Material Chemistry 2004. 3.31
1.TiO2 in rutile structural type belongs to a tetragonal crystal system with
a=5.0;c=3.0A. Ti atoms are located at (0 0 0) and (1/2 1/2 1/2); O atoms
are located at +-(x x 0) and +-(1/2+x 1/2-x 1/2), where x=0.3.
a) How many Ti and O atoms in the cell?
b) What are the coordination number of Ti and O atoms respectively?
c) Locate all neighbor O atoms around Ti and describe the coordination
geometry including bond lengths and angles around Ti.
d) Calculate the density of the crystal, atomic weight: Ti 48, O 16 g.
2.Bragg equation:2dsinq = nl (q為thita l為landa 打不出來) is the basic theory
for understanding the x-ray diffraction; illustrate how it works and what
are the conditions for this equation to be applied?
3.What are Miller indices (h k l) stand for? Powder pattern of a face centered
cubic gives rise only all even or all odd (h k l); what do you expect for
the first 10 lines in terms of (h k l); what is the largest d spacing (in
term of cell length of aA) observed in this case?
4.What are the K-;L-;M-edge absorption of an atom standing for? What are L1,
L2,L3 respectively? Can you use these data to identify the elements in the
material?
5.Compare the advantage and disadvantage of XRD and EXAFS techniques on the
line of geometric information.
6.Describe the pi bonds of one dimensional array consist of p-p and d-d
orbitals; indicating 2,3,4,5,6 centered then extending to a infinite chain
with an equal distance of aA between the center. Try the same with delta
bonds with d-d orbitals, do delta bonds behave the same as pi bonds in terms
of energy band?
7.Explain the bonding character of [PtH4 2-] chain between -14 to -10 eV
according to energy band and DOS given below.(有給你兩張圖)
8.Briefly describe the phenomenon of the hysteresis loop of the magnetization.
Based on this loop, explain which type of material is good for magnetic
memory device and which one is good for motor or transformer cores.
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