Investigation on Structural, Elastic, Electronic and Vibrational Properties of LiTiAl Half-Heusler Compound Using First Principles Methods

Yıl 2017, Cilt: 38 Sayı: 2, 312 - 320, 24.04.2017

Yeşim Moğulkoç Yasemin Öztekin Çiftçi

https://doi.org/10.17776/cumuscij.296598

Cited By: 2

Öz

Heusler
alloys are particularly noticeable in spintronics and thermoelectric
applications. The researches on new and better thermoelectric materials are
increasing rapidly due to the energy crisis and environmental pollution which
are frequently discussed in recent times. Thermoelectric materials are seen as
potential ways to solve these problems. Half-Heusler materials are considered
thermoelectric materials due to their large temperature stability. Typically, half-Heusler crystallizes in a face-centered cubic structure
with alloys  space group (No.216). In this study, the structural, elastic, electronic and vibrational
properties of the Li-based LiTiAl compound with 8 electrons in the primitive
cell were investigated using the VASP package program using the first
principles methods. The 700 eV cutoff energy and 15x15x15 k-points were used in
calculations. The lattice constant has been calculated as 6.191Å. The obtained
structural parameteres are convenient with the results of literature. Band structures, total and partial density
states graphs are drawn as electronic properties. From these calculations, the
band gap of this compound was found to be 9.55 meV. Elastic constants were
calculated from stress-strain rate. The calculated elastic constants show that
this compound is mechanically stable. Phonon frequencies are calculated and the
structure is found dynamically stable.

Anahtar Kelimeler

LiTiAl, Half-Heusler, Vibrational properties, DFT, GGA-PBE.

LiTiAl Yarı-Heusler Alaşımının Yapısal, Elastik, Elektronik ve Titreşimsel Özelliklerinin İlk İlkeler Yöntemleri Kullanılarak İncelenmesi

Öz

Heusler alaşımları özellikle spintronik ve
termoelektrik uygulamalarda önemli ölçüde dikkat çekmektedir. Son zamanlarda
sıklıkla tartışılan enerji krizi ve çevresel kirlilikten dolayı yeni ve daha
iyi termoelektrik malzemelerdeki araştırmalar hızla artmaktadır. Termoelektrik
malzemeler bu problemlerin çözümü için potansiyel yollardan biri olarak
görülmektedir. Yarı-Heusler malzemelerde büyük sıcaklık kararlılıklarından
dolayı termoelektrik malzemeler olarak düşünülmektedir. Tipik olarak
yarı-Heusler alaşımlar  uzay gruplu (No.216)
yüzey merkezli kübik yapıda kristallenir. Bu çalışmada ilkel hücresinde 8
elektrona sahip Li tabanlı LiTiAl bileşiğinin yapısal, elastik, elektronik ve
titreşimsel özellikleri ilk ilkesel yöntemler kullanan VASP paket programı
kullanılarak incelenmiştir. Hesaplamalarda 700 eV kesilim enerjisi ve 15x15x15
k-noktası kullanılmıştır. Örgü sabiti 6.191Å olarak hesaplanmıştır. Elde
edilen yapısal parametreler mevcut literatür sonuçları ile uyumludur.
Elektronik özellikler olarak band yapısı, toplam ve kısmi durum yoğunluğu
grafikleri çizilmiştir. Bu hesaplardan bu bileşiğin band aralığı 9.55 meV
olarak bulunmuştur. Elastik sabitleri zor-zorlanma oranından hesaplanmıştır.
Hesaplanan elastik sabitleri bu bileşiğin mekaniksel olarak kararlı olduğunu
göstermiştir. Fonon frekansları hesaplanmıştır ve yapı kararlı olarak
bulunmuştur. 

Anahtar Kelimeler

LiTiAl, Yarı-Heusler, Titreşimsel özellikler, DFT, GGA-PBE

Kaynakça

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