B. I. Lazoryak

Lomonosov Moscow State University, Moskva, Moscow, Russia

Are you B. I. Lazoryak?

Claim your profile

Publications (115)218.4 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Subsolidus phase relations in the Cs2MoO4–ZnMoO4–Zr(MoO4)2 system were determined and two new compounds, Cs2ZnZr(MoO4)4 and Cs2ZnZr2(MoO4)6, were obtained. The structure of Cs2ZnZr(MoO4)4 (a=5.7919(1) Å, c=8.0490(3) Å; space group P m1; Z=0.5; R=0.0149) belongs to the layered glaserite-like KAl(MoO4)2 structure type where the octahedral Al3+ positions are statistically occupied by 0.5 Zn2++0.5 Zr4+. The second triple molybdate, Cs2ZnZr2(MoO4)6 (a=13.366(1) Å, c=12.253(3) Å, space group R , Z=3, R=0.0324), is isostructural to Cs2MnZr2(MoO4)6 and Cs2M2Zr(MoO4)6 (M=Al, Fe) and contains a mixed 3D framework built of МоO4 tetrahedra and (Zn, Zr)O6 octahedra sharing common vertices. Cesium cations are located in large channels of the framework. The latter compound undergoes a first-order phase transition at 723 K with considerable increasing its ionic conductivity.
    Journal of Physics and Chemistry of Solids 06/2015; 81. DOI:10.1016/j.jpcs.2015.01.015 · 1.59 Impact Factor
  • Source
    [Show description] [Hide description]
    DESCRIPTION: We have prepared solid solutions based on whitlockite-structure ferroelectrics, Ca9 – xPbxR(PO4)7 (R = Sc, Cr, Fe, Ga, In), through Pb substitution for Ca. Single-phase Ca9 – xPbxR(PO4)7 materials with a polar whitlockite-like structure (sp. gr. R3c) exist in the range 0 ≤ x ≤ 1.5 for all of the R metals studied. X-ray powder diffraction profile analysis results for R = In (x = 0.5, 0.8, and 1.0) demonstrate that the trivalent cations reside on the octahedral site M5 of the whitlockite structure, the calcium cation occupy the M1–M3 sites, and the lead cations are located predominantly on the M3 site. Differential scanning calorimetry, dielectric permittivity, and second-harmonic generation data attest to a ferroelectric phase transition, whose temperature is 580–610°C in Ca9R(PO4)7 and decreases monotonically to 480–520°C as x increases to 1.5.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ca 9ex Pb x Eu(PO 4) 7 (0 x 1) solid solutions with a whitlockite-type (or b-Ca 3 (PO 4) 2-type) structure (sp.gr. R3c) were prepared by a standard solid-state method in air. Their luminescent properties under near-ultraviolet (n-UV) light were investigated. Excitation spectra of Ca 9ex Pb x Eu(PO 4) 7 showed the strongest absorption at about 395 nm, which matches well with commercially available n-UV-emitting GaN-based LED chips. Emission spectra indicated an intense red emission due to the 5 D 0 / 7 F 2 transition of Eu 3þ , with a maximum in the intensity for Ca 8.5 Pb 0.5 Eu(PO 4) 7. The emission intensity of Ca 8.5 P-b 0.5 Eu(PO 4) 7 was about 1.8 times higher than that of a Ca 9 Eu(PO 4) 7 phosphor. We suggest that the introduction of Pb 2þ is an efficient approach to enhance luminescence properties of such phosphors. We clarified the influence of the Ca 2þ / Pb 2þ substitution on intensities of three bands for the 5 D 0 / 7 F 0 transition in excitation spectra of Ca 9ex Pb x Eu(PO 4) 7. In addition, we found a reversible first-order phase transition from R3с to R3с symmetry by second-harmonic generation in the range from 753 K (x < 1) to 846 K (x = 0).
    Journal of Alloys and Compounds 05/2015; 647:965-972. DOI:10.1016/j.jallcom.2015.06.123 · 2.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Basalt glasses and fibers with zirconia content in the range from 0 to 7 wt% were obtained using ZrSiO4 as a zirconium source. Weight loss and tensile strength loss of fibers after refluxing in alkali solution were determined. Basalt fiber with 5.7 wt% ZrO2 had the best alkali resistance properties. Alkali treatment results in formation of protective surface layer on fibers. Morphology and chemical composition of surface layer were investigated. It was shown that alkali resistance of zirconia doped basalt fibers is caused by insoluble compounds of Zr4+, Fe3+ and Mg2+ in corrosion layer. Mechanical properties of initial and leached fibers were evaluated by a Weibull distribution. The properties of basalt fibers with ZrSiO4 were compared with AR-glass fibers. The performance of concrete with obtained fibers was investigated.
    Materials and Design 05/2015; 73. DOI:10.1016/j.matdes.2015.02.022 · 3.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Basaltic glass fibers with different lithium oxide (6–14 mol%) and sodium oxide (2–14 mol%) contents were prepared. The influence of Li2O and Na2O content on the process of fiber manufacturing was investigated. Addition of alkali oxides reduced the forming temperature and substantially expanded the fiber-forming temperature ranges. The obtained thermal data from differential thermal analysis revealed a decline in glass transition temperature (Tg) of fibers against the compositional changes. The inclusion of Li2O and Na2O in the glass network led to a reduction in its thermal stability. The obtained X-ray diffraction patterns and IR spectra of Li-rich and Na-rich basaltic glass fibers confirmed the formation of highly polymerized structures such as LiAl(Si2O6) and (Na,K)(AlSiO4), respectively, and relatively depolymerized silicate anions. The effects of potassium–lithium and potassium–sodium ion exchange on the mechanical properties of basaltic glass fibers were investigated. As-received Li-rich and Na-rich basaltic glass fibers were ion-exchanged in potassium nitrate for different exchange times, and their mechanical properties were measured before and after chemical tempering. The measured tensile strength and Young's modulus values of the fibers showed an increase after treatment in molten salt.
    International Journal of Applied Glass Science 05/2015; DOI:10.1111/ijag.12118 · 1.71 Impact Factor
  • Source
    Russian Journal of Inorganic Chemistry 01/2015; 60(1):84-91. DOI:10.1134/S0036023615010118 · 0.55 Impact Factor
  • Source
    Dina Deyneko, Sergey Stefanovich, Bogdan Lazoryak
    [Show abstract] [Hide abstract]
    ABSTRACT: New phosphates Ca9- x Pb x Eu(PO4)7 were obtained by solid state reaction techniques at 1213-1253 K in air atmosphere and were found to be isotypic with whitlockite-type β-Ca3(PO4)2. The unit cell parameters were determinate using Le Bail decomposition. Rietveld method structural refining showed that Eu3+ ions are located statistically with calcium in M1, M2, and M3 sites, whereas Pb2+-ions are preferentially located in the M3. Examination of optical second harmonic generation evidences nonlinear optical activity and confirms polar space group R3c.
    Powder Diffraction 01/2015; DOI:10.1017/S0885715615000068 · 0.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new triple molybdate Na25Cs8Fe5(MoO4)24 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorimetry, Mössbauer and dielectric impedance spectroscopy. Single crystals of Na25Cs8Fe5(MoO4)24 were obtained and its structure was solved (the space group P , a=12.5814(5), b=13.8989(5), c=28.4386(9) Å, α=90.108(2), β=90.064(2), γ=90.020(2)°, V=4973.0(3) Å3, Z=2, R=0.0440). Characteristic features of the structure are polyhedral layers composed of pairs of edge-shared FeO6 and (Fe, Na)O6 octahedra, which are connected by bridging МоО4 tetrahedra. The layers share common vertices with bridging МоО4 tetrahedra to form an open 3D framework with the cavities occupied by the Cs+ and Na+ cations. The compound undergoes first-order phase transformation at 642 K and above this phase transition, electrical conductivity reaches 10−3-10−2 S cm−1. Thus, Na25Cs8Fe5(MoO4)24 may be considered as a promising compound for developing new materials with high ionic conductivity.
    ChemInform 11/2014; 220:217–220. DOI:10.1016/j.jssc.2014.09.004
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The R2(MoO4)3 (R = rare earth elements) molybdates doped with Eu3+ cations are interesting red-emitting materials for display and solid state lighting applications. The structure and luminescent properties of the R2−xEux(MoO4)3 (R=Gd, Sm) solid solutions have been investigated as a function of chemical composition and preparation conditions. Monoclinic (α-) and orthorhombic (β´-) R2−xEux(MoO4)3 (R=Gd, Sm, 0≤x≤2) modifications were prepared by solid-state reaction and their structures were investigated using synchrotron powder X-ray diffraction and transmission electron microscopy. The pure orthorhombic β´-phases could be synthesized only by quenching from high temperature to room temperature for Gd2−xEux(MoO4)3 in the Eu3+-rich part (x > 1) and for all Sm2−xEux(MoO4)3 solid solutions. The transformation from the α-phase to the β´-phase results in a notable increase (~24%) of the unit cell volume for all R2−xEux(MoO4)3 (R = Sm, Gd) solid solutions. The luminescent properties of all R2−xEux(MoO4)3 (R = Gd, Sm; 0≤x≤2) solid solutions were measured, and their optical properties were related to their structural properties. All R2−xEux(MoO4)3 (R= Gd, Sm; 0≤x≤2) phosphors emit intense red light dominated by the 5D0 – 7F2 transition at ~616 nm. However, a change in the multiplet splitting is observed when switching from the monoclinic to the orthorhombic structure, as a consequence of the change in coordination polyhedron of the luminescent ion from RO8 to RO7 for the α- and β´-modification, respectively. The Gd2−xEux(MoO4)3 solid solutions are the most efficient emitters in the range of 0<x<1.5, but have a comparable or even significantly lower emission intensity than Sm2−xEux(MoO4)3 for higher Eu3+ concentrations (1.5≤x≤1.75). Electron energy loss spectroscopy (EELS) measurements revealed the influence of the structure and element content on the number and positions of bands in the UV-visible-infrared regions of the EELS spectrum.
    Chemistry of Materials 11/2014; 26(24). DOI:10.1021/cm503720s · 8.54 Impact Factor
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: a b s t r a c t A new triple molybdate Na 25 Cs 8 Fe 5 (MoO 4) 24 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorimetry, Mössbauer and dielectric impedance spectroscopy. Single crystals of Na 25 Cs 8 Fe 5 (MoO 4) 24 were obtained and its structure was solved (the space group P1, a ¼12.5814(5), b¼ 13.8989(5), c ¼28.4386(9) Å, α¼90.108(2), β¼90.064(2), γ¼90.020(2)1, V¼ 4973.0(3) Å 3 , Z¼ 2, R¼ 0.0440). Char-acteristic features of the structure are polyhedral layers composed of pairs of edge-shared FeO 6 and (Fe, Na)O 6 octahedra, which are connected by bridging МоО 4 tetrahedra. The layers share common vertices with bridging МоО 4 tetrahedra to form an open 3D framework with the cavities occupied by the Cs þ and Na þ cations. The compound undergoes first-order phase transformation at 642 K and above this phase transition, electrical conductivity reaches 10 À 3 –10 À 2 S cm À 1 . Thus, Na 25 Cs 8 Fe 5 (MoO 4) 24 may be considered as a promising compound for developing new materials with high ionic conductivity.
    Journal of Solid State Chemistry 09/2014; 220:217-220. · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Scheelite related compounds (A′,A″)n[(B′,B″)O4]m with B′, B″ = W and/or Mo are promising new materials for red phosphors in pc-WLEDs (phosphor-converted white-light-emitting-diode) and solid-state lasers. Cation substitution in CaMoO4 of Ca2+ by the combination of Na+ and Eu3+, with the creation of A cation vacancies, has been investigated as a factor for controlling the scheelite-type structure and the luminescent properties. Na5Eu(MoO4)4 and NaxEu3+(2–x)/3□(1–2x)/3MoO4 (0.138 ≤ x ≤ 0.5) phases with a scheelite-type structure were synthesized by the solid state method; their structural characteristics were investigated using transmission electron microscopy. Contrary to powder synchrotron X-ray diffraction before, the study by electron diffraction and high resolution transmission electron microscopy in this paper revealed that Na0.286Eu0.571MoO4 has a (3 + 2)D incommensurately modulated structure and that (3 + 2)D incommensurately modulated domains are present in Na0.200Eu0.600MoO4. It also confirmed the (3 + 1)D incommensurately modulated character of Na0.138Eu0.621MoO4. The luminescent properties of all phases under near-ultraviolet (n-UV) light have been investigated. The excitation spectra of these phosphors show the strongest absorption at about 395 nm, which matches well with the commercially available n-UV-emitting GaN-based LED chip. The emission spectra indicate an intense red emission due to the 5D0 → 7F2 transition of Eu3+, with local minima in the intensity at Na0.286Eu0.571MoO4 and Na0.200Eu0.600MoO4 for 613 nm and 616 nm bands. The phosphor Na5Eu(MoO4)4 shows the brightest red light emission among the phosphors in the Na2MoO4–Eu2/3MoO4 system and the maximum luminescence intensity of Na5Eu(MoO4)4 (λex = 395 nm) in the 5D0 → 7F2 transition region is close to that of the commercially used red phosphor YVO4:Eu3+ (λex = 326 nm). Electron energy loss spectroscopy measurements revealed the influence of the structure and Na/Eu cation distribution on the number and positions of bands in the UV-optical-infrared regions of the EELS spectrum.
    Chemistry of Materials 05/2014; 26(10):3238–3248. DOI:10.1021/cm500966g · 8.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Crystallization of basalt fibers containing 0–7 wt% ZrO2 was studied. Fibers were drawn from basalt glasses and annealed in air at different temperatures. Phase composition of obtained samples was determined by XRD. Kinetics of crystallization processes was investigated by DSC. Kinetic models and parameters were estimated for crystallization of spinel-like phase, pyroxene and plagioclase using model-free analysis. It was found that doping of fibers with 1–3 wt% ZrO2 increased Arrhenius parameters of aluminosilicate crystallization. When the zirconia content was 5–7 wt% the crystallization mechanism significantly changed. This phenomenon resulted in increasing of fiber thermal stability.
    Thermochimica Acta 01/2014; 575:238–243. DOI:10.1016/j.tca.2013.11.002 · 2.11 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new hydrogen-containing whitlockite-type phosphate Ca 9 (Fe 0.63 Mg 0.37)H 0.37 (PO 4) 7 : hydrothermal synthesis and structure Abstract: A new hydrogen-containing Ca 9 (Fe 0.63 Mg 0.37) H 0.37 (PO 4) 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 dif-fraction. 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. Ca 9 (Fe 0.63 Mg 0.37)H 0.37 (PO 4) 7 structure is similar to that of other members of the whit-lockite-type family. The presence of hydrogen in the struc-ture leads to the formation of OH-group with one of the oxygen of PO 4 -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.
    Zeitschrift für Kristallographie 01/2014; 229(12):823-830. DOI:10.1515/zkri-2014-1774 · 1.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Na9Sc(MoO4)6 {nonasodium scandium hexakis[tetraoxidomolybdate(II)]} was synthesised by a solid-state method. The basic structure units are polyhedral clusters composed of an ScO6 octahedron and three NaO6 octahedra sharing total edges. The clusters are connected by sharing vertices with bridging MoO4 tetrahedra, forming a three-dimensional framework where the cavities are occupied by the other two crystallographically independent Na atoms.
    Acta Crystallographica Section C Crystal Structure Communications 11/2013; 69(Pt 11):1301-3. DOI:10.1107/S010827011302862X · 0.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: As found by differential thermal analysis, X-ray diffraction and Mössbauer spectroscopy, the heat treatment of basalt glass fibers in air leads to complete iron oxidation and the bulk growth of superparamagnetic magnesioferrite particles which act as nucleation sites for pyroxene crystallization.
    Mendeleev Communications 11/2013; 23(6):361–363. DOI:10.1016/j.mencom.2013.11.021 · 1.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Na 9 Sc(MoO 4) 6 {nonasodium scandium hexakis[tetraoxido-molybdate(II)]} was synthesised by a solid-state method. The basic structure units are polyhedral clusters composed of an ScO 6 octahedron and three NaO 6 octahedra sharing total edges. The clusters are connected by sharing vertices with bridging MoO 4 tetrahedra, forming a three-dimensional framework where the cavities are occupied by the other two crystallographically independent Na atoms.
    Acta Crystallographica Section C Crystal Structure Communications 10/2013; C69:1301-1303. DOI:10.1002/chin.201409006 · 0.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new double molybdate Na9Fe(MoO4)6 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorimetry, X-ray fluorescence analysis, Mössbauer and dielectric impedance spectroscopy. Single crystals of Na9Fe(MoO4)6 were obtained and its structure was solved (the space group R3¯, a=14.8264(2), c=19.2402(3) Å, V=3662.79(9) Å3, Z=6, R=0.0132). The structure is related to that of sodium ion conductor II-Na3Fe2(AsO4)3. The basic structure units are polyhedral clusters composed of central FeО6 octahedron sharing edges with three Na(1)О6 octahedra. The clusters share common vertices with bridging МоО4 tetrahedra to form an open 3D framework where the cavities are occupied by Na(2) and Na(3) atoms. The compound melts incongruently at 904.7±0.2 K. Arrhenius type temperature dependence of electric conductivity σ has been registered in solid state (σ=6.8×10-2 S сm-1 at 800 K), thus allowing considering Na9Fe(MoO4)6 as a new sodium ion conductor.
    Journal of Solid State Chemistry 09/2013; 205:149-153. DOI:10.1016/j.jssc.2013.07.007 · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have prepared Ca9.5 − x Pbx M(PO4)7 (M = Mg, Zn, Cd) and Ca10.5 − x Pbx (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 − x Pbx M(PO4)7 and in the range 0 ≤ x ≤ 2.5 for Ca10.5 − x Pbx (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 08/2013; 49(8). DOI:10.1134/S0020168513080049 · 0.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: a b s t r a c t A new double molybdate Na 9 Fe(MoO 4) 6 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorime-try, X-ray fluorescence analysis, Mössbauer and dielectric impedance spectroscopy. Single crystals of Na 9 Fe(MoO 4) 6 were obtained and its structure was solved (the space group R3, a¼ 14.8264(2), c ¼19.2402(3) Å, V¼ 3662.79(9) Å 3 , Z ¼6, R ¼0.0132). The structure is related to that of sodium ion conductor II-Na 3 Fe 2 (AsO 4) 3 . The basic structure units are polyhedral clusters composed of central FeО 6 octahedron sharing edges with three Na(1)О 6 octahedra. The clusters share common vertices with bridging МоО 4 tetrahedra to form an open 3D framework where the cavities are occupied by Na(2) and Na(3) atoms. The compound melts incongruently at 904.7 7 0.2 K. Arrhenius type temperature depen-dence of electric conductivity s has been registered in solid state (s¼ 6.8 Â 10 À 2 S сm À 1 at 800 K), thus allowing considering Na 9 Fe(MoO 4) 6 as a new sodium ion conductor.
    Journal of Solid State Chemistry 07/2013; 205:149-154. · 2.20 Impact Factor

Publication Stats

727 Citations
218.40 Total Impact Points

Institutions

  • 1990–2015
    • Lomonosov Moscow State University
      • Division of Chemistry
      Moskva, Moscow, Russia
  • 1994–2014
    • Moscow State Forest University
      Mytishi, Moskovskaya, Russia
  • 2010
    • Wake Forest University
      • Department of Chemistry
      Winston-Salem, North Carolina, United States
  • 2005
    • National Institute for Materials Science
      • Advanced Materials Laboratory
      Tsukuba, Ibaraki, Japan
  • 2004–2005
    • Kyoto University
      • Institute for Chemical Research
      Kioto, Kyōto, Japan