Structure, morphological, magnetic and optical properties of CuxMg1-xFe₂O₄ (x = 0, 0.5, 1) nano ferrites synthesized by co-precipitation method

Chemistry & Environment 
T. V. Chinh, , P. K. N. Ho, “Structure, morphological,  co-precipitation method.” 46 
STRUCTURE, MORPHOLOGICAL, MAGNETIC AND OPTICAL 
PROPERTIES OF CuxMg1-xFe2O4 (x = 0, 0.5, 1) NANO FERRITES 
SYNTHESIZED BY CO-PRECIPITATION METHOD 
Tran Van Chinh
1*
, Nguyen Thi Hoai Phuong
1
, Vu Thi Thu Ha
2
, 
Phan Thanh Xuan
1
, Phung Khac Nam Ho
1
Abstract: CuxMg1.xFe2O4 nanoparticles were successfully synthesized by co-
precipitation. The samples were calcined at 900 
o
C for 3 h and X-ray diffraction 
analysis showed that Cu0.5Mg0.5Fe2O4 had a single phase cubic spinel structure, 
while formation of secondary phase of Fe2O3 was observed in XRD patterns of 
CuFe2O4, MgFe2O4. The saturation magnetization (Ms) of Cu0.5Mg0.5Fe2O4 is in 
between the saturation magnetization values of CuFe2O4 and MgFe2O4 
nanoparticles, CuFe2O4 is a ferromagnetic material, while MgFe2O4 and 
Cu0.5Mg0.5Fe2O4 show superparamagnetic behavior. The synthesized spinel ferrites 
were fully characterized using scanning electron microscopy (SEM), FTIR 
spectroscopy, energy dispersive spectroscopy (EDS) and UV-vis spectrophotometry. 
Keywords: Spinel ferrites; Nanoparticles; Ferromagnetic materials; Superparamahnetic. 
1. INTRODUCTION 
Spinel ferrite nanoparticles have a general formula of MFe2O4, where M is a 
divalent metal cation such as Co
2+
, Ni
2+
, Cu
2+
, Mg
2+
, Zn
2+
, Mn
2+
 are promising 
materials because of their unique magnetic and electric properties with chemical and 
thermal stabilities [1]. These materials have been used in many applications, 
including electrochemical supercapacitors [2], lithium-ion batteries [3], magnetic 
fluid hyperthermia [4], biomedical nanotechnology [5], drug delivery [6], gas 
sensors [7]. They have been routinely applied in wastewater treatment, in particular, 
in order to remove toxic metal [8, 9] and degrade organic dye [10, 11]. There are 
various methods for the synthesis of spinel ferrite such as co-precipitation [12], sol-
gel [13], citrate-gel auto-combustion [14], ball-milling [15], 
Magnesium ferrite (MgFe2O4) is a soft magnetic n-type semiconductor with 
and a typical inverse spinel, where Fe
3+
 ions are located in the tetrahedral (A) and 
octahedral (B) sites and Mg
2+
 ions are only located in octahedral sites [16]. 
Copper ferrite (CuFe2O4) is basically an inverse of spinel ferrite and a high 
saturation field [17, 18]. 
In this work, the mixed cubic spinel ferrites nanoparticles CuxMg1-xFe2O4 (x = 0, 
0.5, 1) were synthesized by the co-precipitation method. The structure, morphological, 
optical, and magnetic properties of these spinel ferrites are investigated 
2. EXPERIMENTAL SECTION 
Materials: Ferric chloride hexahydrate FeCl3⋅6H2O (98 %, Xilong-China), 
copper chloride hydrate CuCl2.2H2O (99%, Xilong-China), magnesium chloride 
hydrate MgCl2⋅6H2O (99 %, Xilong-China), sodium hydroxide NaOH (99 %, 
Xilong-China), ethanol (99 %, Xilong-China), deionized water (D.I). All chemicals 
were used as such without any purification. 
Characterization techniques: Structure and crystallinity were analyzed by 
Research 
Journal of Military Science and Technology, Special Issue, No.72A, 5 - 2021 47 
X'Pert PRO PANalytical with a 0.15405 nm Cu-Kα radiation source. The 
morphology, particle size and elemental analysis of the samples were determined 
by a scanning electron microscope energy dispersive X-ray spectroscopy (SEM - 
EDX Hitachi S-4600). Fourier transform infrared spectroscopy (FTIR, TENSOR 
II, Bruker) was employed to investigate the surface functional group adsorbent of 
prepared nanostructured samples. Optical absorption spectra were measured by 
UV-vis spectrophotometer (Jasco V730). Magnetization measurements were 
carried out with a vibrating sample magnetometer (VSM) at room temperature. 
Synthesis of CuxMg1-xFe2O4 (x= 0, 0.5, 1) nanoparticles: The CuxMg1-xFe2O4 
(x=0, 0.5, 1) nanoparticles were prepared using a chemical co-precipitation method 
[19]. The molar ratio of M
2+
/Fe
3+
 (M = Cu, Mg) was kept constant at 1:2. These 
materials in the stoichiometric ratio were dissolved in 100 ml deionized water and 
was vigorously stirred using a magnetic agitator for 15 minutes. A solution NaOH 
5M was dropped to adjust the pH = (9 - 10). The precipitate was heated at 90 
o
C 
under magnetic stirring for 2 hours. After cooling, the solid materials were filtered 
and washed several times by D.I and ethanol. The washed samples were dried at 
100 
o
C for 12 hours and then calcined at temperatures 900 
o
C for 3 hours. 
3. RESULTS AND DISCUSSION 
SEM analysis of the nanoparticles 
Figure 1. SEM images of (a) CuFe2O4, (b) MgFe2O4 
and (c) Cu0.5Mg0.5Fe2O4 nanoparticles. 
The morphologies of CuFe2O4, MgFe2O4 and Cu0.5Mg0.5Fe2O4 nanoparticles 
were studied by a scanning electron microscope (SEM) as shown in figure 1. The 
average size of CuFe2O4 nanoparticles is less than 100 nm with particle 
Chemistry & Environment 
T. V. Chinh, , P. K. N. Ho, “Structure, morphological,  co-precipitation method.” 48 
aggregation into larger particles. The micrograph of MgFe2O4 has formed relative 
spherical particles with nano diameters in the range of 30 - 40 nm. And from fig 
1c, the particles of Cu0.5Mg0.5Fe2O4 are relatively uniform in size with an average 
particle size of approximately 30 nm. The SEM observation of samples showed 
that the average size is in good agreement with their crystallite sizes determined 
from XRD spectra. 
XRD analysis of the samples 
XRD patterns of the CuFe2O4, MgFe2O4 and Cu0.5Mg0.5Fe2O4 nanoparticles 
were analyzed using XRD and shown in fig.2. As can be seen in fig.2, all the 
diffraction peaks at 19.05
o
, 30.35
o
, 35.08
o
, 37.77
o
, 43.97
o
, 54.36
o
, 58.4
o
, 62.48
o
, 
65.09
o
 and 67.23
o
, 74.25
o
. The peaks correspond to the (111), (220), (311), (222), 
(400), (422), (511) (440 ... n of spinel CuFe2O4 (JCPDS 
01-077-0010) and spinel MgFe2O4 (JCPDS 01-089-3084). Moreover, the 
formation of the secondary phase of Fe2O3 (JCPDS 01-085-0599) was observed in 
XRD patterns of CuFe2O4, MgFe2O4. The secondary phase was also reported for 
other ferrites in literatures [20, 21]. While, the XRD pattern of Cu0.5Mg0.5Fe2O4 
sample has only a single spinel phase with diffraction planes (200), (311), (400), 
(422), (511) and (440). Finally, these diffraction peaks of the CuFe2O4, MgFe2O4 
and Cu0.5Mg0.5Fe2O4 are indexed to the cubic crystal structure of the spinel phase 
with the Fd-3m space group. 
The crystallite size for the most intense peak (311) plane was calculated by 
using the Debye-Scherrer formula: 
Where k, λ, B and ϴ are Scherrer constant (0.89), the X-ray wavelength 
(0.15406 nm), the width of the peak at half maximum intensity (radian) and the 
angle of diffraction, respectively [16]. 
The lattice parameter was also calculated from XRD data for all the samples 
using the equation: 
Where (hkl) are Miller indices. 
Table 1. Crystallite size and lattice parameter for the samples. 
Samples Crystallite size (nm) Lattice parameter (Å ) 
CuFe2O4 (x = 1) 32.9 8.4836 
MgFe2O4 (x = 0) 27.9 8.2785 
Cu0.5Mg0.5Fe2O4 (x = 
0.5) 
29.5 8.2940 
The crystallite size and the lattice parameter of the samples is shown in table 1. 
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Journal of Military Science and Technology, Special Issue, No.72A, 5 - 2021 49 
Figure 2. XRD patterns of the CuFe2O4, MgFe2O4 and Cu0.5Mg0.5Fe2O4. 
The calculated lattice parameter for MgFe2O4 is smaller than the lattice 
parameter for CuFe2O4. This can be explained on the basis of ionic radius, where 
the ionic radius of Mg
2+
 ion (0.72 Å) [22] is smaller than that of Cu2+ ion (0.73 Å) 
[22]. When a larger Cu
2+
 ion is replaced by a smaller Mg
2+ 
ion, the lattice 
parameter for Cu0.5Mg0.5Fe2O4 is smaller than the parameter for CuFe2O4 and 
larger than the parameter for MgFe2O4. 
EDX analysis of the nanoparticles 
Figure 3. EDX analysis of (a) CuFe2O4, (b) MgFe2O4 and (c) Cu0.5Mg0.5Fe2O4. 
Chemistry & Environment 
T. V. Chinh, , P. K. N. Ho, “Structure, morphological,  co-precipitation method.” 50 
Elemental analysis of CuFe2O4, MgFe2O4 and Cu0.5Mg0.5Fe2O4 samples based 
on EDX study (fig. 3). Fig. 3 shows the presence of peaks related to their 
constituent elements, with no other impurity. The Cu:Fe; Mg:Fe, and (Cu+Mg):Fe 
atomic ratios estimated by EDX analysis were (14.67:24.65), (13.69:25.52) and 
(12.8:23.17) which are nearly closeto the theoretical ratio of 1:2 in CuFe2O4, 
MgFe2O4 and Cu0.5Mg0.5Fe2O4, respectively. 
FT-IR and Magnetization analysis of the nanoparticles 
The Fourier transform infrared (FTIR) spectra of CuFe2O4, MgFe2O4 and 
Cu0.5Mg0.5Fe2O4 are presented in fig 4a. For three samples, the peaks around 3400 
cm
-1
 and 1600 cm
-1
 are the contribution from the vibration of O-H group of 
adsorbed water or humidity on the surface [23, 24]. In the spinel ferrite structure, 
the metal ions are situated in two different sub-lattices designated as tetrahedral 
(A-site) and octahedral (B-site). The highest IR band ν1, is generally observed in 
the higher frequency range of 600 - 550 cm
-1
, corresponding to the intrinsic 
stretching vibration of the metal-oxygen bond at the tetrahedral site Mtetra-O (A-
site). The lowest IR band ν2, is usually observed in the frequency range of 450 - 
385 cm
-1
, assigned to stretching vibrations of the metal-oxygen bond at the 
octahedral site Mocta-O (B-site) [25, 26]. The values of ν1 and ν2 for samples are 
given in table 2 and confirm the formation of a spinel ferrite structure. 
Table 2. Absorption band (ν1 and ν2) of the samples. 
Samples ν1 (cm
-1
) ν2 (cm
-1
) 
CuFe2O4 (x = 1) 583.11 434.24 
MgFe2O4 (x = 0) 576.13 436.95 
Cu0.5Mg0.5Fe2O4 (x = 0.5) 576.95 433.98 
Figure 4. (a) FTIR spectra and (b) Magnetic hysteresis loops of CuFe2O4, 
MgFe2O4, Cu0.5Mg0.5Fe2O4 nanoparticles. 
Hysteresis loops depicting the variation of magnetization (M, emu/g) and 
magnetic field (H, Oe) are shown in fig. 4b. The saturation magnetization (Ms), 
remanent magnetization (Mr) and coercivity (Hc) for all the samples are listed in 
the table 3. It was seen that the hysteresis loop of CuFe2O4 bears typical 
Research 
Journal of Military Science and Technology, Special Issue, No.72A, 5 - 2021 51 
characteristics of ferromagnetic materials, while MgFe2O4 and Cu0.5Mg0.5Fe2O4 
show superparamagnetic behavior. The values of Ms, Mr, Hc of CuFe2O4 are higher 
than that of both MgFe2O4 and Cu0.5Mg0.5Fe2O4. The saturation magnetization of 
MgFe2O4 is exceptionally low, after replacing Mg
2+
 by Cu
2+
 to enhance the Ms 
value of MgFe2O4. 
Table 3. Saturation magnetization (Ms), remanent magnetization (Mr) 
and coercivity (Hc) of the samples. 
Samples Ms (emu/g) Mr (emu/g) Hc (Oe) 
CuFe2O4 (x = 1) 29.5 13.6 560 
MgFe2O4 (x = 0) 13.1 1.6 83 
Cu0.5Mg0.5Fe2O4 (x = 0.5) 23.1 4.1 83 
Ultraviolet - visible analysis of the samples 
Figure 5. (a) UV-vis absorption spectra and (b) Tauc plot of the CuFe2O4, 
MgFe2O4, Cu0.5Mg0.5Fe2O4 nanoparticles. 
The UV-vis absorption spectra of CuFe2O4, MgFe2O4 and Cu0.5Mg0.5Fe2O4 is 
shown in fig.6a. All the samples show a wide range of absorption from UV to 
visible region (200 nm - 850 nm). The optical absorption strength depends on the 
difference between the photon energy and the band gap as shown in the equation: 
(αhυ)1/n = A(hυ - Eg) 
where h is Planck’s constant (6,626.10-34 Js), υ is the light speed (3.108 ms-1), α is 
the adsorption coefficient, Eg is the band gap energy and A is the absorption. The 
catalyst is assumed to be the direct transition type (n=1/2) for the determination of 
the band gap energy of the photocatalysts. By using the Tauc method, a plot (αhυ)2 
vs hυ was developed as shown in figure 5(b) and the calculated band gaps of 
energy are 1.41 eV, 2.04 eV, 1.65 eV for CuFe2O4, MgFe2O4, Cu0.5Mg0.5Fe2O4 
respectively, indicating that the samples may have visible-light photoactivity. 
4. CONCLUSIONS 
In summary, CuxMg1.xFe2O4 (x = 1, 0.5, 0) nanoparticles were successfully 
synthesized by co-precipitation. At calcined 900 
o
C for 3 hours, Cu0.5Mg0.5Fe2O4 
Chemistry & Environment 
T. V. Chinh, , P. K. N. Ho, “Structure, morphological,  co-precipitation method.” 52 
had a single phase cubic spinel structure, while CuFe2O4, MgFe2O4 had formation 
of secondary phase of Fe2O3 in XRD patterns. The particles sizes of CuFe2O4, 
Cu0.5Mg0.5Fe2O4 and MgFe2O4 were 32.9 nm, 27.9 nm and 29.5 nm, respestively. 
Cu
2+
-doping improves the magnetic properties of magnesium ferrite, as the 
saturation magnetization (Ms) is increased from 13.1 emu/g to 23.1 emu/g. These 
spinel ferrites had small band gap energies of 1.41 eV, 2.04 eV, 1.65 eV for 
CuFe2O4, MgFe2O4, Cu0.5Mg0.5Fe2O4, respectively, indicating that they are used as 
adsorbents/photocatalysts for application in wastewater treatment. 
Acknowledgement: The authors are grateful to the colleagues of the Department of 
Inorganic Chemistry, Institute of Chemistry and Materials. 
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TÓM TẮT 
CẤU TRÚC, HÌNH THÁI HỌC, TỪ TÍNH VÀ TÍNH CHẤT QUANG 
CỦA NANO FERRITE CuxMg1-xFe2O4 (x = 0, 0.5, 1) TỔNG HỢP 
BẰNG PHƯƠNG PHÁP ĐỒNG KẾT TỦA 
Các hạt nano CuxMg1-xFe2O4 đã được tổng hợp thành công bằng phương 
pháp đồng kết tủa. Các mẫu được nung ở 900 oC trong 3 giờ, theo phổ XRD 
mẫu Cu0.5Mg0.5Fe2O4 có cấu trúc đơn pha dạng lập phương, trong khi đó, 
mẫu CuFe2O4 và MgFe2O4 có sự xuất hiện của pha Fe2O3. Từ độ bão hòa 
của Cu0.5Mg0.5Fe2O4 nằm trong khoảng giữa giá trị từ độ bão hòa của 
CuFe2O4 và MgFe2O4. CuFe2O4 là vật liệu sắt từ, Cu0.5Mg0.5Fe2O4 và 
MgFe2O4 là vật liệu siêu thuận từ. Tất cả các spinel ferrite được đánh giá 
một số tính chất như SEM, FT-IR, EDS và phổ UV-vis. 
Từ khóa: Spinel ferrite; Hạt nano; Vật liệu sắt từ; Siêu thuận từ. 
Received Jan 11
th
 2021 
Revised Jan 26
th
 2021 
Published May 10
th 
2021 
Author affiliations: 
1 
Institute of Chemistry and Materials; 
2 
Key Laboratory for Petrochemical and Refinery Technologies. 
 *Corresponding author: chinhpkkq@gmail.com.