International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 22

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1 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 22 Effect of Substitution ION Titanium and Mangan on the Microstructure, Magnet Properties and Microwave Absorption of Barium Hexaferrite with Milling and High-Pressure Ultrasonic Method Novizal 1*), Musfirah, C. F. T 2), Elda Rayhana 3) 1, 2,3 Departemen of Physics, Faculty of Science and Technology Information, Institute Sciences and Technology National, Jakarta 12640, Indonesia *Corresponding author s novizal@istn.ac.id Tel, Abstract-- In this research, We report the magnetic properties of BaFe12O19 (BHF) as a based material by substitution of (Ti 2+ - Mn 2+ ) ions, in the composition of x = 0.0, 0.2, 0.4, 0.6 and 0.8, to determine magnetically and microwave absorption effects on BHF materials. The material preparation was made by milling and high-pressure ultrasonic method. By PSA and XRD analysis, we obtained the particle size of nm and the crystal size of < 70 nm. To reduce BHF particle size, the material was being remilling into 4 hours and after being in a state of powder crystal, followed by sonication process into 6 hours. We obtained the particle size in the composition of x = 0.0 was in the range of nm and in the composition of x = 0.6 and x = 0.8 was in the range of nm to nm. The morphology of the microstructure of the material particles is shown in the SEM results, was in range nm. The magnetic properties of the material were analyzed by using Permagraph EP 3 magnetometer. Data obtained by the analysis showing that by increasing the value of the composition of a substitution impaired the coercivity (282,54 ka/m to 9,81 ka/m). The reduction of particle size from 200 to 50 nm through sonication, give the change of magnetic properties from the permanent magnet to soft magnet, which characterized by decreasing the value of coercivity with increasing substitution composition. The properties also have the effect on the absorption of microwaves that the absorption peaks are shifted to a lower frequency as a result of a decrease in coercivity and reduction in particle size. Index Term-- absorption. BHF, substitution, crystal size, nanoparticle, 1. INTRODUCTION Ten years ago, at the World Summit on the Information Society (WSIS), the international community agreed a common vision to build a people-centred, inclusive and development- oriented information society (ITU 2015). The rapid development of information technology and telecommunications to be a consequence of the increasing use of electronic based equipment and microwave frequency (300 MHz GHz). At present, the development of microwave communications technology and the need for anti-electromagnetic interference coatings has induced to an intense study of electromagnetic wave absorbing materials in last years (Tsonos et al. 2016; Verma et al. 2015). The most studied materials have been ferrites with spinel, garnet, and hexagonal structure. Barium hexagonal ferrite, BaM, is one of the most important hard magnetic materials widely used in many applications. For its high stability, excellent high-frequency response and narrow switching field distribution, BaM has been studied extensively during the last few years. Despite a considerable amount of research published over the past decade related to the magnetic properties and microstructure of substituted barium ferrites, there have been only a few successful breakthroughs regarding to discovery of new compositions, with excellent properties for special applications as high frequency microwave absorbers(rehman et al. 2016; Shams Alam et al. 2016). In order to obtain M-type barium ferrites with improved characteristics and planar anisotropy for applications in the field of high frequency microwave absorbers is necessary to substitute Fe 3+ by other trivalent ions or cation mixtures(adeela et al. 2016; Farhadizadeh et al. 2015). Microwaves at a frequency range of 1-20 GHz is generally used for wireless communications (wireless communications) and will be improved in the future. To offset the impact of radiation of electromagnetic waves (EM) in the frequency range, the necessary material that can act as an absorber of microwave or microwave absorber (Adeela et al. 2016; Tsonos et al. 2016). 2. EXPERIMENTAL SET UP Material substitution hexaferrite BaFe12-2x (M) xo19 with composition x = 0.0, 0.2, 0.4, 0.6 and 0.8, are processed by milling and sonication of high pressure (where M = Ti2 + - Mn4 +), As a base material used to build the substituted material is BaCO 3, Fe 2O 3, TiO 2 and MnCO 3, all with a purity of 98%. Milling process is done by using a ratio of the mass of the ball / powder of 15 and a molecular ratio Fe / Ba of 11. Initially the base material in the milling for 60 hours in the air using 150 ml of benzene to avoid agglomeration of the powder at the bottom and to ensure active participation of materials in the milling

2 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 23 process. During the process every 10 hours done taking the powder for analysis particle size of the material. Powder as a result of milling dried, and sintered at temperatures of 1100oC for 2 hours. Sintered in re-milling for 4 hours and continued with the process of sonication for 5 hours. The X-Ray Diffraction (XRD) of re-milled samples was performed using Philips PW3710 diffractometer with Co-Kα radiation. The bulk densities were measured using FH-MD density meter. The grain morphology was characterized using FEI-F50 Scanning Electron Microscope (SEM). The M-H loops were measured in applied fields of ka/m at room temperature using Permagraph-L magnetometer. The microwave measurement was conducted on ADVANTEST R3770 Vector Network Analyzer. Further a computer program implementing Rietveld refinement used to determine microstructure from a diffraction patterns. Image processing software (Image J 1.47v) used to determine the average grain sizes from SEM photograph. 3. RESULTS AND DISCUSSION A. Phase Analysis and Morphology The results of XRD pattern of sintered samples in Figure 1 looks similar, shows a typical structure of BHF with space group of P63/mmc. All peaks of substituted BHF appear in the same position as the un-substituted BHF, which concluded to a successful synthesized of single phase BHF. x = 0.8 x = 0.6 Intensity (a.u.) x = 0.4 x = x = Fig. 1. XRD patterns BaFe 12-2xTi xmn xo 19 for x = 0,0 0,8 Table 1 shows the quantitative analysis of XRD patterns. Lattice parameter c was found to increase with substitution, while lattice parameter a almost unchanged. It follows the fact that all hexagonal ferrites exhibit constant lattice parameter a and vary lattice parameter c (Huang et al. 2015). The variation in lattice parameters with x indicates that substitutions occurred on crystallographic sites. The increase in lattice parameter with increasing Ti 2+ and Mn 4+ ions may be understood on the basic of ionic radii. The ionic radii for Fe 3+, Ti 2+ and Mn 4+ ions in octahedral coordination is 0.64, 0.86 and 0.53 Å respectively (Joshi et al. 2016). Since ions with larger radii tend to occupy octahedral sites and smaller radii tend to occupy tetrahedral and or bipyramidal sites, we conclude that Ti 2+ ion occupy 4f2 and 2a sites, while Mn 4+ ion occupy 4f1 and 2b sites. This hypothesis is consistent with previous studies on Co-Mn-2Ti, Mn-Sn, and Ti-Ru substituted BHF (Farhadizadeh et al. 2015; Frey et al. 2005; Guerrero et al. 2016).

3 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 24 Table I The Refinement Results of XRD data x R Exp R WP 2 a (Å) c (Å) Volume (Å 3 ) a (Å) c (Å) X Fig. 2. The lattice parameters BaFe 12-2x Ti xmn xo 19 for x = a c Results Rietveld refinement of the XRD data with software High Score Plus (HSP). RExp value of less than 10% indicates good data quality in materials with high crystallinity so RW P value can be smaller than 10%. The average value 2 pretty good, but not so at x = 0.8 which is quite high, though smaller than 2.0 as a standard repair, are shown in Table 1. Lattice parameters (a) relatively constant and the lattice parameters (c) is enlarged with increasing substitution. These results are consistent with the literature concluded that low levels of substitution of the lattice parameter change BHF (c) but the lattice parameters (a) relatively constant (Verma et al. 2015). A small change in x = 0.4 shows the charging 2a and 2b (Verma et al. 2016), which is shown in Figure 2. The logarithmic increase in the size of the crystal with increasing substitution. It is seen that the larger the size of the crystals, a wider distribution with significant increases occurred at x = 0.6 and x = 0.8. These results indicate that substitution of Ti and Mn has a tendency to accelerate the process of crystal growth or facilitate magnification of crystals during the sintering process, Figure 3.

4 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No: x = 0.0 x = 0.2 x = 0.4 x = 0.6 x = 0.8 Frequency (a.u.) Crystallite size (nm) Fig. 3. Crystallite size BaFe 12-2xTi xmn xo 19 for x = Figure 4 shows SEM images of BaFe 12 2xTi xmn xo 19 (x = 0.0 and 0.8) samples. It clearly be seen that the microstructure is affected by substitution. With the aid of Image J software, the average grain size is observed to be increase with increasing x. It also appears that densification decrease with increasing x, it is confirmed with XRD refinement result. a Gray scale value Distance (nm) b Gray scale value Distance (nm) B. Magnetic Properties Fig. 4. Microstructure BaFe 12-2xTi xmn xo 19 : (a) x = 0.0, (b) x = 0.8 The effect of Ti 2+ -Mn 4+ content on magnetic properties for all examined samples are shown in Figure 5. The results show that the undoped BHF sample possesses the largest intrinsic coercivity (Hc = ka/m) which is the characteristic of a hard magnetic material due to strong uniaxial anisotropy along the caxis. Hc decreases as substitution increases, attributed to

5 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 26 the change of the easy axis magnetization from c-axis to c- plane. The low coercivity in x = 0.8 (Hc = 9.18 ka/m), indicates that the domain wall motion is the dominant and the sample become a soft magnetic J (T) x= x=0.2 x= x=0.6 x= H (ka/m) Fig. 5. BaFe 12-2xTi xmn xo 19 hysteresis curve for x = x Table II Results of the calculation of the magnetic properties with methods LAS Ms (T) Mr (T) Hci (ka/m) Ha (ka/m) K 1 (x10 5 J/m 2 ) FMR (GHz) This is due to the substitution 2b in a place that has the largest contribution to the anisotropy (Trukhanov et al. 2015). Coercivity value declined against higher substitution. In addition to enlarging the grain size and the increasing number of network inter-grain obtained from XRD and SEM analysis, substitution value generated magnetic anisotropy orientation is no longer parallel but form an angle with the c-axis. Both of these effects produces coercivity value gets smaller with increasing substitution, Figure 6

6 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 27 J (T) Saturation Remanen Coercivity H (ka/m) Fig. 6. The magnetic properties BaFe 12-2x Ti xmn xo 19 for x = X 0 Anisotropy constant and FMR has the same pattern of decline with increasing substitution directly proportional to the decrease in coercivity. Anisotropy constant value at x = 0.0 (X J/m 2 ) is smaller than the value of single crystal BHF (X J/m 2 ). This is consistent with the fact that the domains with random orientation will reduce the effect of the anisotropy of the sample (Vinnik et al. 2015), Figure 7. K1 FMR K FMR (GHz) Fig. 7. The resonant frequency BaFe 12-2x Ti xmn x O 19 for x = X 12 C. Microwave Absorption Characteristic Figure 8 shows the variation of reflection loss verses frequency for all BaFe 12 2xTi xmn xo 19 samples. There is no loss peaks are observed in undoped BHF because it high ferromagnetic resonance frequency and it show very low microwave absorption. The reflection loss is significant indoped samples. It shows the reflection loss peaks is increase with increasing x, has maximum value at x = 0.6 (25 db) and reduce at x = 0.8 (15

7 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 28 db). The loss peak consistently shifted from high to low frequency, it shows a same trend as the FMR. The FMR phenomenon cannot be characterized due to measurement equipment limitation ( GHz). The observed magnetic spectra are in agreement with the mechanism of natural magnetic resonance involving domain-wall displacement and domain rotation. These motion lag behind the applied magnetic field cause magnetic loss in the material correlated with the area inside the magnetic loops (Trukhanov et al. 2015; Vinnik et al. 2015). This is the reason why x = 0.8 lower in reflection loss as compare to others. Reflection Loss (db) x = 0.0 x = 0.2 x = 0.4 x = 0.6 x = Frequency (GHz) Fig. 8. Reflection Loss of BaFe 12 2xTi xmn xo 19. for x = CONCLUSION This study has demonstrated that the substitution of Ti 2+ and Mn 4+ ions makes considerable change in extrinsic properties in terms of grain size, porosity and intergranular network. The substitution pronouncedly decreases coercivity for whole range of substitution, while increasing magnetization until x = 0.4 and decrease at high substitution. This phenomenon can be understood by the preferential occupation mechanism of Ti 2+ - Mn 4+ ions when replacing Fe 3+ ions at certain level of substitution. Ti 2+ -Mn 4+ substituted BHF can be utilized as good microwave absorber for high frequency above 1 GHz, and the operating frequency can be controlled by substitution ratio of Ti 2+ and Mn ACKNOWLEDGEMENTS Thanks to the Directorate of the Ministry of Research Technology and Higher Education of the Republic of Indonesia, which has funded this research with competitive grants budget by 2016, : 003/SP2H/LT/DRPM/II/2016.so that the study can be completed properly 6. REFERENCES [1] Adeela, N. et al., Structural and magnetic response of Mn substituted Co2 Y-type barium hexaferrites. Journal of Alloys and Compounds, 686, pp Available at: [2] Farhadizadeh, A.R., Seyyed Ebrahimi, S.A. & Masoudpanah, S.M., Magnetic and microwave absorption properties of ZnCosubstituted W-type strontium hexaferrite. Journal of Magnetism and Magnetic Materials, 382, pp Available at: [3] Frey, N.A. et al., Microstructure and magnetism in barium strontium titanate (BSTO)-barium hexaferrite (BaM) multilayers. Materials Research Bulletin, 40(8), pp [4] Guerrero, A.L. et al., Preparation and magnetic properties of the Sr-hexaferrite with foam structure. Journal of Magnetism and Magnetic Materials, 419, pp Available at: [5] Huang, K. et al., Structural and magnetic properties of Casubstituted barium W-type hexagonal hexaferrites. Journal of Magnetism and Magnetic Materials, 379, pp Available at: [6] ITU, Measuring the information society: The ICT development index, [7] Joshi, R. et al., Structural and magnetic properties of Co2+- W4+ ions doped M-type Ba-Sr hexaferrites synthesized by a ceramic method. Journal of Alloys and Compounds. Available at: [8] Rehman, K.M.U. et al., Synthesization and Magnetic Properties of Ba1-xYxFe12O19 Hexaferrites Prepared by Solid- State Reaction Method. Journal of Magnetism and Magnetic Materials. Available at: [9] Shams Alam, R. et al., Magnetic and microwave absorption properties of BaMgx/2Mnx/2CoxTi2xFe12-4xO19 hexaferrite

8 International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:17 No:03 29 nanoparticles. Journal of Magnetism and Magnetic Materials, 402, pp [10] Trukhanov, A.V. et al., Crystal structure and magnetic properties of the BaFe12 xalxo19 (x= ) solid solutions. Journal of Magnetism and Magnetic Materials, 393, pp Available at: [11] Tsonos, C. et al., Electromagnetic wave absorption properties of ternary poly(vinylidene fluoride)/magnetite nanocomposites with carbon nanotubes and graphene. RSC Advances, 6(3), pp Available at: [12] Verma, S. et al., Structural, magnetic and microwave properties of barium hexaferrite thick films with different Fe/Ba mole ratio. Journal of Magnetism and Magnetic Materials, 396, pp Available at: [13] Verma, S. et al., Structural and magnetic properties of Co-Ti substituted barium hexaferrite thick films. Journal of Alloys and Compounds, 678, pp Available at: [14] Vinnik, D.A. et al., Cu-substituted barium hexaferrite crystal growth and characterization. Ceramics International, 41(7), pp Available at: