Menu

 Nawras Sabhan Mohammed

Title

Compton Profile of some specific crystal structure materials

A Thesis byرسالة ماجستير Compton Profile of some specific crystal structure materials

Nawras Sabhan Mohammed

Under the Supervision of

Prof.Dr. Fareed Majeed Mohammed

Asst. prof.Dr.Najat Ahmed Daham

The purpose of this study

The present study is devoted to calculate the Compton profile and investigate the electronic structure for two elements of 3d-transitions metals namely [Ti and Ni] on which we use the RFA and FE models and also compute the values of their alloy Ti-Ni by using the Super Position Model and compare their results with the other available experimental studies.

Abstract:

The inelastic Compton scattering is considered as a powerful tool and very sensitive probe to investigate the electronic structure of different materials namely transition metals, alloys and compound, hence the Compton profile is sensitive to the valence electrons of atoms. The measured Compton profile provides an information about the electron momentum in the sample which is the projection of the electron momentum density on the direction of the scattering vector. The Compton effect was discovered by Sir A. H. Compton in 1923. For thisرسالة ماجستير Compton Profile of some specific crystal structure materials anomalous discovery, Compton was honored by Noble prize in 1927. At that time, Compton's effect was very important to the scientific community because it proved that x or -rays can act not only as waves but also as particles.

Calculations:

Part I(Ti,Ni):

1-Compton profiles of (Ti-bcc,fcc and Ni-fcc)have been calculated by

a.RFA(Renormalized Free Atom) model.

b. Free Electron model.

2- Measured theoretical results have been compared with available experimental data and there was a good agreement between them .

3- The cohesive energy for (Ti. Ni)have been computed and compared with experimental value .

Part II (Ti-Ni alloys):

1-The Compton profiles for alloys(Ti0.74-Ni0.26 and Ti0.65-Ni0.35 )were computed using the superposition model and the theoretical results where compared with the available experimental data and also there was a good agreement between them .

2-For the available data for Free Atom and Free Electron for Ti and Ni and for the sake of comparison we compute the Compton profile for their alloys using the superposition model with the two Invars for each one, and compared their results with the available experimental data .

Conclusion:

— Ti:In this work comparison were made between our theoretical values with the available theoretical and experimental results [17,18].The RFA model shows good agreement with the experiment in the (3d3-4s1) configuration, but Compton profiles values by using free electron model are higher those of experimental. Evidently. The calculated values for cohesive energy by applying RFA model are almost very close to the values given.

— Ni : The calculated theoretical (RFA) values have been compared with the experimental results. The RFA model shows good agreement with the experiment in the (3d8.8-4s1.2) configuration, but Compton profiles value using free electron model higher than of experimental.

— Ti-Ni:In this work we have studied the Compton profiles of the two alloys. Our measurements on metals agree very well with previous experimentaly results and with superposition calculations. The RFA and FE models also predicts reasonably well the overall nature of Compton profiles .In the case of Ti0.74-Ni0.26 and Ti0.35-Ni0.65 the measurement is reproduced very well in term of the superposition model.

— Suggestions

1-A study can be carried out to calculate Compton profiles of (bcc-Ti) by using (APW).

2-A study can be carried out to calculate Compton profiles of (fcc-Ni) by using (APW).

3-From the overall study we wish to suggest that more a refined and precise calculation based on band structure methods is essential to study the electronic structure of fcc-Ti.

—

Go to top