Part-6+(rev).+Unkowns+Ordering++Shape(2018)+CP.ppt

# 30 40 50 60 70 80 90 2 limited information taken by

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30        40         50         60          70         80         90   (2 ) Limited information • Taken by Cu-K  line • It is a single element metal   • It is a cubic crystal • It is shiny. • It is very reactive.  • Etc, etc  -------------  =1.54056 Å --------SC, BCC, FCC or Diamond ----------------------------means metallic, or semiconducting --------------------------------any other properties measurable              density, etc --------------------chemical property Reading Assignment:  Chapter 10  (P.295-302, 311-328) 1.  Read diffraction angle from each peak 2.   This quantity should become very similar  regardless (h k l)  if structure is properly assigned. Bragg s equation 2d hkl sin  =       2a h 2  + k 2  + l 2 sin  = sin 2 h 2  + k 2  + l 2  = 4a 2 2 = constant

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30        40       50       60        70       80       90 Taken by Cu-K  line  It is a single element metal   Cubic Shiny by very reactive Etc, etc  Diffraction equation 2d hkl sin = 2a h 2 + k 2 + l 2 sin = sin 2 h 2 + k 2 + l 2 = 4a 2 Constant                 SC         BCC                     FCC                   Diamond Peak    2 (˚)     (˚)     sin 2        (hkl)   2 /4a 2            (hkl)   /4a 2            (hkl)   /4a 2          (hkl)   /4a 2   1 2 3 4 5 6 36.3 52.0 64.8 76.6 87.8 98.8 18.15 26.6 32.4 38.5 43.9 49.4 0.09704 0.19217 0.28711 0.38413 0.48081 0.57649 (110) 0.04852 (200) 0.04804 (211) 0.04785 (220) 0.04802 (310) 0.04804 (222) 0.04804 (111) 0.03235 (200) 0.04804 (220) 0.03589 (311) 0.03492 (222) 0.04804 (400) 0.03603 (100) 0.09704 (110) 0.09609 (111) 0.09570 (200) 0.09603 (210) 0.09616 (211) 0.09608 (111) 0.03235 (220) 0.04804 (311) 0.02610 (400) 0.02401 (331) 0.02569 (110) (200) (211) (220) (310) (222) Calculate lattice constant      3.497 Å 3.574 Å 3.521 Å 3.515 Å 3.513 Å 3.574 Å __________________      Average 3.514 Å     Look at materials data/other information = Li        a(Li) = 3.5101 Å
Compute intensity   30        40       50       60        70       80       90

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=1.54056 Diffraction equation 2d hkl sin = 2a h 2 + k 2 + l 2 sin = sin 2 h 2 + k 2 + l 2 = 4a 2 2 S=h 2 +k 2 +l 2
Lattice F |F| 2 hkl SC f f 2 all BCC 0 0 h+k+l = odd number 2f 4f 2 h+k+l = even number FCC 0 0 h, k, l   mixed 4f 16f 2 h, k, l   unmixed NaCl 4(f Na  - f Cl )  16(f Na  - f Cl 2   h+k+l = odd number 4(f Na  + f Cl )  16(f Na  + f Cl 2   h+k+l = even number Diamond 0 0 h, k, l   mixed 4f(1- i ) 32f 2 h, k, l   unmixed   and  h+k+l = odd 0 0 h, k, l   unmixed   and (h+k+l)/2 = odd 8f 64f 2 h, k, l   unmixed   and (h+k+l)/2 = even Zinc-blende 0 0

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• Fall '12
• p
• Crystal system

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