Nikita A. Bogachev’s research while affiliated with St Petersburg University and other places

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Publications (18)


Figure 1. The PXRD patterns of selected (TbxM1−x)2(1,4-bdc)3‧4H2O (M = Y, La, Gd; x = 0, 0.01, 0.1, 1) and the simulated XRD pattern of Tb2(1,4-bdc)3‧4H2O single-crystal structure were taken from ref. [35] (a) and unit cell volume (Vu.c.) concentration dependence refined for (TbxM1−x)2(1,4-bdc)3·4H2O (M = Gd, La, Y) (b).
Figure 2. SEM images of (Tb0.5M0.5)2(1,4-bdc)3·4H2O (M = Gd, La, Y).
Figure 3. IR spectra of (Tb 0.5 M 0.5 ) 2 (1,4-bdc) 3 ·4H 2 O and M 2 (1,4-bdc) 3 ·4H 2 O (M = Y, Gd, La, Tb).
Figure 4. TGA curves of selected heterometallic (Tb0.5M0.5)2(1,4-bdc)3‧4H2O (M = Gd, La, Y) and homometallic M2(1,4-bdc)3‧4H2O (M = Tb, Gd, La, Y) terephthalates measured in the temperature range of 35-200 °C.
Figure 5. The normalized emission spectra of (Tb x M 1−x ) 2 (1,4-bdc) 3 ·4H 2 O (M = Y, La, Gd) at the selected Tb 3+ concentrations (given in legend) upon 320 nm excitation. The artefact maxima peaking at 615 nm (marked as *) correspond to the Eu 3+ present as impurities in the gadolinium nitrate used for the synthesis.

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The Structure and Optical Properties of Luminescent Terbium Terephthalate Metal–Organic Frameworks Doped with Yttrium, Gadolinium, and Lanthanum Ions
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November 2024

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36 Reads

Crystals

Anna S. Petrova

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Yulia N. Toikka

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The structural features and luminescent properties of heterometallic Tb–Gd, Tb–La, and Tb–Y terephthalate metal–organic frameworks, namely (TbxM1−x)2(1,4-bdc)3∙4H2O (M = Gd, La, Y), were studied in detail in a wide concentration range (x = 0.001–1). The crystalline phase of synthesized compounds corresponds to Ln2(1,4-bdc)3·4H2O. The lifetime of 5D4 decreased with increased Tb3+ concentration, but PLQY depends non-linearly on the Tb3+ concentration. The 50% substitution of Tb3+ for Y3+, Gd3+, or La3+ ions result in the significant enhancement of photoluminescence quantum yield, up to 1.6 times. The morphology, thermal stability, and vibrational structure of the selected homo- and bi-metallic materials is reported as well.

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Figure 2. Eu 3+ concentration dependence of unit cell volume (Vuc) refined for (EuxM1−x)2(1,4-bdc)3‧4H2O (M = Gd, La, Y).
Figure 3. SEM images of (Eu0.5M0.5)2(1,4-bdc)3·4H2O (M = Gd, La, Y).
The Structure and Optical Properties of Luminescent Europium Terephthalate Antenna Metal–Organic Frameworks Doped by Yttrium, Gadolinium, and Lanthanum Ions

July 2024

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22 Reads

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2 Citations

Molecules

New heterometallic antenna terephthalate MOFs, namely, (EuxM1−x)2bdc3·4H2O (M = Y, La, Gd) (x = 0.001–1), were synthesized by a one-step method from aqueous solutions. The resulting compounds are isomorphic to each other; the crystalline phase corresponds to Ln2bdc3∙4H2O. Upon 300 nm excitation to the singlet excited state of terephthalate ions, all compounds exhibit a bright red emission corresponding to the of 5D0–7FJ (J = 0–4) f-f transitions of Eu3+ ions. The Eu(III) concentration dependence of the photophysical properties was carefully studied. We revealed that Gd-doping results in photoluminescence enhancement due to the heavy atom effect. To quantitatively compare the antenna effect among different compounds, we proposed the new approach, where the quantum yield of the 5D0 formation is used to characterize the efficiency of energy transfer from the ligand antenna to the Eu3+ emitter.



Microcrystalline Luminescent (Eu1-xLnx)2bdc3·nH2O (Ln = La, Gd, Lu) Antenna MOFs: Effect of Dopant Content on Structure, Particle Morphology, and Luminescent Properties

January 2024

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35 Reads

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1 Citation

Molecules

In this work, three series of micro-sized heterometallic europium-containing terephthalate MOFs, (Eu1-xLnx)2bdc3·nH2O (Ln = La, Gd, Lu), are synthesized via an ultrasound-assisted method in an aqueous medium. La3+ and Gd3+-doped terephthalates are isostructural to Eu2bdc3·4H2O. Lu3+-doped compounds are isostructural to Eu2bdc3·4H2O with Lu contents lower than 95 at.%. The compounds that are isostructural to Lu2bdc3·2.5H2O are formed at higher Lu3+ concentrations for the (Eu1-xLux)2bdc3·nH2O series. All materials consist of micrometer-sized particles. The particle shape is determined by the crystalline phase. All the synthesized samples demonstrate an “antenna” effect: a bright-red emission corresponding to the 5D0-7FJ transitions of Eu3+ ions is observed upon 310 nm excitation into the singlet electronic excited state of terephthalate ions. The fine structure of the emission spectra is determined by the crystalline phase due to the different local symmetries of the Eu3+ ions in the different kinds of crystalline structures. The photoluminescence quantum yield and 5D0 excited state lifetime of Eu3+ are equal to 11 ± 2% and 0.44 ± 0.01 ms, respectively, for the Ln2bdc3·4H2O structures. For the (Eu1-xLux)2bdc3·2.5H2O compounds, significant increases in the photoluminescence quantum yield and 5D0 excited state lifetime of Eu3+ are observed, reaching 23% and 1.62 ms, respectively.


Effect of Gd3+, La3+, Lu3+ Co-Doping on the Morphology and Luminescent Properties of NaYF4:Sm3+ Phosphors

March 2023

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58 Reads

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3 Citations

Materials

The series of luminescent NaYF4:Sm3+ nano- and microcrystalline materials co-doped by La3+, Gd3+, and Lu3+ ions were synthesized by hydrothermal method using rare earth chlorides as the precursors and citric acid as a stabilizing agent. The phase composition of synthesized compounds was studied by PXRD. All synthesized materials except ones with high La3+ content (where LaF3 is formed) have a β-NaYF4 crystalline phase. SEM images demonstrate that all particles have shape of hexagonal prisms. The type and content of doping REE significantly effect on the particle size. Upon 400 nm excitation, phosphors exhibit distinct emission peaks in visible part of the spectrum attributed to 4G5/2→6HJ transitions (J = 5/2–11/2) of Sm3+ ion. Increasing the samarium (III) content results in concentration quenching by dipole–dipole interactions, the optimum Sm3+concentration is found to be of 2%. Co-doping by non-luminescent La3+, Gd3+ and Lu3+ ions leads to an increase in emission intensity. This effect was explained from the Sm3+ local symmetry point of view.


Figure 1. The PXRD patterns of (TbxLu1-x)2bdc3‧nH2O (x = 0-1) MOFs synthesized from the diluted (a) and concentrated (b) solutions as well as the PXRD patterns of Tb2bdc3‧4H2O [40], Lu2bdc3‧10H2O [41], and Tb2bdc3 [42] simulated from the single-crystal structures.
The volumes of the initial TbCl 3 and LuCl 3 solutions used for the synthesis of (Tb x Lu 1−x ) 2 bdc 3 ·nH 2 O MOFs.
Cont.
Brightly Luminescent (TbxLu1−x)2bdc3·nH2O MOFs: Effect of Synthesis Conditions on Structure and Luminescent Properties

March 2023

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116 Reads

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6 Citations

Molecules

Luminescent, heterometallic terbium(III)–lutetium(III) terephthalate metal-organic frameworks (MOFs) were synthesized via direct reaction between aqueous solutions of disodium terephthalate and nitrates of corresponding lanthanides by using two methods: synthesis from diluted and concentrated solutions. For (TbxLu1−x)2bdc3·nH2O MOFs (bdc = 1,4-benzenedicarboxylate) containing more than 30 at. % of Tb3+, only one crystalline phase was formed: Ln2bdc3·4H2O. At lower Tb3+ concentrations, MOFs crystallized as the mixture of Ln2bdc3·4H2O and Ln2bdc3·10H2O (diluted solutions) or Ln2bdc3 (concentrated solutions). All synthesized samples that contained Tb3+ ions demonstrated bright green luminescence upon excitation into the 1ππ* excited state of terephthalate ions. The photoluminescence quantum yields (PLQY) of the compounds corresponding to the Ln2bdc3 crystalline phase were significantly larger than for Ln2bdc3·4H2O and Ln2bdc3·10H2O phases due to absence of quenching from water molecules possessing high-energy O-H vibrational modes. One of the synthesized materials, namely, (Tb0.1Lu0.9)2bdc3·1.4H2O, had one of the highest PLQY among Tb-based MOFs, 95%.


Figure 1. Conditions of lead oxide and protective films formation according to Martynov [17] and Müller [18]. The red line indicates the maximum core temperature for currently designed
Figure 2. Electrical equivalent circuit used to fit impedance data.
Figure 3. Niquist plot for iron in LBE: experimental data are marked with squares, solid line represents fittin one. Fitting parameters are: n = 0.964, Q0 = 8.67•10 −10 S•s n /cm 2 , RLBE = 3.02•10 −4 Ω/cm 2 , Roxide = 2.71•10 4 Ω/cm 2 .
Parameters for calculating the limit solubility of oxygen in LBE [49].
Electrochemical Sensors for Controlling Oxygen Content and Corrosion Processes in Lead-Bismuth Eutectic Coolant—State of the Art

January 2023

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93 Reads

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2 Citations

Sensors

Controlling oxygen content in the primary circuit of nuclear reactors is one of the key tasks needed to ensure the safe operation of nuclear power plants where lead-bismuth eutectic alloy (LBE) is used as a coolant. If the oxygen concentration is low, active corrosion of structural materials takes place; upon increase in oxygen content, slag accumulates due to the formation of lead oxide. The generally accepted method of measuring the oxygen content in LBE is currently potentiometry. The sensors for measuring oxygen activity (electrochemical oxygen sensors) are galvanic cells with two electrodes (lead-bismuth coolant serves as working electrode) separated by a solid electrolyte. Control of corrosion and slag accumulation processes in circuits exploring LBE as a coolant is also based on data obtained by electrochemical oxygen sensors. The disadvantages of this approach are the low efficiency and low sensitivity of control. The alternative, Impedance Spectroscopy (EIS) Sensors, are proposed for Real-Time Corrosion Monitoring in LBE system. Currently their applicability in static LBE at temperatures up to 600 °C is shown.


Heterometallic Europium(III)–Lutetium(III) Terephthalates as Bright Luminescent Antenna MOFs

September 2022

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121 Reads

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12 Citations

Molecules

A new series of luminescent heterometallic europium(III)–lutetium(III) terephthalate metal–organic frameworks, namely (EuxLu1−x)2bdc3·nH2O, was synthesized using a direct reaction in a water solution. At the Eu3+ concentration of 1–40 at %, the MOFs were formed as a binary mixture of the (EuxLu1−x)2bdc3 and (EuxLu1−x)2bdc3·4H2O crystalline phases, where the Ln2bdc3·4H2O crystalline phase was enriched by europium(III) ions. At an Eu3+ concentration of more than 40 at %, only one crystalline phase was formed: (EuxLu1−x)2bdc3·4H2O. All MOFs containing Eu3+ exhibited sensitization of bright Eu3+-centered luminescence upon the 280 nm excitation into a 1ππ* excited state of the terephthalate ion. The fine structure of the emission spectra of Eu3+ 5D0-7FJ (J = 0–4) significantly depended on the Eu3+ concentration. The luminescence quantum yield of Eu3+ was significantly larger for Eu-Lu terephthalates containing a low concentration of Eu3+ due to the absence of Eu-Eu energy migration and the presence of the Ln2bdc3 crystalline phase with a significantly smaller nonradiative decay rate compared to the Ln2bdc3·4H2O.


Citations (12)


... Meanwhile, at the Eu 3+ concentration of 9 at.%, the obtained material possessed a structure of [Eu 2 (1,4-bdc) 3 (dmf) 2 (H 2 O) 2 ]. In our previous works, we observed the crystalline phase alternation in (Eu x Lu 1−x ) 2 (1,4bdc) 3 ·nH 2 O and (Tb x Lu 1−x ) 2 (1,4-bdc) 3 ·nH 2 O MOFs [27][28][29][30]. Substitution of up to 90% of Eu 3+ or Tb 3+ by Lu 3+ ions does not affect the crystalline phase of the resulting compounds, Ln 2 (1,4-bdc) 3 ·4H 2 O, which is isostructural to europium and terbium terephthalates, namely Eu 2 bdc 3 ·4H 2 O and Tb 2 bdc 3 ·4H 2 O, correspondingly. ...

Reference:

The Structure and Optical Properties of Luminescent Terbium Terephthalate Metal–Organic Frameworks Doped with Yttrium, Gadolinium, and Lanthanum Ions
Luminescent properties and thermal stability of (Lu0.98Eu0.02)2bdc3·10H2O metal–organic frameworks
  • Citing Article
  • September 2024

Mendeleev Communications

... However, only a few studies have studied such concentration dependences. In our previous work, for (Eu x M 1−x ) 2 (1,4-bdc) 3 ·4H 2 O (M = Gd, La, Y) MOFs, we demonstrated that, at larger Eu 3+ concentrations, for the Eu-Y and Eu-La series, PLQY remains the same (about 9-11%), whereas in the Eu-Gd series, it reaches a maximum of 15% at the Eu 3+ content of 10 at.% and then slightly decreases, reaching 10% in homometallic europium(III) terephthalate [31]. Utochnikova et al. previously reported the Gd 3+ and Y 3+ doping effect on the optical properties of heterometallic solid solutions of (Tb x Y 1−x ) 2 (1,4-bdc) 3 (H 2 O) 4 and Eu x Gd 1−x (dbm) 3 (phen) (dbm-dibenzoylmethanate, phen-o-phenantroline) MOFs [24]. ...

The Structure and Optical Properties of Luminescent Europium Terephthalate Antenna Metal–Organic Frameworks Doped by Yttrium, Gadolinium, and Lanthanum Ions

Molecules

... Meanwhile, at the Eu 3+ concentration of 9 at.%, the obtained material possessed a structure of [Eu 2 (1,4-bdc) 3 (dmf) 2 (H 2 O) 2 ]. In our previous works, we observed the crystalline phase alternation in (Eu x Lu 1−x ) 2 (1,4bdc) 3 ·nH 2 O and (Tb x Lu 1−x ) 2 (1,4-bdc) 3 ·nH 2 O MOFs [27][28][29][30]. Substitution of up to 90% of Eu 3+ or Tb 3+ by Lu 3+ ions does not affect the crystalline phase of the resulting compounds, Ln 2 (1,4-bdc) 3 ·4H 2 O, which is isostructural to europium and terbium terephthalates, namely Eu 2 bdc 3 ·4H 2 O and Tb 2 bdc 3 ·4H 2 O, correspondingly. ...

Microcrystalline Luminescent (Eu1-xLnx)2bdc3·nH2O (Ln = La, Gd, Lu) Antenna MOFs: Effect of Dopant Content on Structure, Particle Morphology, and Luminescent Properties

Molecules

... These materials have wide applications in different emerging elds, such as display devices, light emitting diodes (LEDs), color tunable devices, temperature sensing, development of new lasers, plant cultivation etc. [1][2][3][4][5][6][7] This is possible due to the presence of a large number of meta-stable energy levels in the rare earth ions. [8][9][10][11][12] The rare earth ions, such as Eu 3+ , Tb 3+ , Tm 3+ , Dy 3+ , etc., emit red, green, blue and yellow colors respectively, in different host matrices. 2,[5][6][7] Thus, a combination of these rare earth ions, such as Dy 3+ /Eu 3+ , Sm 3+ /Eu 3+ , Tb 3+ / Eu 3+ , etc. produces color tunable photoluminescence (PL) in different host matrices depending on their concentrations and excitation wavelengths. ...

Effect of Gd3+, La3+, Lu3+ Co-Doping on the Morphology and Luminescent Properties of NaYF4:Sm3+ Phosphors

Materials

... Meanwhile, at the Eu 3+ concentration of 9 at.%, the obtained material possessed a structure of [Eu 2 (1,4-bdc) 3 (dmf) 2 (H 2 O) 2 ]. In our previous works, we observed the crystalline phase alternation in (Eu x Lu 1−x ) 2 (1,4bdc) 3 ·nH 2 O and (Tb x Lu 1−x ) 2 (1,4-bdc) 3 ·nH 2 O MOFs [27][28][29][30]. Substitution of up to 90% of Eu 3+ or Tb 3+ by Lu 3+ ions does not affect the crystalline phase of the resulting compounds, Ln 2 (1,4-bdc) 3 ·4H 2 O, which is isostructural to europium and terbium terephthalates, namely Eu 2 bdc 3 ·4H 2 O and Tb 2 bdc 3 ·4H 2 O, correspondingly. ...

Brightly Luminescent (TbxLu1−x)2bdc3·nH2O MOFs: Effect of Synthesis Conditions on Structure and Luminescent Properties

Molecules

... With respect to iron-based material calculations of the adsorption energy of liquid metal atoms and the escape energy of iron atoms on iron surfaces, bismuth exhibits a greater capacity for adsorption and dissolution corrosion compared to lead on Fe surfaces [8] According to the current literature, two reliable methods have been identified for mitigating the corrosion of steels in lead-bismuth Pb-Bi systems. The first method involves maintaining the oxygen concentration within a specified range [9], and the second method entails applying corrosion-resistant coatings to the surface of the materials [10]. ...

Electrochemical Sensors for Controlling Oxygen Content and Corrosion Processes in Lead-Bismuth Eutectic Coolant—State of the Art

Sensors

... Meanwhile, at the Eu 3+ concentration of 9 at.%, the obtained material possessed a structure of [Eu 2 (1,4-bdc) 3 (dmf) 2 (H 2 O) 2 ]. In our previous works, we observed the crystalline phase alternation in (Eu x Lu 1−x ) 2 (1,4bdc) 3 ·nH 2 O and (Tb x Lu 1−x ) 2 (1,4-bdc) 3 ·nH 2 O MOFs [27][28][29][30]. Substitution of up to 90% of Eu 3+ or Tb 3+ by Lu 3+ ions does not affect the crystalline phase of the resulting compounds, Ln 2 (1,4-bdc) 3 ·4H 2 O, which is isostructural to europium and terbium terephthalates, namely Eu 2 bdc 3 ·4H 2 O and Tb 2 bdc 3 ·4H 2 O, correspondingly. ...

Heterometallic Europium(III)–Lutetium(III) Terephthalates as Bright Luminescent Antenna MOFs

Molecules

... Nanomaterials are a promising area of science and technology development in recent decades. Materials consisting of nanoscale particles of rare-earth metal oxides of the lanthanide group, or including nanoscale components in their composition, are already widely used in industry, because they are able to exhibit new, interesting, and useful properties [1][2][3]. Such features of nanomaterials are explained by the increasing relative proportions of surface atoms in relation to their total number as their particle size decreases. ...

Lanthanide-Ion-Doping Effect on the Morphology and the Structure of NaYF4:Ln3+ Nanoparticles

... [31][32][33] MOFs are a relatively new class of chemical materials with signicant potential for sensor applications due to their large surface area, adjustable pore sizes, multiple functional sites, high stability, and ease of functionalization. 30,[34][35][36][37][38][39] Consequently, the tunable structural and surface properties of MOFs make them promising candidates for catalysis, 28,40 sensing, [41][42][43] drug delivery, 44,45 gas separation, 46,47 and the detection of toxic substances. 48,49 Furthermore, MOFs have shown potential for onsite analysis and real sample analysis in various elds. ...

Ultrasound-Assisted Synthesis of Luminescent Micro- and Nanocrystalline Eu-Based MOFs as Luminescent Probes for Heavy Metal Ions

... The more value of (R/O) (I 610nm /I 591nm ) means the lower crystal symmetry. [25] The obvious change of the value of R/O ratio as well as the shift of XRD pattern strongly indicate the crystal symmetry around the Eu 3 + ion is reduced, and the lower crystal symmetry leads to a high electronic configuration in the f-state of the RE 3 + ion, which breaks the forbidden 4 f transitions and facilitates the enhancement of luminescence of Eu 3 + ions by introducing Gd 3 + ions. [26,27] When the doping concentration of Gd 3 + continues to increase from 1.8 mol % to 2.5 mol %, the clusters of Gd 3 + may be formed which has been reported in previous literatures. ...

Effect of Eu 3+ and Gd 3+ co-doping on morphology and luminescence of NaYF 4 : Eu 3+ , Gd 3+ phosphors
  • Citing Article
  • June 2021

New Journal of Chemistry