In materials, the chemical composition doping or substitution (internal pressure) changes the physical properties. instead of doping and substitution, i want to apply a physical pressure (hydrostatic pressure) in parent compounds and I want to calculate the exact physical pressure where the physical properties changes, by calculation from doping amount and substitution, is it possible to calculate the physical pressure.
Yes, it is possible. I think there are at least two ways.
Way one: one needs to write down a Hamiltonian to find out the ground state energy E of a parent compound. The space group and the lattice constant will be input parameters. By varying the lattice constant, one finds the volume V vs. E relation and convert it to V vs. P relation, i.e., bulk modulus.Then you start your synthesis by doping A2 into the A1 site and get the lattice constant information from X-ray. Assuming the doping is homogeneous and all bonds between A1 and its surrounding, and A2 and its surrounding, have the same force constants, you could take the bulk modulus from the parent compound and calculate the physical pressure.
Way two: assuming you replace 25% A1 by A2 and the doping is completely homogeneous, above calculation can be extended to a 4 times larger "cell", where A2 shows up in four different positions in each cell while other A sites are still occupied by A1. It is possible to directly calculate how much equivalent "hydrostatic pressure" is applied to the system.
To sum up, you could see how many assumptions I have made, and therefore the result is only within a qualitative level.
ok chien , thank you for your answer, i will look over and work it up.,
Dr.chien can you please refer some related paper. it will be help to further understanding for me
- Badges
- Science method