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Dr. Aleksej Zarkov
Vilnius University

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0 Ceramics
0 Nanomaterials
0 Thin Films
0 mixed metal oxides
0 Functional inorganic materials

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mixed metal oxides
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Journal article
Published: 26 August 2021 in Materials
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In this work, lanthanum and manganese co-substitution effects on different properties of bismuth ferrite solid solutions Bi1-xLaxFe0.85Mn0.15O3 (x from 0 to 1) prepared by a sol-gel synthetic approach have been investigated. It was observed that the structural, morphological, and magnetic properties of obtained specimens are influenced by the amount of introduced La3+ ions. Surprisingly, only the compound with a composition of BiFe0.85Mn0.15O3 was not monophasic, and the presence of neighboring phases was determined from X-ray diffraction analysis and Mössbauer measurements. Structural transitions from orthorhombic to cubic and back to orthorhombic were also observed depending on the La3+ amount. Antiferromagnetic behaviour was observed for all of the samples, with the highest magnetisation values for Bi0.5La0.5Fe0.85Mn0.15O3. Additionally, structural attributes and morphological features were evaluated by Raman spectroscopy and scanning electron microscopy (SEM), respectively.

ACS Style

Dovydas Karoblis; Ramunas Diliautas; Kestutis Mazeika; Dalis Baltrunas; Gediminas Niaura; Martynas Talaikis; Aldona Beganskiene; Aleksej Zarkov; Aivaras Kareiva. Lanthanum and Manganese Co-Doping Effects on Structural, Morphological, and Magnetic Properties of Sol-Gel Derived BiFeO3. Materials 2021, 14, 4844 .

AMA Style

Dovydas Karoblis, Ramunas Diliautas, Kestutis Mazeika, Dalis Baltrunas, Gediminas Niaura, Martynas Talaikis, Aldona Beganskiene, Aleksej Zarkov, Aivaras Kareiva. Lanthanum and Manganese Co-Doping Effects on Structural, Morphological, and Magnetic Properties of Sol-Gel Derived BiFeO3. Materials. 2021; 14 (17):4844.

Chicago/Turabian Style

Dovydas Karoblis; Ramunas Diliautas; Kestutis Mazeika; Dalis Baltrunas; Gediminas Niaura; Martynas Talaikis; Aldona Beganskiene; Aleksej Zarkov; Aivaras Kareiva. 2021. "Lanthanum and Manganese Co-Doping Effects on Structural, Morphological, and Magnetic Properties of Sol-Gel Derived BiFeO3." Materials 14, no. 17: 4844.

Editorial
Published: 13 August 2021 in Crystals
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Functional inorganic materials are an indispensable part of innovative technologies, which are essential to the development of many fields of industry

ACS Style

Aleksej Zarkov; Aivaras Kareiva; Loreta Tamasauskaite-Tamasiunaite. Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods. Crystals 2021, 11, 943 .

AMA Style

Aleksej Zarkov, Aivaras Kareiva, Loreta Tamasauskaite-Tamasiunaite. Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods. Crystals. 2021; 11 (8):943.

Chicago/Turabian Style

Aleksej Zarkov; Aivaras Kareiva; Loreta Tamasauskaite-Tamasiunaite. 2021. "Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods." Crystals 11, no. 8: 943.

Journal article
Published: 08 August 2021 in Applied Sciences
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Mineral trioxide aggregate (MTA) is well known as an effective root canal filling material for endodontics therapy. Within MTA, bismuth oxide (Bi2O3) serving as the radiopacifier still has biocompatibility concerns due to its mild cytotoxicity. In the present study, we tried to modify the Bi2O3 radiopacifier by doping hafnium ions via the sol-gel process and investigated the effects of different doping ratios (Bi2-xHfxO3+x/2, x = 0–0.3) and calcination temperatures (400–800 °C). We mixed various precursor mixtures of bismuth nitrate (Bi(NO3)3·5H2O) and hafnium sulfate (Hf(SO4)2) and controlled the calcination temperatures. The as-prepared Hf-doped Bi2O3 radiopacifier powders were investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Portland cement/radiopacifier/calcium sulfate (75/20/5) were mixed and set by deionized water (powder to water ratio = 3:1). Changes in radiopacity, diametral tensile strength (DTS), and in vitro cell viability of the hydrated MTA-like cement were carried out. The experimental results showed that the group containing radiopacifier from sol-gelled Bi/Hf (90/10) exhibited significantly higher radiopacity (6.36 ± 0.34 mmAl), DTS (2.54 ± 0.29 MPa), and cell viability (84.0±8.1%) (p< 0.05) when compared to that of Bi/Hf (100/0) powders. It is suggested that the formation of β-Bi7.78Hf0.22O12.11 phase with hafnium addition and calcining at 700 °C can prepare novel bismuth/hafnium composite powder that can be used as an alternative radiopacifier for root canal filling materials.

ACS Style

Tzu-Sen Yang; May-Show Chen; Cheng-Jyun Huang; Chin-Yi Chen; Agnese Brangule; Aleksej Zarkov; Aivaras Kareiva; Chung-Kwei Lin; Jen-Chang Yang. A Novel Sol-Gel Bi2-xHfxO3+x/2 Radiopacifier for Mineral Trioxide Aggregates (MTA) as Dental Filling Materials. Applied Sciences 2021, 11, 7292 .

AMA Style

Tzu-Sen Yang, May-Show Chen, Cheng-Jyun Huang, Chin-Yi Chen, Agnese Brangule, Aleksej Zarkov, Aivaras Kareiva, Chung-Kwei Lin, Jen-Chang Yang. A Novel Sol-Gel Bi2-xHfxO3+x/2 Radiopacifier for Mineral Trioxide Aggregates (MTA) as Dental Filling Materials. Applied Sciences. 2021; 11 (16):7292.

Chicago/Turabian Style

Tzu-Sen Yang; May-Show Chen; Cheng-Jyun Huang; Chin-Yi Chen; Agnese Brangule; Aleksej Zarkov; Aivaras Kareiva; Chung-Kwei Lin; Jen-Chang Yang. 2021. "A Novel Sol-Gel Bi2-xHfxO3+x/2 Radiopacifier for Mineral Trioxide Aggregates (MTA) as Dental Filling Materials." Applied Sciences 11, no. 16: 7292.

Research article
Published: 28 July 2021 in ACS Biomaterials Science & Engineering
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In the present work, a series of zinc whitlockite (CaxZny(HPO4)2(PO4)12) powders was synthesized by a low-temperature dissolution–precipitation process for the first time. The phase conversion from calcium hydroxyapatite to zinc whitlockite occurred in an acidic medium in the presence of Zn2+ ions. Variable chemical composition of the synthesis products was achieved by changing Ca-to-Zn molar ratio in the reaction mixture. Investigation of the phase evolution as a function of time demonstrated that phase-pure zinc whitlockite powders can be synthesized in just 3 h. It is also demonstrated that single-phase products can be obtained when the Ca-to-Zn ratio in the reaction medium is in the range from 9 to 30. With higher or lower ratios, neighboring crystal phases such as scholzite or calcium hydroxyapatite were obtained. The morphology of the synthesized powders was found to be dependent on the chemical composition, transforming from hexagonal to rhombohedral plates with the increase of Zn content. Thermal stability studies revealed that the synthesized compounds were thermally unstable and decomposed upon heat treatment.

ACS Style

Agne Kizalaite; Inga Grigoraviciute-Puroniene; Dane Romar C. Asuigui; Sarah L. Stoll; Sung Hun Cho; Tohru Sekino; Aivaras Kareiva; Aleksej Zarkov. Dissolution–Precipitation Synthesis and Characterization of Zinc Whitlockite with Variable Metal Content. ACS Biomaterials Science & Engineering 2021, 7, 3586 -3593.

AMA Style

Agne Kizalaite, Inga Grigoraviciute-Puroniene, Dane Romar C. Asuigui, Sarah L. Stoll, Sung Hun Cho, Tohru Sekino, Aivaras Kareiva, Aleksej Zarkov. Dissolution–Precipitation Synthesis and Characterization of Zinc Whitlockite with Variable Metal Content. ACS Biomaterials Science & Engineering. 2021; 7 (8):3586-3593.

Chicago/Turabian Style

Agne Kizalaite; Inga Grigoraviciute-Puroniene; Dane Romar C. Asuigui; Sarah L. Stoll; Sung Hun Cho; Tohru Sekino; Aivaras Kareiva; Aleksej Zarkov. 2021. "Dissolution–Precipitation Synthesis and Characterization of Zinc Whitlockite with Variable Metal Content." ACS Biomaterials Science & Engineering 7, no. 8: 3586-3593.

Journal article
Published: 14 July 2021 in Sustainability
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In the present work, beta-calcium pyrophosphate (β-Ca2P2O7) was investigated as a potential adsorbent for the removal of heavy metal ions from water. Single-phase β-Ca2P2O7 powders were synthesized by a simple, scalable and cost-effective wet precipitation method followed by annealing at 800 °C, which was employed for the conversion of as-precipitated brushite (CaHPO4∙2H2O) to β-Ca2P2O7. Physicochemical properties of the sorbent were characterized by means of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA/DSC), scanning electron microscopy (SEM) and low temperature adsorption–desorption of nitrogen (BET method). The synthesized powders consisted of porous plate-like particles with micrometer dimensions. Specific surface area calculated by the BET method was found to be 7 m2 g−1. For the estimation of sorption properties, the aqueous model solutions containing different metal ions (Al3+, Cd2+, Co2+, Cu2+, Fe2+, Mn2+, Ni2+, Pb2+, Sn2+, Sr2+ and Zn2+) were used. The adsorption test revealed that β-Ca2P2O7 demonstrates the highest adsorption capacity for Pb2+ and Sn2+ ions, while the lowest capacity was observed towards Sr2+, Ni2+ and Co2+ ions. The optimal pH value for the removal of Pb2+ ions was determined to be 2, which is also related to the low solubility of β-Ca2P2O7 at this pH. The adsorption capacity towards Pb2+ ions was calculated as high as 120 mg g−1.

ACS Style

Diana Griesiute; Justina Gaidukevic; Aleksej Zarkov; Aivaras Kareiva. Synthesis of β-Ca2P2O7 as an Adsorbent for the Removal of Heavy Metals from Water. Sustainability 2021, 13, 7859 .

AMA Style

Diana Griesiute, Justina Gaidukevic, Aleksej Zarkov, Aivaras Kareiva. Synthesis of β-Ca2P2O7 as an Adsorbent for the Removal of Heavy Metals from Water. Sustainability. 2021; 13 (14):7859.

Chicago/Turabian Style

Diana Griesiute; Justina Gaidukevic; Aleksej Zarkov; Aivaras Kareiva. 2021. "Synthesis of β-Ca2P2O7 as an Adsorbent for the Removal of Heavy Metals from Water." Sustainability 13, no. 14: 7859.

Paper
Published: 11 June 2021 in CrystEngComm
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The present study investigates thermally induced crystallization and phase evolution of amorphous calcium phosphate (ACP) partially substituted with Fe3+ ions (M/P = 1.5 : 1).

ACS Style

Diana Griesiute; Lauryna Sinusaite; Agne Kizalaite; Andris Antuzevics; Kestutis Mazeika; Dalis Baltrunas; Tomoyo Goto; Tohru Sekino; Aivaras Kareiva; Aleksej Zarkov. The influence of Fe3+ doping on thermally induced crystallization and phase evolution of amorphous calcium phosphate. CrystEngComm 2021, 23, 4627 -4637.

AMA Style

Diana Griesiute, Lauryna Sinusaite, Agne Kizalaite, Andris Antuzevics, Kestutis Mazeika, Dalis Baltrunas, Tomoyo Goto, Tohru Sekino, Aivaras Kareiva, Aleksej Zarkov. The influence of Fe3+ doping on thermally induced crystallization and phase evolution of amorphous calcium phosphate. CrystEngComm. 2021; 23 (26):4627-4637.

Chicago/Turabian Style

Diana Griesiute; Lauryna Sinusaite; Agne Kizalaite; Andris Antuzevics; Kestutis Mazeika; Dalis Baltrunas; Tomoyo Goto; Tohru Sekino; Aivaras Kareiva; Aleksej Zarkov. 2021. "The influence of Fe3+ doping on thermally induced crystallization and phase evolution of amorphous calcium phosphate." CrystEngComm 23, no. 26: 4627-4637.

Journal article
Published: 11 June 2021 in Crystals
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Cerium and chromium co-doped gadolinium aluminum gallium garnets were prepared using sol-gel technique. These compounds potentially can be applied for NIR-LED construction, horticulture and theranostics. Additionally, magnesium and calcium ions were also incorporated into the structure. X-ray diffraction data analysis confirmed the all-cubic symmetry with an Ia-3d space group, which is appropriate for garnet-type materials. From the characterization of the luminescence properties, it was confirmed that both chromium and cerium emissions could be incorporated. Cerium luminescence was detected under 450 nm excitation, while for chromium emission, 270 nm excitation was used. The emission of chromium ions was exceptionally intense, although it was determined that these compounds are doped only by parts per million of Cr3+ ions. Typically, the emission maxima of chromium ions are located around 650–750 nm in garnet systems. However, in this case, the emission maximum for chromium is measured to be around 790 nm, caused by re-absorption of Cr3+ ions. The main observation of this study is that the switchable emission wavelength in a compound of single phase was obtained, despite the fact that doping with Cr ions was performed in ppm level, causing an intense emission in NIR region.

ACS Style

Greta Inkrataite; Gerardas Laurinavicius; David Enseling; Aleksej Zarkov; Thomas Jüstel; Ramunas Skaudzius. Characterization of GAGG Doped with Extremely Low Levels of Chromium and Exhibiting Exceptional Intensity of Emission in NIR Region. Crystals 2021, 11, 673 .

AMA Style

Greta Inkrataite, Gerardas Laurinavicius, David Enseling, Aleksej Zarkov, Thomas Jüstel, Ramunas Skaudzius. Characterization of GAGG Doped with Extremely Low Levels of Chromium and Exhibiting Exceptional Intensity of Emission in NIR Region. Crystals. 2021; 11 (6):673.

Chicago/Turabian Style

Greta Inkrataite; Gerardas Laurinavicius; David Enseling; Aleksej Zarkov; Thomas Jüstel; Ramunas Skaudzius. 2021. "Characterization of GAGG Doped with Extremely Low Levels of Chromium and Exhibiting Exceptional Intensity of Emission in NIR Region." Crystals 11, no. 6: 673.

Journal article
Published: 12 May 2021 in Solid State Sciences
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In the present work, a series of powdered Y1-xGdxFeO3 solid solutions (x from 0 to 1) was prepared by an aqueous sol-gel method. Structural properties of the synthesized species were investigated using powder X-ray diffraction (XRD), Raman and Mössbauer spectroscopies. It was demonstrated that single-phase compounds can be obtained in the whole compositional range between the end members of the series. Raman study revealed a gradual change of the Raman spectra depending on the chemical composition of samples. Room-temperature magnetic properties were shown to be strongly dependent on the ratio of Y3+ and Gd3+ ions in analyzed species. Consistent transition from hysteresis characteristic of YFeO3 to almost linear dependence of magnetization of GdFeO3 was observed with an increase of Gd content in prepared powders. On the other hand, this transition was accompanied by a significant increase of magnetization values.

ACS Style

Dovydas Karoblis; Aleksej Zarkov; Kestutis Mazeika; Dalis Baltrunas; Gediminas Niaura; Aldona Beganskiene; Aivaras Kareiva. YFeO3-GdFeO3 solid solutions: Sol-gel synthesis, structural and magnetic properties. Solid State Sciences 2021, 118, 106632 .

AMA Style

Dovydas Karoblis, Aleksej Zarkov, Kestutis Mazeika, Dalis Baltrunas, Gediminas Niaura, Aldona Beganskiene, Aivaras Kareiva. YFeO3-GdFeO3 solid solutions: Sol-gel synthesis, structural and magnetic properties. Solid State Sciences. 2021; 118 ():106632.

Chicago/Turabian Style

Dovydas Karoblis; Aleksej Zarkov; Kestutis Mazeika; Dalis Baltrunas; Gediminas Niaura; Aldona Beganskiene; Aivaras Kareiva. 2021. "YFeO3-GdFeO3 solid solutions: Sol-gel synthesis, structural and magnetic properties." Solid State Sciences 118, no. : 106632.

Journal article
Published: 25 March 2021 in Molecules
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In the present work, Cr-substituted Mg3Al1−xCrx layered double hydroxides (LDHs) were synthesised through the phase conversion of sol-gel-derived mixed-metal oxides in an aqueous medium. The chromium substitution level in the range of 1 to 25 mol% was investigated. It was demonstrated that all synthesised specimens were single-phase LDHs. The results of elemental analysis confirmed that the suggested synthetic sol-gel chemistry approach is suitable for the preparation of LDHs with a highly controllable chemical composition. The surface microstructure of sol-gel-derived Mg3Al1−xCrx LDHs does not depend on the chromium substitution level. The formation of plate-like agglomerated particles, which consist of hexagonally shaped nanocrystallites varying in size from approximately 200 to 300 nm, was observed. Optical properties of the synthesised Mg3Al1−xCrx LDHs were investigated by means of photoluminescence. All Cr-containing powders exhibited characteristic emission in the red region of the visible spectrum. The strongest emission was observed for the sample doped with 5 mol% Cr3+ ions. However, the emission intensity of samples doped with 1–10 mol% Cr3+ ions was relatively similar. A further increase in the Cr3+ ion concentration to 25 mol% resulted in severe concentration quenching.

ACS Style

Ligita Valeikiene; Inga Grigoraviciute-Puroniene; Arturas Katelnikovas; Aleksej Zarkov; Aivaras Kareiva. Investigation of Structural and Luminescent Properties of Sol-Gel-Derived Cr‑Substituted Mg3Al1−xCrx Layered Double Hydroxides. Molecules 2021, 26, 1848 .

AMA Style

Ligita Valeikiene, Inga Grigoraviciute-Puroniene, Arturas Katelnikovas, Aleksej Zarkov, Aivaras Kareiva. Investigation of Structural and Luminescent Properties of Sol-Gel-Derived Cr‑Substituted Mg3Al1−xCrx Layered Double Hydroxides. Molecules. 2021; 26 (7):1848.

Chicago/Turabian Style

Ligita Valeikiene; Inga Grigoraviciute-Puroniene; Arturas Katelnikovas; Aleksej Zarkov; Aivaras Kareiva. 2021. "Investigation of Structural and Luminescent Properties of Sol-Gel-Derived Cr‑Substituted Mg3Al1−xCrx Layered Double Hydroxides." Molecules 26, no. 7: 1848.

Journal article
Published: 08 March 2021 in Coatings
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In the present work, polycrystalline Bi0.67La0.33Fe0.5Sc0.5O3 thin films were synthesized using a simple and cost-effective chemical solution deposition process employing the spin coating technique. In order to check the feasibility of the fabrication of thin films on various types of substrates, the films were deposited on Pt-coated silicon, silicon, sapphire, corundum, fused silica and glass. Based on the results of thermogravimetric analysis of precursor and thermal stability study, it was determined that the optimal annealing temperature for the formation of perovskite structure is 600 °C. It was observed that the relative intensity of the pseudocubic peaks (001) p and (011) p in the XRD patterns is influenced by the nature of substrates, suggesting that the formed crystallites have some preferred orientation. Roughness of the films was determined to be dependent on the nature of the substrate.

ACS Style

Diana Griesiute; Dovydas Karoblis; Lina Mikoliunaite; Aleksej Zarkov; Andrei Salak; Aivaras Kareiva. Chemical Solution Deposition of La-Substituted BiFe0.5Sc0.5O3 Perovskite Thin Films on Different Substrates. Coatings 2021, 11, 307 .

AMA Style

Diana Griesiute, Dovydas Karoblis, Lina Mikoliunaite, Aleksej Zarkov, Andrei Salak, Aivaras Kareiva. Chemical Solution Deposition of La-Substituted BiFe0.5Sc0.5O3 Perovskite Thin Films on Different Substrates. Coatings. 2021; 11 (3):307.

Chicago/Turabian Style

Diana Griesiute; Dovydas Karoblis; Lina Mikoliunaite; Aleksej Zarkov; Andrei Salak; Aivaras Kareiva. 2021. "Chemical Solution Deposition of La-Substituted BiFe0.5Sc0.5O3 Perovskite Thin Films on Different Substrates." Coatings 11, no. 3: 307.

Journal article
Published: 03 February 2021 in Scientific Reports
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In the present work, gadolinium substitution effects on the properties of yttrium manganite YxGd1−xMn0.97Fe0.03O3 (x from 0 to 1 with a step of 0.2) synthesized by an aqueous sol–gel method have been investigated. Partial substitution of Mn3+ by 57Fe3+ in the manganite was also performed in order to investigate deeper the structural properties of synthesized compounds applying Mössbauer spectroscopy. It was demonstrated that substitution of Y3+ by Gd3+ ions leads to the changes of structural, magnetic and morphological properties of investigated system. The crystal structure gradually transformed from hexagonal to orthorhombic with an increase of Gd3+ content in the crystal lattice. The mixed phase was obtained when x = 0.6, whereas other compounds were determined to be monophasic. Magnetization measurements revealed paramagnetic behavior of all specimens, however magnetization values were found to be dependent on chemical composition of the samples. Solid solutions with orthorhombic structure revealed higher magnetization values compared to those of hexagonal samples. The highest magnetization was observed for pure GdMn0.97Fe0.03O3. Structural properties were investigated by powder X-ray diffraction, Mössbauer, FTIR and Raman spectroscopies. Morphological features of the synthesized specimens were studied by scanning electron microscopy (SEM).

ACS Style

Dovydas Karoblis; Aleksej Zarkov; Edita Garskaite; Kestutis Mazeika; Dalis Baltrunas; Gediminas Niaura; Aldona Beganskiene; Aivaras Kareiva. Study of gadolinium substitution effects in hexagonal yttrium manganite YMnO3. Scientific Reports 2021, 11, 1 -14.

AMA Style

Dovydas Karoblis, Aleksej Zarkov, Edita Garskaite, Kestutis Mazeika, Dalis Baltrunas, Gediminas Niaura, Aldona Beganskiene, Aivaras Kareiva. Study of gadolinium substitution effects in hexagonal yttrium manganite YMnO3. Scientific Reports. 2021; 11 (1):1-14.

Chicago/Turabian Style

Dovydas Karoblis; Aleksej Zarkov; Edita Garskaite; Kestutis Mazeika; Dalis Baltrunas; Gediminas Niaura; Aldona Beganskiene; Aivaras Kareiva. 2021. "Study of gadolinium substitution effects in hexagonal yttrium manganite YMnO3." Scientific Reports 11, no. 1: 1-14.

Research article
Published: 20 January 2021 in Crystal Growth & Design
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The present work investigates the crystallization and phase evolution of amorphous calcium phosphate (ACP) partially substituted with smaller (Mg2+, Zn2+) and larger (Sr2+, Ba2+) divalent ions in the range from 1 to 10 mol % (M/P = 1.5:1). It has been demonstrated that the crystallization of ACP to tricalcium phosphate (TCP) and subsequent phase transformations between TCP polymorphs strongly depend on the nature and concentration of the substituents in the ACP matrix. Two different effects induced by the presence of foreign ions were observed. Substitution with smaller ions did not affect the crystallization temperature but promoted the formation of β-TCP at a significantly lower temperature compared to the phase evolution of pristine ACP. Moreover, the effect of Mg was found to be more significant than that of Zn in the transformation of metastable α-TCP to β-TCP. On the other hand, substitution with larger ions retarded the crystallization process, which was observed at elevated temperatures. While the substitution level of 10 mol % of Sr did not affect the thermal stability of metastable α-TCP, the presence of 10 mol % of Ba stabilized α-TCP crystal structure and totally prevented the phase transition to β-TCP.

ACS Style

Lauryna Sinusaite; Aivaras Kareiva; Aleksej Zarkov. Thermally Induced Crystallization and Phase Evolution of Amorphous Calcium Phosphate Substituted with Divalent Cations Having Different Sizes. Crystal Growth & Design 2021, 21, 1242 -1248.

AMA Style

Lauryna Sinusaite, Aivaras Kareiva, Aleksej Zarkov. Thermally Induced Crystallization and Phase Evolution of Amorphous Calcium Phosphate Substituted with Divalent Cations Having Different Sizes. Crystal Growth & Design. 2021; 21 (2):1242-1248.

Chicago/Turabian Style

Lauryna Sinusaite; Aivaras Kareiva; Aleksej Zarkov. 2021. "Thermally Induced Crystallization and Phase Evolution of Amorphous Calcium Phosphate Substituted with Divalent Cations Having Different Sizes." Crystal Growth & Design 21, no. 2: 1242-1248.

Journal article
Published: 11 January 2021 in Ceramics International
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In the present work, effect of Mn doping on hydrolysis rate of low-temperature synthesized metastable α-tricalcium phosphate (α-TCP) was investigated. α-TCP powders containing different amount of Mn2+ ions (0, 0.5 and 1 mol%) were synthesized by wet co-precipitation process, followed by annealing and crystallization of as-precipitated amorphous calcium phosphate at 700 °C. It was demonstrated that the presence of Mn2+ ions significantly retards hydrolysis rate of α-TCP. While pristine α-TCP fully hydrolyzed with a conversion to calcium-deficient hydroxyapatite in 10 h, complete hydrolysis of α-TCP doped with 0.5 and 1 mol% of Mn occurred only after 20 and 35 h, respectively. Initial and final products were characterized by X-ray diffraction (XRD) analysis, infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Chemical composition of starting and fully hydrolyzed α-TCP powders was determined by inductively coupled plasma optical emission spectrometry (ICP-OES).

ACS Style

Lauryna Sinusaite; Anton Popov; Eva Raudonyte-Svirbutaviciene; Jen-Chang Yang; Aivaras Kareiva; Aleksej Zarkov. Effect of Mn doping on hydrolysis of low-temperature synthesized metastable alpha-tricalcium phosphate. Ceramics International 2021, 47, 12078 -12083.

AMA Style

Lauryna Sinusaite, Anton Popov, Eva Raudonyte-Svirbutaviciene, Jen-Chang Yang, Aivaras Kareiva, Aleksej Zarkov. Effect of Mn doping on hydrolysis of low-temperature synthesized metastable alpha-tricalcium phosphate. Ceramics International. 2021; 47 (9):12078-12083.

Chicago/Turabian Style

Lauryna Sinusaite; Anton Popov; Eva Raudonyte-Svirbutaviciene; Jen-Chang Yang; Aivaras Kareiva; Aleksej Zarkov. 2021. "Effect of Mn doping on hydrolysis of low-temperature synthesized metastable alpha-tricalcium phosphate." Ceramics International 47, no. 9: 12078-12083.

Journal article
Published: 13 December 2020 in Solid State Sciences
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In this study, BiFe1-xMnxO3 (BiFeMnO; x from 0 to 0.5) solid solutions were prepared by low temperature sol-gel processing. It was demonstrated that structural, magnetic and morphological properties of BiFeMnO samples are dependent on the chemical composition of the synthesized BiFe1-xMnxO3 solid solutions. The thermal behaviour of the Bi–Fe–Mn–O precursor gels was investigated by thermogravimetric and differential scanning calorimetry (TG-DSC) measurements. From X-ray diffraction (XRD) analysis it was observed that monophasic BiFe1-xMnxO3 samples have formed up to 25 mol% of substitution. The Rietveld analysis showed that the structure of BiFeMnO specimens can be indexed by rhombohedral or orthorhombic unit cell depending on Mn3+ content. Scanning electron microscopy (SEM) was used to investigate samples morphology and revealed, that smaller particles form when Mn3+ is present inside the structure. Moreover, magnetic properties of solid solutions were also investigated, and antiferromagnetism and weak ferromagnetism were observed for the samples.

ACS Style

Ramunas Diliautas; Aldona Beganskiene; Dovydas Karoblis; Kestutis Mazeika; Dalis Baltrunas; Aleksej Zarkov; Rimantas Raudonis; Aivaras Kareiva. Reinspection of formation of BiFe1-xMnxO3 solid solutions via low temperature sol-gel synthesis route. Solid State Sciences 2020, 111, 106458 .

AMA Style

Ramunas Diliautas, Aldona Beganskiene, Dovydas Karoblis, Kestutis Mazeika, Dalis Baltrunas, Aleksej Zarkov, Rimantas Raudonis, Aivaras Kareiva. Reinspection of formation of BiFe1-xMnxO3 solid solutions via low temperature sol-gel synthesis route. Solid State Sciences. 2020; 111 ():106458.

Chicago/Turabian Style

Ramunas Diliautas; Aldona Beganskiene; Dovydas Karoblis; Kestutis Mazeika; Dalis Baltrunas; Aleksej Zarkov; Rimantas Raudonis; Aivaras Kareiva. 2020. "Reinspection of formation of BiFe1-xMnxO3 solid solutions via low temperature sol-gel synthesis route." Solid State Sciences 111, no. : 106458.

Journal article
Published: 10 December 2020 in Crystals
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In this study, the aqueous sol-gel method was employed for the synthesis of (1−x)SrTiO3-xBiMnO3 solid solutions. Powder X-ray diffraction analysis confirmed the formation of single-phase perovskites with a cubic structure up to x = 0.3. A further increase of the BiMnO3 content led to the formation of a negligible amount of neighboring Mn3O4 impurity, along with the major perovskite phase. Infrared (FT-IR) analysis of the synthesized specimens showed gradual spectral change associated with the superposition effect of Mn-O and Ti-O bond lengths. By introducing BiMnO3 into the SrTiO3 crystal structure, the size of the grains increased drastically, which was confirmed by means of scanning electron microscopy. Magnetization studies revealed that all solid solutions containing the BiMnO3 component can be characterized as paramagnetic materials. It was observed that magnetization values clearly correlate with the chemical composition of powders, and the gradual increase of the BiMnO3 content resulted in noticeably higher magnetization values.

ACS Style

Dovydas Karoblis; Ramunas Diliautas; Eva Raudonyte-Svirbutaviciene; Kestutis Mazeika; Dalis Baltrunas; Aldona Beganskiene; Aleksej Zarkov; Aivaras Kareiva. The Synthesis and Characterization of Sol-Gel-Derived SrTiO3-BiMnO3 Solid Solutions. Crystals 2020, 10, 1125 .

AMA Style

Dovydas Karoblis, Ramunas Diliautas, Eva Raudonyte-Svirbutaviciene, Kestutis Mazeika, Dalis Baltrunas, Aldona Beganskiene, Aleksej Zarkov, Aivaras Kareiva. The Synthesis and Characterization of Sol-Gel-Derived SrTiO3-BiMnO3 Solid Solutions. Crystals. 2020; 10 (12):1125.

Chicago/Turabian Style

Dovydas Karoblis; Ramunas Diliautas; Eva Raudonyte-Svirbutaviciene; Kestutis Mazeika; Dalis Baltrunas; Aldona Beganskiene; Aleksej Zarkov; Aivaras Kareiva. 2020. "The Synthesis and Characterization of Sol-Gel-Derived SrTiO3-BiMnO3 Solid Solutions." Crystals 10, no. 12: 1125.

Journal article
Published: 08 December 2020 in Applied Sciences
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The aim of the work was to check how the introduction of alkali and cobalt ions into a manganese structure can affect the structural disorder and, in consequence, lead to the changes (improvements) of magnetic properties. The high-pressure sintering technique was applied to check if the external factor can modify the magnetization of manganites. Nanocrystalline La0.9A0.1Mn0.9Co0.1O3 (where A is Li, K, Na) powders were synthesized by the combustion technique. The respective powders were used for nanoceramics preparation by the high-pressure sintering technique. The structure and morphology of the compounds were studied by X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Magnetization studies for all compounds were performed in order to check the changes induced by either codoping or the sintering pressure. It was found that the type of the dopant ion and sintering pressure produced significant changes to the magnetic properties of the studied compounds. Alkali ions lead to the stabilization of Co ions in the +2 oxidation state and the formation of positive exchange interactions Mn3+–Mn4+ and Co2+–Mn4+ and the subsequent increase in remanent magnetization. High sintering pressure leads to a decrease in grain size and reduction of long-range ferromagnetic order and lower magnetization.

ACS Style

Paweł Głuchowski; Ruslan Nikonkov; Robert Tomala; Wiesław Stręk; Tatsiana Shulha; Maria Serdechnova; Aleksej Zarkov; Tomas Murauskas; Andrius Pakalaniškis; Ramūnas Skaudžius; Aivaras Kareiva; Andrei Kholkin; Maxim Bushinsky; Sergei Latushka; Dmitry Karpinsky. Impact of Alkali Ions Codoping on Magnetic Properties of La0.9A0.1Mn0.9Co0.1O3 (A: Li, K, Na) Powders and Ceramics. Applied Sciences 2020, 10, 8786 .

AMA Style

Paweł Głuchowski, Ruslan Nikonkov, Robert Tomala, Wiesław Stręk, Tatsiana Shulha, Maria Serdechnova, Aleksej Zarkov, Tomas Murauskas, Andrius Pakalaniškis, Ramūnas Skaudžius, Aivaras Kareiva, Andrei Kholkin, Maxim Bushinsky, Sergei Latushka, Dmitry Karpinsky. Impact of Alkali Ions Codoping on Magnetic Properties of La0.9A0.1Mn0.9Co0.1O3 (A: Li, K, Na) Powders and Ceramics. Applied Sciences. 2020; 10 (24):8786.

Chicago/Turabian Style

Paweł Głuchowski; Ruslan Nikonkov; Robert Tomala; Wiesław Stręk; Tatsiana Shulha; Maria Serdechnova; Aleksej Zarkov; Tomas Murauskas; Andrius Pakalaniškis; Ramūnas Skaudžius; Aivaras Kareiva; Andrei Kholkin; Maxim Bushinsky; Sergei Latushka; Dmitry Karpinsky. 2020. "Impact of Alkali Ions Codoping on Magnetic Properties of La0.9A0.1Mn0.9Co0.1O3 (A: Li, K, Na) Powders and Ceramics." Applied Sciences 10, no. 24: 8786.

Journal article
Published: 27 November 2020 in Open Chemistry
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Traditional Chinese Medicines (TCM) can be contaminated with heavy metals, and therefore, the aim of this study is to analyze the Fe, Mn, Zn, Cu, Cd, Pb, Cr, and phenolic compounds contents in TCM plants used against civilization diseases. Metals were determined by flame atomic absorption spectroscopy (FAAS) for Fe, Mn, Zn, and Cu and inductively coupled plasma-optical emission spectroscopy (ICP-OES) for Pb, Cd, and Cr. The total phenolic, flavonoid, and phenolic acid contents were determined by HPLC and UV/vis spectrometry. The contents of the studied elements were highest in Radix Rehmanniae, whereas lowest in Fructus Lycii and Fructus Crataegi. The studied metals were assayed in the decreasing order: Fe, Zn, Mn, Cu, Cr, Pb, and Cd. Radix Rehmanniae Glutinosae Preparata showed the lowest phenolic composition, while Fructus Lycii showed the richest content. Principal component analysis (PCA) revealed that the contents of ferulic acid, caffeic acid, rutin, and Cu, Cr, and Cd were among the most important factors responsible for the differentiation between the investigated medicinal plants. Cluster analysis (CA) showed that the TCM samples originating from the same botanical plant species were often found in the same cluster, which confirms the similar level of studied elements determined within the samples.

ACS Style

Pawel Konieczynski; Aleksej Zarkov; Agnieszka Viapiana; Mateusz Kaszuba; Lukasz Bielski; Marek Wesolowski. Investigations of metallic elements and phenolics in Chinese medicinal plants. Open Chemistry 2020, 18, 1381 -1390.

AMA Style

Pawel Konieczynski, Aleksej Zarkov, Agnieszka Viapiana, Mateusz Kaszuba, Lukasz Bielski, Marek Wesolowski. Investigations of metallic elements and phenolics in Chinese medicinal plants. Open Chemistry. 2020; 18 (1):1381-1390.

Chicago/Turabian Style

Pawel Konieczynski; Aleksej Zarkov; Agnieszka Viapiana; Mateusz Kaszuba; Lukasz Bielski; Marek Wesolowski. 2020. "Investigations of metallic elements and phenolics in Chinese medicinal plants." Open Chemistry 18, no. 1: 1381-1390.

Journal article
Published: 25 November 2020 in Crystals
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For the first time to the best of our knowledge, cobalt-chromium spinels CoCr2–xGaxO4 with different amounts of gallium (x = 0−2 with a step of 0.5) were synthesized via the aqueous sol–gel route as ceramic pigments. The phase composition, crystallite size, morphological features, and color parameters of new compositions and their corresponding ceramic glazes were investigated using XRD, CIELab, SEM, and optical microscopy. It was demonstrated that the formation of single-phase CoCr2–xGaxO4 samples was problematic. Full substitution of Cr3+ by Ga3+ ion in the spinel resulted in the formation of light blue powders, which yielded violetish blue color for the corresponding ceramic glaze.

ACS Style

Egle Grazenaite; Edita Garskaite; Zivile Stankeviciute; Eva Raudonyte-Svirbutaviciene; Aleksej Zarkov; Aivaras Kareiva. Ga-Substituted Cobalt-Chromium Spinels as Ceramic Pigments Produced by Sol–Gel Synthesis. Crystals 2020, 10, 1078 .

AMA Style

Egle Grazenaite, Edita Garskaite, Zivile Stankeviciute, Eva Raudonyte-Svirbutaviciene, Aleksej Zarkov, Aivaras Kareiva. Ga-Substituted Cobalt-Chromium Spinels as Ceramic Pigments Produced by Sol–Gel Synthesis. Crystals. 2020; 10 (12):1078.

Chicago/Turabian Style

Egle Grazenaite; Edita Garskaite; Zivile Stankeviciute; Eva Raudonyte-Svirbutaviciene; Aleksej Zarkov; Aivaras Kareiva. 2020. "Ga-Substituted Cobalt-Chromium Spinels as Ceramic Pigments Produced by Sol–Gel Synthesis." Crystals 10, no. 12: 1078.

Journal article
Published: 06 November 2020 in Optical Materials
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In this study, praseodymium substituted yttrium aluminium garnet (Y3-xPrxAl5O12; YPrAG (0 ≤ x ≤ 3)) powders were synthesized by an aqueous sol-gel method and investigated. YPrAG samples were characterized by X-ray diffraction (XRD) analysis, solid state nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Luminescence measurements of YPrAG samples were performed as well. It was demonstrated, that three phase regions exist depending on the substitutional level of Pr3+ in Y3-xPrxAl5O12. The single-phase cubic garnets have formed up to x = 0.30. The mixture of garnet and trigonal perovskite (Y1-xPrxAlO3) phase have formed when x is between 0.45 and 2.00. The perovskite phase was the main crystalline phase with further increasing amount of praseodymium, no garnet structure was observed. The amorphous impurity phases were detected by solid state NMR spectroscopy. Two broad and intense emission bands in the UV region peaked at 325 and 381 nm and several sharp emission bands in the visible region were determined by investigating the luminescence properties of the Y3-xPrxAl5O12 mixed-metal oxides.

ACS Style

Andrius Pakalniskis; Arunas Marsalka; Rimantas Raudonis; Vytautas Balevicius; Aleksej Zarkov; Ramunas Skaudzius; Aivaras Kareiva. Sol-gel synthesis and study of praseodymium substitution effects in yttrium aluminium garnet Y3-xPrxAl5O12. Optical Materials 2020, 111, 110586 .

AMA Style

Andrius Pakalniskis, Arunas Marsalka, Rimantas Raudonis, Vytautas Balevicius, Aleksej Zarkov, Ramunas Skaudzius, Aivaras Kareiva. Sol-gel synthesis and study of praseodymium substitution effects in yttrium aluminium garnet Y3-xPrxAl5O12. Optical Materials. 2020; 111 ():110586.

Chicago/Turabian Style

Andrius Pakalniskis; Arunas Marsalka; Rimantas Raudonis; Vytautas Balevicius; Aleksej Zarkov; Ramunas Skaudzius; Aivaras Kareiva. 2020. "Sol-gel synthesis and study of praseodymium substitution effects in yttrium aluminium garnet Y3-xPrxAl5O12." Optical Materials 111, no. : 110586.

Journal article
Published: 19 October 2020 in Chemija
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The development of proton conductive polyacrylate membranes based on acrylonitrile, sodium 4-vinylbenzenesulfonate, acrylic acid, ethylene glycol dimethacrylate and hybrid polyacrylate/silica membranes is reported in this article. Polyacrylate membranes were synthesized via UV-initiated copolymerization; for the synthesis of polyacrylate/silica membranes 3-methacryloxypropyl trimethoxysilane-based sol–gel system was introduced into the polymerizing mixture.

ACS Style

Mariia Zhyhailo; Iryna Yevchuk; Mykhaylo Yatsyshyn; Sergiy Korniy; Oksana Demchyna; Rostyslav Musiy; Rimantas Raudonis; Aleksej Zarkov; Aivaras Kareiva. Preparation of polyacrylate/silica membranes for fuel cell application by in situ UV polymerization. Chemija 2020, 31, 1 .

AMA Style

Mariia Zhyhailo, Iryna Yevchuk, Mykhaylo Yatsyshyn, Sergiy Korniy, Oksana Demchyna, Rostyslav Musiy, Rimantas Raudonis, Aleksej Zarkov, Aivaras Kareiva. Preparation of polyacrylate/silica membranes for fuel cell application by in situ UV polymerization. Chemija. 2020; 31 (4):1.

Chicago/Turabian Style

Mariia Zhyhailo; Iryna Yevchuk; Mykhaylo Yatsyshyn; Sergiy Korniy; Oksana Demchyna; Rostyslav Musiy; Rimantas Raudonis; Aleksej Zarkov; Aivaras Kareiva. 2020. "Preparation of polyacrylate/silica membranes for fuel cell application by in situ UV polymerization." Chemija 31, no. 4: 1.