Journal of Superconductivity and Novel Magnetism

, Volume 30, Issue 1, pp 171–177 | Cite as

Microwave Absorption Properties of Ba–M Hexaferrite with High Substitution Levels of Mg–Ti in X Band

Original Paper


BaFe12−x Mg0.5x Ti0.5x O 19 nanoparticles were synthesized by using a modified sol–gel method. In order to investigate electromagnetic (EM) wave absorption properties of Mg–Ti-substituted barium hexaferrite nanoparticles, composites including ferrite (filler) and acrylic resin (matrix) with a weight ratio of 70:30 (ferrite/resin) were prepared. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), alternative gradient force magnetometer (AGFM), and vector network analyzer (VNA) were used to investigate the morphological, structural, magnetic, and EM wave absorption characteristics of the samples. The XRD results indicated that by the modified sol–gel synthesis method, the substituted compounds were a single-phase hexagonal ferrite for x=0 to x=5. FE-SEM images showed that the particle sizes were almost in a range of 35–50 nm. With an increase in the substitution level from x=0 to x=5, the maximum magnetization and coercivity decreased from 53.2 emu/g and 4900 Oe to 8.6 emu/g and 50 Oe, respectively. The reflection loss patterns of the samples showed that EM wave absorption was improved with an increase in the substitution levels, and the effect of substitution level on the intensity of EM wave absorption was discussed. The best reflection loss value was −55 dB obtained by the sample with x=5 in the frequency of 10.8 GHz. The results indicated that the composites containing Mg–Ti-substituted barium hexaferrite nanoparticles with high substitution levels synthesized by the modified sol–gel process can be considered as suitable EM wave absorbers in X-band applications.


Sol–gel Electromagnetic Reflection loss Barium hexaferrite Magnetic 

1 Introduction

Different wireless communication systems such as local area network (LAN) systems, mobile phones, and Bluetooth devices operate in the microwave frequency range [1, 2, 3, 4]. The widespread use of electromagnetic (EM) wave-emitting devices intensifies the EM wave pollution crisis. Therefore, EM wave interference shielding and EM wave-absorbing materials, which have the ability of wideband EM wave absorption, are very interesting [4]. EM wave-absorbing materials reduce electromagnetic radiations by converting electromagnetic energy into heat. By coating military structures like ships, planes, and vehicles with EM wave-absorbing materials, radar cross section is reduced. As a result, detectability is lowered. An absorbing material should be able to cause favorable loss in the necessary frequency range [1, 2]. This loss is originated in dielectric and magnetic phenomena. Thus, to achieve maximum loss in a vast frequency range, selecting the material and controlling its dielectric and magnetic properties are of high importance. So far, various materials such as carbon materials [5, 6], polymers [7, 8], magnetic metals [9, 10], ferrites [11, 12], non-ferrite ceramics [13, 14], and hybrid materials [15, 16] have been studied to evaluate their capability of absorbing EM waves. Among these materials, ferrites are frequently applied due to their absorbing power [17, 18, 19]. Among ferrites, substituted M-type hexaferrites are among the most applicable types of ferrites because of their high stability, efficient high frequency response, and switching properties [3, 20]. M-type hexaferrites are utilized in permanent magnets, magnetic recording media, and microwave-absorbing materials [21]. The magnetic loss in hexaferrites is caused by the magnetic resonance phenomenon, which originates in domain wall motions and spin–rotation relaxations. Anisotropic field in M-type ferrites such as barium ferrite is close to 1.36 MA/m corresponding for a natural resonance frequency of 47.6 GHz [22]. By substituting Fe 3+ ions in hexaferrite structure with elements like Zn–Ti, Cu–Ti, Ni–Zr, and Co–Mo, it is possible to manipulate the resonance frequency and other magnetic properties [23]. Solid-state synthesized Mg–Ti-substituted barium hexaferrite has previously been reported to have good EM wave absorption properties [24]. Although a solid-state method is conventional and convenient to produce most ceramic compounds, it has some shortcomings. For instance, obligatory high calcination temperature results in coarse and fused particles; in addition, inasmuch as starting materials in this method cannot be mixed in an atomic scale, producing substituted compounds will encounter constrictions. In addition, it is not often simply possible to introduce high percentages of substituted elements without forming secondary phases in desired compounds. Thus, to synthesize substituted compounds, methods like sol–gel ending in a homogeneous distribution of componential atoms are more preferable. However, using a conventional sol–gel method to produce Mg–Ti-substituted barium hexaferrite encounters various difficulties [20]. Fortunately, all the challenges for sol–gel synthesis of Mg–Ti-substituted barium hexaferrite have been resolved by some important modifications in a conventional sol–gel process. In this study, BaFe12−x Mg0.5x Ti0.5x O 19 compounds, 0≤x≤5, with nanosize particles were synthesized by a modified sol–gel process. The effects of Mg–Ti high substitution levels on magnetic and microwave absorption properties of BaFe12−x Mg0.5x Ti0.5x O 19 sol–gel-synthesized nanoparticles were investigated for the first time. The results suggested that Mg–Ti-substituted barium hexaferrites with high substitution levels were suitable candidates for X-band microwave absorbers.

2 Experimental

Analytical grade chemicals including barium carbonate (BaCO3), iron nitrate [Fe(NO3)3⋅9H 2O], magnesium nitrate [Mg(NO3)2⋅6H 2O], titanium tetra-isopropoxide (TTIP), ammonium nitrate (NH4 NO 3), citric acid (CA), and ethylene glycol (EG) were used as starting materials to synthesize a series of BaFe12−x Mg0.5x Ti0.5x O 19 in a compositional range of x=0–5. More complete details and basics of the current modified sol–gel method have been reported in our previous work [20]. In brief, iron nitrate, magnesium nitrate, barium carbonate, and citric acid are dissolved in water according to the proportion Ba:Fe:Mg:Ti:CA = 1:(12−x):(0.5x):(0.5x):20, and they are stirred in a water bath at 80 C. Then, in a separate beaker, TTIP will be added to 10 times water in volume. White precipitations caused by this process, after being rinsed by distilled water, are mixed with water, hydrogen peroxide, and citric acid, based on the ratio of CA:H2 O 2:H2O(:TTIP) = 1:2:2(:1) in a water bath at 80 C. As a result, a transparent yellowish orange solution is achieved, and this solution will be added to another solution containing citric acid, iron nitrate, magnesium nitrate, and barium carbonate prepared earlier. Later on, pH of the sol, by adding NH3, will be increased by 7. By adding NH3, pH will be kept in a range between 7 and 8. Afterwards, NH4 NO 3 will be added to achieve a transparent and homogeneous sol. Now, ethylene glycol will be added to the former mixture so that the ingredients’ proportion of the final sol will be Ba:Fe:Mg:Ti:CA:NH4 NO 3:EG = 1:(12−x):(0.5x):(0.5x):20:28:20. Consequently, this sol will be stirred up at 80 C to eliminate water and concentrate. Then, it is put in an oven at a temperature of 80 C to achieve a dry gel. Now, this will be ground and put in a furnace in order to combust. This material will be milled for an hour, heated at a rate of 4.5 to 950 C/min, and calcined for 5 h. Static magnetic properties are measured using an alternating gradient force magnetometer (VSM/AGFM; Meghnatis Daghigh Kavir Co., Iran). The final product will be mixed with acrylic resin in various ratios to prepare microwave absorption measurement samples. These samples will be shaped as pellets (with a diameter of 6 cm) at the pressure of 2000 Psi and temperature of 200 C. The EM wave absorption properties are measured by a metal back method in a frequency range of 8–12 GHz using a vector network analyzer (VNA; Agilent/HP 8722ES).

3 Results and Discussion

Figure 1 depicts the XRD patterns related to BaFe12−x (Mg0.5Ti0.5) x O 19 compounds. All these patterns indicate the formation of single-phase hexaferrites. The patterns reveal an acceptable substitution of elements even in larger substitution levels like x=5. The average crystallite size by the Scherrer formula in various BaFe12−x (Mg0.5Ti0.5) x O 19 compounds varies from 30 to 50 nm.
Fig. 1

af XRD patterns of BaFe12−x (Mg0.5Ti0.5) x O 19 for x=0 to x=5

Figure 2 is related to the typical non-calcined precursor of BaFe12−x (Mg0.5Ti0.5) x O 19 after gel combustion step, which can be seen in the form of aggregates of 40–200 nm. The formative particles of these aggregates are spherical of the same size with a diameter of 15–20 nm. Figure 3 shows the typical FE-SEM image of calcined BaFe12−x (Mg0.5Ti0.5) x O 19. Of course, since nanoparticles highly tend to form aggregates, the aggregates of 50–200 nm are seen in the image. In addition, it is indicated that aggregates are composed of globular particles of 25–30 nm. Findings of this observation are in line with the results of the well-known Scherrer formula mentioned above. This observation shows that the sizes of original particles, which are with a high probability of having the same size as crystallites according to the Scherrer estimation, have only increased by about 10 nm.
Fig. 2

Typical FE-SEM image of the non-calcined precursor of BaFe12−x (Mg0.5Ti0.5) x O 19 after gel combustion step

Fig. 3

Typical FE-SEM image of Mg–Ti-substituted barium hexaferrite nanoparticles after calcination at 950 C

Figure 4 shows the hysteresis loop curves for the different Mg–Ti-substituted Ba-hexaferrite samples. As it is visible, the coercivity (H c) is decreased from 4900 to 50 Oe when X is increased from 0 to 5. The decrease in H c is contingent upon the particle size and magnetocrystalline anisotropy. Considering that the particle sizes for the samples with different substitution values are almost similar, it can be concluded that H c reduction is a consequence of the decrease in magnetocrystalline anisotropy. In addition, the previous reports alleged that substitutional elements in hexaferrites can decrease the magnetocrystalline anisotropy and can lead to the coercivity reduction [20, 25, 26].
Fig. 4

Hysteresis loop curves of BaFe12−x (Mg0.5Ti0.5) x O 19 for x=0 to x=5

There are five sites in the unit cell of M-type barium hexaferrite in which Fe 3+ ions could be found. The sites consist of trigonal bipyramidal 2b, tetrahedral 4f1, and octahedral 4f2, 12k, and 2a. The downward spin of Fe 3+ ions at 4f1 and 4f2 sites is canceled by upward spins in the other sites. The remaining Fe 3+ ions with upward spins make the net magnetization for the M-type barium hexaferrite. Substitution of different ions can change the magnetic properties of the Ba–M hexaferrite. Stepankova et al. [27] reported 4f2, 2b, and 12k sites as the most favorable sites for Ti 4+. They also reported 2a site as the most favorable site for Mg 2+ ions. However, it has been shown that site occupancies of Mg 2+ and Ti 4+ can change depending on the synthesis process and the increase in substitution level (X) [20]. Substitution of Mg 2+ and Ti 4+ as non-magnetic ions instead of ferric ions in the Ba–M hexaferrite can weaken the superexchange interactions (Fe 3+–O–Fe 3+) resulting in magnetization decrease, though the maximum magnetization values for samples (x=0 to 2; about 53.2 emu/g) do not show an important change. This can be explained by the occupation of the sites with downward spins and intact counterbalance between opposite magnetic moments for lower substitution levels. However, for the samples with higher substitution levels (x=3 to 5), the maximum magnetization values (41, 27, and 8.6 emu/g, respectively) have a decreasing trend. This is because of the occupation of upward spin sites by non-magnetic Mg and Ti ions, which significantly weakens the superexchange interactions of the type Fe 3+–O–Fe 3+ and the net magnetization.

Measurement of microwave-absorbing properties was carried out by a VNA and metal back method. Herein, the absorbing properties are expressed as a reflection loss (RL) value. According to the transmission line theory, reflection loss for a metal-backed absorbing single layer and normal incident electromagnetic wave RL are formulated as follows [18, 28, 29]:
$$ \text{RL}=-20\log \left| {\frac{Z_{\text{in}} -1}{Z_{\text{in}} +1}} \right| $$
where Z 0 is the free space impedance and Z in is the input impedance of the absorbing layer
$$ Z_{\text{in}} =\frac{Z_{\text{in}} }{Z_{0} }=\sqrt{\frac{\mu_{\mathrm{r}} }{\varepsilon_{\mathrm{r}} }} \cdot \tan h \left( {j2\pi fd\frac{\sqrt{\varepsilon_{\mathrm{r}} \mu_{\mathrm{r}} } }{c}} \right) $$
where μ r and ε r are the relative complex permeability and permittivity, respectively; c is the speed of light; d is the layer thickness; and f is the frequency. When Z in is equal to Z 0, the best absorbing material is achieved. This situation is called matching impedance condition. Reflection loss values of −10 and −20 dB mean that the absorbing material can absorb 90 and 99 % of the incident wave, respectively [3]. The term of absorption bandwidth represents the width of the frequency range, and a certain reflection loss value is obtained.
According to the transmission line theory, the ferromagnetic resonance frequency (f r) for the M-type hexaferrite could be expressed by the following equation [18]:
$$ 2\pi f_{\mathrm{r}} =\gamma H_{\mathrm{a}} $$
where H a is the anisotropy field and γ=2.8 MHz/Oe is the gyromagnetic ratio. f r in M-type hexaferrites is in the range of 50–60 GHz. Substitution of different elements in a hexaferrite can change the anisotropy field (H a) which causes the f r to shift down [18]. Therefore, ferromagnetic resonance could occur in a practical frequency range.
The samples with various substitution levels to investigate the microwave absorption characteristics were assessed. In this study, the samples based on the shape of peak patterns of reflection loss test are categorized and studied as A and B. To make a comparison between the groups in the X band, the RL curves of both groups in a similar sample thickness of 3.4 mm in superimposed forms are presented in Fig. 5. Group A contains samples with substitution levels of x=0, x=1, and x=2. In these three samples, peak patterns have irregular shapes, and despite the variation and the amount of substituent elements, overt displacement of peak positions in the samples with the same thickness is not observable (Fig. 5a).
Fig. 5

Reflection loss versus frequency plots for BaFe12−x Mg0.5x Ti0.5x O 19 a group A (x=0 to x=2) and b group B (x=3 to x=5)

In the samples of group B, which have substitution levels of x=3, x=4, and x=5 (Fig. 5b), based on the formula of BaFe12−x Mg0.5x Ti0.5x O 19, the absorption patterns differ from what is seen in group A. For group B, the number of peaks clearly falls, and in almost all samples, one peak is only visible. This peak, along with the increase in the substitution percentage, not only shifts to higher frequencies but also extends in intensity and broadness.

As it is apparent, the sample of x=5 in the mentioned sample thickness has covered the whole X band with an absorption intensity of −10 dB. In addition, the gradual shift along with the rise of substitution level is noticeable in Fig. 6. According to this comparison, the sample of x=5 enjoys the most appropriate absorption behavior of absorption intensity and bandwidth in the X band.
Fig. 6

Variation of reflection loss versus frequency for BaFe7Mg2.5Ti2.5 O 19 in different absorber layer thicknesses in X-band frequency range

Although the sample of x=5 has covered −10 dB in the whole X band with a sample thickness of 3.4 mm (Fig. 6), along with the fall of thickness accompanying the shift of absorption peak toward high frequencies, the absorption bandwidth in −20 dB will increase. The bandwidth in −20 dB for the thicknesses of 3.2, 3.4, and 3 mm is 0.5, 1.25, and 2.25 GHz, respectively.

As can be seen in Fig. 6, the RL\(_{\min }\) dip shifts toward higher frequencies with sample thickness reduction. Furthermore, it is visible that the absorption intensity is increasing as the thickness is reduced. This can be explained by a quarter-wave principle [28]. When an EM wave encounters a metal-backed absorbing material, it is partially reflected from absorber–metal and air–absorber interfaces. For absorbers satisfying the quarter-wave thickness criteria, the reflected waves, which are out of phase by 180 , cancel each other at the air–absorber interface.

The quarter-wave thickness criteria can be formulated as follows [28]:
$$ t_{\mathrm{m}} =\frac{nc}{4f_{\mathrm{m}} \sqrt{\left| {\varepsilon_{\mathrm{r}} \mu_{\mathrm{r}} } \right|} }\;\;\;(n=1,3,5,\ldots) $$
where f m and t m are the peak frequency and matching thickness, respectively, and μ r and ε r are the relative complex permeability and permittivity coefficients, respectively. For higher frequencies, the above criterion is satisfied at reduced sample thicknesses. Therefore, when the thickness is reduced, a more intense absorption occurs as a result of the cancelation phenomena. When the absorber thicknesses cannot satisfy the above criteria, only incomplete cancelation happens, giving weaker absorption. The matching frequency decreases nearly linearly with the increment of the absorber thickness.

It is discussed in the literature that the absorption peaks of substituted M-type hexaferrites due ferromagnetic resonance losses are located in the Ku band and the absorption peaks should be shifted to lower frequencies because of the increase in substitution level [21, 25, 30]. Therefore, it can be deduced that observed losses in the X band should be due to dielectric losses.

Table 1 is related to the lattice parameters of different BaFe12−x Mg0.5x Ti0.5x O 19 compositions. It has been shown that the c-axis lattice parameter in BaFe12−x Mg0.5x Ti0.5x O 19 has an increasing trend for x=0 to 2, but for x=3 to 5, this trend becomes decreasing [20]. It is reported that for higher substitution levels (x=3 to 5) in BaFe12−x Mg0.5x Ti0.5x O 19, pseudo-tetrahedral 2b lattice sites are more preferred sites for Ti 4+ cations [20]. Therefore, the reduction of c-axis lattice parameter has been ascribed to the occupation of 2b sites by Ti 4+ cations. Moreover, it is reported that Ti 4+ cations in the adjacent trigonal bipyramids of 2b sites have a diffusional motion forming a dynamic disorder in a hexaferrite unit cell [20]. It seems that the dielectric losses of BaFe12−x Mg0.5x Ti0.5x O 19 in the X band are due to resonance losses of Ti 4+ cations’ diffusional motion in adjacent 2b sites. Hence, by increasing the substitution level in BaFe12−x Mg0.5x Ti0.5x O 19 more 2b sites are occupied by Ti 4+ cations and, consequently, more powerful dielectric resonance loss occurs. However, certifiable high substitution levels of Mg and Ti ions in BaFe12−x Mg0.5x Ti0.5x O 19 like those reported in this paper by the specially modified sol–gel method have not been reported before [20]. Therefore, dielectric losses because of high substitution levels (x=3 to 5) may rarely have been observed before. These results show that BaFe12−x Mg0.5x Ti0.5x O 19 with high substitution levels (x=3 to 5) can lead to efficient X-band microwave absorbers.
Table 1

Variations of lattice parameters for different BaFe12−x Mg0.5x Ti0.5x O 19 compositions


Chemical composition

a-axis (Å)

c-axis (Å)

X-ray density


BaFe12 O 19





BaFe11Mg0.5Ti0.5 O 19





BaFe10Mg1.0Ti1.0 O 19





BaFe9Mg1.5Ti1.5 O 19





BaFe8Mg2.0Ti2.0 O 19





BaFe7Mg2.5Ti2.5 O 19




4 Conclusion

A modified sol–gel method was used to synthesize Mg–Ti-substituted barium hexaferrite nanoparticles. XRD patterns showed that BaFe12−x Mg0.5x Ti0.5x O 19 compounds for x=0 to x=5 were a single-phase hexagonal ferrite. It was found that particle sizes of BaFe12−x Mg0.5x Ti0.5x O 19 compounds were in a range of 35–50 nm. The maximum magnetization (from 53.2 to 8.6 emu/g) and coercivity (from 4900 to 50 Oe) of the BaFe12−x Mg0.5x Ti0.5x O 19 (x=0–5) were reduced by increasing x from 0 to 5, and the reflection loss dip values were increased. The best reflection loss (−55 dB) was for the sample with x=5 (absorber thickness of 3 mm) in the frequency of 10.8 GHz in the X-band range. Considering the fact that magnetic loss mechanisms for substituted hexagonal ferrites occur in Ku frequency range and the absorption peaks shift to lower frequencies by an increase in substitution level, the absorption peaks of BaFe12−x Mg0.5x Ti0.5x O 19 (x = 0–5) were ascribed to dielectric loss mechanisms. This research indicated that barium hexaferrite nanoparticles with high levels of substitution, synthesized by the modified sol–gel process, could be used as effective X-band microwave absorbers.



The authors would like to acknowledge the financial support provided by the Electroceramics Research Center of MUT University. We also gratefully appreciate the assistance of Dr. O. Khani and Dr. Y. Zare in the course of conducting this research.


  1. 1.
    Jazirehpour, M., Ebrahimi, S. S.: J. Alloys Compd. 639, 280–288 (2015)CrossRefGoogle Scholar
  2. 2.
    Jazirehpour, M., Ebrahimi, S. S.: J. Alloys Compd. 638, 188–196 (2015)CrossRefGoogle Scholar
  3. 3.
    Narang, S. B., Kaur, P., Bahel, S., Singh, C.: J. Magn. Magn. Mater. 405, 17–21 (2016)ADSCrossRefGoogle Scholar
  4. 4.
    Baniasadi, A., Ghasemi, A., Nemati, A., Azami Ghadikolaei, M., Paimozd, E.: J. Alloys Compd. 583, 325–328 (2014)CrossRefGoogle Scholar
  5. 5.
    Jian, X., Chen, X., Zhou, Z., Li, G., Jiang, M., Xu, X., Lu, J., Li, Q., Wang, Y., Gou, J.: Phys. Chem. Chem. Phys. 17, 3024–3031 (2015)CrossRefGoogle Scholar
  6. 6.
    Wang, L., Huang, Y., Li, C., Chen, J., Sun, X.: Phys. Chem. Chem. Phys. 17, 2228–2234 (2015)CrossRefGoogle Scholar
  7. 7.
    Chen, Y., Zhang, S., Liu, X., Pei, Q., Qian, J., Zhuang, Q., Han, Z.: Macromolecules (2015)Google Scholar
  8. 8.
    Sharma, M., Singh, M. P., Srivastava, C., Madras, G., Bose, S.: ACS Appl. Mater. Interfaces 6, 21151–21160 (2014)CrossRefGoogle Scholar
  9. 9.
    Guo, C., Xia, F., Wang, Z., Zhang, L., Xi, L., Zuo, Y.: J. Alloys Compd. 631, 183–191 (2015)CrossRefGoogle Scholar
  10. 10.
    Lv, H., Ji, G., Wang, M., Shang, C., Zhang, H., Du, Y.: J. Alloys Compd. 615, 1037–1042 (2014)CrossRefGoogle Scholar
  11. 11.
    Huang, X., Zhang, J., Lai, M., Sang, T.: J. Alloys Compd. 627, 367–373 (2015)CrossRefGoogle Scholar
  12. 12.
    Wang, L., Yu, H., Ren, X., Xu, G.: J. Alloys Compd. 588, 212–216 (2014)CrossRefGoogle Scholar
  13. 13.
    Yuan, X., Cheng, L., Kong, L., Yin, X., Zhang, L.: J. Alloys Compd. 596, 132–139 (2014)CrossRefGoogle Scholar
  14. 14.
    Luo, H., Xiong, G., Chen, X., Li, Q., Ma, C., Li, D., Wu, X., Wan, Y.: J. Alloys Compd. 593, 7–15 (2014)CrossRefGoogle Scholar
  15. 15.
    Shen, X., Song, F., Yang, X., Wang, Z., Jing, M., Wang, Y.: J. Alloys Compd. 621, 146–153 (2015)CrossRefGoogle Scholar
  16. 16.
    Xu, F., Ma, L., Huo, Q., Gan, M., Tang, J.: J. Magn. Magn. Mater. 374, 311–316 (2015)ADSCrossRefGoogle Scholar
  17. 17.
    Alam, R. S., Moradi, M., Nikmanesh, H., Ventura, J., Rostami, M.: J. Magn. Magn. Mater. 402, 20–27 (2016)ADSCrossRefGoogle Scholar
  18. 18.
    Alam, R. S., Moradi, M., Rostami, M., Nikmanesh, H., Moayedi, R., Bai, Y.: J. Magn. Magn. Mater. 381, 1–9 (2015)ADSCrossRefGoogle Scholar
  19. 19.
    Asl, M.J.P, Ghasemi, A., Gordani, G.R.: J. Supercond. Nov. Magn. 29, 795–801 (2016)CrossRefGoogle Scholar
  20. 20.
    Jazirehpour, M., Shams, M., Khani, O.: J. Alloys Compd. 545, 32–40 (2012)CrossRefGoogle Scholar
  21. 21.
    Jamalian, M., Ghasemi, A.: J. Supercond. Nov. Magn. 28, 3293–3299 (2015)CrossRefGoogle Scholar
  22. 22.
    Meng, P., Xiong, K., Wang, L., Li, S., Cheng, Y., Xu, G.: J. Alloys Compd. 628, 75–80 (2015)CrossRefGoogle Scholar
  23. 23.
    Sözeri, H., Mehmedi, Z., Kavas, H., Baykal, A.: Ceram. Int. 41, 9602–9609 (2015)CrossRefGoogle Scholar
  24. 24.
    Shams, M. H., Salehi, S. M. A., Ghasemi, A.: Mater. Lett. 62, 1731–1733 (2008)CrossRefGoogle Scholar
  25. 25.
    Baniasadi, A., Ghasemi, A., Ghadikolaei, M.A., Nemati, A., Paimozd, E.: J. Mater. Sci. Mater. Electron. 27, 1901–1905 (2016)CrossRefGoogle Scholar
  26. 26.
    Jamalian, M., Ghasemi, A., Paimozd, E.: J. Electron. Mater. 43, 1076–1082 (2014)ADSCrossRefGoogle Scholar
  27. 27.
    Stepankova, H., Kohout, J., Simsa, Z.: J. Magn. Magn. Mater. 104, 411–412 (1992)ADSCrossRefGoogle Scholar
  28. 28.
    Molaei, M., Rahimipour, M.: Mater. Chem. Phys. 167, 145–151 (2015)CrossRefGoogle Scholar
  29. 29.
    Mosleh, Z., Kameli, P., Poorbaferani, A., Ranjbar, M., Salamati, H.: J. Magn. Magn. Mater. 397, 101–107 (2016)ADSCrossRefGoogle Scholar
  30. 30.
    Jamalian, M.: J. Magn. Magn. Mater. 378, 217–220 (2015)ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Electroceramics Research CenterMalek Ashtar University of TechnologyShahin ShahrIran

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