| 1. |
- Darakchieva, Vanya, et al.
(author)
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Lattice parameters, deviations from Vegards rule, and E-2 phonons in InAlN
- 2008
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 93:26, s. 261908-
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Journal article (peer-reviewed)abstract
- The lattice parameters of InxAl1-xN in the whole compositional range are studied using first-principle calculations. Deviations from Vegards rule are obtained via the bowing parameters, delta(a)=0.0412 +/- 0.0039 A and delta(c)=-0.060 +/- 0.010 A, which largely differ from previously reported values. Implications of the observed deviations from Vegards rule on the In content extracted from x-ray diffraction are discussed. We also combine these results with x-ray diffraction and Raman scattering studies on InxAl1-xN nanocolumns with 0.627 <= x <= 1 and determine the E-2 phonon frequencies versus In composition in the scarcely studied In-rich compositional range.
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| 2. |
- Mattesini, Maurizio, et al.
(author)
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Elastic properties and electrostructural correlations in ternary scandium-based cubic inverse perovskites : A first-principles study
- 2009
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 79, s. 125122-
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Journal article (peer-reviewed)abstract
- Wehave performed ab initio calculations for the cubic inverse-perovskite Sc3EN(E=Al,Ga,In) systems to study their electronic band-structures and elastic properties.In this study, we used the accurate augmented plane waveplus local orbital method to find the equilibrium structural parametersand to compute the full elastic tensors. The obtained single-crystalelastic constants were used to quantify the stiffness of theSc-based ternary nitrides and to appraise their mechanical stability. Thesite-projected density of states, Fermi surfaces, and the charge-density plotshave also been used to analyze the chemical bonding betweenthe Sc6N cluster and the surrounding metallic lattice of eitherAl, Ga, or In atoms. Our calculations show that Sc3GaNhas the largest covalent Sc-N bonding-type character with the highestYoung, shear, and bulk moduli. Compared with the other twoisoelectronic systems, it also behaves as the most brittle materialwith a relatively large elastic anisotropy.
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| 3. |
- Mikhaylushkin, Arkady, et al.
(author)
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Stability of the ternary perovskites Sc3EN (E=B,Al,Ga,In) from first principles
- 2009
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In: PHYSICAL REVIEW B. - 1098-0121. ; 79:13, s. 134107-
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Journal article (peer-reviewed)abstract
- Mechanical and thermodynamic stability of the isoelectronic ternary inverse perovskites Sc3EN (E=B,Al,Ga,In) has been studied from first principles. We confirm stability of recently synthesized cubic phases Sc3AlN and Sc3InN, and predict the stability of cubic Sc3GaN and a triclinic phase aP20-Sc3BN. Substantial phonon softening in Sc3AlN and Sc3GaN is observed indicating a possibility that structural defects could form readily. In accord, our experiments show that magnetron sputter deposited films contain regions with high density of nonperiodic stacking faults along the < 111 > growth direction. We suggest that defect-free crystals may exhibit anomalies in the carrier properties, promising for electronic applications.
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| 4. |
- Tasnadi, Ferenc, et al.
(author)
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Significant configurational dependence of the electromechanical coupling constant of B0.125Al 0.875 N
- 2009
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:15, s. 151911-
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Journal article (peer-reviewed)abstract
- Currently, AlN is the preferred material in electroacoustic applications but modern applications necessitate the synthesis of materials with a range of electroacoustic properties. Among the promising candidates are the wurtzite Boron-containing AlN alloys. In here we study theoretically some of the material properties of wurtzite B0.125Al0.875N. The results indicate that wurtzite B0.125Al0.875N exhibits a strong configurational dependence of the electromechanical coupling constant. It is further shown that the lattice parameters as well as the stiffness constants are less sensitive of the atomic configuration and comply well with the Vegard's rule.
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| 5. |
- Zhang, Hongbin, et al.
(author)
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Electric-field control of surface magnetic anisotropy : a density functional approach
- 2009
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In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 11:043007
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Journal article (peer-reviewed)abstract
- In a recent experiment, Weisheit et al ( 2007 Science 315 349) demonstrated that the coercivity of thin L1(0) FePt and FePd films can be modified by the external electric field in an electrochemical environment. Here, this observation is confirmed by density functional calculations for the intrinsic magnetic anisotropy. The origin of the effect is clarified by means of a general and simple method to simulate charged metal surfaces. It is predicted that the coercivity of thin CoPt films is much more susceptible to electric field than that of FePt films.
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