Alexander V. Knotko

Dr. Alexander V. Knotko


Research Focus & Metrics

Academic Career Length

27Years (2000-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
25 April 2022 in Materials
Verified
Journal Article
Open access
PDF file
Tatiana V. SafronovaTatiana V. Safronova
Tatiana V. Safronova
AKAndrey Kiselev
Andrey Kiselev
ISIrina Selezneva
Irina Selezneva
TSTatiana Shatalova
Tatiana Shatalova
YLYulia Lukina
Yulia Lukina
AKAlexander V. Knotko
Alexander V. Knotko
Ceramic samples based on β-calcium pyrophosphate β-Ca2P2O7 were prepared from powders of γ-calcium pyrophosphate γ-Ca2P2O7 with preset molar ratios Ca/P = 1, 0.975 and 0.95 using firing at 900, 1000, and 1100 °C. Calcium lactate pentahydrate Ca(C3H5O3)2⋅5H2O and monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O were treated in an aqua medium in mechanical activation conditions to prepare powder mixtures with preset molar ratios Ca/P containing calcium hydrophosphates with Ca/P = 1 (precursors of calcium pyrophosphate Ca2P2O7). These powder mixtures containing calcium hydrophosphates with Ca/P = 1 and non-reacted starting salts were heat-treated at 600 °C after drying and disaggregation in acetone. Phase composition of all powder mixtures after heat treatment at 600 °C was presented by γ-calcium pyrophosphate γ-Ca2P2O7 according to the XRD data. The addition of more excess of monocalcium phosphate monohydrate Ca(H2PO4)2·H2O (with appropriate molar ratio of Ca/P = 1) to the mixture of starting components resulted in lower dimensions of γ-calcium pyrophosphate (γ-Ca2P2O7) individual particles. The grain size of ceramics increased both with the growth in firing temperature and with decreasing molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t melt = 984 °C), formed from monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O, acted similar to a liquid phase sintering additive. It was confirmed by tests in vitro that prepared ceramic materials with preset molar ratios Ca/P = 1, 0.975, and 0.95 and phase composition presented by β-calcium pyrophosphate β-Ca2P2O7 were biocompatible and could maintain bone cells proliferation.

1 July 2014 in Doklady Chemistry
Verified
Journal Article
Closed access
PDF file
SKSergey Klimonsky
Sergey Klimonsky
TBT. Bakhia
T. Bakhia
AKAlexander V. Knotko
Alexander V. Knotko
ALA. V. Lukashin
A. V. Lukashin

1 March 2016 in Journal of Solid State Chemistry
Verified
Journal Article
Closed access
AMA.V. Morozkin
A.V. Morozkin
AKAlexander V. Knotko
Alexander V. Knotko
VYV.O. Yapaskurt
V.O. Yapaskurt
MMMarianne Moedlinger
Marianne Moedlinger
MPM. Pani
M. Pani
SMS.K. Malik
S.K. Malik

23 August 2023 in Catalysts
Verified
Journal Article
Open access
PDF file
AVAndrey E. Vertepov
Andrey E. Vertepov
AFAnna A. Fedorova
Anna A. Fedorova
ABAlexander M. Batkin
Alexander M. Batkin
AKAlexander V. Knotko
Alexander V. Knotko
KMKonstantin Maslakov
Konstantin Maslakov
AKAlexander L Kustov
Alexander L Kustov
A series of mixed copper (II)—zinc oxide catalysts supported on unmodified and ceria-modified silica supports were synthesized using β-cyclodextrin as a template. The novelty of this work lies in the use of cyclosextrins for the template synthesis of catalyst supports. The obtained samples were analyzed by XRD, SEM-EDX, low-temperature nitrogen physisorption, XPS, and EPR. The magnetic properties of the catalysts were also measured. The thermal decomposition of precursors was analyzed by TGA combined with mass-spectrometric analysis of the evolved gases. The effects of the support pore size, the nature of the active phase and its loading, as well as the sequence of component deposition on the catalyst performance in the CO2 conversion to methanol were studied. The catalysts with cerium added at the gelation stage demonstrated the best performance. The selectivity of these samples reaches values of more than 90% over a fairly ide temperature range, with the productivity reaching 480 g/kg cat·h at 300 °C.

23 February 2022 in Preprints.org
Verified
Preprint
Open access
PDF file
Tatiana V. SafronovaTatiana V. Safronova
Tatiana V. Safronova
AKAndrey S. Kiselev
Andrey S. Kiselev
ISIrina Selezneva
Irina Selezneva
TSTatiana Shatalova
Tatiana Shatalova
YLYulia Lukina
Yulia Lukina
AKAlexander V. Knotko
Alexander V. Knotko
Ceramic samples based on b-calcium pyrophosphate b-Ca2P2O7 were prepared using firing at 900, 1000, and 1100 oC from powders of g-calcium pyrophosphate g-Ca2P2O7 with preset molar ratios Ca/P=1; 0,975 and 0,95. To prepare powders of g-calcium pyrophosphate g-Ca2P2O7 with preset molar ratio Ca/P=1; 0,975 and 0,95 powder mixtures based on calcium lactate pentahydrate Ca(C3H5O3)2⋅5H2O and, monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O were treated in an aqua medium in mechanical activation conditions, dried, disaggregated in acetone, and heat-treated at 600 oC. The phase composition of powder mixtures after treatment if planetary mill in aqua medium included both brushite CaHPO4⋅2H2O or monetite CaHPO4, and starting salts. The phase composition of all powder mixtures after disaggregation in acetone in planetary mill included monetite CaHPO4 and starting salts. After heat treatment at 600 oC according to the XRD data phase composition of all powder mixtures was presented by g-calcium pyrophosphate g-Ca2P2O7. The grain size of ceramics increased both with the growth of firing temperature and with decreasing of molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t melt =960–968 oC) formed from monocalcium phosphate monohydrate Ca(H2PO4)2⋅H2O acted like a liquid phase sintering additive. It was confirmed by tests in vitro, that prepared ceramic materials with preset molar ratio Ca/P=1; 0,975 and 0,95 and phase composition presented by b-calcium pyrophosphate b-Ca2P2O7 according to XRD data were biocompatible and could maintain bone cells proliferation.

6 January 2023 in Materials
Verified
Journal Article
Open access
PDF file
RKRustam Kamilov
Rustam Kamilov
JYJahongir Z. Yuldoshev
Jahongir Z. Yuldoshev
AKAlexander V. Knotko
Alexander V. Knotko
AGAnastasia V. Grigorieva
Anastasia V. Grigorieva
The double perovskite halides A2BIBIIIX6 provide flexibility for various formulation adjustments and are of less toxicity in comparison with well-discussed complex lead halide derivatives. Such type of structure can be formed by replacing two Pb2+ ions in the cubic lattice with a pair of non-toxic heterovalent (monovalent and trivalent) metal cations, such as silver and indium. The aim of this work is to briefly characterize the phase equilibria in the ternary system CsBr-AgBr-InBr3 and investigate the thermodynamic availability of synthesis of Cs2AgInBr6 double perovskite phase by solid-state sintering or melt crystallization. The results demonstrate the unfeasibility of the Cs2AgInBr6 phase but high stability of the corresponding binary bromides perspective for optoelectronics.