What is phase in material science

[Shriphysics]

What is 1111 phase in material science

Hi Guys,
I wonder if someone tells me about what are the rules for nomenclature of phases in materials.
Generally I read like 1111 phase, 122 family, 11 system. I don't understand completely about this. Does they talk about composition or something else?
for ex.- BaFe2As2 is 122 phase material, LaFeAsO is 1111 family compound.
Kindly guide me in any related context.

Thanks in advance.
Shriphysics

 

[Mapes]

Hi, Shriphysics, welcome to PF. Looks like just the relative molar amounts of each component, no? That is, LaFeAsO is 1111 because it's La₁Fe₁As₁O₁.

 

[Shriphysics]

Hi Mapes,
Thanks for reply...I was also thinking same but wanted to confirm from someone.
Anyway now I wonder if you know FeTe is 11 phase no problems about it, but when we prepare a composite Fe(1)Se(0.5)Te(0.5) then also we say it as 11 phase, why its not like 1 1/2 1/2 phase??

 

[Mapes]

I haven't worked with this particular material, but my best guess is that FeX is a binary compound between iron and X, and that selenium can substitute for tellurium in the crystal structure. From a crystal structure standpoint, therefore, things don't change much for FeTe_xSe_1-x as x varies from 1 to 0. But this is just my speculation.

 

[alphy]

Phase in material science refers to the physical state of a material at a certain temperature and pressure. This can include solid, liquid, gas, or even a combination of these states. In material science, the term "phase" is often used to describe the structural arrangement of atoms or molecules in a material.

The 1111 phase in material science refers to a specific type of crystal structure known as the tetragonal structure. This structure is characterized by a four-fold symmetry and is commonly found in materials such as iron-based superconductors. The numbers in the term refer to the ratio of elements in the material, in this case, one atom of La (lanthanum), one atom of Fe (iron), one atom of As (arsenic), and one atom of O (oxygen).

The nomenclature of phases in materials is based on the chemical composition and crystal structure of the material. This helps to identify and differentiate between different materials and their properties. For example, the 122 phase refers to a structure with two atoms of Ba (barium), two atoms of Fe (iron), and one atom of As (arsenic). Similarly, the 11 system refers to a material with one atom of Ba (barium) and one atom of Fe (iron).

I hope this helps to clarify the concept of phases in material science. If you have any further questions, please let me know.