TY  - JOUR
AU  - Ivanovski, Valentin N.
AU  - Cekić, Božidar Đ.
AU  - Umićević, Ana
AU  - Barudžija, Tanja
AU  - Schumacher, G.
AU  - Mađarević, Ivan
AU  - Koteski, Vasil J.
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/249
AB  - Perturbed angular correlation measurements of the hyperfine interactions of the Ta-181 probe in the polycrystalline intermetallic Ni3Al doped with 0.5 and 5 at.% Hf were performed in the temperature range 78-1230 K. The observed local hyperfine fields at the Hf-181/Ta-181 probe showed that Hf atoms are substituting on Al sites in the L1(2) structure of Ni3Al. The two minor electric quadrupole interactions that were found for each Ni3Al alloy are discussed taking into account the L1(2) cubic structure and its two tetragonal distortions: D0(22) and L6(0). The presence of two tetragonal transformations of the parent cubic L1(2) lattice in 0.5 at.% Hf and 5 at.% Hf doped Ni3Al was revealed by X-ray diffraction. The ab initio calculations, performed with the projector augmented wave method correctly reproduce the experimental results and enable discussion on the structural and electronic properties of the polycrystalline alloys. The experimental and theoretical investigations showed that hafnium additions prefer aluminum sites in Ni3Al. (C) 2014 Elsevier B.V. All rights reserved.
T2  - Journal of Alloys and Compounds
T1  - Site preference of Hf dopant in Ni3Al alloys: A perturbed angular correlation study
VL  - 622
SP  - 541
EP  - 547
DO  - 10.1016/j.jallcom.2014.10.132
ER  - 

@article{
author = "Ivanovski, Valentin N. and Cekić, Božidar Đ. and Umićević, Ana and Barudžija, Tanja and Schumacher, G. and Mađarević, Ivan and Koteski, Vasil J.",
year = "2015",
abstract = "Perturbed angular correlation measurements of the hyperfine interactions of the Ta-181 probe in the polycrystalline intermetallic Ni3Al doped with 0.5 and 5 at.% Hf were performed in the temperature range 78-1230 K. The observed local hyperfine fields at the Hf-181/Ta-181 probe showed that Hf atoms are substituting on Al sites in the L1(2) structure of Ni3Al. The two minor electric quadrupole interactions that were found for each Ni3Al alloy are discussed taking into account the L1(2) cubic structure and its two tetragonal distortions: D0(22) and L6(0). The presence of two tetragonal transformations of the parent cubic L1(2) lattice in 0.5 at.% Hf and 5 at.% Hf doped Ni3Al was revealed by X-ray diffraction. The ab initio calculations, performed with the projector augmented wave method correctly reproduce the experimental results and enable discussion on the structural and electronic properties of the polycrystalline alloys. The experimental and theoretical investigations showed that hafnium additions prefer aluminum sites in Ni3Al. (C) 2014 Elsevier B.V. All rights reserved.",
journal = "Journal of Alloys and Compounds",
title = "Site preference of Hf dopant in Ni3Al alloys: A perturbed angular correlation study",
volume = "622",
pages = "541-547",
doi = "10.1016/j.jallcom.2014.10.132"
}

Ivanovski, V. N., Cekić, B. Đ., Umićević, A., Barudžija, T., Schumacher, G., Mađarević, I.,& Koteski, V. J.. (2015). Site preference of Hf dopant in Ni3Al alloys: A perturbed angular correlation study. in Journal of Alloys and Compounds, 622, 541-547.
https://doi.org/10.1016/j.jallcom.2014.10.132

Ivanovski VN, Cekić BĐ, Umićević A, Barudžija T, Schumacher G, Mađarević I, Koteski VJ. Site preference of Hf dopant in Ni3Al alloys: A perturbed angular correlation study. in Journal of Alloys and Compounds. 2015;622:541-547.
doi:10.1016/j.jallcom.2014.10.132 .

Ivanovski, Valentin N., Cekić, Božidar Đ., Umićević, Ana, Barudžija, Tanja, Schumacher, G., Mađarević, Ivan, Koteski, Vasil J., "Site preference of Hf dopant in Ni3Al alloys: A perturbed angular correlation study" in Journal of Alloys and Compounds, 622 (2015):541-547,
https://doi.org/10.1016/j.jallcom.2014.10.132 . .

TY  - JOUR
AU  - Ivanovski, Valentin N.
AU  - Cekić, Božidar Đ.
AU  - Umićević, Ana
AU  - Belošević-Čavor, Jelena
AU  - Schumacher, G.
AU  - Koteski, Vasil J.
AU  - Barudžija, Tanja
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5625
AB  - The Time Differential Perturbed Angular (TDPAC) measurements of nuclear quadrupole interactions (NQIs) at Ta-181 ion probe in the polycrystalline intermetallic alloy gamma-Ni3Al doped with 0.2 at. % Hf were performed in the temperature range 78-1230K, in order to determine the lattice location of Hf atoms in the ordered gamma-Ni3Al structure. The two NQIs obtained are discussed within the present L1(2) cubic structure and a tetragonal distortion of L1(2) to another two DO22 and L6(0) type structures. The first low frequency NQI at the site of the Ta-181 ion-probe after substitution of aluminum for hafnium in DO22 at ambient temperature, is v(Q1)(300 K) = 39(1) MHz with eta(1) = 0. The corresponding high frequency value on the second crystallographic site in L6(0), is v(Q2)(300 K) = 204(14) MHz with eta(2) = 0.47(11). These two NQIs have different temperature behavior. The presence of both DO22 and L6(0) tetragonal distortions of the parent cubic L1(2) lattice, detected after adding 0.2 at. % Hf, are with modulations to the lattice constant (a) with a ratio (c/a), 2.04 and 0.87, respectively. Ab initio calculations of electronic and structural properties and hyperfine parameters at the Ta-181 ion probe of the gamma-Ni3Al-0.2 at. % Hf alloy were performed using the full potential augmented plane wave plus local-orbital (APW+lo) method as implemented in the WIEN2k code. The accuracy of the calculations and comparison with the experimental results enabled us to identify the observed hyperfine interactions and to infer the EFG sign that cannot be measured in conventional TDPAC measurements. (C) 2013 AIP Publishing LLC.
T2  - Journal of Applied Physics
T1  - Hf dopants in gamma -Ni3Al alloy
VL  - 114
IS  - 6
DO  - 10.1063/1.4818317
ER  - 

@article{
author = "Ivanovski, Valentin N. and Cekić, Božidar Đ. and Umićević, Ana and Belošević-Čavor, Jelena and Schumacher, G. and Koteski, Vasil J. and Barudžija, Tanja",
year = "2013",
abstract = "The Time Differential Perturbed Angular (TDPAC) measurements of nuclear quadrupole interactions (NQIs) at Ta-181 ion probe in the polycrystalline intermetallic alloy gamma-Ni3Al doped with 0.2 at. % Hf were performed in the temperature range 78-1230K, in order to determine the lattice location of Hf atoms in the ordered gamma-Ni3Al structure. The two NQIs obtained are discussed within the present L1(2) cubic structure and a tetragonal distortion of L1(2) to another two DO22 and L6(0) type structures. The first low frequency NQI at the site of the Ta-181 ion-probe after substitution of aluminum for hafnium in DO22 at ambient temperature, is v(Q1)(300 K) = 39(1) MHz with eta(1) = 0. The corresponding high frequency value on the second crystallographic site in L6(0), is v(Q2)(300 K) = 204(14) MHz with eta(2) = 0.47(11). These two NQIs have different temperature behavior. The presence of both DO22 and L6(0) tetragonal distortions of the parent cubic L1(2) lattice, detected after adding 0.2 at. % Hf, are with modulations to the lattice constant (a) with a ratio (c/a), 2.04 and 0.87, respectively. Ab initio calculations of electronic and structural properties and hyperfine parameters at the Ta-181 ion probe of the gamma-Ni3Al-0.2 at. % Hf alloy were performed using the full potential augmented plane wave plus local-orbital (APW+lo) method as implemented in the WIEN2k code. The accuracy of the calculations and comparison with the experimental results enabled us to identify the observed hyperfine interactions and to infer the EFG sign that cannot be measured in conventional TDPAC measurements. (C) 2013 AIP Publishing LLC.",
journal = "Journal of Applied Physics",
title = "Hf dopants in gamma -Ni3Al alloy",
volume = "114",
number = "6",
doi = "10.1063/1.4818317"
}

Ivanovski, V. N., Cekić, B. Đ., Umićević, A., Belošević-Čavor, J., Schumacher, G., Koteski, V. J.,& Barudžija, T.. (2013). Hf dopants in gamma -Ni3Al alloy. in Journal of Applied Physics, 114(6).
https://doi.org/10.1063/1.4818317

Ivanovski VN, Cekić BĐ, Umićević A, Belošević-Čavor J, Schumacher G, Koteski VJ, Barudžija T. Hf dopants in gamma -Ni3Al alloy. in Journal of Applied Physics. 2013;114(6).
doi:10.1063/1.4818317 .

Ivanovski, Valentin N., Cekić, Božidar Đ., Umićević, Ana, Belošević-Čavor, Jelena, Schumacher, G., Koteski, Vasil J., Barudžija, Tanja, "Hf dopants in gamma -Ni3Al alloy" in Journal of Applied Physics, 114, no. 6 (2013),
https://doi.org/10.1063/1.4818317 . .

TY  - JOUR
AU  - Mechler, S.
AU  - Schumacher, G.
AU  - Koteski, Vasil J.
AU  - Riesemeier, H.
AU  - Schaefers, F.
AU  - Mahnke, Heinz-Eberhard
PY  - 2010
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/4080
AB  - Local structures of amorphous and quasicrystalline phases in Zr-Ti-Ni and Zr-Ti-Ni-Cu alloys have been studied by means of x-ray absorption spectroscopy. The amorphous phases show a high degree of icosahedral short-range order. In all investigated systems local order around Cu and Ni atoms was found to be nearly identical pointing to site substitution of Ni by Cu as the reason for an improved glass forming ability when Ni is partly substituted by Cu. The results strengthen an icosahedral cluster based approach for the structure of metallic glasses and indicate the importance of the medium-range order on glass formation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467265]
T2  - Applied Physics Letters
T1  - Local structure and site substitution in amorphous and quasicrystalline Zr-Ti-Ni-(Cu) alloys
VL  - 97
IS  - 4
DO  - 10.1063/1.3467265
ER  - 

@article{
author = "Mechler, S. and Schumacher, G. and Koteski, Vasil J. and Riesemeier, H. and Schaefers, F. and Mahnke, Heinz-Eberhard",
year = "2010",
abstract = "Local structures of amorphous and quasicrystalline phases in Zr-Ti-Ni and Zr-Ti-Ni-Cu alloys have been studied by means of x-ray absorption spectroscopy. The amorphous phases show a high degree of icosahedral short-range order. In all investigated systems local order around Cu and Ni atoms was found to be nearly identical pointing to site substitution of Ni by Cu as the reason for an improved glass forming ability when Ni is partly substituted by Cu. The results strengthen an icosahedral cluster based approach for the structure of metallic glasses and indicate the importance of the medium-range order on glass formation. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467265]",
journal = "Applied Physics Letters",
title = "Local structure and site substitution in amorphous and quasicrystalline Zr-Ti-Ni-(Cu) alloys",
volume = "97",
number = "4",
doi = "10.1063/1.3467265"
}

Mechler, S., Schumacher, G., Koteski, V. J., Riesemeier, H., Schaefers, F.,& Mahnke, H.. (2010). Local structure and site substitution in amorphous and quasicrystalline Zr-Ti-Ni-(Cu) alloys. in Applied Physics Letters, 97(4).
https://doi.org/10.1063/1.3467265

Mechler S, Schumacher G, Koteski VJ, Riesemeier H, Schaefers F, Mahnke H. Local structure and site substitution in amorphous and quasicrystalline Zr-Ti-Ni-(Cu) alloys. in Applied Physics Letters. 2010;97(4).
doi:10.1063/1.3467265 .

Mechler, S., Schumacher, G., Koteski, Vasil J., Riesemeier, H., Schaefers, F., Mahnke, Heinz-Eberhard, "Local structure and site substitution in amorphous and quasicrystalline Zr-Ti-Ni-(Cu) alloys" in Applied Physics Letters, 97, no. 4 (2010),
https://doi.org/10.1063/1.3467265 . .

TY  - JOUR
AU  - Koteski, Vasil J.
AU  - Mahnke, Heinz-Eberhard
AU  - Belošević-Čavor, Jelena
AU  - Cekić, Božidar Đ.
AU  - Schumacher, G.
PY  - 2008
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/3551
AB  - The lattice relaxation around Mo, Ru, Hf, Ta, W and Re in Ni is investigated by means of X-ray absorption spectroscopy. For all of the investigated concentrations the substitutional lattice position is confirmed except for the higher Hf concentration where different phases are observed. Ail outward relaxation of the neighboring atoms is detected with clear trends of increasing nearest neighbor distances with decreasing valence for the 5d impurities, and separate trends for the 4d impurities. Ab initio supercell calculations within the linearized augmented plane wave formalism are used to complement the experimental results and allow for a better interpretation of the experimental trends in terms of the electronic structure of the impurity. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
T2  - Acta Materialia
T1  - Experimental and theoretical study of lattice relaxation around refractory atoms in nickel
VL  - 56
IS  - 17
SP  - 4601
EP  - 4607
DO  - 10.1016/j.actamat.2008.05.015
ER  - 

@article{
author = "Koteski, Vasil J. and Mahnke, Heinz-Eberhard and Belošević-Čavor, Jelena and Cekić, Božidar Đ. and Schumacher, G.",
year = "2008",
abstract = "The lattice relaxation around Mo, Ru, Hf, Ta, W and Re in Ni is investigated by means of X-ray absorption spectroscopy. For all of the investigated concentrations the substitutional lattice position is confirmed except for the higher Hf concentration where different phases are observed. Ail outward relaxation of the neighboring atoms is detected with clear trends of increasing nearest neighbor distances with decreasing valence for the 5d impurities, and separate trends for the 4d impurities. Ab initio supercell calculations within the linearized augmented plane wave formalism are used to complement the experimental results and allow for a better interpretation of the experimental trends in terms of the electronic structure of the impurity. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.",
journal = "Acta Materialia",
title = "Experimental and theoretical study of lattice relaxation around refractory atoms in nickel",
volume = "56",
number = "17",
pages = "4601-4607",
doi = "10.1016/j.actamat.2008.05.015"
}

Koteski, V. J., Mahnke, H., Belošević-Čavor, J., Cekić, B. Đ.,& Schumacher, G.. (2008). Experimental and theoretical study of lattice relaxation around refractory atoms in nickel. in Acta Materialia, 56(17), 4601-4607.
https://doi.org/10.1016/j.actamat.2008.05.015

Koteski VJ, Mahnke H, Belošević-Čavor J, Cekić BĐ, Schumacher G. Experimental and theoretical study of lattice relaxation around refractory atoms in nickel. in Acta Materialia. 2008;56(17):4601-4607.
doi:10.1016/j.actamat.2008.05.015 .

Koteski, Vasil J., Mahnke, Heinz-Eberhard, Belošević-Čavor, Jelena, Cekić, Božidar Đ., Schumacher, G., "Experimental and theoretical study of lattice relaxation around refractory atoms in nickel" in Acta Materialia, 56, no. 17 (2008):4601-4607,
https://doi.org/10.1016/j.actamat.2008.05.015 . .