TY  - JOUR
AU  - Ribić, Vesna
AU  - Recnik, Aleksander
AU  - Drazic, Goran
AU  - Podlogar, Matejka
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2021
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1471
AB  - In our recent study (Ribie et al. 2020) we reported the structure of inversion boundaries (IBs) in Sb2O3 -doped ZnO. Here, we focus on IBs that form in SnO2-doped ZnO. Using atomic resolution scanning transmission electron microscopy (STEM) methods we confirm that in SnO2-doped ZnO the IBs form in head-to-head configuration, where ZnO4 tetrahedra in both ZnO domains point towards the IB plane composed of a close packed layer of octahedrally coordinated Sn and Zn atoms. The in-plane composition is driven by the local charge balance, following Pauling's principle of electroneutrality for ionic crystals, according to which the average oxidation state of cations is 3+. To satisfy this condition, the cation ratio in the IB-layer is Sn4+ : Zn2+ =1:1. This was confirmed by concentric electron probe analysis employing energy dispersive spectroscopy (EDS) showing that Sn atoms occupy 0.504 +/- 0.039 of the IB layer, while the rest of the octahedral sites are occupied by Zn. IBs in SnO2-doped ZnO occur in the lowest energy, IB3 translation state with the cation sublattice expansion of Delta IB(zn-zn) of +91 pm with corresponding O-sublattice contraction Delta IB(O-O) of -46 pm. Based on quantitative HRTEM and HAADF-STEM analysis of in-plane ordering of Sn and Zn atoms, we identified two types of short-range distributions, (i) zigzag and (ii) stripe. Our density functional theory (DFT) calculations showed that the energy difference between the two arrangements is small (similar to 6 meV) giving rise to their alternation within the octahedral IB layer. As a result, cation ordering intermittently changes its type and the direction to maximize intrinsic entropy of the IB layer driven by the in-plane electroneutrality and 6-fold symmetry restrictions. A long-range in-plane disorder, as shown by our work would enhance quantum well effect to phonon scattering, while Zn2+ located in the IB octahedral sites, would modify the the bandgap, and enhance the in-plane conductivity and concentration of carriers.
PB  - Međunarodni Institut za nauku o sinterovanju, Beograd
T2  - Science of Sintering
T1  - TEM and DFT Study of Basal-plane Inversion Boundaries in SnO2-doped ZnO
EP  - 252
IS  - 2
SP  - 237
VL  - 53
DO  - 10.2298/SOS2102237R
ER  - 

@article{
author = "Ribić, Vesna and Recnik, Aleksander and Drazic, Goran and Podlogar, Matejka and Branković, Zorica and Branković, Goran",
year = "2021",
abstract = "In our recent study (Ribie et al. 2020) we reported the structure of inversion boundaries (IBs) in Sb2O3 -doped ZnO. Here, we focus on IBs that form in SnO2-doped ZnO. Using atomic resolution scanning transmission electron microscopy (STEM) methods we confirm that in SnO2-doped ZnO the IBs form in head-to-head configuration, where ZnO4 tetrahedra in both ZnO domains point towards the IB plane composed of a close packed layer of octahedrally coordinated Sn and Zn atoms. The in-plane composition is driven by the local charge balance, following Pauling's principle of electroneutrality for ionic crystals, according to which the average oxidation state of cations is 3+. To satisfy this condition, the cation ratio in the IB-layer is Sn4+ : Zn2+ =1:1. This was confirmed by concentric electron probe analysis employing energy dispersive spectroscopy (EDS) showing that Sn atoms occupy 0.504 +/- 0.039 of the IB layer, while the rest of the octahedral sites are occupied by Zn. IBs in SnO2-doped ZnO occur in the lowest energy, IB3 translation state with the cation sublattice expansion of Delta IB(zn-zn) of +91 pm with corresponding O-sublattice contraction Delta IB(O-O) of -46 pm. Based on quantitative HRTEM and HAADF-STEM analysis of in-plane ordering of Sn and Zn atoms, we identified two types of short-range distributions, (i) zigzag and (ii) stripe. Our density functional theory (DFT) calculations showed that the energy difference between the two arrangements is small (similar to 6 meV) giving rise to their alternation within the octahedral IB layer. As a result, cation ordering intermittently changes its type and the direction to maximize intrinsic entropy of the IB layer driven by the in-plane electroneutrality and 6-fold symmetry restrictions. A long-range in-plane disorder, as shown by our work would enhance quantum well effect to phonon scattering, while Zn2+ located in the IB octahedral sites, would modify the the bandgap, and enhance the in-plane conductivity and concentration of carriers.",
publisher = "Međunarodni Institut za nauku o sinterovanju, Beograd",
journal = "Science of Sintering",
title = "TEM and DFT Study of Basal-plane Inversion Boundaries in SnO2-doped ZnO",
pages = "252-237",
number = "2",
volume = "53",
doi = "10.2298/SOS2102237R"
}

Ribić, V., Recnik, A., Drazic, G., Podlogar, M., Branković, Z.,& Branković, G.. (2021). TEM and DFT Study of Basal-plane Inversion Boundaries in SnO2-doped ZnO. in Science of Sintering
Međunarodni Institut za nauku o sinterovanju, Beograd., 53(2), 237-252.
https://doi.org/10.2298/SOS2102237R

Ribić V, Recnik A, Drazic G, Podlogar M, Branković Z, Branković G. TEM and DFT Study of Basal-plane Inversion Boundaries in SnO2-doped ZnO. in Science of Sintering. 2021;53(2):237-252.
doi:10.2298/SOS2102237R .

Ribić, Vesna, Recnik, Aleksander, Drazic, Goran, Podlogar, Matejka, Branković, Zorica, Branković, Goran, "TEM and DFT Study of Basal-plane Inversion Boundaries in SnO2-doped ZnO" in Science of Sintering, 53, no. 2 (2021):237-252,
https://doi.org/10.2298/SOS2102237R . .

TY  - JOUR
AU  - Ribić, Vesna
AU  - Recnik, Aleksander
AU  - Komelj, Matej
AU  - Kokalj, Anton
AU  - Branković, Zorica
AU  - Zlatović, Mario
AU  - Branković, Goran
PY  - 2020
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1376
AB  - Today, ab-initio calculations are becoming a powerful tool to perform virtual experiments that have the capacity to predict and to reproduce experimentally observed non-periodic features, such as interfaces, that are responsible for quantum properties of materials. In our paper we investigate 2D quantum-well structures, known as inversion boundaries OM. Combining atomistic modeling, DFT calculations and HRTEM analysis we provide a new fundamental insight into the structure and stability of Sb-rich basal-plane IBs in ZnO. DFT screening for potential IB model was based on the known stacking deviations in originating wurtzite structure. The results show that the model with A beta-B alpha-A beta C-gamma B-beta C sequence (IB3) is the most stable translation for Sb-doping, as opposed to previously accepted A beta-B alpha-A beta C-gamma A-alpha C (IB2) model. The key to the stability of IB structures has been found to lie in their cationic stacking. We show that the energies of constituting stacking segments can be used to predict the stability of new IB structures without the need of further ab-initio calculations. DFT optimized models of IBs accurately predict the experimentally observed IB structures with lateral relaxations down to a precision of similar to 1 pm. The newly determined cation sublattice expansions for experimentally confirmed IB2 and IB3 models, Delta(IB(zn-zn)) are +81 pm and +77 pm, whereas the corresponding O-sublattice contractions Delta(IB(0-0)) are -53 pm and -57 pm, respectively. The refined structures will help to solve open questions related to their role in electron transport, phonon scattering, p-type conductivity, affinity of dopants to generate IBs and the underlying formation mechanisms, whereas the excellent match between the calculations and experiment demonstrated in our study opens new perspectives for prediction of such properties from first principles.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Acta Materialia
T1  - New inversion boundary structure in Sb-doped ZnO predicted by DFT calculations and confirmed by experimental HRTEM
EP  - 648
SP  - 633
VL  - 199
DO  - 10.1016/j.actamat.2020.08.035
ER  - 

@article{
author = "Ribić, Vesna and Recnik, Aleksander and Komelj, Matej and Kokalj, Anton and Branković, Zorica and Zlatović, Mario and Branković, Goran",
year = "2020",
abstract = "Today, ab-initio calculations are becoming a powerful tool to perform virtual experiments that have the capacity to predict and to reproduce experimentally observed non-periodic features, such as interfaces, that are responsible for quantum properties of materials. In our paper we investigate 2D quantum-well structures, known as inversion boundaries OM. Combining atomistic modeling, DFT calculations and HRTEM analysis we provide a new fundamental insight into the structure and stability of Sb-rich basal-plane IBs in ZnO. DFT screening for potential IB model was based on the known stacking deviations in originating wurtzite structure. The results show that the model with A beta-B alpha-A beta C-gamma B-beta C sequence (IB3) is the most stable translation for Sb-doping, as opposed to previously accepted A beta-B alpha-A beta C-gamma A-alpha C (IB2) model. The key to the stability of IB structures has been found to lie in their cationic stacking. We show that the energies of constituting stacking segments can be used to predict the stability of new IB structures without the need of further ab-initio calculations. DFT optimized models of IBs accurately predict the experimentally observed IB structures with lateral relaxations down to a precision of similar to 1 pm. The newly determined cation sublattice expansions for experimentally confirmed IB2 and IB3 models, Delta(IB(zn-zn)) are +81 pm and +77 pm, whereas the corresponding O-sublattice contractions Delta(IB(0-0)) are -53 pm and -57 pm, respectively. The refined structures will help to solve open questions related to their role in electron transport, phonon scattering, p-type conductivity, affinity of dopants to generate IBs and the underlying formation mechanisms, whereas the excellent match between the calculations and experiment demonstrated in our study opens new perspectives for prediction of such properties from first principles.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Acta Materialia",
title = "New inversion boundary structure in Sb-doped ZnO predicted by DFT calculations and confirmed by experimental HRTEM",
pages = "648-633",
volume = "199",
doi = "10.1016/j.actamat.2020.08.035"
}

Ribić, V., Recnik, A., Komelj, M., Kokalj, A., Branković, Z., Zlatović, M.,& Branković, G.. (2020). New inversion boundary structure in Sb-doped ZnO predicted by DFT calculations and confirmed by experimental HRTEM. in Acta Materialia
Pergamon-Elsevier Science Ltd, Oxford., 199, 633-648.
https://doi.org/10.1016/j.actamat.2020.08.035

Ribić V, Recnik A, Komelj M, Kokalj A, Branković Z, Zlatović M, Branković G. New inversion boundary structure in Sb-doped ZnO predicted by DFT calculations and confirmed by experimental HRTEM. in Acta Materialia. 2020;199:633-648.
doi:10.1016/j.actamat.2020.08.035 .

Ribić, Vesna, Recnik, Aleksander, Komelj, Matej, Kokalj, Anton, Branković, Zorica, Zlatović, Mario, Branković, Goran, "New inversion boundary structure in Sb-doped ZnO predicted by DFT calculations and confirmed by experimental HRTEM" in Acta Materialia, 199 (2020):633-648,
https://doi.org/10.1016/j.actamat.2020.08.035 . .