In this study, ferrihydrite (Fhy) nanoparticles (NPles) synthesized by the radiation chemical method (RCM) from an iron nitrate alcohol solution were annealed in air at temperatures ranging from 100 to 1200 degrees C. The effects of annealing temperature on the phase transformation and basic physicochemical properties of the annealed Fhy nanopowders (NPs) were investigated. Fhy NPles annealed at 400 degrees C and above can be converted to hematite NPles. The X-ray diffraction (XRD) pattern of the RCM-synthesized product corresponded to two-line (2 L) Fhy NPles, with no additional peaks, confirming their chemical purity. Up to 200 degrees C, no significant phase transformation of Fhy NPles was observed; at 300 degrees C, Fhy transformed into maghemite, which further transformed into hematite at 400 degrees C. TEM/HRTEM analysis showed the formation of mesoporous agglomerates consisting of amorphous-crystalline NPles approximately 2 nm in size in the Fhy S95 sample annealed at 95 degrees C. Selected area electron diffraction (SAED) images indicated the presence of two crystalline phases in sample S95: FeO and zero-valence Fe. The specific surface area (SSA) of mesoporous Fhy NPles varied non-monotonically between 100 and 500 degrees C, peaking at 53.2 m(2)/g at 300 degrees C. X-ray photoelectron spectroscopy (XPS) analysis revealed a minor nitrogen impurity, likely from the initial iron nitrate precursor, and a significant amount of adsorbed carbon on the developed porous surface of Fhy NPles. The phase composition of annealed Fhy samples correlated with their photoluminescent (PL) spectra. In samples S400 and S500 containing hematite, a small ferromagnetic contribution emerged, disrupting the linear magnetization-field dependence observed in samples S0-S200. Thus, the properties of 2 L Fhy nanoparticles produced by the radiation chemical method can be modified through thermal annealing while maintaining their potential biomedical applications as nanocontainers for drug delivery and contrast agents.

The effect of the substitution of [GeO4]4− groups by [PO4]3 in the anionic sublattice of apatite-structure inorganic luminophores activated with Eu3+ ions on their luminescence and crystal chemical properties has been studied. A number of solid solutions with a general formula of Ca2La7.2Eu0.8(GeO4)6−x(PO4)xO2 (x = 0.18, 0.3, 0.48, 0.6, 0.78) have been synthesized. Using the luminescence spectroscopy and electron paramagnetic resonance (EPR) methods, it has been shown that Eu3+ in the structure of the synthesized crystal phosphors undergoes reduction to Eu2+. For compounds with x = 0.18 and 0.48, the effect of the composition on the strength of the crystal field acting on Eu3+ ions has been shown. The phonon sublattice has been studied by the IR and Raman spectroscopy methods. A decrease in the integrated luminescence intensity for the selected type of substitution has been shown. The data obtained can be used to design effective luminophores for some fields of technology, such as the design of scitillation detectors, television systems, and photodiodes.

In this study, 2 -line ferrihydrite (2L Fh) nanoparticles (NPles)were synthesized by radiation -chemical method from an alcoholic solution of iron (III) nitrate for the first time. The X-ray diffraction analysis confirmed that the synthetic powder exhibited the characteristic pattern of 2L Fh NPles. DSC-TG analysis conducted in air atmosphere further verified the formation of 2L Fh. SEM analysis showed the presence of mesoporous plate -like structures in the 2L Fh powder, consisting of aggregates of NPs with an average size of approximately 20 nm. The absence of impurity peaks on the X-ray diffractograms and energy dispersion spectra (EDX) confirmed the chemical purity of the produced 2L Fh NPles. Additionally, the XPS method detected the presence of nitrogen and carbon adsorbed to the developed surface of the 2L Fh plates. 2L Fh NPles, when dried in air at a temperature of 50 degree celsius, rapidly dissolved in water. 2L Fh NPles alcohol suspensions were stabilized using surfactants polyethylenimine (PEI) and acetylacetone (AcAs). 2L Fh NPles showed good photocatalytic properties when irradiated with ultraviolet light of methyl violet (MV) dye. These 2L Fh NPles, synthesized using an environmentally friendly radiation -chemical method, have immense potential for applications in biomedicine and photocatalysis.

Ag doped Bi2O3 nanopowders (NPs) were produced by pulsed electron beam evaporation (PEBE) under vacuum. The solid phase synthesis in an electric furnace on air was used for silver doping of bismuth oxide. Different physicochemical properties of NPs have been studied. The specific surface area of (SSA) Ag- Bi2O3 NPs was 23.7 m2/g. Air annealing (200 °C) caused decreased crystallinity and an increase in the SSA of both pure and Ag-doped bismuth oxide. The dominant phase in not annealed/annealed Ag doped Bi2O3 NPs at 200 °C and 300 °C was β -phase Bi2O3. The thermal stability of the pure and Ag-doped Bi2O3 NPs was maintained at 300–350 °C. The phase transition β→α occurred with a further increase in temperature. The annealing temperature could effectively change the physicochemical properties of the Bi2O3 NPs.

The manifestation of ytterbium ions in the microcrystals of the Sr2Y6.8YbSi6O26:Er0.2 solid solution with apatite structure was studied on the basis of low-temperature photoluminescence (PL) spectroscopy and spectral-kinetic measurement data. Intracenter down-conversion luminescence of Er3+ ions in the visible and IR ranges was detected. Up-conversion luminescence of Er3+ ions is observed upon IR excitation due to excitation of Yb3+ ions and subsequent energy transfer Yb3+ -> Er3+. Overlapping bands at 412 and 430 nm with a Stokes shift of less than 0.3 eV are observed in the PL spectra at room temperature. These emission bands are assigned to the spinallowed and spin-forbidden 4f135d -> 4f14 transitions from the low-spin and high-spin exciting states of Yb2+ ion, respectively. The PL decay kinetics for transitions from the low-spin states is characterized by a dominant component tau = 0.39 ns. An alternative model of Yb3+ luminescence center associated with a charge transfer band does not explain the data of low-temperature (5K) PL spectroscopy. At T = 5 K, a new wide emission band with a maximum at 696 nm and a Stokes shift of 1.1 eV appears in the PL spectrum. Two options of this PL band nature are considered. The first is the luminescence of defects having a vacancy nature. The second possible option is the manifestation of anomalous luminescence of Yb2+ ions, which occupy a different crystallographic position in the apatite crystal structure.

A mesoporous amorphous crystalline nanopowder (NP) Si-SiO2 with a specific surface area (SSA) of 35 m2/g was produced by pulsed electron beam evaporation (PEBE) of a compact of micron commercial SiO2 powder (0.9 m2/g). Si semimetal nanoparticles (NPles) reduced in for vacuum (approximate to 4 Pa) had a marked effect on the thermal and luminescent properties of the Si-SiO2 nanoparticles compared to the properties of amorphous SiO2 NPles produced earlier by PEBE evaporation of a target compound made from NP Aerosil 90 (Degussa). Photocatalytic capabilities of Si-SiO2 nanoparticles were evaluated. NPles Si-SiO2 showed high antioxidant activity on HELA cancer cells.

During electron beam evaporation of green-emitting (λex=980 nm) silicate upconversion (UC-PL) bulk phosphors Sr2Y6.8YbEr0.2Si6O26, amorphous nanoparticles of size 2.7 nm are formed. The nanoparticles are globules formed during condensation of chains consisting of SiO4 tetrahedra. When the globules are excited with radiation of λex=980 nm, the luminescence color becomes red and its intensity increases 80 times compared with bulk phosphors. It has been shown that luminescence is influenced by nonradiative processes between different transitions of Er3+ ions. There is a threshold population of the Er3+ and Yb3+ levels (level 2F5/2) in the region of relatively low pumping powers. Above this threshold, a sharp increase in the intensity of upconversion photoluminescence occurs. We show that the produced nanophosphors have a core consisting of a combination of SiO tetrahedra (n = 0, 1, 2), while Er, Yb, Sr, and Y ions are on the surface of the globules. Owing to this structure of the globules, the interaction of Er and Yb ions with nucleus defects, which usually suppress the luminescence, decreases. Probably, for this reason the luminescence intensity increases. Our findings reveal that new effective non-linear materials can be designed for converting IR radiation into visible radiation. The produced effective phosphors can hold promise as fluorescent probes in bioresearch, for fundamental therapy, as well as for new display technologies.

This work establishes for the first time that imposing of permanent magnetic field ledt o shift of peaks in ranges of photoluminescence of nanopowders CaF2 and BaF2. Ranges of shift of peaks to the red area of a spectrum depended on the size of magnetic field. A transformation of peaks occurs as a result of interaction of own magnetic field of nanofluorides with external magnetic field caused by structural defects of nanopowders. Deconvolution of spectra allowed to identify the split of the first peak of both nanofluorides to a quadruplet, and the second to a doublet at the size of magnetic field of 0.1 T. At increase in magnetic field the quadruplet of the first peak disappears, and the doublet of the second significantly differs for ferromagnetic CaF2 and para-ferromagnetic BaF2. Besides, spectra of both nanofluorides contain peaks at 616 nm that aren't observed in the field of 0.1 T but appear in the field of 0.15 T, and are possibly caused by the center of coloring.

Polycrystalline phosphors with a Sr2Y8-x-yYbyTmxSi6O26 (x=0.005-0.5, y=0.2,0.3) total formula were synthesized. Nanoluminophor has been obtained from the Sr2Y7.695Yb0.3Tm0.005Si6O26 microcrystalline sample by the vacuum electron been evaporation, in the amorphous state, with the ~10.6 nm particle size. It is found, raman spectra undergoing modification by the transition from bulk- to nanosize state. Photoluminescene spectra micro- and nanophosphors are studied. Intensity of the blue emission, by the UV ligth excitation, grows in the x=0.005-0.02 region, with the x increasing. Upconversion photoluminescence (UPCL) spectra of the bulk phosphors and nanosample based on the Sr2Y7.695Yb0.3Tm0.005Si6O26 were measurd. At the pumping power around 70.8 mW, by the laser source with the λ=980 nm, thereshold population of the 3F3 level of Tm3+ ions exist. At a power higher 70.8 mW, a sharp increase of the luminescence intensityof the bulk- and nanophosphor occurs. For the 3H4->3H6 transition thereshold pumping power absent. This indicates that, pumping, during Yb->Tm energy transer, is a single photon process.

Conformational changes of heme and globin in fractionated rat erythrocytes have been investigated using Raman spectroscopy. The results obtained show that normal isoforms (common variants) of hemoglobin, which plays a key role in oxygen transport and a protective role against oxidative stress, are dominant (more than 80%) in rat blood. However, heavy chain (3%) and light chain isoforms (11%) formed as a result of protein polymerization or degradation perform important roles in the body because they also function in signal transmission and binding to exogenous ligands.

Amorphous-crystalline nanoparticles (NPles) of maghemite (gamma-Fe2O3) were successfully prepared by a radiation-chemical method using a precursor-heptahydrate of iron (II) sulfate. Synthesized NPles were quasi-spherical agglomerates 200-300 nm in size with an uneven surface covered with thin, porous, randomly oriented, elongated plates of irregular shape, with sharp vertices. The amorphous component of NPles included ultra-fine NPles maghemite about 2 nm in size. Stepwise annealing of the original nanopowder (NP) in air showed a phase transformation of NPles along the following path: maghemite + amorph (RT-150 degrees C) -> amorph (200-500 degrees C) -> hematite (570-1050 degrees C). The hematite NP produced after annealing at a temperature of 575 degrees C showed good texture characteristics: the specific surface area (SSA) increased from 21 to 36.8 m(2)/g, the pore volume increased from 0.04 to 0.15 cm(3)/g, while maintaining the particle nanosize of not more than 38 nm. X-ray photoelectron spectroscopy (XPS) showed the presence of the following elements on the surface of the synthesized NPles -S, C, O, Fe and N (N only in the original sample S0) and increased O-Fe bond with an increase in annealing temperature. The paramagnetic properties of the studied NPles indicate the prospect of their use as contrast agents in magnetic resonance imaging (MRI).

ZrO2 and Ag doped ZrO2 powders were prepared from mixtures of ZrO2 and AgNO3 commercial powders (99:1 and 95:5 wt %) by pulsed electron beam evaporation (PEBE) in vacuum. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), textural and magnetic analysis, photocatalytic test, photoluminescence spectroscopy (PL) and cell cytology (Vero and Hela). XRD analysis confirmed the presence of monoclinic ZrO2 phase and cubic Ag phase in the final product. HRTEM pictures showed a large range of particle sizes approximately from 10 to 500 nm; the spherical silver nanoparticles (NPles) (10 nm) were observed on the ZrO2 particle surfaces. Ferromagnetic contribution in pure ZrO2 powder was 0,002 emu/g, and in Ag doped ZrO2 powders it reached 0,016 emu/g. It was found that Ag doped ZrO2 powders showed increased photocatalytic activity in methyl orange (MO) compared with pure ZrO2 NPles. The produced powders can be used to kill Hela cancer cells, as low (<0.1 wt) Ag photocatalysts and in other applications.

Tests of bulk- and nanosized radiopaque contrast agents based on solid solutions of La1-xGdxTaO4, Sr2R8 (1-x-y) ErxYbyM6O26, (R=Y, La, M=Si, Ge), and Gd2O3 are presented. The bulk substances were synthesized from the corresponding oxides in the solid phase. Nanoparticles were produced in vacuum by the pulse electron beam evaporation method. The obtained nano-samples have K-jumps of X-ray radiation absorption in the 10-100 keV region of energies. This opens up prospects for the use of nanoparticles as X-ray contrast agents (radiopaque agents). The gel suspensions based on the bulk solid solutions La1-xGdxTaO4 (x = 0 – 0.18) allow for continuous and smooth alteration of radiopaque contrast agents, thus expanding the fields of their application. Gel substances based on LaTaO4 and Gd2O3 NPs have a higher contrast than bulk substance.

The present work studies europium-ion spectroscopic features in solid solutions based on silicate-tungstates Ca2La6.8Eu1.2Si5.6W0.4O26.4 and Ca8Eu2Si3W3O26 microcrystalline powders with the crystal structure of silicate apatite and scheelite respectively. The spectroscopic features were studied by means of photoluminescence spectroscopy and X-ray excited luminescence at temperatures 4.6, 90 and 295 K. In Ca2La6.8Eu1.2Si5.6W0.4O26.4 only intensive luminescence was observed, which was characterized by a set of 5D0 → 7FJ dominant intraconfigurational transitions for Eu3+ ion. In Ca8Eu2Si3W3O26, both 5D0→ 7FJ intraconfigurational transitions for Eu3+ ion and wide 430 nm emission band corresponding to host self-trapped exciton (STE) emission are observed. This STE emission band is reabsorbed by the f – f absorption of Eu3+ ions by means of energy transfer from host to Eu3+. The asymmetry coefficient which characterizes the shape of the emission spectrum of Eu3+ ions strongly depends on the energy of exciting photons. The Eu3+ ion might occupy two nonequivalent crystallographic sites. Some features of this phenomenon were discussed.

The aim of this study was to develop new gel X-ray contrast agents (RCA), in which the substances are tantalates of rare-earth elements or solid solutions based thereon in micro and nanosized states. The next aim was to provide an increase in contrast over time, which would improve diagnostic accuracy and reduce radiation exposure to patients. Orthotantalats MTaO4 (M = Y, La, Gd) and solid solutions La1-xGdxTaO4 were considered as such substances. The RCA were examined in vitro and in vivo. When gel lanthanum orthotantalate was used as a RCA for contrast studies of the bile passages, this method exhibited a high resolving power in the examination of the hepatic tree and the gallbladder and in the diagnostics of intracavitory masses in ducts and the gallbladder. In contrast to iodine-containing urografin, this RCA has no negative effect on the mucous tunic of the bile passages of laboratory animals. Using the substitutional solid solutions, one can continuously change the specific effectiveness of RCA by gradual varying of the composition and the average size of the substance particles.

A bulk phosphor composition Sr2Y6.8YbEr0.2Si6O26 was synthesized. A nanophosphorus in an amorphous state was obtained from this sample by the method of pulsed electron beam evaporation. The spectra of upconversion photoluminescence of bulk and nanosamples were studied. In the field of pumping power of nanosample with 78 mW laser radiation with a wavelength of 980 nm, there is a threshold population of energy levels Er3+. Laser radiation carries out resonant pumping of 4I13/2 → 4F9/2 transition. Then there is an intensive red radiation upon transition 4F9/2 → 4I15/2. A photon avalanche was found in the nanophosphore, at which the intensity of red radiation increases ∼80 times compared to the bulk phosphorus.

In this work the method of pulsed electron beam evaporation (PEBE) in vacuum (4 Pa) was used to produce the mesoporous multiphase (alpha, beta and amorphous) amorphocrystalline nanopowder (ACN) of Bi2O3 with specific surface area (SSA) up to 23 m(2)/g. The effect of thermal annealing on the properties of Bi2O3 ACN was investigated in vacuum and in air. Using the HTXRD method in a vacuum (10(-4) mbar) in the RT-510 degrees C temperature range, the phase transformation of the NP was established according to the scheme (alpha + beta + amorph) ->(200 degrees C) (alpha + beta + R)->(280 degrees C)(alpha + R)->(510 degrees C)(alpha). The formation of uniform Bi amorphocrystalline nanoparticles (droplets) with a size of 3-5 nm was observed on the surface of all bismuth oxide samples (S200, S300 and S500) that were annealed in air in the temperature range of 200-500 degrees C, respectively, due to extrusion of liquid Bi from the volume to the surface of large nanoparticles (NPles) forming the framework of 3D nanoparticle agglomerates during the cooling of the annealed NPs. The presence of NPles of metallic Bi in the original sample was confirmed directly by HRTEM and indirectly by RS, DSC and PCL. The magnetic behavior of annealed samples confirmed their diamagnetic nature. The weak ferromagnetic response (3-4 memu/g) in the as prepared sample was associated with its very defective structure. The photocatalytic activity of NPs was confirmed in decomposition of MO colorant during UV irradiation. (C) 2021 Published by Elsevier B.V.

Mesoporous nanocrystal BaF2 nanopowders (NPs) have been obtained with the pulsed electron beam evaporation (PEBE) technique. The transformation of the structure and morphology of BaF2 nanoparticles (NPles) induced by thermal annealing in air at temperatures of 200, 400, and 900 degrees C has been monitored with the XRD, SEM, and HRTEM methods. The HRTEM analysis has shown the presence of three polymorph phases (cubic, octahedral, and hexagonal) in the unannealed NP. Upon the transition into the nanoscale, diamagnetic (DM) BaF2 (in the volume state) has demonstrated both paramagnetic (PM) and ferromagnetic (FM) responses at room temperature. The thermal analysis (TA) has confirmed the strong adsorption of CO2 while synthesizingthe BaF2 NP via PEBE method and adsorption of different NOx oxides following irradiation of the BaF2 NP (in air by 700 keV electrons) The appearance of the FM contribution in the diamagnetic BaF 2 NP after annealing at a temperature of 600-900 degrees C is likely associated with the achievement of the percolation threshold with an increase of the BaO oxide concentration. This is in agreement with the well-known theoretical predictions of d0 magnetism in N-doped (C-doped) BaO. The appearance and variations of the FM contribution to the BaF2 NP irradiated by 700 keV electrons are likely connected with an increase of the NOx oxide concentration (due to an increase of the time of electron irradiation), which confirms the hypothesis on the appearance of the FM response in solid-state N (C)-BaO solutions. The FM decrease with time is indicative of the surface character of d0 magnetism in the barium fluoride under study.