EBB245 Material Characterisations Lecture 2. X-ray Diffraction Methods Dr Zainovia Lockman Lecture 2. X-ray Diffraction Methods Dr Zainovia Lockman 1

Contents of Lecture 1. Active learning and group work activities 2. Quantitative measurement by XRD 3. Diffraction Intensity 1. Active learning and group work activities 2. Quantitative measurement by XRD 3. Diffraction Intensity 2

1. ACTIVE LEARNING AND GROUP WORK ACTIVITIES 4

AL 1: In pairs, answer this question Given an unknown powders, write down the steps on how to identify what the powders are? 5

AL 2: Thin film phase determination Given a thin film with thickness of 1  m deposited on a single crystal silicon. The film is unknown. You are to find out the phase presents in the film by using XRD. Answer the following questions to help you identify the phase. 1. Sketch a configuration of Bragg-Brentano geometry. 2. Does this geometry suitable for thin film measurement? 3. If not then explain why not? 4. Suggest an arrangement which could be used to measure thin film? Given a thin film with thickness of 1  m deposited on a single crystal silicon. The film is unknown. You are to find out the phase presents in the film by using XRD. Answer the following questions to help you identify the phase. 1. Sketch a configuration of Bragg-Brentano geometry. 2. Does this geometry suitable for thin film measurement? 3. If not then explain why not? 4. Suggest an arrangement which could be used to measure thin film? 6

XRD of zirconia 7

Background knowledge. What is zirconia? Zirconia, ZrO 2 is an oxide of zirconium Zirconia is an important engineering ceramic Zirconia has 3 polymorphs: Monoclinic Tetragonal Cubic Monoclinic zirconia exists at room temperature Tetragonal and cubic are high temperature phase. Tetragonal and cubic phases can be stabilised at room temperature if zirconia is doped with yittria (Y 2 O 3 ) or ceria (CeO 2 ) Doping is a process when impurities are intentionally added to the material. When impurity like yittria is added to zirconia powder, the cubic zirconia can be achieved even at room temperature. Zirconia, ZrO 2 is an oxide of zirconium Zirconia is an important engineering ceramic Zirconia has 3 polymorphs: Monoclinic Tetragonal Cubic Monoclinic zirconia exists at room temperature Tetragonal and cubic are high temperature phase. Tetragonal and cubic phases can be stabilised at room temperature if zirconia is doped with yittria (Y 2 O 3 ) or ceria (CeO 2 ) Doping is a process when impurities are intentionally added to the material. When impurity like yittria is added to zirconia powder, the cubic zirconia can be achieved even at room temperature. 8

Polymorphs of Zirconia 9

10 This is a diffraction pattern of zirconia film on zirconium. Identify the polymorph. You are given the ICDD of monoclinic, tetragonal and cubic zirconia and also zirconium. 2  (deg) Intensity (a.u)

Name and formula Reference code: ICSD name:Zirconium Oxide Empirical formula:O 2 Zr Chemical formula:ZrO 2 Crystallographic parameters Crystal system:Monoclinic Space group:P21/c Space group number:14 a (Å): b (Å): c (Å): Alpha (°): Beta (°): Gamma (°): Calculated density (g/cm 3 ): 5.82 Volume of cell (10^ Z: 4.00 RIR: 3.52 Subfiles and Quality Subfiles:Inorganic Alloy, metal or intermetalic Corrosion Modelled additional pattern Quality:Calculated (C) Comments ICSD collection code: Test from ICSD:No R value given. References Primary reference:Calculated from ICSD using POWD-12++, (1997) Structure:Hann, R.E., Suitch, P.R., Pentecost, J.L., J. Am. Ceram. Soc., 68, 285, (1985) ICDD of Zirconia- monoclinic 11

Peak list No. h k l d [A] 2Theta[deg] I [%]

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2. Quantitative Measurement Quantitative measurement can be done to determine relative amount of compounds or phases in a sample of compound/phase mixtures The intensity of the diffraction peaks of a particular crystalline phase in a phase mixture depends on the weight fraction of the particular phase of the mixture. Thus, weights fraction can be gathered by measuring the intensities of the peaks assigned to a particular phase. Quantitative measurement can be done to determine relative amount of compounds or phases in a sample of compound/phase mixtures The intensity of the diffraction peaks of a particular crystalline phase in a phase mixture depends on the weight fraction of the particular phase of the mixture. Thus, weights fraction can be gathered by measuring the intensities of the peaks assigned to a particular phase. 16

3. Diffraction Intensity Recall that to produce XRD spectrum, diffraction conditions stated in Bragg’s Law must be satisfied However satisfying such conditions does not guarantee that we can detect or see diffraction from crystallographic planes because there is an issue of diffraction intensity Recall that to produce XRD spectrum, diffraction conditions stated in Bragg’s Law must be satisfied However satisfying such conditions does not guarantee that we can detect or see diffraction from crystallographic planes because there is an issue of diffraction intensity 17

What is XRD? What is it use for? Why is it an important tool in materials engineering? What are the limitations? 18