How to calculate lattice parameters?

[nakamura25]

Dear Friends,

I read some articles about alloys. Most articles have a table listing lattice parameters (a,b,c-axis) and unit cell volumes. But they never explain how those data come from.

How do we get those data? By comparing XRD images with PDF databases? Or by calculation?

Example:
La(Ni3.8)Al(Mn0.2)
a = 5.0902 angstrom
b = 4.0812 angstrom
c = 0.8018 angstrom
v = 91.5765 cubic angstrom

Thank you in advance for your kindly answer!

 

[f95toli]

Usually via XRD.
It IS possible to calculate lattice parameters of some simple alloys, but values you find in tables are (nearly) always experimental data.

 

[nakamura25]

Usually via XRD.
It IS possible to calculate lattice parameters of some simple alloys, but values you find in tables are (nearly) always experimental data.

Thank you for answering!
Experimental Data?
Do you mean someone did experimental works and made them into databases (like jcpds cards)? And the article writers just quoted those data and made a table of it.

 

[Rajini]

Hi,
yes someone, technician, or a person who know how to work with a XRD...
The complete molecular structure can be obtained from crystal XRD provided your sample is crystalline (i exactly don't know how long will it take to make one experiment). By this method you get complete data, almost everything about the structure in internal coordinates and so on..

 

[nakamura25]

Hi,
yes someone, technician, or a person who know how to work with a XRD...
The complete molecular structure can be obtained from crystal XRD provided your sample is crystalline (i exactly don't know how long will it take to make one experiment). By this method you get complete data, almost everything about the structure in internal coordinates and so on..

Thanks! Now I understand how it is done.
Happy New Year!

 

[That was mine]

$${\cal L}_R = \sum_{i=1}^G \bar{E}^i_R(i\kern+0.1em /\kern-0.55em \partial - g_1Y_E \kern+0.1em /\kern-0.65em B)E^i_R + \bar{D}^i_R(i\kern+0.1em /\kern-0.65em D - g_1Y_D \kern+0.1em /\kern-0.65em B)D^i_R + \bar{U}^i_R(i\kern+0.15em /\kern-0.65em D - g_1Y_U \kern+0.1em /\kern-0.65em B)U^i_R$$

 

[That was mine]

Cool.

 

[nakamura25]

$${\cal L}_R = \sum_{i=1}^G \bar{E}^i_R(i\kern+0.1em /\kern-0.55em \partial - g_1Y_E \kern+0.1em /\kern-0.65em B)E^i_R + \bar{D}^i_R(i\kern+0.1em /\kern-0.65em D - g_1Y_D \kern+0.1em /\kern-0.65em B)D^i_R + \bar{U}^i_R(i\kern+0.15em /\kern-0.65em D - g_1Y_U \kern+0.1em /\kern-0.65em B)U^i_R$$

Do you have a website defining those parameters?
Thanks!

 

[phy.gelman]

Hi,
In our univesity we have X-Ray laboratory.They do such these things.By using inverse lattice and compering with experimental images you can find axis valuse.