Report exp 2 - X-ray Diffraction Method PDF

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Revision No: 1 / 2016

DEPARTMENT OF MANUFACTURING AND MATERIALS ENGINEERING

NAME AND MATRIC NO: 1. MUHAMMAD HAZWAN BIN SA’ADON (1818941) 2. MUHAMMAD HAZIQ HAKMAL BIN JAILANI (1810915) 3. MUHAMMAD AMIRUL BIN ABDUL HADI (1817877) 4. NUR AFIQAH BINTI ROSDI (1819664) 5. NUR FADHILLAH BINTI MOHD FADZIR (1819586) GROUP NAME: 3 SECTION: 1 DATE OF EXPERIMENT: 25 June 2020 TITLE OF EXPERIMENT: X-ra y Diff Diffrra c ti tio o n Me th tho ods LECTURER: Dr. Nur Idayu Binti Ayob DEMONSTRATOR: -TECHNICAL STAFF AND LABORATORY: -DATE OF SUBMISSION: 9 July 2 0 2 0 For grader’s use only Assessment

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INTRODUCTION X-ray diffraction method is one of the materials characterization method in industry. This method are the most effective methods for determining the crystal structure of materials. This method does not make use the composition of materials element to identify the chemical compound from their crystalline structure. This means different compound that have the same composition can be identified. X-ray diffraction is also a non-destructive method and can be used to identify structures, phases, preferred crystal orientations (texture), and other structural parameters, such as average grain size, crystallinity, strain, and crystal defects. XRD analysis involved the Bragg’s law (nλ = 2dsinθ). A sample is placed at the center of instrument and illuminated with a monochromatic beam of x-rays. The x-ray tube and the detector move in a synchronized motion. When an x-ray hit an atom, the atom elastic scattering happens where the x-ray energy is re-admitted back a new x-ray with the same energy as the original. In respect with a crystal, repeating arrangement of atoms x-rays are scattered by the regularly spaced atom. At very specific angle, the scattered wave constructively interferes resulting in diffraction. The signal coming from the sample is recorded and graphed where peaks are observed related to the atomic structure of the sample. Only the constructive interference will be graph on the XRD pattern. Then, the analysis is made by inspecting the peak produced.

OBJECTIVE 1. To identify phase(s) present in material 2. To determine crystal structure and lattice parameter(s) of each phase

APPARATUS X-Ray Diffractometer (myscope virtual instrument), rich iron powder, poor iron powder.

PROCEDURE The samples that have been analysed are poor and rich iron containing samples. The individual particle size of the sample should be below 45 microns. The samples have been prepared before being analysed. Firstly, the rich iron sample is put in the well of the sample holder. Then pressing the sample and scrape off whatever comes out of the well. Then the sample was flattened and make sure it holds together on its own. This condition has been verified by tip it up by 45 degrees and make sure that it is holding. The rich iron sample then was analysed using XRD simulations. Firstly, power on the simulator. The rich iron sample was loaded into the sample holder of the diffractometer. The starting and ending angle are set to 30(degree) and 70 (degree) respectively. The current was set to 40mA and 40kV for the power. Step size is 0.10 degree and 1.6 sec time per step was set. The rich iron sample is scanned. After this scan, the sample must be scanned again using cobalt as a source and the current is changed to 35mA. The result for XRD pattern is obtained. Then the sample is unloaded and power off the diffractometer. These steps are repeated using poor iron sample.

RESULTS 1. Rich Iron Sample

Figure 1: XRD pattern for rich iron sample

2. Poor Iron Sample

Figure 2: XRD pattern for poor iron sample

DISCUSSIONS MUHAMMAD HAZIQ HAKMAL BIN JAILANI (1810915) X-ray diffraction is a technique used in materials science for determining the atomic and molecular structure of a material. This is done by irradiating a sample of the material with incident X-rays and then measuring the intensities and scattering angles of the X-rays that are scattered by the material. The intensity of the scattered of X-rays are plotted as a function of the scattering angle, and the structure of the material is determined from the analysis of the location, in angle, and the intensities of scattered intensity peaks. Based on the result obtain from the virtual XRD method, both rich and poor iron use different angle, 2𝜃. For rich iron, 2𝜃 use is 35º, 43.5º, 55º, 60º and 63º. Bragg’s Law equation 𝑛𝜆

𝑑 = 2 sin 𝜃 will be used to determine the miller indices and interplanar distance, thus determine the crystal structure. The Miller Indices (hkl) is 1.292, 1.961, 3.047, 3.57 and 3.902 respective to the angles. For poor iron, 2𝜃 use is 38º, 44º, 55º, 64º and 78º. The Miller Indices (hkl) is 1.514, 2.005, 2.047, 4.011 and 5.661 respective to the angles. As we can see, peaks in graph for poor iron is higher than peaks in graph for rich iron. From the peaks of the graph, we can decide the atom position is (100) for peak 1, (110) for peak 2, (111) for peak 3, (111) for peak 4 and (200) for peak 5 for rich iron. The atom position is (100) for peak 1, (110) for peak 2, (111) for peak 3, (200) for peak 4 and (210) for peak 5. Based on the result and graph of XRD obtained, we can see that the angle 2θ is different for both poor and rich iron. The range of angle for rich iron is smaller than poor iron. From the Bragg’s law equation, the miller indices and lattice parameter can be determined. From the calculated result, we can conclude that the crystal structure for both irons is BCC with lattice parameter of 0.291nm each. The crystal structure also can be proved by the atom position. The atom position for both poor and rich iron shows similarities at 55º with coordinate of (111). This summation of atom position will help to differentiate the crystal structure. If the total is even, then the crystal structure is BCC. For the precaution, there is less errors produce by this experiment because it is computerized result. The result involving manual calculations such as miller indices and lattice parameters need to be precisely calculated. The source should be change to cobalt to avoid fluorescence. Thus, more accurate result.

MUHAMMAD AMIRUL BIN ABDUL HADI (1817877) X-ray diffraction (XRD) is a technique used to measure the average spacings between layers of atoms, to find the crystal structure of a material and many more information of a material. XRD emits electrons and targeted on the material while the detector rotates slowly at different angle so many information can be obtained due to fine powder materials contained many crystals at a random angle. By doing so, the Bragg’s equation can be satisfied. The structure of the material can be determined through the analysis of the angle and the intensities of the scattered peaks. From the data obtained for rich iron sample, it shows that the angles of the peak formed at 17.5ᴼ, 21.75ᴼ, 27.5ᴼ, 30.0ᴼ and 31.5ᴼ respectively while for the poor iron sample, the peaks formed at 19.0ᴼ, 22.0ᴼ, 27.5ᴼ, 32.0ᴼ and 39.0ᴼ respectively. The angle is used to determine the Miller Indices by using Bragg’s equation. The wavelength used is 0.154nm thus, the Bragg’s equation can be used to determine the Miller Indices, and the atom position of the material. XRD method help to understand more about the material by giving information of the crystal structure. The atom position plays the main role in determining the crystal structure of the material. The Miller Indices (hkl) found in reach iron samples are 1.292, 1.961, 3.047, 3.57 and 3.902. As for the poor iron the Miller Indices are 1.514, 2.005, 2.047, 4.011 and 5.661 respectively. Thus, the atom position for the peaks in rich iron sample are (100), (110), (111), (111) and (200). However, for the poor iron (100), (110), (111), (200) and (210) are the atom position. It is found that both iron sample show a crystal structure of body centred cubic (BCC). In addition, the peak obtained from poor iron sample is much higher than rich iron sample, some of the peak just reach beyond the scale of the graph. In short, the Bragg’s equation must be satisfied with information such as the wavelength and the angle of the peak intensities in order to get information of the material such as crystal structure and etc. XRD method is used to gain many information of a material for a better understanding of the characteristics of the material. There is no error in this experiment because it is a virtual experiment. For the precautions for the real lab experiment, the source should be change to cobalt to avoid fluorescence and giving a high quality diffractogram for more accurate result. Lastly, complete shielding should be applied to prevent from the X-ray radiation that can harm the people around it.

MUHAMMAD HAZWAN BIN SA’ADON (1818941) X-ray diffraction is a method which is used for the primary characterization of material properties like internal structure of crystal. The diffraction depends on two factor which are the crystal structure and the wavelength. X-ray diffraction is analyzed based on constructive interference of monochromatic x-ray. Monochromatic x-ray is produced by using filter such as copper and cobalt. XRD works on the principle of Bragg’s law equation, which is 𝑛λ = 2𝑑𝑠𝑖𝑛𝜃. Each plane of the crystal structure only reflecting a small fraction of the radiation where Bragg’s reflection can occur only for wavelength λ < 2d. In XRD pattern, there are three significance of peak shape that we can see which are peak position, peak width and peak intensity. In this experiment, two samples which are rich iron sample and poor iron sample in the form of powder. This experiment is done virtually using XRD simulation from online simulator, Myscope. These samples are known to have BCC crystal structure. Hence all the calculation is done based on this structure. The angle between the incident and scattered beam, 2θ for iron rich and poor rich samples are identified. Then, we use the Bragg’s equation to find the interplanar distance, d. The lattice parameter for both samples is calculated to be 0.291nm. Finally, the miller indices (atomic position) is obtained by comparing with the corresponding hkl value for primitive cubic class. The miller indices for rich iron sample are (100), (110), (111), (111) and (200) respectively. While, for poor iron sample are (100), (110), (111), (200) and (210) respectively. In order to classify either a material has body body-centered cubic, BCC or facecentered cubic, FCC, we need to sum the miller indices, (hkl). If the summation of miller indices is an even number, then the material has BCC crystal structure. If not, we have to see if the miller indices have all even or all odd number to confirm the FCC crystal structure. From the result, the miller indices, (hkl) of both samples cannot be used to determine the crystal structure because they met neither BCC nor FCC requirement of structure factor of the both lattices. These errors may occur due to the fluorescence effect from copper source that lead to high background level and loss of peak intensity. This could be avoided by using cobalt source radiation. Precaution steps should be prioritized in this experiment as we are dealing with x-ray that could damage our body. These precautions are to wear suitable PPE and follow all the safety requirement when handling the X-ray diffractometer. For the result part, one should

make a closest approximation of the 2θ value in the XRD patterns. This will help to reduce errors during calculations.

NUR AFIQAH BINTI ROSDI (1819664) X-Ray Diffractometer (XRD) analysis which the study of crystal structure is used to identify the crystalline phases present in a material and thereby reveal chemical composition information. XRD is useful for evaluating minerals, polymers, corrosion products, and unknown materials. In most cases, the samples are analyzed by powder diffraction using samples prepared as finely ground powders. It allows one to ascertain the molecular structure of a crystalline material by diffracting x-rays through the sample. XRD analyzer obtains interference patterns reflecting lattice structures by varying the angle of incidence of the XRay beam. Once the beam is separated, the scatter, also called a diffraction pattern, indicates the sample’s crystalline structure. There are two samples used which are rich iron and poor iron. From the graph, each diffraction peak is attributed to the scattering from a specific set of parallel planes of atoms. In this experiment, the miller indices (hkl), interplanar distance (d), lattice parameter (a), and crystal structure of the sample were obtained by using XRD analysis. Bragg’s law relates the diffraction angle, 2θ, to d. For rich iron sample, the diffraction angles are 35°, 43°, 55°, 60° and 63°. For poor iron sample, the diffraction angles are 38°, 44°, 55°, 64° and 78°. The formula to get interplanar distance, d is 𝑑 =

𝑛λ

2𝑠𝑖𝑛θ

. The value of d for rich iron are 0.2566nm, 0.2078nm,

0.1667nm, 0.1540nm and 0.1473nm while for poor iron are 0.2365nm, 0.2055nm, 0.1667nm, a 2

0.1453nm and 0.1223nm. The miller indices (hkl) with formula ℎ2 + 𝑘 2 + 𝑙 2 = ( d) are used to identify the different planes of atoms. It can be determined from the values of d and a. The position of atom of rich iron are (100), (110), (111), (111) and (200) while for poor iron are (100), (110), (111), (200) and (210). From the result, rich and poor iron are both body-centered cubic (BCC). To get a better result for the experiment, the sample need to be taken care very carefully. By adjusting the divergence slit and beam mask for largest possible irradiated area and use spinning sample stage can reduce the graininess. To get the preferred orientation, press the powder without ‘rubbing’ the surface and use back-loading sample holder. The better result gives the exact crystalline phases of the material.

NUR FADHILLAH BINTI MOHD FADZIR (1819586) X-ray diffraction (XRD) is a technique to identify and characterize the atomic structure of materials based on their diffraction pattern. This technique is primarily used for crystalline material. Diffraction occurs when an incident beam of X-rays interacts with target material is scattering the X-ray from the atoms. The scattered X-rays undergo the constructive and destructive interference. The diffraction of X-ray is described by Bragg’s Law, n(lambda)=2d sin (theta). All possible diffraction directions of the lattice due to random orientation of the material can be obtained by scanning the sample through a range of 2(theta) angles. The X-ray diffraction pattern obtained can tell what is in the sample, the structure of the sample and the arrangement of the atoms of the sample. The wavelength of X-Ray used as a source is 0.154nm. The interplane spacing, d for each values of theta for rich and poor iron samples are calculated using Bragg’s law. The d value has Miller indices (h, k, l) is calculated for both samples using for different angle values. From the Miller indices, the crystal structure of the atom can be obtained. If the sum of miller indices is even, the material has BCC crystal structure. From the calculated result, it can be seen iron has BCC crystal structure at angle 2 (theta) of 43.5 (degree) and 63 (degree) for rich iron sample and 44(degree) and 64(degree) for poor iron sample. The source of radiation must be chosen properly to avoid misinterpretation. The cobalt source is preferable to produce high quality diffractogram for correct interpretation of the phase of a material. In real practice, some precautions must be taken seriously to avoid from getting large percentage of errors in the result and the hazard from the X-ray radiation as it can give bad effect to the health.

CONCLUSION For the conclusion, XRD result can determine the crystal structure or phases present in the material. With the information given by the simulation such as the interplanar distance, miller indices, angle, we can decide the phase present in both poor and rich iron. The lattice parameter for poor and rich iron is same value with 0.291nm each. The result clearly shows the phase present in each iron is Body Centered Cubic (BCC) crystal. By using simulation only, the students cannot experience the value of originality and familiarity compare to handle it by themselves. Thus, the true objective of this experiment is not achieved. For recommendation, cobalt should be use as the source instead of copper to avoid fluorescence in the background.

REFERENCES 1. Mos, Y. M., Vermeulen, A. C., Buisman, C. N., & Weijma, J. (2017). X-Ray Diffraction of Iron Containing Samples: The Importance of a Suitable Configuration. Solid State Phenomena, 262, 545-548. doi:10.4028/www.scientific.net/ssp.262.545 2. X-Ray Diffraction. (n.d.). SpringerReference. doi:10.1007/springerreference_219033 3. Introduction to Materials Characterization[1]. (2019). Materials Characterization, 34. doi:10.31399/asm.hb.v10.a0006669 4. Kaufmann, E. N. (2012). Common Concepts in Materials Characterization, Introduction. Characterization of Materials. doi:10.1002/0471266965.com001.pub2 5. Bunaciu, Andrei A. & UdriŞTioiu, Elena & Aboul-Enein, Hassan. (2015). X-Ray Diffraction: Instrumentation and Applications. Critical reviews in analytical chemistry / CRC. 45. 10.1080/10408347.2014.949616....