Fedorenko, E.

Kryvobok, R. V.

Lisachuk, G.

Prytkina, M.

Zakharov, A.

Electronic National Technical University &quot;Kharkiv Polytechnic Institute&quot; Institutional Repository (eNTUKhPIIR)

*Denotes Presenter Electronic Materials and Applications 2016 55Abstracts(EMA-S6-P015-2016) Controlling Spin Ordering in Rare-Earth Perovskite VanadatesN. Wagner*1; J. Rondinelli1; 1. Northwestern University, USAWe investigate the role and influence of local structure distortions on the antiferromagnetic spin ordering temperatures for large A-site radii RVO3 perovskites (R=Yb-La) using a combination of data analytics (DA) and density functional theory (DFT). First, mode crystallography is used to parameterize the structural phase space. Next, we identify the important local structural features that correlate strongly with the Néel temperatures using Pearson correla-tion coefficients and principal component analysis. From this data, we then formulate a regression model using gradient boosted deci-sion trees (GBDT) that returns the relative importance of each feature in predicting the Néel temperature. Our analysis indicates that the amplitude of the subtle Jahn-Teller active mode, which leads to variations in the V-O bond lengths and angles, could be used as an effective structural control parameter to modify the spin ordering temperature. We then validate these data-driven structure-property relationship in artificial vanadate structures using Néel temperatures based on both our GBDT model and a model Hamiltonian using DFT energies. This combined DA-DFT approach allows us to gauge the accuracy of existing models for the critical ordering tempera-tures in vanadates and opens possible strategies to deterministically design materials with targeted magnetic ordering temperatures.(EMA-S6-P016-2016) Displacement Radiation Effects in Ferroelectric BaTiO3: A Molecular Dynamics StudyY. Ma*1; 1. University of Wisconsin-Eau Claire, USADisplacement radiation effect can create a large number of defects in materials that may have a significant impact on the performance of materials and devices. For ferroelectrics, these defects will not only lead to polarization loss but also result in other serious problems such as ferroelectric fatigue and imprint failure. To obtain an atom-istic understanding of the radiation effects in ferroelectric materials, the displacement radiation cascades in BaTiO3 were simulated using molecular dynamics simulations with a modifed shell model. Primary knock-on atoms with different energies were introduced to the system and the resulting defects distribution and associated polarization loss were analyzed. Compressive strain was then intro-duced and it was found that the number of defects created decreases with increasing strain. Furthermore, polarization reversal was simulated to investigate the effect of radiation on the coercive field. Finally, the impact of the displacement radiation on the domain structure was studied.(EMA-S6-P017-2016) Effects of doping on the magnetic ordering in EuTiO3Z. Gui*1; A. Janotti1; 1. University of Delaware, USAEu-based perovskites have attracted considerable attention due to the strong spin-lattice coupling, that can potentially lead to robust multiferroicity. One particular member is EuTiO3 (ETO), which is a complex oxide that displays a large magneto-electric effect, and undergoes a series of structural and magnetic phase transitions when subjected to pressure or epitaxial strain. ETO adopts a cubic structure and is paramagnetic at high temperatures, while at very low temperatures it transforms to an antiferrodistortive tetragonal structure with a G-type antiferromagnetic (AFM) ordering. Several approaches have been presented to tune the magnetic ordering from the G-type antiferromagnetism to the F-type ferromagnetism, often relying on external pressure or epitaxial strain. Doping at the euro-pium sites or creating oxygen vacancies have also been proposed to lead to ferromagnetism. However, the fundamental mechanism by which excess from impurities or defects lead to ferromagnetic ordering is unclear. In this study, we explore the effects of doping on the magnetic ordering in EuTiO3 through first-principles calculations. We show how itinerant carriers in the Ti-d-derived conduction-band states interact with the lower-lying europium f states, inducing an alignment of the large moments on the europium ions. The effects of doping on different types of magnetic ordering are considered, and possible ways of doping are discussed.(EMA-S7-P018-2016) Development of radio transparent ceramic materialsR. V. Kryvobok*1; G. Lisachuk1; A. Zakharov1; E. Fedorenko1; M. Prytkina1; 1. National Technical University “Kharkiv Polytechnic Institute”, UkraineIn recent times, scientists attention is paid to the synthesis of glass-ceramic and ceramic radio transparent materials based on celsian and slavsonite, which are characterized by ε ≤ 6-8, tgδ ≤ 1-50 • 10-4, have high melting temperature (1650 and 1760 ° C) low coefficient of thermal expansion ≤ 3,8 • 10-6 K-1 and high mechan-ical strength (E = 110 ÷ 115 GPa). With the purpose to expand the composition of radio transparent ceramic materials with low dielec-tric and high mechanical properties, the experiment was conducted with using of the simplex-lattice planning (Sheffs plans)). The area of technological compositions in ternary system SrO-Al2O3-SiO2 with the content of the components SrO - 25-45 wt. %, SiO2 - 30-50 wt. %, Al2O3 - 25-35 wt. % was selected for studying. Preparation of the samples was performed by the following technology. Raw ingre-dients was milled in a porcelain mill to the residue 4 - 6% on sieve 10,000 Holes. / Cm2. Pressing of the samples was performed on a hydraulic press P-125 at the specific pressure of 20 MPa. Pressed samples were dried in the oven at 110 ° C for 1 hour. Firing of samples was conducted in a laboratory oven at a temperature range of 1250-1450 ° C. On the basis of the research, new compositions of radio transparent ceramic materials, which are characterized by reduced values of dielectric permittivity (ε) - 5-9 and dielectric loss tangent (tg δ) - 60-110 • 10-4 were set.(EMA-S7-P019-2016) Densification and Nanostructural Features of Al2O3 Ceramics Prepared with Nanoscale Powders by Microwave-assisted SinteringN. Cho*1; H. Yun1; D. Jeong1; 1. Inha University, The Republic of KoreaAl2O3 can be used for various engineering applications owing to its unique and useful physical features. Since the nanotechnology was introduced a few decades ago, much efforts has been made to fabri-cate nano-grained Al2O3 ceramics for various applications. In this study, densification and nanostructural features of Al2O3 ceramics prepared with nanoscale powders by microwave-assisted sintering (MWS) were investigated. To investigate the effects of initial powder size on the densification, Al2O3 powders with an average size of a few hundred nm were prepared and sintered by MWS and conventional sintering (CS). A MWS furnace equipped with a microwave gener-ator (frequence: 2.45 GHz, power: 4 kW) was used. The structural features of the initial nanoscale powders and ceramics were exam-ined by X-ray diffraction and transmission electron microscopy. The activation energy of the sintering processes was estimated to appre-ciate the kinetic behaviors of densification. The MWS of nanoscale powders yielded a relative density (RD) of over 90% when sintered at temperatures down to ~1200oC, whereas the same RD was achieved over ~1500oC by CS. In addition, nano-grained Al2O3 ceramics with RD of >90% can be obtained by MWS method. It was found that the response of nanoscale powders to microwave turns out to be more significant as the initial powder size decreases.(EMA-S8-P020-2016) BaTiO3 doped ceramics fractal sources dielectric propertiesV. Mitic*1; L. Kocic1; V. Paunovic1; 1. Faculty of Electronic Engineering, SerbiaThe rare earth doped BaTiO3-ceramics is investigated regarding their microstructural and dielectric characteristics influenced by the triple fractality “source”. Doped BaTiO3 were prepared using conventional solid state reaction and sintering at 1320 oC. Additive materials ensure the upper grain limit size to be 2-10 mm. Dielectric measurements were carried out as a function of temperature up to 180°C. The low doped samples (0.01wt%) sintered at 1320°C, display the high value of dielectric permittivity (er = 2300), at room 

Development of radio transparent ceramic materials

Library of National Technical University "Kharkiv Polytechnic Institute"

*Denotes Presenter Electronic Materials and Applications 2016 55
Abstracts
(EMA-S6-P015-2016) Controlling Spin Ordering in Rare-Earth 
Perovskite Vanadates
N. Wagner*1; J. Rondinelli1; 1. Northwestern University, USA
We investigate the role and influence of local structure distortions 
on the antiferromagnetic spin ordering temperatures for large 
A-site radii RVO3 perovskites (R=Yb-La) using a combination of 
data analytics (DA) and density functional theory (DFT). First, 
mode crystallography is used to parameterize the structural phase 
space. Next, we identify the important local structural features that 
correlate strongly with the Néel temperatures using Pearson correla-
tion coefficients and principal component analysis. From this data, 
we then formulate a regression model using gradient boosted deci-
sion trees (GBDT) that returns the relative importance of each 
feature in predicting the Néel temperature. Our analysis indicates 
that the amplitude of the subtle Jahn-Teller active mode, which leads 
to variations in the V-O bond lengths and angles, could be used as 
an effective structural control parameter to modify the spin ordering 
temperature. We then validate these data-driven structure-property 
relationship in artificial vanadate structures using Néel temperatures 
based on both our GBDT model and a model Hamiltonian using 
DFT energies. This combined DA-DFT approach allows us to gauge 
the accuracy of existing models for the critical ordering tempera-
tures in vanadates and opens possible strategies to deterministically 
design materials with targeted magnetic ordering temperatures.
(EMA-S6-P016-2016) Displacement Radiation Effects in 
Ferroelectric BaTiO3: A Molecular Dynamics Study
Y. Ma*1; 1. University of Wisconsin-Eau Claire, USA
Displacement radiation effect can create a large number of defects in 
materials that may have a significant impact on the performance of 
materials and devices. For ferroelectrics, these defects will not only 
lead to polarization loss but also result in other serious problems 
such as ferroelectric fatigue and imprint failure. To obtain an atom-
istic understanding of the radiation effects in ferroelectric materials, 
the displacement radiation cascades in BaTiO3 were simulated 
using molecular dynamics simulations with a modifed shell model. 
Primary knock-on atoms with different energies were introduced 
to the system and the resulting defects distribution and associated 
polarization loss were analyzed. Compressive strain was then intro-
duced and it was found that the number of defects created decreases 
with increasing strain. Furthermore, polarization reversal was 
simulated to investigate the effect of radiation on the coercive field. 
Finally, the impact of the displacement radiation on the domain 
structure was studied.
(EMA-S6-P017-2016) Effects of doping on the magnetic ordering 
in EuTiO3
Z. Gui*1; A. Janotti1; 1. University of Delaware, USA
Eu-based perovskites have attracted considerable attention due to 
the strong spin-lattice coupling, that can potentially lead to robust 
multiferroicity. One particular member is EuTiO3 (ETO), which is 
a complex oxide that displays a large magneto-electric effect, and 
undergoes a series of structural and magnetic phase transitions 
when subjected to pressure or epitaxial strain. ETO adopts a cubic 
structure and is paramagnetic at high temperatures, while at very 
low temperatures it transforms to an antiferrodistortive tetragonal 
structure with a G-type antiferromagnetic (AFM) ordering. Several 
approaches have been presented to tune the magnetic ordering from 
the G-type antiferromagnetism to the F-type ferromagnetism, often 
relying on external pressure or epitaxial strain. Doping at the euro-
pium sites or creating oxygen vacancies have also been proposed 
to lead to ferromagnetism. However, the fundamental mechanism 
by which excess from impurities or defects lead to ferromagnetic 
ordering is unclear. In this study, we explore the effects of doping 
on the magnetic ordering in EuTiO3 through first-principles 
calculations. We show how itinerant carriers in the Ti-d-derived 
conduction-band states interact with the lower-lying europium f 
states, inducing an alignment of the large moments on the europium 
ions. The effects of doping on different types of magnetic ordering 
are considered, and possible ways of doping are discussed.
(EMA-S7-P018-2016) Development of radio transparent ceramic 
materials
R. V. Kryvobok*1; G. Lisachuk1; A. Zakharov1; E. Fedorenko1; M. Prytkina1; 
1. National Technical University “Kharkiv Polytechnic Institute”, Ukraine
In recent times, scientists attention is paid to the synthesis of 
glass-ceramic and ceramic radio transparent materials based on 
celsian and slavsonite, which are characterized by ε ≤ 6-8, tgδ ≤ 
1-50 • 10-4, have high melting temperature (1650 and 1760 ° C) low 
coefficient of thermal expansion ≤ 3,8 • 10-6 K-1 and high mechan-
ical strength (E = 110 ÷ 115 GPa). With the purpose to expand the 
composition of radio transparent ceramic materials with low dielec-
tric and high mechanical properties, the experiment was conducted 
with using of the simplex-lattice planning (Sheffs plans)). The area 
of technological compositions in ternary system SrO-Al2O3-SiO2 
with the content of the components SrO - 25-45 wt. %, SiO2 - 30-50 
wt. %, Al2O3 - 25-35 wt. % was selected for studying. Preparation of 
the samples was performed by the following technology. Raw ingre-
dients was milled in a porcelain mill to the residue 4 - 6% on sieve 
10,000 Holes. / Cm2. Pressing of the samples was performed on a 
hydraulic press P-125 at the specific pressure of 20 MPa. Pressed 
samples were dried in the oven at 110 ° C for 1 hour. Firing of 
samples was conducted in a laboratory oven at a temperature range 
of 1250-1450 ° C. On the basis of the research, new compositions 
of radio transparent ceramic materials, which are characterized by 
reduced values of dielectric permittivity (ε) - 5-9 and dielectric loss 
tangent (tg δ) - 60-110 • 10-4 were set.
(EMA-S7-P019-2016) Densification and Nanostructural 
Features of Al2O3 Ceramics Prepared with Nanoscale Powders by 
Microwave-assisted Sintering
N. Cho*1; H. Yun1; D. Jeong1; 1. Inha University, The Republic of Korea
Al2O3 can be used for various engineering applications owing to its 
unique and useful physical features. Since the nanotechnology was 
introduced a few decades ago, much efforts has been made to fabri-
cate nano-grained Al2O3 ceramics for various applications. In this 
study, densification and nanostructural features of Al2O3 ceramics 
prepared with nanoscale powders by microwave-assisted sintering 
(MWS) were investigated. To investigate the effects of initial powder 
size on the densification, Al2O3 powders with an average size of a few 
hundred nm were prepared and sintered by MWS and conventional 
sintering (CS). A MWS furnace equipped with a microwave gener-
ator (frequence: 2.45 GHz, power: 4 kW) was used. The structural 
features of the initial nanoscale powders and ceramics were exam-
ined by X-ray diffraction and transmission electron microscopy. The 
activation energy of the sintering processes was estimated to appre-
ciate the kinetic behaviors of densification. The MWS of nanoscale 
powders yielded a relative density (RD) of over 90% when sintered at 
temperatures down to ~1200oC, whereas the same RD was achieved 
over ~1500oC by CS. In addition, nano-grained Al2O3 ceramics with 
RD of >90% can be obtained by MWS method. It was found that the 
response of nanoscale powders to microwave turns out to be more 
significant as the initial powder size decreases.
(EMA-S8-P020-2016) BaTiO3 doped ceramics fractal sources 
dielectric properties
V. Mitic*1; L. Kocic1; V. Paunovic1; 1. Faculty of Electronic Engineering, 
Serbia
The rare earth doped BaTiO3-ceramics is investigated regarding 
their microstructural and dielectric characteristics influenced by 
the triple fractality “source”. Doped BaTiO3 were prepared using 
conventional solid state reaction and sintering at 1320 oC. Additive 
materials ensure the upper grain limit size to be 2-10 mm. Dielectric 
measurements were carried out as a function of temperature up 
to 180°C. The low doped samples (0.01wt%) sintered at 1320°C, 
display the high value of dielectric permittivity (er = 2300), at room 


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Development of radio transparent ceramic materials

Abstract

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Electronic National Technical University "Kharkiv Polytechnic Institute" Institutional Repository (eNTUKhPIIR)

Library of National Technical University "Kharkiv Polytechnic Institute"

Development of radio transparent ceramic materials

Abstract

Similar works

Full text

Available Versions

Electronic National Technical University &quot;Kharkiv Polytechnic Institute&quot; Institutional Repository (eNTUKhPIIR)

Library of National Technical University "Kharkiv Polytechnic Institute"

Electronic National Technical University "Kharkiv Polytechnic Institute" Institutional Repository (eNTUKhPIIR)