites.Scanning electron microscope （SEM） image shows that La doping constrains the growth of NiCuZn ferrite,which is more uniform.La doping improves magnetic properties of NiCuZn ferrite when x ≤ 0.03.The saturation magnetization （Ms） increases first;when x =0.03,the highest value is 75.35 A.m2.kg-1.The permeability increases to the maximum value with frequency and then decreases with the concentration of La3＋ increasing.When x =0.03,the maximum value of real permeability at 1 MHz is 333.5,and the loss angle tangent （tanδ） is not more than 0.02.La doping improves the properties of NiCuZn ferrite,which can be applied to low-frequency filters.
La-Co substituted M-type barium ferrites （BaM） were prepared by traditional solid state method and sintered at low tem- perature （1173 K）. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and vibrating sample magnetometer （VSM） were employed to investigate the influence of La-Co on the structure and magnetic properties of the samples. By sintering at 1173 K for 6 h in air, single phase M-type barium ferrites with chemical composition of Ba（LaCo）xFel〉z^Oj9 （x=0.0~）.5） were formed. M-H curves showed that the magnetic properties of barium ferrites were obviously effected by La-Co substitution. The saturation magnetization （Ms） and coercivity （He） reached the maximum value of 65.15 AmZ/kg and 4165 Oe, respectively. This behavior was attributed to the sites of La-Co substitutions and the particles size. SEM revealed that the shape of ferrite particles was influenced by La-Co substitution.
