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Briddon, Patrick
Publications (3 of 3) Show all publications
Wagner, P., Ivanovskaya, V. V., Rayson, M., Briddon, P. & Ewels, C. P. (2013). Mechanical properties of nanosheets and nanotubes investigated using a new geometry independent volume definition (ed.). Paper presented at . Journal of Physics: Condensed Matter, 25(15), 155302
Open this publication in new window or tab >>Mechanical properties of nanosheets and nanotubes investigated using a new geometry independent volume definition
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2013 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, no 15, p. 155302-Article in journal (Refereed) Published
Abstract [en]

Cross-sectional area and volume become difficult to define as material dimensions approach the atomic scale. This limits the transferability of macroscopic concepts such as Young's modulus. We propose a new volume definition where the enclosed nanosheet or nanotube average electron density matches that of the parent layered bulk material. We calculate the Young's moduli for various nanosheets (including graphene, BN and MoS2) and nanotubes. Further implications of this new volume definition such as a Fermi level dependent Young's modulus and out-of-plane Poisson's ratio are shown.

National Category
Computational Mathematics
Research subject
Scientific Computing
Identifiers
urn:nbn:se:ltu:diva-12358 (URN)10.1088/0953-8984/25/15/155302 (DOI)000316622400006 ()2-s2.0-84875665752 (Scopus ID)b7bd0654-366e-4cd9-affb-91dd55a92e5f (Local ID)b7bd0654-366e-4cd9-affb-91dd55a92e5f (Archive number)b7bd0654-366e-4cd9-affb-91dd55a92e5f (OAI)
Note
Validerad; 2013; 20130322 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Camps, I., Coutinho, J., Mir, M., Rayson, M. & Briddon, P. (2012). Elastic and optical properties of Cu2ZnSn(SexS1 − x)4 alloys: density functional calculations (ed.). Paper presented at . Semiconductor Science and Technology, 27(11)
Open this publication in new window or tab >>Elastic and optical properties of Cu2ZnSn(SexS1 − x)4 alloys: density functional calculations
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2012 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 27, no 11Article in journal (Refereed) Published
Abstract [en]

Cu2ZnSn(S1 − xSex)4 (CZT(S, Se)) is emerging as a very credible alternative to CuIn1 − xGaxSe2 (CIGS) as the absorber layer for thin film solar cells. The former compound has the important advantage of using abundant Zn and Sn instead of the expensive In and Ga. A better understanding of the properties of CZT(S, Se) is being sought through experimental and theoretical means. Thus far, however, very little is known about the fundamental properties of the CZT(S, Se) alloys. In this work, theoretical studies on the structural, elastic, electronic and optical properties of CZT(S, Se) alloys through first-principles calculations are reported. We use a density functional code (aimpro), along with the Padé parametrization for the local density approximation to the exchange correlation potential. For the alloying calculations we employed 64 atom supercells (approximately cubic) with a 2 × 2 × 2 k-point sampling set. These supercells possess a total of 32 chalcogen species and the CZTSexS1 − x alloys are described by using the ordered alloy approximation. Accordingly, to create a perfectly diluted alloying host, the species type of the 32 chalcogen sites is selected randomly with uniform probability x and 1 − x for Se and S, respectively. Properties of alloys (structural, elastic, electronic and optical) are obtained by averaging the results of ten supercell configurations generated for each composition. For each configuration, lattice vectors and atomic positions were allowed to relax (although enforcing the tetragonal lattice type) and the Murnaghan equation of state was fitted to the total energy data. The results presented here permit a better understanding of the properties of the CZT(S, Se) alloys which in turn result in the design of more efficient solar cells.

National Category
Computational Mathematics
Research subject
Scientific Computing
Identifiers
urn:nbn:se:ltu:diva-9173 (URN)10.1088/0268-1242/27/11/115001 (DOI)000310447200001 ()2-s2.0-84868024307 (Scopus ID)7bce84d9-55ae-4cb9-842e-d7a735dee256 (Local ID)7bce84d9-55ae-4cb9-842e-d7a735dee256 (Archive number)7bce84d9-55ae-4cb9-842e-d7a735dee256 (OAI)
Note
Validerad; 2012; Bibliografisk uppgift: Art.no 115001; 20120927 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Jones, R., Briddon, P. & Öberg, S. (1992). First-principles theory of nitrogen aggregates in diamond (ed.). Paper presented at . Philosophical Magazine Letters, 66(2), 67-74
Open this publication in new window or tab >>First-principles theory of nitrogen aggregates in diamond
1992 (English)In: Philosophical Magazine Letters, ISSN 0950-0839, E-ISSN 1362-3036, Vol. 66, no 2, p. 67-74Article in journal (Refereed) Published
Abstract [en]

Local-density-functional theory is used to evaluate the structure, vibrational bands and electronic properties of two point defects in diamond a pair of adjacent substitutional N atoms and a vacancy surrounded by four N atoms. These defects are important as they are possible models of the A and B centres seen in type Ia diamond. For the A centre we find a N─N bond length of 2·14 Å, an occupied electronic energy level near midgap and four infrared absorption bands with frequencies close to the experimental values. For the model of the B centre we find a N─C length of 1·49 Å an occupied triplet electronic level within the gap consistent with the recent suggestion that the N9 absorption band is due to this defect and again vibratory modes in close agreement with experiment. These results provide strong evidence as to the validity of the models for the A and B centres.

National Category
Computational Mathematics
Research subject
Scientific Computing
Identifiers
urn:nbn:se:ltu:diva-13149 (URN)10.1080/09500839208214688 (DOI)A1992JG01500003 ()c5411bcf-ee8b-4795-be67-063371f48c6b (Local ID)c5411bcf-ee8b-4795-be67-063371f48c6b (Archive number)c5411bcf-ee8b-4795-be67-063371f48c6b (OAI)
Note
Godkänd; 1992; 20130109 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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