[Lab 2] X-Ray Diffraction1. PurposeX-Ray Diffraction (XRD) is a method in materials science used to determine the atomic and molecular structure of a crystal, as the beam of incident X-rays diffract in many directions due to the crystalline structure of the material. The purpose of this experiment is to obtain an understanding of the characteristics and the principle of Bragg’s law, observe the relationship between Bragg’s law and the lattice structures and get to learn how to operate the XRD equipment. In order to accurately find out the information on the unknown two samples provided for this experiment, the peak values found from the JCPDS card were analyzed.2. TheoryWhen X-rays are irradiated to crystals, some of them undergo diffraction, and their diffraction angles and intensities are unique for each substance. The components of the unknown arbitrary sample can be identified by comparing its diffraction patterns with diffraction patterns obtained from a known material. Therefore, lights are parallel to each other and the optical path difference between the rays is exactly 1λ, 2λ, 3λ, and so on. That is, the optical path difference must be nλ, and n must be an integer. Among the rays scattered by A and B, only the rays that satisfy these conditions are those shown in Figure 1 as I and II.The first condition that I and II should satisfy, their common scattering angle should be equal to the angle of incidence θ (incident angle = reflection angle), and the second condition is nλ=2dsinθ, where n = 1, 2, 3, … and so on.Data obtained through X-ray diffraction experiments can be used to know what an unknown sample is. This data can be compared with data from already known substances to determine which substances are contained in the sample. This method is called qualitative analysis using XRD. Point Commission on Powder Diffraction Standards (JCPDS) cards are mainly used as data on already known materials. The JCPDS is a file that collects and classifies diffraction dto the base of the stage. Then, the instrument software was installed, and the scanning options were set up with two-theta scan range in degrees, step size, number of steps per scan, and time per step. After scanning the samples, the x-ray intensities were plotted against the two-theta angle. With the results, the FWHM values were calculated, angles were converted to d-spacing using the Bragg equation, and the XRD data was compared for both data.4. Results & Analysis XRD Pattern of Raw Data 1 XRD Pattern of Sample 2 Full Width at Half the Maximum (FWHM) values for Sample 22θMaxHalfx1x2FWHM(x2-x1)Peak 114.651441569784.514.5714.710.14Peak 228.4442644622328.3628.560.2Peak 332.116924412231.9832.320.34Peak 434.3987493.534.2134.40.19Peak 537.40143275137.537.3137.580.27Peak 644.82833225112.544.745.020.32Peak 748.9702532016048.8949.130.24Peak 851.765541427151.6452.030.39Peak 960.620691587960.5460.730.19Peak 1061.436841226161.361.680.38Peak 1162.9058913366.562.8263.130.31 Calculated values usin0.6206930.310350.198.452858Peak 1061.4368430.718420.384.244208Peak 1162.9058931.452950.315.242945Average crystallite size = 6.124 nmAs seen in graph 1, it can be observed that the X-ray diffraction pattern does not have noticeable peaks. The ranges of the intensities for this material only varies throughout the values of approximately 20 to 100. From this, we can presume that the raw data from the first sample is an amorphous material.According to graph 2, it is obvious that the raw data from sample 2 is a crystalline material as it has a total of 11 peaks. However, the 2θ of 32.1169, 37.40143, 51.80635, 61.41643, and 62.90589 did not have a full width at half the maximum (FWHM) value. Thus, these values were excluded from the peaks, and the calculated FWHM values is shown in table 1. In table 2, the distance between the crystal planes were calculated using the Bragg’s law . The wavelength was given as 1.54056 Å (Cu).In graph 2, compared to the JCPDS card provided for this experiment, d to be 6.124 nm.5. ConclusionThe goal of this experiment was to obtain knowledge upon how X-ray diffraction is used to identify whether the sample material is crystalline or non-crystalline and determine the size and structure of the material when it is crystalline. In this experiment, the data of the given unknown data was compared with the JCPDS card to find out the information of the unknown samples. Calculations of the wavelength, angle, and interplanar distance of the given graph using the Bragg's law were done, and the crystallite sizes were also computed using the Scherrer’s equation for each peak.From the analyses above, it can be concluded that the raw data for sample 1 was an amorphous material due to the small range of values in the arbitrary intensities. On the other hand, the raw data for sample 2 showed several peaks throughout the whole diffraction pattern, which means that the material is crystalline. The results were very similar to the JCPDS card of provided, but the
Title: Recrystallization and FiltrationPurpose: The purpose of this lab is to separate and refine two substances with similar solubility using acid and base properties.Theory: Recrystallization is a method of purifying crystalline substances using the differences in solubilities, as the solution may contain undesired impurities. In other words, if the solids are heated to a suitable solvent and cooled down slowly, the solubility of the solution is generally reduced and extract crystals.
X-ray Diffraction Report (X-선 회절 실험 레포트)
