I need the density of this ferrite (m/V). Who has calculated it before or has a suggestion?
theoretical density is calculated as: no. of atoms of each type in a unit cell multiplied by their respective atomic weights (g/mol) divided by (unit cell volume (in cm3) into Avogadro's number )
Use a free program like PowderCell (ftp.bam.de) and generate a structure file which is quite easy using the data Volker proposed. Examples show how to do this, e.g.
CELL 8.4000 8.4000 8.4000 90.000 90.000 90.000
Fe 26 0.1250 0.1250 0.1250 0.5800
13 0.4200
Al 13 0.5000 0.5000 0.5000 0.3850
24 0.5950
22 0.0150
O O2- 0.2631 0.2631 0.2631
RGNR 227 2
You need the cell parameter in angstroem and degrees, followed by the atomic positions (Name (string considering the first 4 positions inclusing blanks), periodic number, x,y,z, SOF (site occupation factor).
Substitutions are written behind. No name is required and since the atomic positions are the same the next number describes SOF for the substituent given by the periodic number. For O no SOF is given what is intrepreted as 1 (i.e. 100%)
The last number behind the keyword RGNR is the space group number. The 2 means the seeting as described in the international Tables.
The given example describes a (Fe,Al,Cr,V)3 O4. All SOF of one position cannot be higher than 1 which means 100% occupied. The Al position in the example is only
occupied by 99.5%.
The software automatically calculates the X-ray density taking the atomic positions, substitutions, occupations and the lattie parameter into account.
Sorry, but in the example given before blanks disappeared for the substitutions. :-( There are at least 4 blanks required to mark that this is a susbtituion of the formerly defined position. However ftp.bam.de contains many examples where the principle becomes clear.
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