Maria Milanova

• PhD
• Principal Investigator at Sofia University "St. Kliment Ohridski"

Four different-sized carbon microspheres, CS, obtained by a facile hydrothermal method, are applied as a hard template for the preparation of a series of macroporous LaFeO3. The average particle size of the CS obtained is between 0.350 and 0.700 µm. The macroporous LaFeO3 are tested in a Fenton-like activation of peroxymonosulfate, PMS, for oxidati...

The solvothermal synthesis of LnCl3.nH2O with terephthalic acid (benzene-1,4-dicarboxylic acid, H2BDC) produced metal–organic frameworks (LnBDC), [Ln2(BDC)3(H2O)4]∞, where Ln = Sm, Eu, Tb, and Dy. The materials obtained were characterized by a number of physico-chemical techniques. The influence of the ionic radius of the lanthanides on the microst...

“Core/shell” composites are based on a ferrite core coated by two layers with different properties, one of them is an isolator, SiO2, and the other is a semiconductor, TiO2. These composites are attracting interest because of their structure, photocatalytic activity, and magnetic properties. Nanocomposites of the “core/shell” МFe2O4/SiO2/TiO2 (М =...

The synthesis of orthoferrites of the type La 1−x Ce x FeO 3+x/2 , x = 0.00, 0.01, 0.03, 0.05, and 0.07, by applying a simple and effective mechanochemical transformation from the constituent oxides is presented. Physicochemical methods such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, and Brunauer...

Pure HfW2O8- and Ln3+-containing solid solutions, Hf1−xLnxW2O8−x/2 (Ln = Eu, Tm, Lu), were synthesized using the hydrothermal method. The lanthanide ions were selected based on the differences between their ionic radii. A content of the Ln3+ ions in the range of 0.01–0.15 mol with a step of 0.02 was used for Hf1−xLnxW2O8−x/2 preparation, although t...

Light-emitting phosphors, doped with lanthanide ions of Tb(III) and Sm(III) of the type Gd1.97-y SmyTb0.03(MoO4)3 (y = 0.01-0.11, step 0.02) and Gd1.95-xSm0.05Tbx(MoO4)3 (x = 0.01-0.09, step 0.02), were synthesized and characterized by X-ray diffraction, UV-Vis spectroscopy, scanning and transmitting electron microscopy (SEM, TEM) as well as photol...

A synthetic procedure combining high energy ball-milling and calcination at 900 °C was applied to obtain mixed metal oxides of the type Zn1−xNixFe2O4 (x = 0.25; 0.5; 0.75). The formation of spinel-like structures and the phase composition were confirmed by XRD in combination with Mössbauer, IR and Raman spectroscopy. The crystallite size was analys...

Editorial to the Special Issue of Crystals (ISSN 2073-4352) "Rare-Earths-Doped Materials"

ZnFe 2 O 4 /rGO/g-C 3 N 4 ternary nanocomposite photocatalysts with different ZnFe 2 O 4 /g-C 3 N 4 weight ratio (0.5, 0.75, 1) were prepared by a stepwise solvothermal method using ethylene glycol as the solvent. Physicochemical methods such as X-ray diffraction, UV-Vis diffuse reflectance spectroscopy and photoluminescence spectroscopy were appli...

The mixed metal oxides NiFe 2 O 4 and Zn 0.5 Ni 0.5 Fe 2 O 4 with a spinel-like structure, pure and modified with the lanthanide ions Eu(III) and Tb(III), were prepared by a sol-gel process in which propylene oxide was used as a gelling agent and then tested as photocatalysts. The photocatalytic activity was studied under polychromic visible light...

Ferrites of the type MFe2O4, where M = Zn, Co, and Mg, were prepared via a sol-gel procedure using propylene oxide as a gelating agent. Silver nanoparticles with an average size of 6 nm were prepared in the presence of the ferrite powders in suspension using raffinose as a reducing agent in a basic water solution. Nine samples of the ferrite/silver...

Cobalt ferrite CoFe2O4 with spinel-like structure, modified with different contents of Hf(IV), was synthesized by a sol-gel method using propylene oxide as a gelating agent. The impact of the Hf(IV) content on the physicochemical characteristics of the catalysts and on the oxidation of ethyl acetate used as model molecule was studied. The phase hom...

The method of Time Differential γγ Perturbed Angle Correlations (TDPAC) was used to gain additional information on the position of different doping ions in the crystal structure of ferrites with spinel-like structure. For this purpose ferrites of the type MFe2O4 (M(II) = Co, Zn, Ni) were doped with the radionuclides ¹⁴⁰La(¹⁴⁰Ce), ¹⁷²Lu(¹⁷²Yb), ¹⁷²H...

The hydrothermal method was used to obtain pure and Eu(III)-modified ZrW 2 O 8. Tungstates modified with 1, 2, and 5 mol% Eu(III) were synthesized in order to investigate the influence of Eu(III) doping on the properties of zirconium tungstate. The samples obtained were phase homogeneous as shown by XRD. High temperature XRD was used to follow the...

The distribution coefficients for REE were determined on two modern extraction chromatographic resins (DN and UTEVA) and for some non-REE on UTEVA were determined using different acidic solutions. Separation strategies for purification of REE from other elements were researched as well as some possible separations of individual REE. All elements re...

The distribution of some rare-earth elements (REE) on DN resin (TODGA loaded resin by Triskem international) was determined from different concentrations of two inorganic (HCl, HClO4) and two organic acids (CH3COOH, CCl3COOH). The separation of Ac from REE is researched, as well as some separation possibilities of the elements within the REE. The d...

In order to study the possibilities for the incorporation of lanthanide ions in the spinel crystal lattice, cobalt ferrite CoFe2O4 modified by the lanthanide ions Ce(III), Nd(III), аnd Dy(III) was prepared using the sol-gel method, and two diffraction techniques, XRD and neutron diffraction, were applied to detect the position of the lanthanide ion...

A combination of thermal and mechanical (high energy ball milling) treatment was applied in an attempt to obtain polycrystalline mixed metal binary and ternary oxides of the type CoxZn1-xFe2O4 (x = 0; 0.25; 0.5; 0.75; 1). The synthetic procedure used successfully produced single-phased, homogeneous ZnFe2O4, CoFe2O4, and Co0.75Zn0.25Fe2O4, as well a...

The distribution of some rare-earth elements (REE) on UTEVA resin was determined from different concentrations of inorganic (HCl, HNO3, HClO4, HPF6) and one organic acid - CCl3COOH. Low sorption of all REE in the range of 1M – 5M HNO3 was observed. In more concentrated HNO3, a rapid increase of the distribution coefficients (Kd) was noticed with an...

Thin film deposition techniques, such as dip coating, spin coating, and spray pyrolysis, are applied for the production of SiO2-, poly-(methylmethacrylate) (PMMA)-, and SiO2-/polyester-based “hybrid” matrices. The factors influencing the film properties are briefly discussed. The morphology of the films presented is studied by different microscopy...

Using radioisotope markers the distribution coefficients (Kd) of the following elements In, Sn, Sb, Te, Bi, Co, Fe, Nb, Sr, Ba, Ag, Cd, Zr, Hf and Ti were determined with different concentrations of HCl, H2SO4 and HNO3 for the extraction chromatographic resin Uranium and TEtraValent Actinides (UTEVA). This data can be used for separation of element...

The spinel-type ferrites NiFe2O4 and Zn0.5Ni0.5Fe2O4 modified by lanthanide ions Eu³⁺ and Tb³⁺ were prepared by a sol-gel process with propylene oxide as a gelating agent. The phase homogeneity of the samples was tested by XRD and Mössbauer spectroscopy. Transmission electronic microscopy used for characterisation of the morphology of the samples r...

Nanosized copper ferrite-type materials (CuxFe3–xO4, 0 ≤ x ≤ 1) have been prepared by combination of co-precipitation and mechanochemical activation and/or thermal treatment. The crystalline structure and morphology of the obtained ferrite nanopowders have been characterized by different instrumental methods, such as Powder X-ray diffraction (PXRD)...

Nickel ferrites with different Ni content, NixFe3–xO4, 0 ≤ × ≤ 1, are technologically important materials for microwave, electronic, and magnetic storage devices. They are members of solid-solution series of spinel-type materials (Fe3O4–NiFe2O4) having specific magnetic properties and different degree of electron delocalization. They demonstrate go...

The effect of the addition of small amounts of rare earths (Ln=La, Ce, Nd and Gd) to alumina supported copper-cobalt spinel oxide on the catalysts efficiency in CO and CH4 oxidation and in NO decomposition was investigated. Samples of Ln/CuCo/Al catalyst were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (X...

Series of nanostructured zinc ferrite-type materials ZnxFe3-xO4 (x= 0.25, 0.5, 1) with average crystallite size about 8 nm prepared by co-precipitation or co-precipitation and mechanochemical treatment were tested for photocatalytical degradation of Malachite green oxalate as model contaminant in aqueous solution under UV-light. The performed exper...

The compound 3,3’-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) was synthesized by the Knoevenagel reaction. Crystals, suitable for X-ray data collection were grown by slow evaporation from an ethanol solution. The product 3,3’-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one)∙ethanol crystallizes in the monoclinic system, space...

The complex of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methyl)]bis-(4-hydroxy-2H-1-benzopyran-2-one), Tb(C25H15O7)3.5H2O, was successfully immobilized by a simple technique in transparent SiO2-based matrix. The films and monoliths obtained were studied by IR spectroscopy, fluorescent spectroscopy and microscopy. The micromorp...

The aim of this study was to investigate by atomic force microscopy and multifractal analysis the three-dimensional (3-D) of surface micromorphology of the complex of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methyl)]bis-(4-hydroxy-2H-1-benzopyran-2-one),Tb(C25H15O7)3 · 5H2O immobilized in transparent SiO2-based films by a simp...

The structural complexity of the 3D surface of poly(methylmethacrylate) films with immobilized europium β-diketonates is studied by atomic force microscopy and fractal analysis. Fractal analysis of surface roughness revealed that the 3D surface has fractal geometry at nanometer scale. The poly(methylmethacrylate), PMMA, as immobilization matrix is...

For the first time, data on the effect of TiO2 modification by N-doping or by carbon nanotubes on the photocatalytic destruction of endocrine disrupting compounds 17α-ethynylestradiol (EE2) and 17β-estradiol (E2) in aqueous solutions are reported. A possibility to accomplish photocatalytic process under halogen lamp irradiation is shown. The cataly...

An amorphous complex of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methylene)]bis-(4-hydroxy-2H-1-benzopyran-2-one), Tb(H2L)3, was successfully synthesized and characterized. IR- and 1H-NMR-spectroscopy were used to investigate the coordination of the ligand around the Tb(III) ion. Values for the quantum yield and the life time...

The aim of presented paper was to study preparation of catalytic materials for water purification. Iron oxide (Fe3O4) samples supported on activated carbon were prepared by wet impregnation method and low temperature heating in an inert atmosphere. The as-prepared, activated and samples after catalytic test were characterized by Mössbauer spectrosc...

Ru(II)-tris (4,7-diphenyl-1,10-phenanthroline) dichloride immobilized in matrices from sol-gel produced SiO2, SiO2-citric acid/ethylene glycol polyester hybrid or poly (methylmetacrylate) is explored as a sensor for determination of dissolved oxygen in white and red wines. The significant overlapping of the 612 nm spectral bands of the oxygensensit...

The paper presents a review of literature data on the occurrence of endocrine disruption compounds in the effluents from wastewaters treatment plants, surface, underground and drinking waters and sediments. General data concerning their action on the living organisms (mainly fish) are given. The peculiarities of the methods for removal/degradation...

Microcomposites consisting of TiO2 and ThF4 or UO3 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of the respective additives. X-ray diffraction study reveals small effect of the latter on TiO2 phase composition and cell parameters and significant influence on the crystallite size and UV/Vis reflectance spectra. The...

The paper considers the possibilities for mechanochemical synthesis of rare earth complexes. The complex Eu(TTA)3·phen (HTTA — 2-thenoyltrifluoroacetone, phen — 1,10-phenanthroline) is synthesized by mechanical treatment of a mixture of EuCl3.6H2O, HTTA, phen and NaOH in planetary ball mill Pulverisette 7 for 30 min at 800 min−1. The non reacted st...

Due to their excellent photo-catalytic activities making TiO2 nanoparticles applicable as self-cleaning and anti-bacterial agents, as well as for UV protection and environmental purification, a great potential for multi-functionalization of fabrics by TiO2 nanoparticles is considered. In order to improve the durability of nanoparticles at a fabric...

A complex of Nd(III) with 3,3'-[(4-chlorphenyl)methylene]bis-(4-hydroxy-2H- 1-benzopyran-2-one) (symbol L15) was immobilized in poly(methylmethacrylate) (PMMA) films and the properties of the composites obtained were studied. The films contained 1 wt. % of the complex and were deposited by spin- and dip- coating techniques. The IR spectroscopy data...

Au/CeO2–CoOx catalysts were synthesized using two methods for the mixed support preparation: co-precipitation (CP) or mechanochemical activation (MA). The catalysts were characterized by means of XRD, HRTEM, XPS, Raman spectroscopy and TPR measurements. It was established that the catalyst prepared by MA exhibited much higher activity in the reacti...

The purpose of this article is to study the influence of gamma irradiation on the sorption capacity and photocatalytic activity of commercially available TiO2 Degussa P25. The photocatalyst was gamma-irradiated at ambient temperature with doses 8–60 kGy (137Cs, dose rate 2 kGy/24 h) and then stored until analysis/tests in liquid N2. X-ray diffracti...

Commercial product Degussa TiO2 P25, sol-gel produced TiO2 and TiO2 modified by carbon nanotubes addition (5% of the TiO2 mass) are tested as photocatalysts for the degradation of endocrine disrupting compound 17α-ethynylestradiol (1 µM aqueous solution). The molecular and crystal structure, phase composition, crystallite size, specific surface are...

TiO2-based photocatalysts doped with 10 wt.% Nd3+ or 1.8 wt.% nitrogen are synthesized by a sol–gel method using Ti-butoxide and Nd(NO3)3 or aqueous ammonia as starting materials. The resulting powder crystal structure, textural properties, morphology, IR, UV/Vis and X-ray photoelectron spectra are studied. The photocatalytic activity was tested fo...

Sol-gel produced TiO2 is gamma-irradiated at ambient temperature (Cs-137, dose rate 2 kGy/24 h) with doses 8-60 kGy and stored up to the analysis/tests in liquid N-2. Phase composition, crystal cell parameters, crystallites size, textural properties (morphological grains size, specific surface area), EPR behaviour and UV-vis. reflectance spectra of...

Microcomposites consisting of TiO2 (or Ce-doped TiO2) and ThO2 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of ThO2. X-ray diffraction study reveals the effects of ThO2 (compared to the ThO2-free TiO2, obtained by the same method) on the anatase interplanar distances, crystallites size and phase composition. The p...

Thin films of ferrites of the type MIIFe2O4 (M = Cu, Mg, Zn) are prepared by spray-pyrolysis using ethylene glycol solutions of mixed-metal citric complexes of the respective metals at substrate temperature between 350 °C and 450 °C and post-deposition annealing at 480–750 °C in air. Phase composition, crystal structure, morphology and adhesion of...

Microcomposites are produced consisting of optically active Ru (II)-tris(4,7-diphenyl-1,10-phenanthroline)dichloride (Rudpp) immobilized in poly(methylmethacrylate) prepared by polymerization of the monomer or by using chlorophorm solution of the polymer. The morphology of films and membranes (up to 1.5 mm in thickness) is studied in dependence of...

The properties of composites prepared by the immobilization of Eu(III) complexes with dibenzoylmethane and thenoyltrifluoracetone in poly(methylmethacrylate) are studied. The matrices are produced by polymerization of the monomer or by using chloroform solution of the polymer. The films produced from polymerized monomer by dip-coating or spray-pyro...

Organic–inorganic hybrid materials produced from tetraethoxysilane, citric acid and ethylene glycol in different mole ratios and consisting of Si–O–Si and Si–O–C nets are prepared and their molecular structure (IR and NMR spectroscopy), morphology (fluorescent microscopy, SEM and AFM), thermochemical behavior and fluorescence properties (excitation...

Results on the influence of mechanoactivation (3–30 min) in a planetary ball mill on the composition, crystal structure, IR spectra and morphology of EuCl3·6H2O, dibenzoylmethane (HDBM) and mixtures of EuCl3·6H2O — HDBM and EuCl3·6H2O — HDBM — 1,10-phenathroline (phen) are presented. Mechanoactivation leads to a decrease of interplanar distances of...

The main goal of this short review is to present the most valuable attempts that have been made in the past decades to shift the absorption of TiO2 from UV- to the visible-light region by lanthanide doping. In order to understand the other factors by which doping of TiO2 with lanthanides can increase the photocatalytic activity under solar irradiat...

The X-ray powder diffractogram of the europium complex Eu(DBM) 3 (DBM - dibenzoylmethane) is reported for the first time. It is shown that the mixed-ligand complex Eu(DBM)3.dpp (dpp - 1,4-diphenyl-1,10-phenanthroline) is X-ray amorphous. The 1H and 13C NMR spectra of Eu(DBM) 3, Eu(DBM) 3.phen (phen - 1,10-phenanthroline) and Eu(DBM) 3.dpp are inter...

The paper presents the results of the synthesis of complexes of the type Eu(DBM)3 and Eu(DBM)3·Q (DBM-dibenzoylmethane, Q-1,10-phenantroline or 4,7-diphenyl-1,10-phenantroline) and of Tb- and Nd-complexes with the newly-synthesised coumarin derivates 3,3′-[(4-chlorphenyl)methylene)bis(4-hydroxy-2H-chromen-2-one), 3,3′-[(3,5-dimethoxy-4-hydroxy)meth...

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A polymerized complex technique was used to prepare high-purity pyrochlore Y2Ti2O7 powders at 750°C. Heating of a mixed solution of citric acid (CA), ethylene glycol (EG), and yttrium and titanium ions, with a molar ratio of CA:EG:Y:Ti = 5:20:1:1, at 130°C produced a yellowish transparent polymeric gel without any precipitation; this material was u...

The complexes of europium with dibenzoylmethane (= HDBM) and mixed-ligand complexes containing 1,10-phenanthroline (= phen) or 4,7-diphenyl-1,10-phenanthroline (= dpp) are synthesized by different methods (already proposed in the literature) and their elemental composition, I.R., 1H and 13C NMR, and fluorescence excitation and emission spectra, as...

A short review of recent investigations of the authors on the Ru(II)-based optical oxygen sensors is presented focused on the influence of: (i) type of the supporting matrix (SiO2 or polymethylmetacrylate based), (ii) precursors used (tetraethoxysilane, ormosil-type alkoxosilanes, methylmetacrylate, polymethylmetacrylate), (iii) method applied for...

The complex of europium with dibenzoylmethane and mixed-ligand complex containing 1,4-diphenyl-1,10-phenantroline is entrapped in SiO2-based sol-gel produced immobilization matrices. The IR spectra, thermochemical behavior, photoluminescence properties of the obtained composites and the influence of the synthetic conditions (composition of the sol,...

A short review is presented on the authors, investigations on the influence of the crystal structure and the morphology on the sorption ability and photocatalytic activity under UV-irradiation of thin TiO2 films produced by spray-deposition process. Commercially available TiO2 (Degussa P25 and Tronox), titania modified by mechanoactivation as well...

C156H172Eu2N2O 18S2, monoclinic, P121/c1 (no. 14), a = 21.1458(4) Å, b = 24.4509(5) Å, c = 28.1465(5) Å, ) = 111.528(1)°, V = 13537.5 Å3, Z = 4, Rgt(F) = 0.034, wRref(F2) = 0.092, T = 103 K.

The photocatalytic activity of TiO2 films deposited on different substrates by the spray-drying method using suspensions of commercially available TiO2 (Degussa P25 or Tronox) as starting material was studied. The influence of the type of the initial TiO2, preparation conditions (temperature of the substrate during the film deposition, temperature...

Samples of pure aluminium and aluminium alloy were heated at 150 kPa and 130 °C in ethylene glycol (EG)–water mixture (volume ratio 1:1) for 172 h (8–12 h heating, 12–16 h pause). The corrosion of the metals was characterised by the transfer of Al into solution, changes in the surface morphology of the samples and their electrochemical behaviour. F...

Films are deposited by dip- or spin-coating in gels produced from tetraethoxysilane (TEOS), octyltriethoxysilane (OtEOS) or mixtures of TEOS and OtEOS (mole ratio1:1) as well as TEOS and methyltriethoxysilane (MtEOS) (mole ratio 1:3). The Stern–Volmer constants and the response to oxygen of Ru(II)-tris(4,7-diphenyl-1,10-phenathroline) dichloride im...

The possibility to use the photoluminescence of Ru(II) tris(4,7-diphenyl-1,10-phenathroline) dichloride, immobilized in sol-gel produced SiO2-based matrix for the determination of dissolved oxygen concentration in beer is studied. Organically-modified silane (octyltriethoxysilane) and mixtures from tetraethoxysilane and octyltriethoxysilane are use...

The results reported concern the characterization of thin layer SiO2-based matrices with an oxygen sensing component Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline) immobilized, when a sol–gel process along with dip- and spin-coating deposition methods are used.SEM, TEM and AFM study, assisted by X-ray energy dispersive microanalysis reveals the infl...

The results from DSC and thermogravimetric analysis of gels produced from a mixture of tetraethoxysilane (TEOS) and octyltriethoxysilane (OtEOS) both with and without immobilized Ru(II) tris(4,7-diphenyl-1,10-phenanthroline) dichloride as well as DSC and TG data for films deposited by deep-or spin-coating from the same gels, are reported. The initi...

The composition, some spectral characteristics, and thermal decomposition of solid lanthanide–titanium (lanthanide (Ln) = Y, La, Ce) and lanthanide–titanium citrates (CA) and tartrates (TA) have been studied. The com-plexes have been prepared in ethylene glycol medium at conditions modeling those of the polymerized-complex method applied for Ln 2 T...

Thin films of La2Ti2O7 have been deposited on fused silica and Si substrates by a spray pyrolysis method using ethylene glycol solution of La(III)-Ti(IV)-citrate complexes as starting material and O2 as a carrier gas. The composition, crystal structure and morphology of the films are studied.

The cocrystallization of Ce2(SO4)3 and La2(SO4)3 is studied in aqueous and H2SO4 (150 g/dm3) solutions at 25 °C and 64 °C. The effect of the formation of inner sphere sulfate complexes of the type LnSO 4+ in determining the composition of the equilibrium phases is revealed.

Al-and Y-Al-citric complexes have been synthesized in ethylene glycol medium at conditions close to the ones used in polymerized complex method and their composition and spectral characteristics have been studied. Proofs have been found for the formation in the bimetallic system of a mixed-metal Al-Y-complex. Doubly ionized and esterified ligands t...

A polymerized complex technique was used to prepare high-purity pyrochlore Y2Ti2O7 powders at 750°C. Heating of a mixed solution of citric acid (CA), ethylene glycol (EG), and yttrium and titanium ions, with a molar ratio of CA:EG:Y:Ti = 5:20:1:1, at 130°C produced a yellowish transparent polymeric gel without any precipitation; this material was u...

The composition, IR, C and H NMR spectral characteristics and thermochemical behavior of La‐, Ti‐ and bimetallic La‐Ti‐tartrates (potential precursors of La2Ti2O7), obtained in ethylene glycol, were studied. The comparison of their main characteristics with those of the analogous citric complexes contributes to the elucidation of the processes invo...

Solid state La-Ti-citrate complexes are isolated from ethylene glycol and water solutions. The elemental composition of the compounds is determined, the 13C- and 1H-NMR and IR spectra are analysed, and their thermochemical behaviour is studied. It is found out that the ethylene glycol is present in the complex, prepared at 40°C, mainly as an adduct...

The influence of mechanoactivation on the overall solubility of CaSO4 · 2H2O and of phosphogypsum in water and in diluted acids (10% HCl, 7% H2SO4) as well as on the leaching of rare earths from phosphogypsum have been studied. The mechanoactivation is performed in a centrifugal ball mill in air and in suspension with the acids mentioned above. Par...

The synthesis of a new type of complexes of Y, Nd and Er with mono-(2-ethylhexyl) phosphoric acid is reported. The elemental composition, IR-spectral data and thermogravimetric analysis prove the presence of both mono-and bivalent ions of the acid as ligands as well as of NO3-ions. The IR-spectrum is interpreted in comparison with those of other la...

The thermochemical behaviour of solid-state complexes of lanthanum with mono-(2-ethylhexyl) phosphoric acid (H2B) (La(HB)3·1.5H2O and La2B3·3H2O) was studied. The thermal decomposition of these complexes proceeds without melting to yield La(PO3)3 and a mixture of La(PO3)3 and LaPO4, respectively. La(HB)31.5H2O decomposes via dehydration (323–383 K)...

A polymerized complex technique was utilized to prepare high-purity La2Ti2O7 and Nd2Ti2O7. Heating of mixed solutions of citric acid (CA), ethylene glycol (EG), La (or Nd) and Ti ions with a molar ratio of CA:EG:La(or Nd):Ti = 5:20:1:1 at 130°C produced a yellowish transparent polymeric gel without any precipitation, which has subsequently used as...

IR-spectra of the solid state lanthanum complexes with mono-and bis-(2-ethylhexyl) phosphoric acids (H2B, resp. HA) are studied. It is confirmed that La coordinates HA as LaO6-octahedra, connected through -La-O-P-O-La-bridging bonds. The so fixed polynucleous chains form the crystal structure of the complex. The obtained IR-spectral data as well as...

A polymerized complex technique was used to prepare high-purity pyrochlore Y{sub 2}Ti{sub 2}O{sub 7} powders at 750 C. Heating of a mixed solution of citric acid (CA), ethylene glycol (EG), and yttrium and titanium ions, with a molar ratio of Ca:EG:Y:Ti = 5:20:1:1, at 130 C produced a yellowish transparent polymeric gel without any precipitation; t...

The elemental composition, IR spectrum and thermal decomposition of the precipitate obtained during interaction of a Ce(NO3)3-acetone solution and a partially neutralized mixture of bis- and mono-(2-ethylhexyl) phosphoric acid are studied. It is established that the precipitate represents CeA3NO3, whereas under the same experimental conditions Pr,...