LEARNING LOG 2: Observe‚ Connect and Reflect on Your Learning PART III – Symmetry in Crystals The most striking examples of symmetry…are crystals. Herman Weyl Period Focus Image Question Your Observations Complete at the end of Week 5 Image 5 Uvarovite is a gemstone rich in chromium. What are your main observations about uvarovite symmetry from studying the external form? (30 - 40 words) (2 marks) What is your personal favourite gemstone and what is its space group. (up to
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II. Crystal Structure A. Lattice‚ Basis‚ and the Unit Cell B. Common Crystal Structures C. Miller Indices for Crystal Directions and Planes D. The Reciprocal Lattice A. Lattice‚ Basis‚ and Unit Cell An ideal crystalline solid is an infinite repetition of identical structural units in space. The repeated unit may be a single atom or a group of atoms. An important concept: crystal structure = lattice + basis = + lattice: a periodic array of points in space. The environment surrounding
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APL102: Materials Science and Engineering Minor Test I 28th. Aug. 2014 Maximum Marks 60 1 Why do we not have an end-centred tetragonal lattice? Consider both the cases of end centring: (a) centring of opposite square faces of the unit cell and (b) centring of opposite rectangular faces of the unit cell. 12 2 Draw a plane in a BCC unit cell . Show your choice of origin and axes. Include in your drawing all the close packed directions lying in this plane and give their Miller indices
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Group B: Model Answer GROUP B MODEL ANSWER Yoshida et al.‚ Flexibility of Hydrogen Bond and Lowering of Symmetry in Proton Conductor‚ Symmetry 2012‚ 4‚ 507-516. DO NOT PLAGIARISE THIS MODEL ANSWER PLAGIARISM FROM ANY SOURCE AUTOMATICALLY LEADS TO A ZERO SCORE Paragraph 1 M3H(XO4)2 compounds are used for electrolytic fuel cells (where M=K‚ Rb ‚Cs; X=S‚ Se). At different temperatures‚ the compound exhibits different degrees of symmetry. There are 3 distinct phases observed. Below 369K
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GROUP B MODEL ANSWER Howard et al.‚ Temperature-induced structural changes in CaCl2‚ CaBr2 and CrCl2: A synchrotron X-ray powder diffraction Phys. Rev. B 72‚ 214114 (2005). DO NOT PLAGIARISE THIS MODEL ANSWER Paragraph 1 The polymorphs involved are the halides in tetragonal rutile (TiO2) structure and the halides in so-called calcium chloride structure. As the name implies‚ the unit cell of halides in tetragonal rutile structure is tetragonal‚ with the lattice parameters a=b≠c and α=β=γ=90o
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GROUP B MODEL ANSWER Yoshida et al.‚ Flexibility of Hydrogen Bond and Lowering of Symmetry in Proton Conductor‚ Symmetry 2012‚ 4‚ 507-516. DO NOT PLAGIARISE THIS MODEL ANSWER PLAGIARISM FROM ANY SOURCE AUTOMATICALLY LEADS TO A ZERO SCORE Paragraph 1 M3H(XO4)2 compounds are used for electrolytic fuel cells (where M=K‚ Rb ‚Cs; X=S‚ Se). At different temperatures‚ the compound exhibits different degrees of symmetry. There are 3 distinct phases observed. Below 369K‚ the phase 3 structure belongs
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TERMPAPER TOPIC:- imperfection in solid’s NAME:-MILAN RAJAWAT Regd. No.:-11004886 Section:-M2R16 Roll No.:-B16 Subjet:-MEC208 INTRODUCTION For a crystalline solid we have tacitly assumed that perfect order exists throughout the material on an atomic scale. However‚ such an idealized solid does not exist; all contain large numbers of various defects or imperfections. As a matter of fact‚ many of the properties of materials are profoundly sensitive to
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Preparation and Ferroelectric Characterization of Calcium doped Barium Titanate ceramics ABSTRACT Barium Titanate (BT) is widely used in electro-optical and electroceramic industry because of its ferroelectric‚ thermoelectric and piezoelectric properties when it assumes the tetragonal structure. In addition to its Lead free composition‚ its perovskite structure allows variation of ionic size and small displacement of atoms that lead to the distortion of the structure which has a profound
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Group A: Model Answer GROUP A MODEL ANSWER Haines et al.‚ A neutron diffraction study of quartz-type FePO4: high-temperature behavior and α-β phase transition Z. Kristallogr. 218‚ 193-200 (2003). DO NOT PLAGIARISE THIS MODEL ANSWER Paragraph 1 This research paper discussed about the structural evolution of FePO4 from temperature range of 294K to 1073K. The cell parameters and atomic coordinates in the α phase tend to wars the value obtained in the high-temperature β-phase and exhibit first order
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Hey I just met you‚ and this is crazy‚ but heres my number‚ so call me maybe. Pointless scores all the possible Laue groups consistent with the crystal class‚ which is based on cell dimension restraints. It does this by matching potential symmetry equivalent reflections. For chiral systems‚ the Laue group uniquely implies the point group. It then checks sets of reflections which may be systematically absent to suggest a possible spacegroup. There is also a check for lattice centering‚ ie a check
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