DETERMINATION OF PARTICLE SIZE AND LATTICE CONSTANT OF COPPER AND COBALT COMPOUNDS USING XRD TECHNIQUE
Anurag Geete1 and B. D. Shrivastava2
1Department of Physics, SRGBN College, Sanawad, Khargone 451111, Madhya Pradesh, INDIA
2Maharaja Bhoj Govt. P. G. College, Dhar 454001, Madhya Pradesh, INDIA
Abstract - X-ray diffraction (XRD) is a non-destructive technique for determining the chemical composition and structure of the compound. In present study, copper [Cu(II)] and cobalt [Co(II)] complexes were synthesized using various Aniline/Toluidine dithiocarbamate.
The formed metal complexes were processed like washing and drying, grinding and mixing to yield a homogenous powder. The thoroughly mixed and ground dry powder complexes were used for XRD studies and different structural and chemical parameters were determined using XRD. The synthesized complexes were studied and characterized at room temperature. For this purpose the Cu and Co Kα radiation was used during XRD investigation. The XRD pattern of 2θ ranging between 10° and 60°were recorded. The indexing of the XRD pattern was carried out using the Joint Committee for Powder diffraction optical phenomenon computer code (JCPDF). The lattice constants (Å) and particle size (nm) of copper and cobalt complexes were determined using Bragg’s equation and Scherrer’s equation, respectively. The results of present investigation revealed that the particle size ranged 46.7-125.3 nm and 39.7-117.3 whereas Lattice constant ranged 4.76- 7.79 Å and 7.57-10.57 Å for different complexes of copper [Cu(II)] and cobalt [Co(II)], respectively. The investigation further showed that all the synthesized complexes are crystalline in nature, electrically neutral and thermally stable.
Keywords: X-ray diffraction, metal complexes, lattice constant, particle size, copper, cobalt, dithiocarbamate, aniline.
1 INTRODUCTION
X-rays are electromagnetic radiations, which lie between ultraviolet and gamma rays in the electromagnetic spectrum (Selman and Thomas, 1985). X-rays are characterized by the relatively short wavelengths of 0.01 Å to 100 Å with hard X-rays on one end and soft X-rays on the other they are conventionally produced by either the conversion of the kinetic energy of charged particles into radiation or the excitation of atoms in a target upon which fast moving electrons impinge (Chang et al., 1997). The former produces a continuous spectrum of X-rays where the latter gives rise to characteristic lines of nearly monochromatic X-rays.
X-rays have been used as powerful tools in analytical, physical, chemical, biological and structural characterization of matter (Attwood and Sakdinawat, 2017).
X-ray diffraction (XRD) is a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions.
The analyzed material is finely ground, homogenized, and average bulk composition is determined (Azaroff et al., 1974). Max von Laue, in 1912, discovered that crystalline substances act as three-dimensional diffraction gratings for X-ray wavelengths similar to the spacing of planes in a crystal lattice (Bunaciu et al., 2015). X-ray diffraction is now a common technique for the study of crystal structures and atomic spacing. X-ray diffraction is based on constructive interference of monochromatic X-rays and a crystalline sample.
These X-rays are generated by a cathode ray tube, filtered to produce monochromatic radiation, collimated to concentrate, and directed toward the sample. The interaction of the incident rays with the sample produces constructive interference (and a diffracted ray) when conditions satisfy Bragg's Law (nλ=2d sin θ) (Bragg, 1934). The principle of Bragg’s law is applied in the construction of instruments such as Bragg spectrometer, which is often used to study the structure of crystals and molecules. This law relates the wavelength of electromagnetic radiation to the diffraction angle and the lattice spacing in a crystalline sample. These diffracted X-rays are then detected, processed and counted. By scanning the sample through a range of 2θ angles, all possible diffraction directions of the lattice should be attained due to the random orientation of the powdered material. Conversion of the diffraction peaks to d-spacing allows identification of the mineral because each mineral has
a set of unique d-spacing’s. Typically, this is achieved by comparison of d-spacing’s with standard reference patterns. X-ray diffraction is most widely used for the identification of unknown crystalline materials (e.g. minerals, inorganic compounds). Determination of unknown solids is critical to studies in geology, environmental science, material science, engineering and biology (Al-Jaroudi et al., 2007). Since 1970 the application of X-ray spectroscopy is in use for studying the structural parameters of complexes.
Copper (II) exists as [Cu(H2O)6]2+ in aqueous solution, and this complex exhibits the fastest water exchange rate (speed of water ligands attaching and detaching) for any transition metal aquo complex. Compounds that contain a carbon-copper bond are known as organ copper compounds. Copper undergo substitution with alkyl halides to form coupling products; as such, they are important in the field of organic synthesis. Similarly, Cobalt is a chemical element is a weakly reducing metal that is protected from oxidation by a passivating oxide film. The molecular compounds and polyatomic ions of cobalt are classified as coordination complexes, that is, molecules or ions that contain cobalt linked to several ligands. As the copper and cobalt elements lying between s and p block elements of the periodic table are known as transition elements. A transition metal complexes consist of a transition metal (such as cobalt and copper) coordinated or bonded with one or more ligand like natural or anionic nonmetal species. Transitional metal complexes are important in catalysis, material synthesis. Photochemistry and biological systems and possess diverse chemical, optical and magnetic properties. Transition metal ions usually form complexes with well- defined number of ligand. The metal complexes of copper and cobalt has been synthesised by chemical method and studied using XRD technique to explore the potential application of these metals in various fields.
2 MATERIALS AND METHODS
Present study was conducted at the Department of Physics, Devi Ahilya University, Indore (MP). Present work is divided in two parts viz. laboratory synthesis of chemical ligands and complexes followed by XRD studies of synthesized metal complexes (Fig. 1).
Figure 1 Scheme for XRD study 2.1 Ligand Preparation
The copper and cobalt complexes were prepared with the ligands of Chloroaniline, Fluoroaniline, Nitroaniline, and Toluidine dithiocarbamate (Pandeya and Kaul, 1982).
Aniline is the simplest aromatic amine (Hatton et al., 1962). Aniline is an organic compound having a phenyl group attached to an amino group whereas dithiocarbamate is a functional group and is the analog of a carbamate in which both oxygen atoms are replaced by sulfur atoms. Dithiocarbamates readily undergo S-alkylation and methyl dimethyldithiocarbamate can be prepared by methylation (Fackler et al., 1973). The ligands of different aniline and toluidine with dithiocarbamate were prepared by following standard methods. Many primary and secondary amines react with carbon disulfide and sodium hydroxide to form metal salts of dithiocarbamate (Critchfield and Johonson, 1956). Briefly, the various ditiocarbamate ligands were prepared by adding 0.01 M of desired aniline/toluidine to
Then 0.01 M carbon disulphide was added dropwise. The formed precipitate was filtered off, washed with acetone and dried in vacuum and further these compounds were used in synthesis of Cu/Co complexes.
2.2 Synthesis of Cu/Co Metal Complexes
The Cu/Co complexes were prepared with ligands of Chloroaniline, Nitroaniline, toluidine and Fuloroaniline dithiocarbamate by following the standard protocols. The Cu/Co complexes with ligands were prepared by mixing 1:2 molar quantities of respective metal salt and ligand. The copper salt (CuSO4) was dissolved in distilled water and ligands were dissolved in ethanol. The two solutions were mixed with continuous stirring. The complex produced in the form of precipitate was filtered off, washed with acetone and water in equal quantities (1:1). The products were dried in vacuum.
2.3 XRD Study of Copper and Cobalt Complexes
XRD is a non-destructive technique for determining the chemical composition and structure of the compound. All seven copper [Cu(II)] complexes synthesized were studied and characterized at room temperature. Forthis purpose the Cu Kα radiation was used during XRD investigation. The XRD pattern of 2θ ranging between 10° and 60°were recorded. The XRD measurements were carried out on Bruker D-8 Advance X-ray diffractometer (Mehta et al., 2017). The indexing of the XRD pattern was carried out using the Joint Committee for Powder diffraction optical phenomenon computer code (JCPDF).
2.4 Determination of Lattice Constants (Å)
The lattice constants were determined using Bragg’s equation for all the complexes synthesized (Jauncey, 1924; Delhez et al., 1982). The Bragg’s equation used are as follows:
2d sinθ = nλ
Where, d is the interplaner distance and calculated as
𝑑 =
𝑎ℎ2+ 𝑙2+𝑘2 ; θ is the incident angle; n is positive integer; λ is the wavelength of incident radiation and h, k and l are the Miller Indices.
2.5 Determination of Particle Size (nm)
The particle size of all the complexes were determined using the Scherrer’s equation as follows (Birks and Friedman, 1946; Monshi et al., 2012):
𝜏 = 𝐾𝜆 𝛽𝐶𝑜𝑠𝜃
Where, τ is the particle size; K is the dimentionless shape factor; λ is the wavelength of incident radiation; β is the line broadening at half the maximum intensity and θ is the Bragg angle.
3 RESULTS
3.1 Cu/Co Metal Complexes
The details of synthesized metal complexes viz., abbreviation, complex name and their molecular formulas of Cu and Co are presented in Table 1 and Table 2, respectively.
Table 1 Details of Copper [Cu(II)] complexes
Abbreviation Complex name Molecular formula Cu-1 Cu(o-Chloroaniline dithiocarbamate)2 Cu(C7H4S2NCl)2
Cu-2 Cu(p-Toluidine dithiocarbamate)2 Cu(C8H7NS2)2
Cu-3 Cu(o-Nitroaniline dithiocarbamate)2 Cu(C7H4N2S2O2)2
Cu-4 Cu(4-Fluoroaniline dithiocarbamate)2 Cu(C7H4S2NF)2
Cu-5 Cu(p-Chloroanilinedithiocarbamate)2 Cu(C7H4S2NCl)2
Cu-6 Cu(p-Nitroaniline dithiocarbamate)2 Cu(C7H4N2S2O2)2
Cu-7 Cu(o-Toludinedithiocarbamate)2 Cu(C8H7NS2)2
Table 2 Details of Cobalt [Co(II)] complexes
Abbreviation Complex Name Molecular Formula Co-1 Co(o-Nitroaniline dithiocarbamate)2 Co(C7H4N2S2O2)2
Co-2 Co(p-Nitroaniline dithiocarbamate)2 Co(C7H4N2S2O2)2
Co-3 Co(m-Nitroaniline dithiocarbamate)2 Co(C7H4N2S2O2)2
Co-4 Co(o-Chloroaniline dithiocarbamate)2 Co(C7H4S2NCl)2
Co-5 Co(p-Chloroaniline dithiocarbamate)2 Co(C7H4S2NCl)2
Co-6 Co(4-Fluoroaniline dithiocarbamate)2 Co(C7H4S2NF)2
Co-7 Co(p-Toluidine dithiocarbamate)2 Co(C8H7NS2)2
3.2 XRD studies of Copper [Cu(II)] Complexes XRD Pattern of Copper complexes
The X ray diffraction patterns of the synthesized copper complexes are presented in Fig. 2.
Figure 2 XRD Pattern of synthesized copper (II) complexes 3.3 Particle size of Cu(II) Complexes
The particle size of the various copper complexes under study is presented in Table 3.
Table 3 Particle size and lattice constant of synthesized copper [Cu(II)] complexes Abbreviation Cu(II) complex Particle size(nm) Lattice constant (Å)
Cu-1 Cu(o-Chloroaniline dithiocarbamate)2 69.4 4.76
Cu-2 Cu(p-Toludine dithiocarbamate)2 48.9 7.28
Cu-3 Cu(o-Nitroaniline dithiocarbamate)2 69.4 4.86
Cu-4 Cu(p-Fluoroaniline dithiocarbamate)2 73.7 6.17
Cu-5 Cu(p-Chloroaniline dithiocarbamate)2 125.3 6.74
Cu-6 Cu(p-Nitroaniline dithiocarbamate)2 46.7 7.79
Cu-7 Cu(m-Nitroaniline dithiocarbamate)2 65.4 6.84
The particle size of Cu(II) complexes ranged between 46.7 nm and 125.3 nm. The highest particle size of 125.3 nm was observed for the copper complex synthesized using p- Chloroaniline dithiocarbamate (Cu-5) whereas the lowest particle size was recorded for Cu-6 complex [Cu(p-Nitroaniline dithiocarbamate) ]. The copper complexes followed the below
Cu-5 > Cu-4 > Cu-3 > Cu-1 > Cu-7 > Cu-2 > Cu-6
The synthesized copper complexes showed noticeable difference in particle size (Table 3). The earlier reported findings are found in line with the present results (Mishra et al., 2010; Mishra and Jain, 2013; Sharma et al., 2017; Sharma et al., 2019).
3.4 Lattice Constant of Cu(II) Complexes
The Lattice constant for various copper complexes under study is presented in Table 3. The Lattice constant of Cu(II) complexes ranged between 4.76 Å and 7.79 Å. The copper complex synthesizes using p-Nitroaniline dithiocarbamate (Cu-6) and o-Chloroaniline dithiocarbamate (Cu-1) showed highest and lowest lattice constant values, respectively. The copper complexes followed the below trend with respect to the Lattice constant:
Cu-6> Cu-2> Cu-7> Cu-5> Cu-4> Cu-3 > Cu-1
The synthesized copper complexes did not show noticeable difference in Lattice constant (Table 3). The earlier results are similar to the present findings (Mishra et al., 2010; Mishra and Jain, 2013; Sharma et al., 2017; Sharma et al., 2019).
3.5 XRD Studies of Cobalt [Co(II)] Complexes XRD Pattern of Cobalt complexes
The X ray diffraction patterns of the synthesized cobalt complexes are presented in Fig. 3.
Figure 3 XRD Pattern of synthesized cobalt [Co(II)] complexes Particle size of Co(II) complexes
The particle size of the various cobalt complexes under study is presented in Table 4.
Table 4 Particle size and lattice constant of synthesized cobalt [Co(II)] complexes Abbreviation Co(II) complex Particle size (nm) Lattice constant (Å)
Co-1 Co(o-Nitroaniline dithiocarbamate)2 71.1 10.57
Co-2 Co(p-Nitroaniline dithiocarbamate)2 52.2 7.97
Co-3 Co(m-Nitroaniline dithiocarbamate)2 39.7 9.86
Co-4 Co(o-Chloroaniline dithiocarbamate)2 59.1 8.67
Co-5 Co(p-Chloroaniline dithiocarbamate)2 117.3 8.28
Co-6 Co(4-Floroaniline dithiocarbamate)2 60.4 8.34
Co-7 Co(p-Toludine dithiocarbamate)2 75.6 7.57
The particle size of Co(II) complexes ranged between 39.7 nm and 117.3 nm. The highest particle size of 117.3 nm was observed for the cobalt complex synthesized using p- Chloroaniline dithiocarbamate (Co-5) whereas the lowest particle size was recorded for Co-3 complex [Co(m-Nitroaniline dithiocarbamate)2]. The cobalt complexes followed the below trend with respect to the particle size:
Co-5 > Co-7 > Co-1 > Co-6 > Co-4 > Co-2 > Co-3
The synthesized cobalt complexes showed noticeable difference in particle size due to the nature and position of ligand and ligand forming group, respectively (Table 4). The earlier reported works are in conformity with present findings (Marco et al., 2000; Mishra et al., 2012; Malviya et al., 2014).
3.6 Lattice Constant of Co(II) Complexes
The Lattice constant of Co(II) complexes ranged between 7.57 Å and 10.57 Å. The cobalt complex synthesizes using o-Nitroaniline dithiocarbamate (Co-1) showed highest Lattice constant whereas the Co(II) complexed formed with p-Toluidine dithiocarbamate (Co-7) recorded lowest value of Lattice constant. The cobalt complexes followed the below trend with respect to the Lattice constant:
Co-1 > Co-3> Co-4 > Co-6> Co-5 > Co-2> Co-7
The synthesized cobalt complexes showed noticeable difference in Lattice constant due to the nature and position of ligand and ligand forming group, respectively (Table 4).
The earlier reported works are in conformity with present findings (Marco et al., 2000;
Mishra et al., 2012; Malviya et al., 2014).
4 CONCLUSION
The X-ray diffraction investigation revealed that the particle size ranged 46.7-125.3 nm and 39.7-117.3 whereas Lattice constant ranged 4.76-7.79 Å and 7.57-10.57 Å for different complexes of copper [Cu(II)] and cobalt [Co(II)], respectively. The investigation further showed that all the synthesized complexes are crystalline in nature, electrically neutral and thermally stable.
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