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 . .

TY  - CONF
AU  - Ribić, Vesna
AU  - Rečnik, Aleksander
AU  - Kokalj, Anton
AU  - Dražić, Goran
AU  - Podlogar, Matejka
AU  - Daneu, Nina
AU  - Komelj, Matej
AU  - Luković Golić, Danijela
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2018
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2434
AB  - Zinc oxide is an important semiconducting material that finds wide ranging applications. There has been considerable interest in ZnO as a low cost, non-toxic and highly stable thermoelectric. In order to enhance its properties for these purposes it is frequently doped with other compounds, usually oxides. Special impact on the improvement of TE properties in doped ZnO have planar defects. So far it  is well known that certain dopants trigger formation of inversion boundary (IB) in wurtzite structure of ZnO. These planar defects are interesting because they affect material properties and morphology of grains. In our study we investigated structure and chemistry of basal plane inversion boundaries in polycrystalline ZnO using conventional transmission electron microscopy and high-resolution electron microscopy. Based on HRTEM images we reconstructed models of IBs that are formed in addition of In, Sn and Sb as dopants. IBs can also be found in pyramidal planes and can be classified as head-to-head (→│←) or tail-to-tail (←│→) configuration depending on the orientation of the polar c-axis. By defining the zinc planes as A, B, or C and the oxygen planes as α, β or γ the perfect ZnO crystal structure has the AαBβAαBβ stacking sequence. Translation obtained from images is compared with three different, so far known, types of the head-to-head IB translations with octahedral coordination of cations at IB-plane: (i) IB with βγβγ׀α׀βαβα stacking of the cation sublattice, as observed with Sb doping1, (ii) IB with αγαγ׀α׀βαβα, as observed with In, Fe and Sn2 doping and (iii) IB with βαβα׀γ׀βαβα as observed with Mn3 doping (Figure 1). The generated models were examined in terms of stability by DFT calculations implemented in the Quantum-Espresso package.
PB  - Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade Hydrogen Economy Initiative Serbia, Belgrade, Belgrade, Serbia
C3  - PROGRAMME AND THE BOOK OF ABSTRACTS / 3rd International Symposium on Materials for Energy Storage and Conversion - mESC-IS 2018
T1  - Structural characterization of Inversion Boundaries in Doped ZnO
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2434
ER  - 

@conference{
author = "Ribić, Vesna and Rečnik, Aleksander and Kokalj, Anton and Dražić, Goran and Podlogar, Matejka and Daneu, Nina and Komelj, Matej and Luković Golić, Danijela and Branković, Zorica and Branković, Goran",
year = "2018",
abstract = "Zinc oxide is an important semiconducting material that finds wide ranging applications. There has been considerable interest in ZnO as a low cost, non-toxic and highly stable thermoelectric. In order to enhance its properties for these purposes it is frequently doped with other compounds, usually oxides. Special impact on the improvement of TE properties in doped ZnO have planar defects. So far it  is well known that certain dopants trigger formation of inversion boundary (IB) in wurtzite structure of ZnO. These planar defects are interesting because they affect material properties and morphology of grains. In our study we investigated structure and chemistry of basal plane inversion boundaries in polycrystalline ZnO using conventional transmission electron microscopy and high-resolution electron microscopy. Based on HRTEM images we reconstructed models of IBs that are formed in addition of In, Sn and Sb as dopants. IBs can also be found in pyramidal planes and can be classified as head-to-head (→│←) or tail-to-tail (←│→) configuration depending on the orientation of the polar c-axis. By defining the zinc planes as A, B, or C and the oxygen planes as α, β or γ the perfect ZnO crystal structure has the AαBβAαBβ stacking sequence. Translation obtained from images is compared with three different, so far known, types of the head-to-head IB translations with octahedral coordination of cations at IB-plane: (i) IB with βγβγ׀α׀βαβα stacking of the cation sublattice, as observed with Sb doping1, (ii) IB with αγαγ׀α׀βαβα, as observed with In, Fe and Sn2 doping and (iii) IB with βαβα׀γ׀βαβα as observed with Mn3 doping (Figure 1). The generated models were examined in terms of stability by DFT calculations implemented in the Quantum-Espresso package.",
publisher = "Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade Hydrogen Economy Initiative Serbia, Belgrade, Belgrade, Serbia",
journal = "PROGRAMME AND THE BOOK OF ABSTRACTS / 3rd International Symposium on Materials for Energy Storage and Conversion - mESC-IS 2018",
title = "Structural characterization of Inversion Boundaries in Doped ZnO",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2434"
}

Ribić, V., Rečnik, A., Kokalj, A., Dražić, G., Podlogar, M., Daneu, N., Komelj, M., Luković Golić, D., Branković, Z.,& Branković, G.. (2018). Structural characterization of Inversion Boundaries in Doped ZnO. in PROGRAMME AND THE BOOK OF ABSTRACTS / 3rd International Symposium on Materials for Energy Storage and Conversion - mESC-IS 2018
Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade Hydrogen Economy Initiative Serbia, Belgrade, Belgrade, Serbia..
https://hdl.handle.net/21.15107/rcub_rimsi_2434

Ribić V, Rečnik A, Kokalj A, Dražić G, Podlogar M, Daneu N, Komelj M, Luković Golić D, Branković Z, Branković G. Structural characterization of Inversion Boundaries in Doped ZnO. in PROGRAMME AND THE BOOK OF ABSTRACTS / 3rd International Symposium on Materials for Energy Storage and Conversion - mESC-IS 2018. 2018;.
https://hdl.handle.net/21.15107/rcub_rimsi_2434 .

Ribić, Vesna, Rečnik, Aleksander, Kokalj, Anton, Dražić, Goran, Podlogar, Matejka, Daneu, Nina, Komelj, Matej, Luković Golić, Danijela, Branković, Zorica, Branković, Goran, "Structural characterization of Inversion Boundaries in Doped ZnO" in PROGRAMME AND THE BOOK OF ABSTRACTS / 3rd International Symposium on Materials for Energy Storage and Conversion - mESC-IS 2018 (2018),
https://hdl.handle.net/21.15107/rcub_rimsi_2434 .

TY  - CONF
AU  - Ribić, Vesna
AU  - Rečnik, Aleksander
AU  - Dražić, Goran
AU  - Komelj, Matej
AU  - kokalj, Anton
AU  - Podlogar, Matejka
AU  - Daneu, Nina
AU  - Bernik, Slavko
AU  - Radošević, Tina
AU  - Luković Golić, Danijela
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2017
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2463
AB  - Various dopants are known to produce inversion boundaries (IBs) in ZnO, causing polarity inversion across the interface. These are found either in basal or pyramidal planes and can be of head-to-head or tail-to-tail configuration with respect to the orientation of the polar c-axis. The dopants, known to produce IBs in ZnO are: In2O3, Fe2O3, Mn2O3, Ga2O3, SiO2, SnO2, TiO2 and Sb2O3. While some of IBs have been studied in detail, many IB structures remain unresolved. In our study we investigated structure and chemistry of basal plane inversion boundaries in SnO2-doped ZnO. The formation of IBs in this system was first reported by Daneu et al. (2000)1 and using high-resolution transmission electron microscopy the same group attempted to solve structure and chemistry of Sn-rich IBs.2 Implementing an innovative analytical approach based on acquiring multiple EDS spectra with concentric electron probes they showed that Sn4+ ions do not occupy the full IB layer, but rather one half of the layer. This suggested an average oxidation state of III+ for the cations comprising the IB plane. Based on electron micro-diffraction and HRTEM study Daneu et al.1,2 reported that Sn-rich IBs are head-to-head oriented with interfacial cations located in trigonal prismatic sites, however, the exact atomic arrangement of Sn along IB has not been determined. To identify the translation state and atomic arrangement on Sn-rich IBs in ZnO we performed quantitative HRTEM and HAADF-STEM analysis of SnO2-doped ZnO/Bi2O3 ceramics. IBs in ZnO grains were observed for two low-index orientations, [100] and [120], to obtain a 3D information on the translation state of the IB plane. The coordination site of interfacial cations was shown to be octahedral.
472
Translation obtained from images is compared with three different, so far known, types of the head-to-head IB translations with octahedral coordination of cations at IB-plane: (i) IB with stacking of the cation sublattice, as observed with Sb doping, (ii) IB with, as observed with In and Fe doping and (iii) IB with as observed with Mn doping. For Sn-doped ZnO translations turned out to be (ii) , the same as the one occurring in In- and Fe-doped ZnO. Based on experimental observations of local atomic arrangement, HRTEM and HAADF-STEM image simulations were performed for two different in-plane distributions of Sn and Zn atoms, to better understand experimental image contrast on IBs. The generated models will be further used for ab-initio calculations aimed at determining the electronic structure of IBs.
PB  - Ruđer Bošković Institute and Croatian Microscopy Society, Rovinj (Croatia)
C3  - 13th Multinational Congress on Microscopy, Rovinj, Croatia, 2017
T1  - TEM study of basal-plane inversion boundaries in Sn‐Doped ZnO
SP  - 471
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2463
ER  - 

@conference{
author = "Ribić, Vesna and Rečnik, Aleksander and Dražić, Goran and Komelj, Matej and kokalj, Anton and Podlogar, Matejka and Daneu, Nina and Bernik, Slavko and Radošević, Tina and Luković Golić, Danijela and Branković, Zorica and Branković, Goran",
year = "2017",
abstract = "Various dopants are known to produce inversion boundaries (IBs) in ZnO, causing polarity inversion across the interface. These are found either in basal or pyramidal planes and can be of head-to-head or tail-to-tail configuration with respect to the orientation of the polar c-axis. The dopants, known to produce IBs in ZnO are: In2O3, Fe2O3, Mn2O3, Ga2O3, SiO2, SnO2, TiO2 and Sb2O3. While some of IBs have been studied in detail, many IB structures remain unresolved. In our study we investigated structure and chemistry of basal plane inversion boundaries in SnO2-doped ZnO. The formation of IBs in this system was first reported by Daneu et al. (2000)1 and using high-resolution transmission electron microscopy the same group attempted to solve structure and chemistry of Sn-rich IBs.2 Implementing an innovative analytical approach based on acquiring multiple EDS spectra with concentric electron probes they showed that Sn4+ ions do not occupy the full IB layer, but rather one half of the layer. This suggested an average oxidation state of III+ for the cations comprising the IB plane. Based on electron micro-diffraction and HRTEM study Daneu et al.1,2 reported that Sn-rich IBs are head-to-head oriented with interfacial cations located in trigonal prismatic sites, however, the exact atomic arrangement of Sn along IB has not been determined. To identify the translation state and atomic arrangement on Sn-rich IBs in ZnO we performed quantitative HRTEM and HAADF-STEM analysis of SnO2-doped ZnO/Bi2O3 ceramics. IBs in ZnO grains were observed for two low-index orientations, [100] and [120], to obtain a 3D information on the translation state of the IB plane. The coordination site of interfacial cations was shown to be octahedral.
472
Translation obtained from images is compared with three different, so far known, types of the head-to-head IB translations with octahedral coordination of cations at IB-plane: (i) IB with stacking of the cation sublattice, as observed with Sb doping, (ii) IB with, as observed with In and Fe doping and (iii) IB with as observed with Mn doping. For Sn-doped ZnO translations turned out to be (ii) , the same as the one occurring in In- and Fe-doped ZnO. Based on experimental observations of local atomic arrangement, HRTEM and HAADF-STEM image simulations were performed for two different in-plane distributions of Sn and Zn atoms, to better understand experimental image contrast on IBs. The generated models will be further used for ab-initio calculations aimed at determining the electronic structure of IBs.",
publisher = "Ruđer Bošković Institute and Croatian Microscopy Society, Rovinj (Croatia)",
journal = "13th Multinational Congress on Microscopy, Rovinj, Croatia, 2017",
title = "TEM study of basal-plane inversion boundaries in Sn‐Doped ZnO",
pages = "471",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2463"
}

Ribić, V., Rečnik, A., Dražić, G., Komelj, M., kokalj, A., Podlogar, M., Daneu, N., Bernik, S., Radošević, T., Luković Golić, D., Branković, Z.,& Branković, G.. (2017). TEM study of basal-plane inversion boundaries in Sn‐Doped ZnO. in 13th Multinational Congress on Microscopy, Rovinj, Croatia, 2017
Ruđer Bošković Institute and Croatian Microscopy Society, Rovinj (Croatia)., 471.
https://hdl.handle.net/21.15107/rcub_rimsi_2463

Ribić V, Rečnik A, Dražić G, Komelj M, kokalj A, Podlogar M, Daneu N, Bernik S, Radošević T, Luković Golić D, Branković Z, Branković G. TEM study of basal-plane inversion boundaries in Sn‐Doped ZnO. in 13th Multinational Congress on Microscopy, Rovinj, Croatia, 2017. 2017;:471.
https://hdl.handle.net/21.15107/rcub_rimsi_2463 .

Ribić, Vesna, Rečnik, Aleksander, Dražić, Goran, Komelj, Matej, kokalj, Anton, Podlogar, Matejka, Daneu, Nina, Bernik, Slavko, Radošević, Tina, Luković Golić, Danijela, Branković, Zorica, Branković, Goran, "TEM study of basal-plane inversion boundaries in Sn‐Doped ZnO" in 13th Multinational Congress on Microscopy, Rovinj, Croatia, 2017 (2017):471,
https://hdl.handle.net/21.15107/rcub_rimsi_2463 .