Dina V. Deyneko
Moscow State University
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Featured researches published by Dina V. Deyneko.
Inorganic Materials | 2013
Dina V. Deyneko; S. Yu. Stefanovich; A. V. Mosunov; O. V. Baryshnikova; Bogdan I. Lazoryak
We have prepared Ca9.5 − xPbxM(PO4)7 (M = Mg, Zn, Cd) and Ca10.5 − xPbx(PO4)7 solid solutions. A polar whitlockite-like (sp. gr. R3c) crystal structure exists in the range 0 ≤ x ≤ 1.5 for all of the M cations in Ca9.5 − xPbxM(PO4)7 and in the range 0 ≤ x ≤ 2.5 for Ca10.5 − xPbx(PO4)7. X-ray powder diffraction profile analysis results for Ca8.5PbCd(PO4)7 powder demonstrate that the small divalent M cations reside predominantly on the octahedral site M5 of the whitlockite structure, the calcium cation occupy the M1–M3 sites, and the lead cations are located primarily on the M4 site. Differential scanning calorimetry, second-harmonic generation, and dielectric permittivity data indicate that all of the synthesized phosphates are high-temperature ferroelectrics. The highest Curie temperatures are offered by the x = 0.5 materials, in which most of the lead resides in the spacious oxygen polyhedra M4 and only a small amount of lead is incorporated into the smaller polyhedra around M1–M3. The nonlinear optical activity has a maximum in the middle of the solid-solution series and is an order of magnitude higher than that of the parent, lead-free phases.
Inorganic Materials | 2016
Dina V. Deyneko; Vladimir A. Morozov; S. Yu. Stefanovich; Alexei A. Belik; Bogdan I. Lazoryak; Oleg I. Lebedev
Structural changes in Sr9In(PO4)7 during the antiferroelectric (AFE) phase transition are studied by X-ray powder diffraction, electron microscopy, second-harmonic-generation, and dielectric measurements. Sr9In(PO4)7 complements a group of Ca3(VO4)2-type ferroelectric (FE) phosphates and vanadates and is the first example of an AFE material in this family. Antiparallel shifts of Sr atoms from their average positions and ordering of the P1O4 tetrahedra form two contributions in the structural mechanism of the AFE phase transition: a displacive contribution and an order-disorder constituent, respectively. The displacive and order-disorder type of structural changes may account for the obtained value of the Curie–Weiss constant (C ~ 104 K) which is in between the value usually observed for pure displacive (C ~ 105 K) and that for orderdisorder phase transitions (C ~ 103 K). The structural mechanism of the AFE phase transition in Sr9In(PO4)7 is very similar to that of the FE phase transition in Ca9R(PO4)7 and Ca9R(VO4)7. Both displacive and orderdisorder contributions are responsible for the physical properties of the Ca3(VO4)2-type materials.
Zeitschrift Fur Kristallographie | 2018
Bogdan I. Lazoryak; Dina V. Deyneko; S. M. Aksenov; Sergey Yu. Stefanovich; E. A. Fortalnova; Darya A. Petrova; O. V. Baryshnikova; Miron Kosmyna; Aleksey N. Shekhovtsov
Abstract Single crystals of Ca9Y(VO4)7 (1), Ca9Y(VO4)7:Li+ (2) and Ca9Y(VO4)7:Mg2+ (3) were grown by the Czochralski method. Their chemical composition was analyzed by ICP spectroscopy and their crystal structure was examined by single crystal X-ray analysis. The crystals are characterized by trigonal symmetry, space group R3c. Hexagonal unit-cell parameters are as follows: a=10.8552(1) Å, c=38.0373(2) Å, V=3881.65(1) Å3 for 1; a=10.8570(1) Å, c=38.0161(3) Å, V=3880.77(4) Å3 for 2; a=10.8465(1) Å, c=38.0366(2) Å, V=3875.36(3) Å3 for 3. All crystals are characterized by β-Ca3(PO4)2-type structure with statistical distribution of Ca2+ and Y3+ over M1, M2 and M5 sites in different ratios and with completely empty M4-cationsite. The impurity of Mg2+cations in structure 2 has been detected in octahedral M5 site. Ferroelectric phase transitions are evidenced by DSC and SHG. At about 1220 and 1300 K, they demonstrate phase transitions. Upon heating the symmetry of the crystal structure changes according to the scheme R3c→R3̅c→R3̅m and is restored during consequent cooling. The first of them is of ferroelectric and the second of non-ferroelectric nature. Even a small amount of impurities in Ca9Y(VO4)7 structure is accompanied by a noticeable decrease in the temperature of the ferroelectric-paraelectric phase transition.
Zeitschrift Fur Kristallographie | 2014
Dina V. Deyneko; S. M. Aksenov; Vladimir A. Morozov; Sergey Yu. Stefanovich; O. V. Dimitrova; Oksana V. Barishnikova; Bogdan I. Lazoryak
Abstract A new hydrogen-containing Ca9(Fe0.63Mg0.37)H0.37(PO4)7 phosphate with the whitlockite-type structure has been synthesized by a hydrothermal method and its structure has been studied by the single-crystal X-ray diffraction. The compound crystallizes in the trigonal space group R3c (traditional for compounds with the whitlockite-type structure) with unit-cell parameters: a=10.3533(1) Å, c=37.1097(4) Å. The structure has been determined using the “charge flipping” method. Ca9(Fe0.63Mg0.37)H0.37(PO4)7 structure is similar to that of other members of the whitlockite-type family. The presence of hydrogen in the structure leads to the formation of OH-group with one of the oxygen of PO4-tetrahedra. Based on an analysis of the bond valence sums (BVS) a conclusion has been made about localization of H atoms in the structure. Smaller values of BVS for O1 and O10 atoms than ones for other oxygen atoms indicate localization of H atoms between them in a position with site symmetry 18b.
Inorganic Chemistry | 2018
S. M. Aksenov; N. A. Yamnova; Elena Yu. Borovikova; A. S. Volkov; D. A. Ksenofontov; O. V. Dimitrova; O. A. Gurbanova; Dina V. Deyneko; Fabrice Dal Bo; Peter C. Burns
The bismuth(III) oxophosphate Bi3(PO4)O3 was obtained by hydrothermal synthesis. The unit cell has a = 5.6840(6) Å, b = 7.0334(7) Å, c = 9.1578(9) Å, α = 78.958(2)°, β = 77.858(2)°, γ = 68.992(2)°, V = 331.41(6) Å3, space group P1̅, and Z = 2. The crystal chemical formula that reflects the presence of oxo-centered tetrahedra and triangles is 2D[OIIIOIV2Bi3](PO4). The crystal structure contains [O3Bi3]3+∞∞-heteropolyhedral corrugated layers parallel to (001), which alternate along [001] with isolated (PO4) tetrahedra. The structural complexity parameters are v = 22 atoms, IG = 3.459 bits/atoms, and IG,total = 76.107 bits/unit cell, and thus Bi3(PO4)O3 is the simplest pure bismuth(III) oxophosphate.
CrystEngComm | 2018
Bogdan I. Lazoryak; Dina V. Deyneko; S. M. Aksenov; Vadim V. Grebenev; Sergey Yu. Stefanovich; K. N. Belikov; Miron Kosmyna; Alexey Shekhovtsov; Adrian Sulich; W. Paszkowicz
Grown by the Czochralski method, pure magnesium and lithium doped Ca9Y(VO4)7 single crystals (Ca9Y(VO4)7 (C1), Ca9Y(VO4)7:Li (C2) and Ca9Y(VO4)7:Mg (C3), respectively) are characterized by means of chemical analysis, X-ray diffraction analysis and high-temperature dielectric spectroscopy. All crystals demonstrate good structural performance with almost isotropic micromosaics, free of extended defects and mechanical stress. Evidences for mobile domain structure are observed below the ferroelectric Curie temperature at 1213 ± 5 K. The temperatures of ferroelectric-paraelectric phase transitions in Ca9Y(VO4)7, Ca9Y(VO4)7:Li and Ca9Y(VO4)7:Mg almost coincide. In the paraelectric phase in these crystals, there is another phase transition at 1293 ± 5 K. The electrical nature and temperatures of both transitions are in agreement with the sequence of phases R3c → Rc → Rm earlier suggested to occur at the same temperatures in Ca9Y(VO4)7 on the basis of other experimental evidences. In all temperature modifications of R3c, Rc, and Rm, the Ca9Y(VO4)7:Li crystal has the highest activation energy and two-orders lower Ca2+ ionic conductivity in comparison with nominally pure Ca9Y(VO4)7 with the conductivity of Ca9Y(VO4)7:Mg lying in between. The observed influence of guest atoms is connected with different structural roles of lithium and magnesium in whitlockite crystal lattices where atoms of lithium all reside in unique M4 atomic sites crossing ion-conduction pathways. Magnesium atoms iso-structurally substitute for calcium in position M5 and have a smaller effect on fast Ca2+ transport.
Powder Diffraction | 2017
Daria A. Petrova; Dina V. Deyneko; Sergey Yu. Stefanovich; S. M. Aksenov; Bogdan I. Lazoryak
Novel compounds Ca 8− x Pb x ZnBi(VO 4 ) 7 (0 ≤ x ≤ 1.5) solid solution with the whitlockite-type structure were synthesized by a standard solid-state method. The unit-cell parameters were determined by X-ray powder diffraction and using Le Bail decomposition. The crystal structural of Ca 6.5 Pb 1.5 ZnBi(VO 4 ) 7 was refined by Rietveld method. It is found that Pb 2+ cations occupy a half of the M 3 site, whereas the M 1 and M 2 sites are predominantly occupied by calcium with admixture of Bi 3+ cations. The M 5 site is fully occupied by Zn 2+ cations. The M 4 site in the structure of studied sample remains vacant and does not participate in the cations arrangement. Optical second harmonic generation demonstrates high non-linear optical activity. Dielectric investigations confirm polar space group R 3 c . Changes in the non-linear optical and ferroelectric parameters are matched with lead and zinc cation distribution over the sites of the whitlockite-type structure.
Crystallography Reports | 2017
N. A. Yamnova; S. M. Aksenov; Vladimir S. Mironov; A. S. Volkov; E. Yu. Borovikova; O. A. Gurbanova; O. V. Dimitrova; Dina V. Deyneko
The new potassium–bismuth–nickel oxophosphate obtained by hydrothermal synthesis in the Bi(OH)3–NiCO3–K2CO3–K3PO4 system is studied by X-ray diffraction, IR spectroscopy, and Raman spectroscopy. Parameters of the orthorhombic cell are as follows: a = 13.632(1) Å, b = 19.610(2) Å, and c = 5.4377(3) Å; V = 1452.64(2) Å3; and space group Pnma. The structure is solved and refined to the final discrepancy factor R1 = 5.76% in the anisotropic approximation of atomic displacements using 3606 reflections with I > 2σ(I). The crystal-chemical formula (Z = 4) is KBi4{Ni2O4(PO4)3}, where the composition of the layer nickel–phosphate polyanion is enclosed in braces. Theoretical calculations show that all exchange spin interactions between Ni2+ ions are antiferromagnetic and very weak (J < 0.1 cm–1) because of the polyatomic character of bridging Ni–O–P–O–Ni and Ni–O–Bi–O–Ni groups. Thus, this compound is expected to be paramagnetic with very weak antiferromagnetic exchange interactions and appreciable energy of zero-field splitting of the spin levels of Ni2+ ions.
Journal of Alloys and Compounds | 2015
Dina V. Deyneko; Vladimir A. Morozov; Joke Hadermann; A.E. Savon; D. Spassky; Sergey Yu. Stefanovich; Alexei A. Belik; Bogdan I. Lazoryak
Journal of Alloys and Compounds | 2017
Alexei A. Belik; Vladimir A. Morozov; Dina V. Deyneko; A.E. Savon; O. V. Baryshnikova; Evgeniya S. Zhukovskaya; Nikolay G. Dorbakov; Yoshio Katsuya; Masahiko Tanaka; Sergey Yu. Stefanovich; Joke Hadermann; Bogdan I. Lazoryak