| Five series of M-type hexagonal ferrite samples with the chemical compositions Ba(1-x)Y,Fe12O19(x-0.00,0.02,0.05,0.08,0.10,0.13),Sr0.7YxLa0.3-xFe12-yCoy019(x=0.00,0.05,0.1 0,0.15&y=0.30,0.25,0.20,0.15),SrO.35La0.4OCa0.25Fe11.6Co0.4O19,Sr0.3La0.48Ca0.25 n[Fe(2-0.4/n)O3]Co0.4(n=5.5,5.6,5.7,5.8,5.9,6.0),and Sr1-xCe,0.6Fe2O3(0.00≤x0.30)were prepared by solid state reaction.The XRD examination established single phase M-type hexaferrite structure for all five series of samples namely Ba(1-x)Y,Fe12O19(x=0.00,0.02,0.05,0.08,0.10,0.13),Sr0.7YxLa0.3-xFe12-yCoy,O19(x=0.00,0.05,0.10,0.15&=0.30,0.25,0.20,0.15),Sr0.35La0.40Ca0.25Fe11.6Co0.4O19,Sr0.3La0.48Ca0.25n[Fe(2-0.4/n)O3]Co0.4(n=5.5,5.6,5.7,5.8,5.9,6.0),and Sr1-xCexO.6FeO3(0.00≤x≤0.30).The lattice parameters were found to increase as the contents of the substituted cations increased,which is accredited to the ionic sizes of the occupied cations.The c/a ratio was found be in the range 3.910-3.916 which is in the acceptable range.The SEM profiles show regular hexagonal platelets with homogeneous grain size ranging from 0.5 to 1μm.The coercivity values of all samples are in the range of M-type hexaferrites and are consistent with reduction in grain size and these changes in coercivity are resulted due to domain wall pinning fields at grain boundaries.Brief overview of the classification in the M-type hexaferrites:1-Traditional ceramic method was used to make M-type hexaferrite Ba(1-x)YXFe12O19 magnetic powder and magnets.Calcine samples were analyzed by using XRD.Single segment of magnetoplumbite was found after analyzing the magnet powder compositions by XRD with the intensity of x= 0.00,0.02,0.05,0.08,0.10,0.13.Attractiveness of magnets was studied systematically by using yttrium cation content.VSM instrument was used to measure the intensification of magnetic field of magnets.Different Yttrium content(x)were used to estimate the coercivity(Hcj)and magnetization saturation(σS)in Ba(1-x)YxFe12O19 magnetic powders,during this estimation increased value of coercivity(Hcj)ensured the decrease in saturation magnetization(σs)value.At x=0.13,value of magnetic properties were maximum.2-Solid state reaction was used to prepare M-type hexaferrite Sr0.7YxLa0.3,xFe12-y CoyO19(x=0.00,0.05,0.10,0.15&,y-0.30,0.25,0.20,0.15)magnetic powder.Phase constituents of magnet powders were examined by using XRD.Magnetic properties of samples were estimated by using Vibrating Sample Magnetometer(VSM)equipment.We reported our investigation of yttrium content on crystalline size characterization and magnetic properties of the material.It is originate that the desirable quantity of y3+ replacement may curiously increase the magnetization saturation(σs)and enhance the coercivity(Hcj).(σs)and(Hcj)with the Y3+addition at 1250 0C temperature first increased but then decreased gradually.3-Conventional Ceramic Reaction Methodology has been utilized for the preparation of M-type hexagonal ferrites of Sr0.35La0.40Ca0.2sFe11.6Co0.4O19 magnets.X-ray diffraction has been performed for phase determination of the magnetic powders.At calcination temperatures ranging from 1220 to 1330 ℃,the synchronize compost of the magnetic powders comprised of M-type hexagonal ferrites together with a small amount of impurity phase such as a-Fe203 were co-existed.At calcination temperature above 1270 ℃,single-phase M-type hexaferrites can be obtained.The particles seemed to be in a hexagonal platelike mould which spread-out homogeneously were examined by field emission scanning electron microscopy.The magnetic edibility of the magnetic powders was intended by permanent magnetic measurement test equipment vibrating sample magnetometer.Magnetic properties,such as specific saturation magnetization,coercivity and remanence were temperature-dependent.However,with the increase of sintering temperature,i.e.above 1270-C,saturation magnetization was increased while the coercivity showed reversed order.4-M-type strontium hexaferrite with composition of Sr0.3La0.48Ca0.25 n[Fe(2-0.4/n)O3]Co0.4(n=5.5,5.6,5.7,5.8,5.9,6.0)magnetic powder were synthesized by using facile ceramic route methodology.The structural,morphological and other properties were examined by using XRD,VSM and electron microscopy respectively.There is a single magnetoplumbite segment in the magnetic powders containing(5.5≤n≤5.8)and(n≥5.9)magnetic some impurities begin to seem in the structure.The magnets have shaped hexagonal structures.Magnetic properties of the samples were metric by permanent magnetic measuring equipment Vibrating Sample Magnetometer,respectively.We report our investigation of n-iron content on crystalline size characterization and magnetic properties of the specimen.It is originate that the desirable quantity of n-iron content substitution may curiously increase saturation magnetization(σs)and intrinsic coercivity(Hcj)With the iron addition for the same sintering temperature at 1260℃,(σS)and(Hcj)first increase and then decrease gradually.5-Ce3+ ions doped M-type hexaferrite Sr1-xCe,0.6Fe203(0.00≤x≤0.30)magnetic powder and magnets existed to ready according to the conventional ceramic process.The results of X-ray diffraction measurements showed the M-type hexagonal structure.There was a single magneto plumbite segment is obtained for the magnetic powders with x from 0.00 to 0.15,and a-Fe2O3 as a second phase appears when Ce composition x≥0.15.The micrographs of the sintered precursor were characterized by a field emission scanning electron microscopy(FE-SEM).The sintered magnets are formed of hexagonal shaped crystals.The magnetic properties of the magnets were measured by a B-H hysteresis curve measurements at room temperature.The effects of the Ce composition(x)on the permanent magnetic properties of the magnets were studied systematically.As a result,the remanence(Bτ)first increases with the increase of Ce composition(x)from 0.00-0.15 and then decreases when Ce composition(x)≥0.15.Moreover,the intrinsic coercivity(Hcj),magnetic induction coercivity(Hcb)and maximum energy product((BH)max)decrease obviously with the x increases.The ratios Hk/Hcj first increases with Ce composition(x)from 0.00-0.15,and the Hk/kj ratio decreases when x≥0.15. |
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