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DOI: 10.14738/aivp.92.9963
Publication Date: 25th April, 2021
URL: http://dx.doi.org/10.14738/aivp.92.9963
Effect of Ba Ion on Phase Formation, Microstructure and
Photocatalytic Properties of the Cual2o4 Nanoparticle
Kh. Roumaih*, Shaban I. Hussein
*Reactor Physics Dept., Reactors Division, Nuclear Research Center, Egyptian
Atomic Energy Authority, Abou Zabal P O 13759, Cairo Egypt
ABSTRACT
The phase purity, microstructure, functional groups, optical and photocatalytic
properties were studied for the Cu1-xBaxAl2O4 (x= 0.0, 0.1, and 0.3). The Cu1-
xBaxAl2O4 was synthesis by the sol-gel method. The XRD spectra of the parent
sample showed a single-phase structure with the space group Fd-3m:2. At x=0.1, the
CuAl2O4 structure formed along with CuBaAl10O17, while the BaAl2O4 and
CuBaAl10O17 formed at x = 0.3. The analysis of FTIR spectra confirmed the formation
of the hexagonal phase structure for x = 0.1 and 0.3. The images of HR-TEM show
nanorods along with nanograins for the samples which contain Ba ions. The optical
analysis proved the increasing trend in bandgap energy (Eg) with increasing Ba ion
doping. The photodegradation was evaluated for the degradation of methylene blue
and methyl orange dyes under visible light irradiation. The copper barium
aluminate is colored materials so, may be used as a ceramic pigment, also they are
useful for humidity sensors application. The novelty of this work, some physical
properties of the compound CuBaAl10O17, which is very rarely studied in the
literature, will be known.
Keywords: Copper Barium Aluminate; CuBaAl10O17; Nanorods; Hexagonal Phase;
Photocatalytic Activity; Ceramic Pigment and Humidity Sensors Application.
1. INTRODUCTION
The highly abundant elements in the earth's crust are copper and aluminum; these
elements are the oldest ones used by humans due to nontoxic and easily disposed of
after their intended use. So, copper and aluminum oxides have many applications in
the industry. There are many forms of copper with aluminum as the oxide copper
aluminate (CuAlO2) and the spinel copper dialuminate (CuAl2O4). The copper
aluminate (CuAlO2) is a hexagonal crystal structure with lattice parameter a=2.856
Å and c=16.943 Å [1] and distinguished by thermal stability at 1000°C - 1200°C,
depending on the percentage of copper contained in the sample [2]. The spinel
CuAl2O4 is the useful one of the copper - aluminum oxide family, which has a cubic
crystal structure (a=8.075 Å) [3] and is thermally stable at 612°C - 1000°C [2]. At
lower temperatures, the copper and aluminum oxides yield a mixture, whereas at
high temperatures the CuAl2O4 is transformed intoCuAlO2 [4].
The aluminate spinels possess many properties such as high thermal stability, lower
temperature sinterability, high mechanical resistance, low surface acidity, increased
hardness, and better diffusion [5, 6]. These properties make them useful materials
as pigments, ceramics, optical materials, and catalysts catalysts [7-9]. So many
reports studied the aluminate family hosts different transition metals [10-19]. On
the other hand, Barium aluminates are significant materials; they possess chemical
and thermal stability and act as a promising host material for transition metal
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European Journal of Applied Sciences, Volume 9 No. 2, April 2021
Services for Science and Education, United Kingdom
activators. So, it has many applications such as refractory cement, catalysts,
humidity sensors, and especially phosphor materials with high initial luminescence
intensity, long afterglow, and chemical stability[20-21].
The copper aluminate spinel prepared at high-temperature [7, 17, and 19] has a high
surface area, so it is active in the degradation of some organic compounds.
Nowadays, the useful and attractive technique for the preparation of the copper
aluminate spinels was the sol-gel method compared with other techniques [17-19].
The sol-gel technique has many advantages as the simple cost, preparation at low
temperatures, and producing pure and ultrafine powders.
Up to our knowledge, no studies report on the nanoparticles of copper barium
aluminate. The phase formation, microstructure, and optical properties studied in- depth of the compound Cu1-xBaxAl2O4 (x= 0.0, 0.1, and 0.3). Then the photocatalytic
reactions for Cu1-xBaxAl2O4 done using two organic pollutants; methylene blue and
methyl orange. Herein, the novelty of this work is to know some physical properties
of the compound CuBaAl10O17.
2. EXPERIMENTAL
2.1 Preparation Of The Samples
The compound Cu1-xBaxAl2O4 with x= 0.0, 0.1, and 0.3 (for simplicity named by S1,
S2, and S3 respectively) were prepared by the sol-gel method using the raw
materials Cu(NO3)2, Al(NO3)3-9H2O, BaCl2, and citric acid. The original materials
were dissolved individually in distilled water by using a magnetic stirrer for 30
minutes at room temperature, and then the solutions were mixed and stirred again.
After complete dissolution, a blue solution was obtained. After that, added drops of
the ammonia solution until the pH reached 7, we got a dark green solution. Then the
solution was heated on a hot-plate forming a green-brown gel which is decomposed
by spontaneous self-ignition, foaming and puffing, leaving behind a voluminous
brown fluffy powder. The final powder was left on a hot-plate for 2 h to dry. Figure
1 shows the final color of all powders obtained after annealing at 800-1200 oC, for
the S1, and S2 have Havana ocher color, but the sample S3 has bright gray (silver)
color.
2.2 Characterization Of The Samples
Powder XRD pattern recorded using a Philips X’pert diffractometer with Cu-Kα
radiation (λ=1.5406 Å) and nickel filter at a scanning step of 0.02◦, in the 2θ range
of 10–80◦. The lattice constant (a Å), the crystallite size (Z nm), and phase
concentration (C %) were calculated by using the MAUD program [22]. The
refinement of the structural parameters continued until convergence is reached
with the goodness of fit (S) around 1.0. The morphology of all samples was observed
by High-Resolution Transmission Electron Microscopy (HTEM-Model JEM-2100) to
determine the particle size (D nm).
To identify the chemical bonds and functional groups of our system, the FTIR
spectrum was recorded in the wavenumber range of 400–4000 cm−1, using Perkin
Elmer, Spectrum 100, USA. The UV- diffuse reflectance spectra (DRS) spectroscopy
(JASCO Corp., V-570) in the range of 190-2500 cm−1 to find the bandgap energy.
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Roumaih, K., & Hussein, S. I. (2021). Effect of Ba Ion on Phase Formation, Microstructure and Photocatalytic Properties
of the Cual2o4 Nanoparticle. European Journal of Applied Sciences, 9(2). 212-233.
URL: http://dx.doi.org/10.14738/aivp.92.9963
Photocatalytic activity of the synthesized compounds carried out for a cationic dye
(methylene blue-MB) and ionic dye (methyl orange-MO) under visible light of power
9w in time intervals from 30 to 120 min., 0.01 mg of the catalyst added to 5 ml of 1
mM dye solution. Before illumination, the catalyst and dye solution was stirred
magnetically under dark light for 30 min to reach the adsorption equilibrium
between them. The solution was filtered, centrifuged, and analyzed using a UV–
visible spectrometer. The percentage of degradation was calculated based on the
equation [23].
% degradation = [(C0-Ct) / C0] × 100 = [(A0-At) / A0] × 100 (1)
where C0 and A0 are the initial concentration and the absorbance of dye espectivily,
and Ct and At are the concentration and the absorbance at a time interval espectivily.
3. RESULTS AND DISCUSSION
3.1 XRD Analysis
The initial XRD spectra of the parent sample as-prepared showed many diffraction
peaks like an amorphous phase, which was difficult to identify the crystal structure
as shown in the inset of Fig 2. This means the chemical reaction was not complete
during the synthesis, so the crystal structure does not fully form. Therefore, the
compound Cu1-xBaxAl2O4 was annealed at different temperatures according to Ba
content. The phase transformations during the annealing treatment for all samples
were monitored by the XRD as shown in Fig 2.
Figures 3a-c showed the refinement XRD spectra of all samples, which exhibits the
profile fitting and separation of overlapping peaks. Where the markers are related
to the experimental data, and the solid lines show the calculated data using
Rietveld's method, a good agreement between the experiment and the calculated
spectra. Table 1 shows the phase purity, crystal structure, grain size, cell
parameters, and other properties of all samples at 800 and 1200 oC temperatures.
One can notice that (Table 1) the increment in the r(XRD), r(EX), and the grain size by
increasing the doping of the Ba ions, this means the grain boundary region will
decreases, i. e., the samples become denser by increasing the doping of the Ba ions.
Figure 3a demonstrates the XRD spectra of the sample S1 comply well defined
characteristic spinel structure, where no extra peaks belong to any phase, which
indicates that the single-phase of cubic spinel structure of CuAl2O4 is formed at a
temperature 800°C, which agreed with the previous literature [15, 24-25]. The
characteristics peaks of the sample S1 with the following Miller indices peaks [2 2
0], [3 1 1], [4 0 0], [4 2 2], [5 1 1], and [4 4 0] matched very well with copper
aluminate card of the Crystallography Open Database (COD) ID: 9005717 and were
assigned as spinel cubic structure with the space group Fd-3m:2: with the lattice
constant a = 8.076 Å which agrees with O'Neill et., al. [26]. Fig 3b shows the XRD
spectra of the sample S2 which is complicated because there are many peaks,
indicating a multiphase or two phases, were formed of the sample S2. By using the
MUAD program [22], the two phases are the cubic phase of CuAl2O4 (P1), and the
hexagonal phase of BaCuAl10O17 (P2) with the space group P63/mmc, where the
concentration of the (P1) is 49.9% and the (P2) is 50.1% as mentioned in Table 1.
Because the BaCuAl10O17 (P2) is very rarely studied in the literature, its reflection
peaks are identical to the Ba0.5Sr0.5CuAl10O17 with COD ID 2002518 [27]. This is an