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This article presents new findings obtained from the study of formation conditions, crystal structure, thermal, spectral, optical properties and electronic band structure of zinc glycolate Zn(OCH 2 CH 2 O). This compound was synthesized by heating the solutions of zinc formate Zn(HCOO) 2 ·2H 2 O in ethylene glycol (A) or in a mixture of ethylene glycol and distilled water (B). The crystal structure of Zn(OCH 2 CH 2 O) has been studied using the X-ray powder diffraction method. It is shown that the crystal structure is built via zigzag joining of [Zn 4 O 12 C 8 H 16 ] tetracycles with the tetrahedrally coordinated zinc (ZnO 4). Zinc atoms inside the tetracycles and the tetracycles themselves are interconnected with oxygen bridges. Complex anions OCH 2 CH 2 O2- are bonded to zinc atoms by chelation. The unit cell parameters of Zn(OCH 2 CH 2 O) are as follows: the tetragonal structure, space group I4 1 /a (88−2), Z = 16, a = b = 11.08673(9) Å, c = 11.5902(1) Å, V = 1424.62(2) Å3. The IR and Raman spectra of Zn(OCH 2 CH 2 O) correlate fully with the results of structural analysis. Under UV excitation, the luminescence spectra of Zn(OCH 2 CH 2 O) samples synthesized following the methods (A) and (B) are characterized by emission maxima at 460 nm (blue luminescence) and 540 nm (yellow-green luminescence), respectively. Yellow-green luminescence is due to the presence of an admixture of zinc oxide nanoparticles of size 10 nm in the sample. The electron density functional method is employed to study the electronic band structure and chemical bonding in Zn(OCH 2 CH 2 O). It is shown that the 3dZn orbitals are covalently bonded to 2pO orbitals so that an octagon is formed, where the zinc atoms of four neighboring ZnO 4 tetrahedrons are linked through their vertices. The feasibility of synthesizing a layered structure of Zn(OCH 2 CH 2 O) is analyzed on the basis of ab initio calculations and Voigt-Reuss-Hill theory. [ABSTRACT FROM AUTHOR]

The polycrystalline orthophosphate Pb 0.954(3) Mn 2 (PO 4) 2 was obtained at 830 ​°C in a melt with NaCl. This compound is isostructural to SrMn 2 (PO 4) 2 (structural type Mg 3 (PO 4) 2): its triclinic system, a ​= ​8.86706(7) Å, b ​= ​9.00697(8) Å, c ​= ​10.35293(10) Å, α ​= ​123.9418(5)°, β ​= ​91.1907(5)°, γ ​= ​89.8282(7)°, space group P 1 ¯ , Z ​= ​4 (R w p = ​1.47%, Rp ​= ​1.13%, χ2 ​= ​2.234, R(F2) ​= ​3.73%) can be described as a hexagonal close packing of phosphate groups. Octahedral, tetrahedral, and trigonal-bipyramidal voids within the [PO 4 ]-packing provide positions for 8-fold and 10-fold [PbO x ] and distorted octahedron [MnO 6 ]. To maintain the valence balance, lead deficiency must be compensated for by a change in the oxidation state of a part of manganese: Pb 0.954(3) Mn+2 1.908 Mn+3 0.092 (PO 4) 2. The IR and Raman spectroscopy of the sample were studied. The energy of the optical band gap E g determined by the Tauc plot method is 4.2 ​eV. Crystallization of lead barium phosphate in NaCl melt. [Display omitted] • A new double orthophosphate Pb 0.954(3) Mn 2 (PO 4) 2 was synthesized in NaCl melt. • The crystal structure, IR, RS of the double orthophosphate were studied. • The band gap of the new compound is 4.2 ​eV. [ABSTRACT FROM AUTHOR]

• Two solid solutions: Sr 2-x La x MnSbO 6 (x = 0.25, 0.50. 0.67 and 0.75) and Sr 1.5 La 0.5 Mn 1+x Sb 1-x O 6 (x = 0.25 and 0.50) were prepared through solid state synthesis at ordinary condition. • The chemical composition, crystal structure and magnetic properties of SS were studied based on mixed Mn2+/Mn3+ and Mn3+/Mn4+ oxidation states, respectively. • The structure of first group samples was characterized by the monoclinic space group P 2 1 / n containing alternating MnO 6 and SbO 6 octahedra with unit cell volume increasing with × and prevailing antiferromagnetic exchange interaction at low temperatures. • The result of change of a ratio of Mn/Sb in Sr 1.5 La 0.5 Mn 1+x Sb 1-x O 6 in favor of Mn (x = 0.25 and 0.5) is phase separation of system on the orthorhombic Pnma and ferromagnetic rhombohedral Rc phases. Solid solutions (SS) based on Sr 2 MnSbO 6 and SrLaMnSbO 6 with mixed oxidation states of Mn have been prepared by solid state synthesis under standard conditions. The structural and magnetic properties of Sr 2-x La x MnSbO 6 and Sr 1.5 La 0.5 Mn 1+y Sb 1-y O 6 have been studied using X-ray diffraction data and magnetic susceptibility χ and magnetization σ measurements at 2–400 K. The samples of the first group crystallize in the monoclinic space group P 2 1 / n , their unit cell volume increases with × due to the formation of mixed Mn3+/Mn2+ valence. The change of the Weiss constant Θ sign from positive to negative with variation of ×, as well as the divergence between FC and ZFC dependences χ(T) below 40 K and spin-glass behavior indicate that the dominant exchange interactions between Mn3+ and Mn2+ cations in Sr 2-x La x MnSbO 6 are of antiferromagnetic nature. The samples of the second group (at y = 0.25 and 0.50) were characterized as non-uniform, containing apparently two phases with a mixed Mn3+/Mn4+ state. The composition of the phases was established approximately by studying their structural and magnetic characteristics. The composition and crystal structure of the main phases are similar to those of the monoclinic samples described above. The secondary phases are identified as rhombohedral (space group R 3 ¯ c) with ferromagnetic properties with T C of 304.2 K (y = 0.25) and 365 K (y = 0.50). [ABSTRACT FROM AUTHOR]

Abstract: New germanate–vanadates with the general formula BiCa4−x La x (VO4)3−x (GeO4) x O, x=1−3, have been synthesized by the nitrate–citrate method and characterized. Structural refinement based on X-ray powder diffraction data showed that these compounds are isostructural with BiCa4(VO4)3O (space group P6 3 /m (N 176), Z=2, а=9.8327–9.8755(3), and с=7.1203–7.2133(2)). They may be viewed as continuous series of solid solutions where Ca2+ and V5+ cations in the crystal lattice of vanadate BiCa4(VO4)3O are replaced by La3+ and Ge4+ cations. In the process of substitution, the La3+ cations occupy mainly the 4f lattice sites of the germanate–vanadate oxyapatites, but the filling of the 4f and 6h lattice sites in the germanate BiCaLa3(GeO4)3 is equivalent. IR and Raman spectra were studied. The Raman spectra clearly show a two-mode behavior: the lines of GeO4 and VO4 are separated from each other, and the (V/Ge)O4 tetrahedra exhibit a quasi-independent behavior. [Copyright &y& Elsevier]

Abstract: The double perovskite Mn2FeSbO6 has been synthesized under pressure 6GPa and temperature 1000°C. The crystal structure refinement of Mn2FeSbO6 was carried out with the GSAS program suite using X-ray diffraction data. XRD pattern of Mn2FeSbO6 was indexed with a monoclinic unit cell (space group P21/n) with parameters: a =5.2431(3)Å, b =5.3935(3)Å, c =7.6358(5)Å, β =89.693(2)°, V =215.927Å3, Z =2. It found that Fe and Sb atoms are completely ordered in 2d and 2c positions of double perovskite structure respectively. According to XPS measurements, manganese in this compound is present as Mn2+, whiles the iron – as Fe3+. Magnetization measurements revealed the presence about 3mass% of ferromagnetic impurity in the sample. Dependence of AC susceptibility χ″ from temperature showed that magnetic properties compound are determined probably by transformation in antiferromagnetic state below 19.5K. [Copyright &y& Elsevier]

Abstract: The complex oxide Sr4LiMn2O9 belonging to the A3n+3m A′ n Mn3m+n O9m+6n family (m =3, n =1) was prepared from a mixture of SrCO3 and LiMn2O4 in a microwave furnace by the solid state reaction. The results of structural refinements and magnetic properties are presented. The crystal structure of Sr4LiMn2O9 was solved using simultaneously X-ray and neutron diffraction data with the GSAS program in the space group P321 with unit cell parameters: a =9.5721(7)Å, c =7.8264(5)Å, V =621.025Å3, Z =3. Sr4LiMn2O9 was found to contain 2 independent 1D chains of face-shared polyhedrons with a sequence of two octahedrons and one trigonal prism. The chains are separated by strontium cations. The refinement results show that the octahedrons and trigonal prisms in the first chain orderly contain Mn and Li, respectively, whereas the second chain is characterized by mixed occupation of these structural positions. The temperature dependence of the magnetic susceptibility of Sr4LiMn2O9 was found to be due to antiferromagnetically coupled dimers from magnetic Mn cations. [Copyright &y& Elsevier]

[Display omitted] • The phosphors were synthesized according to precursor technology using Y 1-x (Er/Yb) x (HCOO) 3. • The crystal structure of ytterbium formate was established for the first time. • The (Y 0.9 Er 0.02 Yb 0.08) 2 O 3 sample exhibited the strongest reddish-orange color luminescence. The (Y 0.9 Er 0.1-x Yb x) 2 O 3 (x = 0, 0.02, 0.05, 0.07, 0.08, 0.09) and Y 1-(0.02+y) Er 0.02 Yb y O 3 (y = 0.05, 0.07, 0.09, 0.11) solid solutions have been synthesized by the precursor technique using mixed anhydrous formates. The crystal structure of ytterbium formate, Yb(HCOO) 3 , was established for the first time. The structural parameters and phase purity of the synthesized precursors and oxides were determined by X-ray phase analysis. The average sizes of crystallites are in the 60–80 nm range. The upconversion spectra of solid solutions exhibit a weak green and an intense red line attributed to 2H 11/2 ,4S 3/2 →4I 15/2 and 4F 9/2 →4I 15/2 transitions of Er3+ ions. The green and red emissions of (Y 0.9 Er 0.1-x Yb x) 2 O 3 and Y 1-(0.02+y) Er 0.02 Yb y O 3 oxides are caused by two-photon conversion processes. The effect of dopant (erbium and ytterbium) concentration and Er3+/Yb3+ ratio on the intensity of upconversion emission were established, the contribution of upconversion green luminescence decreases with increasing the ytterbium concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anhydrous La(CH 3 COO) 3 was synthesized and its thermal decomposition was analyzed. • Decomposition products include acetone and carbon dioxide, indicating pyrolytic decarboxylation. • DFT calculations refined hydrogen positions. • La(CH 3 COO) 3 has a wide band gap of 5.49 eV, suitable for deep UV applications. Acetate complexes of rare earth elements are extensively studied compounds known for their diverse properties and potential applications and lanthanum acetate hydrate is commercially available. In this work, a powdered anhydrous lanthanum acetate (La(CH 3 COO) 3) sample was prepared by dissolving lanthanum oxide (La 2 O 3) in an excess of acetic acid (CH 3 COOH) and distilled water (H 2 O), followed by direct evaporation at 150 °C. The decomposition of La(CH 3 COO) 3 was studied, showing initiation around 300 °C and conclusion at ≥700 °C, with four distinct thermal events (I–IV) of mass loss. Gas phase identification revealed acetone and carbon dioxide as decomposition products, indicating pyrolytic decarboxylation. The final thermal effect (IV) is linked to the decomposition of La 2 O 2 CO 3 to La 2 O 3. The DFT refinement of atomic coordinates of hydrogen atoms, which were unavailable from experiment, was successfully performed. Obtained structural data was checked using vibrational spectroscopy method. The calculated electronic band structure of La(CH 3 COO) 3 indicates it as an indirect wide band gap material with values of direct transition close to indirect. The optical bandgap is found to be 5.49 eV, suggesting that the charge transfer in La(CH 3 COO) 3 can be optically activated with wavelengths shorter than 226 nm, which falls within the deep UV (DUV) region. [ABSTRACT FROM AUTHOR]

Abstract: The crystal structure of apatite Sr5(CrO4)3(Cu0.586O) was solved using X-ray diffraction data with GSAS program in the space group P63/m with hexagonal unit cell parameters: a =10.0292(1), c =7.4623(1)Å, V =650.033(8) Å3, and Z =2. This compound is stable up to 1473K in air. It was found that copper in the form of Cu+ cations is located in infinite linear (CuO)−1 chains inserted into the tunnels parallel to the hexagonal c axis. The chains contain about 40% vacancies in copper positions. The experimental value of the effective magnetic moment (μ eff) for the 1Cr atom in formula Sr5(CrO4)3(Cu0.586(4)O) (1.671 μ B) is slightly smaller than the theoretical moment (1.732 μ B) calculated in the assumption that all chromium is present as Cr5+ cations and copper as Cu+. [Copyright &y& Elsevier]

The structure, oxygen non-stoichiometry, defect equilibrium, and thermodynamic properties of perovskite-type Pr 0.5 Ba 0.25 Sr 0.25 MnO 3– δ manganite were studied. It was shown that the manganite can be air synthesized in one step at 1450 °C. Though having a disordered arrangement of Pr, Ba, and Sr atoms, the compound crystallizes with a tetragonal structure (S.G. I 4 /mcm) due to the regular tilts of MnO 6 octahedra. The oxygen content in oxide as a function of oxygen partial pressure and temperature was measured by coulometric titration, and the data were used for the modeling of defect equilibrium. The oxygen content measurements show stability of the manganite at 973–1223 K and oxygen pressure decrease down to 10−16–10−12 atm. The equilibration of defects in Pr 0.5 Ba 0.25 Sr 0.25 MnO 3- δ involves oxygen exchange with the gaseous ambient, intrinsic electron excitation, and oxygen disordering reactions. According to thermodynamic calculations, oxygen sites available for oxygen exchange are characterized by praseodymium-rich coordination. The disordering caused by the half substitution of barium by strontium leads to a lower energy of chemical bonding of the labile oxygen in Pr 0.5 Ba 0.25 Sr 0.25 MnO 3– δ compared to the parent Pr 0.5 Ba 0.5 MnO 3– δ manganite. PrBa 0.5 Sr 0.5 Mn 2 O 6- δ was investigated in terms of structural features, phase stability, oxygen non-stoichiometry, defect equilibrium, and thermodynamic properties. [Display omitted] • The deep Sr doping in Pr 0.5 Ba 0.25 Sr 0.25 MnO 3– δ results in an enhanced phase stability. • PBSM crystallizes with tetragonal structure due to regular tilts of MnO 6 octahedra. • Oxygen sites available for exchange in PBSM are characterized by Pr-rich coordination. • The disordering in PBSM structure is caused by the half substitution of Ba by Sr. • Energy of chemical bonding of the labile oxygen in PBSM lower than in parent PBM. [ABSTRACT FROM AUTHOR]

Development of the technologies for energy storage and conversion requires a search for compounds with high diffusion of alkali and alkaline-earth ions. Here, we present the results of comprehensive studies, including synthesis, powder X-ray diffraction, experiments on impedance and 23Na NMR spectroscopy, as well as ab initio calculations, which were carried out to explore the sodium diffusion in scheelite-like Na 5 M (MoO 4) 4 with M = Y, La, Bi, and in related solid solutions Na 5- x M 1- x Zr x (MoO 4) 4 (0.05 ≤ x ≤ 0.1), which were synthesized for the first time. Our investigations reveal that the Na-ion mobility increases in the sequence Y → La → Bi and with growing x. For Na 4.9 Bi 0.9 Zr 0.1 (MoO 4) 4 the highest ion conductivity was found: ∼10−4 S/cm at T = 450 °C, which is comparable to that of the NASICON-type molybdates. From the temperature variations of the 23Na NMR spectra and DFT calculations, the mechanism of sodium-ion diffusion was established at the atomic-scale level. [ABSTRACT FROM AUTHOR]

The phase composition of the system BaCo 2 (VO 4 ) 2 –Ba(CoPO 4 ) 2 has been studied. At room temperature two miscibility gaps have been detected, with the formation of substitutional solid solutions Ba(CoV 1-x P x O 4 ) 2 for x = 0.4–0.5 basing on the γ-BCPO structure type. An increase in the vanadium cation concentration leads to the stabilization of the rhombohedral crystal lattice. The crystallographic characteristics of two new phosphate - vanadates Ba(CoV 0.5 P 0.5 O 4 ) 2 and Ba(CoV 0.6 P 0.4 O 4 ) 2 isostructural to γ-BCPO have been obtained, their crystal structures have been described, and their magnetic properties have been analyzed. It was shown that in α-BCPO, as distinct from other examined phases, a three-dimensional ferromagnetic ordering characterized by a wide hysteresis loop takes place at low temperatures. The enhanced values of the magnetic moment in the paramagnetic phase BaCo 2 (VO 4 ) 2 and solid solutions based on γ-BCPO are attributed to the peculiarities of the crystal environment. [ABSTRACT FROM AUTHOR]

Prepared by the precursor method, lithium-doped cadmium oxide samples were synthesized using mixed formates of Cd 1- x Li x (HCOO) 2 ·2H 2 O (0 ≤  x  ≤ 0.075) as a precursor. NMR spectra were obtained on the lithium nuclei incorporated in cadmium oxide; and it is demonstrated that there is only one type of impurity centers to be found. The first-principle method using a projector augmented wave (PAW) approach is applied to carry out electronic band structure calculations and to analyze optical absorption spectra for the cases of lithium atoms occupying interstitial sites and of lithium atoms substituting for cadmium or oxygen atoms. Calculations are carried out to determine energy-efficient preferences for sites of impurity centers, which indicate as the most probable the presence of lithium atoms at the interstitial sites, with vacancies observed in the cadmium sublattice. The presence of lithium atoms at the interstitial sites appears to be explaining the conductivity increase and the red-shift of the absorption edge observed in experiments. [ABSTRACT FROM AUTHOR]

Samples of nanostructured zinc oxide with wurtzite structure and different morphologies of aggregates have been synthesized using oxalate ZnC 2 O 4  ∙ 2H 2 O, glycerolate Zn(OCH 2 OCHCH 2 OH), formate Zn(HCOO) 2  ∙ 2H 2 O, glycolate Zn(OCH 2 CH 2 O), formate glycolate Zn(HCOO)(OCH 2 CH 2 O) 1/2 , acetate Zn(CH 3 COO) 2  ∙ 2H 2 O, succinate Zn(OO(CH 2 ) 2 OO) and hydroxide Zn(OH) 2 as precursors. The optical absorption and the EPR spectra were measured at room temperature, whereas the magnetic properties were assessed in the temperature range from 5 to 330 K. All synthesized samples exhibit ferromagnetic properties both at 5 K and at room temperature. [ABSTRACT FROM AUTHOR]

Optically transparent Mg 1−x Mn x Al 2 O 4 (x = 0.005; 0.00005) nanoceramics were obtained by thermobaric synthesis. Varying the parameters of thermobaric synthesis leads to a controlled modification of crystallographic parameters, such as the lattice constant, the region of coherent scattering, and residual strain. It is shown that as a result of thermobaric pressing, intrinsic and impurity structural defects are formed, the concentration of which depends on the P-T parameters. Two stages of thermobaric synthesis were found, differing by both crystallographic and optical parameters. In optically transparent nanoceramics, a correlation between the residual strain and a scattering coefficient associated with localization of impurity manganese ions in anti-site positions of spinel was found. Thermobaric synthesis of optical nanoceramics can be used as a method of compressing nanosized objects in an optical spinel matrix while maintaining such objects in a metastable state. • The thermobaric synthesis was used to obtain transparent MgAl 2 O 4 :Mn nanoceramics characterized by the presence of strain. • Manganese ions are localized in both normal and anti-site positions, thus stimulating a strain change in the spinel matrix. • Directed redistribution of impurity centers over positions makes it possible to control the optical properties of ceramics. [ABSTRACT FROM AUTHOR]

Сomplex sodium-containing oxides are of interest for the search and development of new materials for many practical applications. This paper presents the results of multiscale experimental and theoretical studies aimed to explore the mechanism of sodium-ion diffusion in the scheelite-related Na 2 Zr(MoO 4) 3 and Na 4 Zr(MoO 4) 4. These molybdates were synthesized by the precursor (formate) method. Ab initio modeling of sodium migration predicts a barrier of 1.0–1.2 eV for long-range sodium diffusion, which is confirmed by the impedance spectroscopy and the 23Na NMR experiments. Our results allow us to assume the existence in Na 4 Zr(MoO 4) 4 of an additional, much faster motional process (with energy barrier of 0.5–0.6 eV) associated with localized ion jumps. [ABSTRACT FROM AUTHOR]

Both pristine and Eu3+-doped scandium-potassium complex sulfate KSc(SO 4) 2 has been obtained with 99% yield via crystallization from solutions. The high-temperature XRPD and thermal studies revealed an enantiotropic first-order phase transition at 700–725 K and standard pressure. In the temperature region 724–754 K, the low-temperature stable monoclinic polymorph, β- KSc(SO 4) 2 (sp.gr. С 2/ m), coexists with the high-temperature trigonal modification, α -KSc(SO 4) 2 (sp.gr. P 321), with decomposition at ∼1120 K. DFT calculations confirmed this rank of polymorphs and a low hospitality of their Sc-sublattices for Eu3+ cations. Under UV excitation, the KSc 0.98 Eu 0.02 (SO 4) 2 sample exhibits Eu3+ luminescence at 570−720 nm. Heating of the sample from 298 K to 423 K leads to a luminescence fading of 13% and to its a sharp decline at elevated temperatures. Kinetic studies have shown that the lifetime depends on the chosen excitation wavelength and temperature. An Х -band resonance in the sample of KSc(SO 4) 2 :Eu3+ has been detected in the temperature range of 299–500 K. The EPR spectra are interpreted assuming the presence of sulfate radicals. [Display omitted] • Eu3+–doped and undoped KSc(SO 4) 2 was prepared in a high yield on scandium by hydrochemical method. • Polymorphism of KSc(SO 4) 2 was unveiled throughout high-temperature XRPD and thermal studies. • Relative stability and electronic properties of KSc(SO 4) 2 polymorphs were analyzed by DFT calculations. • Optical characteristics of KSc(SO 4) 2 :Eu3+ have been studied in the range of 298–473 K. • EPR spectra are interpreted under the assumption of the presence of sulfate radicals. [ABSTRACT FROM AUTHOR]

Abstract: Polycrystalline Nd0.7Sr0.3MnO3 was quenched from 1300K to 300K and 80K after it had been subjected to a high quasihydrostatic pressure of 9GPa. Such high pressure and high temperature treatment (HPT) results in significant changes of the crystallochemical parameters—Mn–O lengths and Mn–O–Mn angles within unchanged lattice symmetry of the Pnma-type. A strong increase of the resistivity and a large decrease of the FM–PI transition temperature were detected for the Nd0.7Sr0.3MnO3 HPT treated samples. The intrinsic characteristic T MI(T C) (T MI is the metal–insulator and T C is the ferromagnetic–paramagnetic transition temperature) correlates with the change of the Mn–O(1)–Mn angle, which is consistent with the double exchange model of the ferromagnetic metallic state in manganites. Remarkable electroresistive (ER) and magnetoresistive (MR) effects appear after HPT treatment, which were not present in the starting Nd0.7Sr0.3MnO3 sample. The structure sensitive properties such as resistivity, MR and ER effects correlate with the change of the nanograin sizes after HPT treatment. Nonlinear current–voltage characteristics showing a hysteresis appear for HPT treated samples at low temperatures. The transport in granular Nd0.7Sr0.3MnO3 samples is likely defined by spin-dependent scattering of charge carriers inside the ferromagnetic metallic grains with embedded small charged isolating islands and by jumping over charged insulating barriers at the intergrain boundaries, which can be strongly affected by the external electric and magnetic fields. [Copyright &y& Elsevier]

Abstract: Calcium yttrium tetrametagermanates Y2CaGe4O12 doped with Er3+ and Er3+/Yb3+ reveal upconversion emission in visible spectral range under near-infrared excitation, λ ex =980nm. For the solid solution Er x Y2−x CaGe4O12 concentration dependencies for the green and red lines of the visible emission around 526nm (2H11/2 → 4I15/2), 545nm (4S3/2 → 4I15/2) and 670nm (4F9/2 → 4I15/2) show the optimal value for the sample x =0.2. The power dependence of the visible luminescence measured at room temperature in the low-power limit indicates two-photon upconversion process. Direct intensification of the upconversion emission signals has been achieved by ytterbium sensitizing. The other upconversion excitation mechanism in Y2CaGe4O12:Er3+ is discussed for an 808nm incident laser irradiation. A scheme of excitation and emission routes involving ground/excited state absorption, energy transfer upconversion, nonradiative multiphonon relaxation processes in trivalent lanthanide ions in Y2CaGe4O12:Er3+ and Y2CaGe4O12:Er3+, Yb3+ has been proposed. Conditions for visible emission occurrence under quasi-resonance λ ex =1064nm excitation depending on pump power values are considered. In the low-power regime only near-infrared emission caused by the transition 4I13/2 → 4I15/2 in erbium ions has been detected. [ABSTRACT FROM AUTHOR]

Abstract: Luminescent properties of the new group of crystalline optical materials Ln2CaGe4O12, Ln=Dy, Ho, Er, Tm, Yb were studied under laser excitation at λ=976nm in the stationary mode. Er2CaGe4O12, Ho2CaGe4O12 and also the solid solution Ln x Y2− x CaGe4O12 (0⩽x⩽2) may be used in photonics as optical elements, such as converters and resonance amplifiers. [Copyright &y& Elsevier]

In this work, indium doped LiMgPO4 is first considered as a dosimetric material. We present studies of the structural properties and thermally stimulated luminescence (TSL), as well as electronic structure of pure and indium doped LiMgPO4. We observed a nonmonotonic shift in the TSL peak with increasing indium concentration (x), which was associated with two different indium sites. We demonstrated that In3+ predominantly replaces Mg2+, but at indium concentration of less than 1%, it occupies the Li+ positions. The variation in indium substitution site affects also the depth of electron traps. Doping of LiMgPO4 with indium changes not only the TSL glow curves, but also the spectra of thermoluminescence. The spectrum of undoped LiMgPO4 consists of two broad bands located in the UV region (λ = 350 nm) and in the red region (λ = 640 nm), while there is only one line (λ = 630 nm) in the TSL spectra of LiMgPO4:In3+. The mechanism of thermoluminescence in pure and indium doped LiMgPO4 is discussed. Image 1 • The position of TSL peak depends on the indium concentration in LiMgPO 4 : In. • In3+ replaces Li + at x < 1%, but Mg2+ at a higher indium concentration. • The depth of electron traps depends on the indium site. • The TSL spectrum of LiMgPO4 consists of red and UV wide bands. • Indium eliminates oxygen vacancies in LiMgPO4 and dampens the UV part of TSL. [ABSTRACT FROM AUTHOR]

New apatite-type NaLa 9- x Tm x (GeO 4) 6 O 2 (x = 0.025–0.8) germanates (space group P 6 3 / m , Z = 1) have been prepared using both the citrate technique and the conventional solid state method. The samples were characterized by powder X-ray diffraction, scanning electron microscopy, diffuse reflectance and photoluminescence spectroscopy. Photoluminescence measurements of NaLa 9- x Tm x (GeO 4) 6 O 2 compounds were carried out both in the 425–850 nm range under 356 nm excitation and in the infrared region under 808 nm excitation. The most intensive lines at 453 nm, 478 nm and in 625–850 nm wavelength range are associated with the 1D 2 → 3F 4, 1G 4 → 3H 6 and a series of 1G 4 → 3F 4 , 3F 2 → 3H 6 , 3H 4 → 3H 6 transitions in Tm3+ ions. The spectra measured in the infrared spectral range consist of two broad emission bands centered at 1440 nm and 1810 nm, which correspond to the cascade 3H 4 °→°3F 4 and 3F 4 °→°3H 6 transitions in Tm3+. The influence of dopant content and temperature on possible mechanisms promoting the population of Tm3+ excited states has been studied. [ABSTRACT FROM AUTHOR]

Gallium-doped aluminum oxide (Al 1– x Ga x) 2 O 3 with γ-Al 2 O 3 (spinel) structure has been synthesized by the precursor method using the formate Al 1- x Ga x (OH)(HCOO) 2 as a precursor. The examination of Al 1- x Ga x (OH)(HCOO) 2 (x = 0.0, 0.1, 0.2, 0.3, 0.4) was carried out by X-ray powder diffraction, Infrared, Raman spectroscopy and differential-thermal methods. The solid solutions γ-(Al 1- x Ga x) 2 O 3 with х ≤0.2 have been synthesized by thermolysis of precursors in helium atmosphere at 700 °C; they exhibit white-blue emission under UV excitation, whose intensity lowers with increasing dopant concentration. As an independent method, the DFT calculations confirmed thermodynamically the stability field of γ-(Al 1 -x Ga x) 2 O 3 solid solutions and the NMR data on relative abundance of Al and Ga within the tetrahedral and octahedral sites in the metal sublattice. Furthermore, the structural and thermodynamic properties of carbon-containing impurities within these compounds were suggested theoretically as possible models of luminescence emission centers. The experimentally observed Ga-dependent quenching of luminescence was explained using the competition between C 2p and Ga 4p states within the band gap of γ-Al 2 O 3. Image 1 • According to XRPD, Infrared and Raman data, Al 1- x Ga x (OH)(HCOO) 2 are isostructural. • Thermolysis of Al 1- x Ga x (OH)(HCOO) 2 with х ≥ 0.3 results in non-single-phase products. • The luminescence intensity is found to decrease with growing gallium concentration. [ABSTRACT FROM AUTHOR]

• Thin-walled hollow spherical aggregates of V2O3(R 3 ¯ c) were prepared by spray pyrolysis. • Many intercrystalline boundaries and pores contribute to high microstrain in SP-sample. • Structure transformation into monoclinic phase does not occur down to 100 К. • SP-aggregates exhibit metallic conductivity down to 80 K. Antiferromagnetic regions were found to coexist with paramagnetic phase at T ≤ 115 K. In the development of nanostructured V 2 O 3 materials, the topical issue is to elucidate the factors that affect the temperature of a metal-insulator transition (MIT). In this work, we study the structural, magnetic and electrical properties of V 2 O 3 thin-walled microsphere prepared by spray-pyrolysis (SP). Low-temperature XRD and TEM revealed that SP-microspheres contain the anisotropic (50×20 nm) nanocrystallites with a preferred (001)-orientation along the sphere surface and show moderate biaxial compressive stresses. SP-aggregates exhibit a high concentration of intercrystallite boundaries and inner pores, which induce high lattice microstrains. Structural, magnetic and electrical properties showed no evidence of MIT down to 100 K. NMR investigations indicated that antiferromagnetic areas appear at temperatures below 115 K. Comparative studies were performed on V 2 O 3 50 nm nanoparticles prepared by thermolysis using the same parent vanadyl solution. The findings suggest that a high defect concentration and microstrains rather than compressive stresses lead to the suppression of MIT. [Display omitted] [ABSTRACT FROM AUTHOR]

The complex oxide SrFe 0.7 Mo 0.3 O 3− δ was obtained by combustion of the organometallic precursor in air followed by annealing in an argon flow at 1350 °C, and characterized with the help of X-ray and electron diffraction methods. Oxygen nonstoichiometry and electrical conductivity data were collected in the oxygen partial pressure range from 10 –19 to 0.5 atm at temperatures 750–950 °C. The as-prepared single phase oxide SrFe 0.7 Mo 0.3 O 3− δ with the cubic double perovskite structure (SG Fm 3 m ) is shown to undergo a structural transition to the tetragonal double perovskite phase (SG I 4 mmm ) in the result of reducing treatment at p O 2 = 10 −12 atm and 950 °C. The ordered phases are characterized by a strong anti-site disordering of iron and molybdenum and nearly zero long-range ordering parameter. The maximal concentration of n-type carriers is about four times larger than of p-type carriers in the studied limits of oxygen pressure and temperature. The mobility of p-type carriers is found to vary within ~ 0.02–0.03 cm 2 V −1 s −1 with the migration energy of about 0.4 eV, while the n-type mobility being approximately twice higher does not practically depend on temperature. Such features as good electrical conductivity, which can rise up to 40 S cm −1 in reducing conditions and a considerable amount of oxygen vacancies favorable for fast oxygen ion transport are beneficial for application of SrFe 0.7 Mo 0.3 O 3 −δ as anode material in SOFCs and oxygen membrane for hydrogen generation by a water splitting. [ABSTRACT FROM AUTHOR]

The polycrystalline samples of BaNi 2 (V 1− x P x O 4) 2 (x ​= ​0–1) were prepared via a solution combustion synthesis. The study of the crystal structure shows that the substitution of vanadium (5+) cations by smaller phosphorus (5+) cations leads to compression of the [Ni 2 (V 1− x P x O 4) 2 ] ∞ layers in the ab plane with a decrease in the unit cell volume of BaNi 2 (V 1− x P x O 4) 2. As a result, the BaO 12 polyhedra are elongated along the c axis. The melting point increases monotonically with increasing phosphorus concentration. The linear dependence of the relative elongation (Δ L/L 0) of samples on temperature after 500 ​°C becomes S-shaped. The electrical conductivity (σ) of BaNi 2 (V 1− x P x O 4) 2 was measured in the range of 300–900 ​°C. Electron transfer in BaNi 2 (V 1− x P x O 4) 2 established to occur along the Ni–O–Ni chains and is explained by the formation of Ni3+. [Display omitted] • BaNi 2 (V 1− x P x O 4) 2 features the layered crystal structure. • The rhombohedral lattice BaNi 2 (V 1− x P x O 4) 2 exists in the x range from 0 to 1. • The melting temperature of BaNi 2 (V 1− x P x O 4) 2 increases with phosphorus content. • Electrical conductivity and thermal expansion of BaNi 2 (V 1− x P x O 4) 2 are studied. • Electron transfer occurs along the Ni–O–Ni chains. [ABSTRACT FROM AUTHOR]

White-emitting luminescent γ-Al 2 O 3 :C have been synthesized by the precursor method using the basic aluminum formate Al(OH)(HCOO) 2 as a precursor. The synthesis of Al(OH)(HCOO) 2 was implemented according to the original technique based on the interaction of Al(NO 3 ) 3 ·9H 2 O and formic acid in aqueous medium during heating. The X-ray powder diffraction study showed that Al(OH)(HCOO) 2 crystallizes in monoclinic symmetry with space group C 2 and unit cell parameters a = 8.8629(2) Å, b = 9.9890(2) Å, c = 10.2413(1) Å, β = 106.223(1)°, and V = 870.58(3) Å. It was established that the products of thermolysis of Al(OH)(HCOO) 2 in helium atmosphere at 600–1100 °C exhibit white luminescence, whose intensity lowers when the precursor annealing temperature grows and the concentration of carbon decreases. The electronic band structure and the energy of preference of different positions in the lattice of ideal γ-Al 2 O 3 to be occupied by impurity atoms were calculated by first-principles method. The calculations showed that the luminescence is due to the presence of carbon atoms in the interstitial sites of spinel structure. [ABSTRACT FROM AUTHOR]

NH 4 V 3 O 7 micro-sized crystals have been successfully synthesized via a conventional hydrothermal synthesis route. The products were characterized by means of X-ray and neutron powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, static magnetization measurements, and electrochemical cycling. The diffraction patterns of NH 4 V 3 O 7 can be indexed in the monoclinic space group P2 1 with the cell parameters a = 12.247(5) Å, b = 3.4233(10) Å, c = 13.899(4) Å, β = 87.72(3)°, and V = 582.3(4) Å 3 . The crystal structure is built up of (V 3 O 7 )-layers with V 4+ -and V 5+ -ions, which occupy oxygen octahedra and tetrahedra, respectively. The (V 3 O 7 )-layers are bonded by (NH 4 ) + -ions. Analysis of the magnetization data confirms that 2/3 of the V-ions are 4 + associated with S = 1/2. Roughly half of them are strongly coupled to antiferromagnetic dimers (J = 720 K), the other half is only weakly (J of several 10 K) antiferromagnetically interacting. Electrochemical cycling shows reversible lithium de-/intercalation into the layered NH 4 V 3 O 7 host structure with an initial specific discharge capacity of 310 mAh/g at 7 mA/g. [ABSTRACT FROM AUTHOR]

Single-phase samples of cadmium pyroniobate and metaniobate were successfully prepared by solid-state synthesis. The crystal structures of cadmium niobates were refined by full-profile fitting of X-ray powder diffraction patterns. The thermal behavior of cadmium niobates in air was studied by thermogravimetric (TG), differential thermal analysis (DTA) and X-ray powder diffraction at elevated temperatures. Found that CdNb 2 O 6 is stable in air up to 1150 °C, Cd 2 Nb 2 O 7 – up to 1120 °C. Above these temperatures these niobates undergoes a solid state decay with volatilization of cadmium oxide, resulting in formation of metaniobate CdNb 2 O 6 from Cd 2 Nb 2 O 7 , and niobium oxide Nb 2 O 5 from CdNb 2 O 6 . [ABSTRACT FROM AUTHOR]

[Display omitted] • Al 2 O 3 :nC composite was prepared by the precursor method. • Effect of microstructure on the sorption properties of Al 2 O 3 :nC has been studied. • Al 2 O 3 :nC has a much larger sorption affinity to (La, Ce, U) ions compared to Al 2 O 3 powders. The nanostructured Al 2 O 3 :nC composites with enhanced chemical activity and higher solubility of oxide in acids have been synthesized. For the synthesis, an organometallic precursor, produced by thermal treatment of a mixture of Al(NO 3) 3 ·9H 2 O with ethylene glycol, was heated in helium atmosphere at 700–1100 °C. X-ray powder diffraction, selected-area electron diffraction and transmission electron microscopy revealed the formation of a homogeneous amorphous mass with indistinguishable boundaries between the oxide and carbon components at 700–1000 °C, while annealing at 1100 °C provoked the crystallization of γ-Al 2 O 3 nanoparticles, forming a clear Al 2 O 3 /carbon interface. This specific microstructure provides a high sorption affinity of the composite for La (III), Ce (III), U (VI) ions in aqueous solutions, which is significantly higher than that of microcrystalline aluminum oxides. [ABSTRACT FROM AUTHOR]

The ball-like ZnS microparticles assembled of nanoparticles with the size of 3–5 nm were synthesized by chemical bath deposition using thiourea as sulfur agent. Their defectiveness was examined by electron paramagnetic resonance (EPR) and high-resolution transmission electron microscopy (HRTEM). Multiple imperfections of ZnS lattice were visualized using HRTEM, where the patterns of the grain boundaries between sphalerite and wurtzite appear the most legible and often. Inherency of such a grain boundary to individual nanoparticle, hence, the Janus morphology of synthesized ZnS nanoparticles, was confirmed using molecular dynamics simulations of their stability. The extremely intense EPR response was obtained, which interpretation assumes the presence of intrinsic electric field arising due to a giant dipole moment across the interface within Janus nanoparticle. The powders of such sedimented ZnS particles exhibited an enhanced photocatalytic activity in reaction of hydroquinone oxidation under visible light irradiation, employing neither alteration of the band gap of ZnS nor any doping of ZnS lattice. • Ball-like ZnS microparticles are synthesized by chemical bath deposition. • Individual ZnS microparticle is assembled of nanoparticles with the size of 3–5 nm. • Microparticles exhibit numerous boundaries between sphalerite and wurtzite grains. • Particle constitution fits into framework of model of the Janus ZnS nanoparticles. • Janus-ZnS exhibits photocatalytic activity without band gap alteration or doping. [ABSTRACT FROM AUTHOR]

The electrical conductivity of SrFe0.67Ta0.33O3−δ measured in the oxygen partial pressure range from 10−20 to 0.5atm at 700–950°C, exhibits an anomalous and reversible increase in moderately reducing atmospheres, substantially contributed by oxygen ion transport. The coulometric titration studies in combination with the electron and X-ray diffraction analyses show that this trend correlates with the separation of oxygen-deficient disordered cubic perovskite and Ta-rich double perovskite domains of nanometer-scale size. Mössbauer spectroscopy demonstrated that the predominant state of iron cations in the vicinity of this transition is trivalent. Further reduction leads to the formation of Fe2+ states responsible for increasing n-type electronic conductivity, whilst no traces of wustite or oxygen vacancy-ordered brownmillerite phases were detected. The ion conduction in partially reduced SrFe0.67Ta0.33O3−δ is significantly higher compared to SrFe0.7Ta0.3O3−δ and SrFe0.6Ta0.4O3−δ under similar conditions, which may indicate an important role of the interfacial boundary enlarged due to the perovskite phase separation. [ABSTRACT FROM AUTHOR]

NewACu3V4O12(A=Gd, Tb, Er) phases have been prepared at high pressure and high-temperature conditions (P∼8–9 GPa,T∼1000°C) in a toroid-type high pressure cell. These compounds crystallize in the cubic symmetry with a perovskite-like structure. At ambient pressure, they are paramagnetic and have activation-type conductivity. The effect of high pressure (10–50 GPa) on the electrical properties of the materials was analyzed in the temperature range from 78 to 300 K. Pressure ranges of the transition from activation type to metallic conductivity have been determined. The crystal structure ofACu3V4O12(A=Gd, Tb, Er) was found to be stable up to 50 GPa. [ABSTRACT FROM PUBLISHER]

Abstract: In the Mg4− x Ni x Nb2O9 (0⩽x⩽4) system two ranges of solid solution have been found. One of the solid solutions has a corundum-related structure type (space group ); the second one adopts the II-Ni4Nb2O9 structure type (space group Pbcn). The unit cell constants and atomic positions have been determined and refined using neutron powder diffraction data. Electron diffraction and high-resolution transmission electron microscopy (HRTEM) from MgNi3Nb2O9 crystals identify the presence of planar defects and the intergrowth of several (structurally related) phases. The magnetic susceptibility of Mg3NiNb2O9, measured in the temperature range T=2–300K, shows no indications of magnetic ordering at low temperatures, while for MgNi3Nb2O9 there is a magnetic ordering at temperatures below 45.5K. [Copyright &y& Elsevier]

Abstract: Rietveld refinement of the crystal and magnetic structures of Li x MnO2 (x =0.98, 1.00, 1.02) are performed using neutron and X-ray measurements. A significant structural disorder due to the presence of manganese ions in lithium positions (MnLi) and lithium ions in manganese ones (LiMn) is found to be a common feature of Li0.98MnO2, Li1.00MnO2, and Li1.02MnO2. An essential anisotropy of the thermal-expansion coefficients of the lithium manganese oxides is observed in the temperature range of 1.5–300K. Furthermore, the distortion of the oxygen octahedral environment around the manganese ions decreases when the temperature lowers. This is attributed to the strong exchange interactions between parallel exchange-coupled Mn chains. First-principles calculations of the effective exchange-interaction parameters in Li16Mn16O32 confirm the essential antiferromagnetic interactions between the chains. In addition, a hypothetical (Li15Mn)Mn16O32 structure where a lithium atom located between the Mn double layers is replaced by a manganese atom is considered. The calculations reveal that the presence of such defects results in appearance of a ferromagnetic component that agrees with the magnetic measurements. [Copyright &y& Elsevier]

Abstract: The method of thermodynamic simulation was used to study chemical interactions in the cathode half-cell of lithium-ion battery, which contained LiCoO2 as cathode active material and a LiPF6 solution as the electrolyte. It was shown that in the temperature range 298–400K in thermodynamic equilibrium state a layer of solid products of chemical reaction formed on the cathode/electrolyte interface. The layer predominantly consisted of LiF and LiPO3 in the molar ratio about 2:1 (corresponding to the volume ratio 2:3). In equilibrium state also some soluble interaction products formed, namely: CoF2 (considerable quantity), POF3 and PF5. The concentration of the later two substances was small, but it increased with increase of the temperature. Furthermore, in equilibrium state oxygen gas formed as a product of chemical interactions in cathode half-cell. Thermodynamic characteristics of Co2O3 and LiCoO2 compounds were determined using a set of calculation methods. [Copyright &y& Elsevier]

Abstract: A new complex oxide Y2Cd2/3Re4/3O7 with hexagonal cell parameters a =7.3564(2)Å, c =17.7092(5)Å (space group P3121, z =6, zirkelite structure type) was synthesized from Y3ReO8, ReO2, metallic Re and CdO under pressure 6GPa and temperature 1500°C. Magnetic susceptibility measured in the temperature range from 2 to 300K depends little on temperature above ∼50K and is indicative of a delocalized or intermediate character of d electrons of Re5+ cations. [Copyright &y& Elsevier]

Abstract: A new rhenium (IV) dioxide crystallized in the rutile-type structure was successfully synthesized by a solid-state route and characterized by elemental analyses, X-ray and neutron powder diffraction. The structure obtained is tetragonal (space group P42/mnm) with the lattice constants and . The electronic properties of rutile-like ReO2 were investigated by means of the projected augmented wave (PAW) method within both LDA and LDA+U approximations. The results revealed that the antiferromagnetic ordering is favorable for this system with the local magnetic moments about per Re atom. O 2p–Re 5d hybridization is important, and a covalent bonding between O and Re atoms occurs. [Copyright &y& Elsevier]

• Structure and thermodynamics of defect equilibrium in Sr 1− x Ce x FeO 3− δ is studied. • A part of anion sites in Sr 1− x Ce x FeO 3− δ was found to be unavailable for oxygen ions. • Incommensurate structure with modulation wave vector 0.41 a * is detected for x ≥ 0.1. • Enthalpy and entropy of defect formation reactions in Sr 1− x Ce x FeO 3− δ is determined. • Under reducing conditions concentration of Ce3+ ions is higher than that of Fe2+. The structure, oxygen non-stoichiometry, and defect equilibrium in perovskite-type Sr 1− x Ce x FeO 3− δ (x = 0.05, 0.10, 0.15, 0.20) were studied. X-ray diffraction showed the formation of a cubic structure for all compositions. The electron diffraction detected an incommensurate structure with a modulation wave vector 0.41 a* in compositions with x ≥ 0.10. The phenomenon is assumed to originate from a strong steric disturbance attributed to a large difference in ionic radii of cerium and strontium. The data on the oxygen content acquired in wide ranges of oxygen partial pressure and temperature were used for the modeling of defect equilibrium in oxides. A part of anion vacancies in Sr 1− x Ce x FeO 3− δ was found to be inaccessible for oxygen ions. The main factors of cerium substitution impact on the thermodynamic parameters of defect formation reactions in Sr 1− x Ce x FeO 3− δ were revealed to be lattice contraction, steric disturbance, and cerium reduction to Ce3+. The concentration of Ce3+ ions in Sr 1− x Ce x FeO 3− δ under reducing conditions was found to be substantially greater than that of Fe2+. Interrelations between thermodynamic quantities of oxygen in Sr 1− x Ce x FeO 3− δ and thermodynamic parameters of defect formation reactions were considered. [ABSTRACT FROM AUTHOR]

Alluaudite-type compounds are currently considered as a promising class of materials for sodium-ion batteries, and understanding of the diffusion processes in them is very important. Using the 23Na MAS NMR and ab initio calculations, we established the mechanism of sodium diffusion in Na 4–2 x M 1+ x (MoO 4) 3 (M ​= ​Mg, Zn, Cd) depending on the type of M -element and x. A comparison of the results obtained for various alluaudite-type compounds shows the crucial effect of the M -cation on the Na-ion dynamics in this class of materials. Higher concentration and charge of M -element increase the concentration of vacancies in the Na-sublattice and enhance the sodium mobility. Moreover, the Na dynamics increases with the M -ion size. The occupancy of the M site and the type of T atom in the T O 4 group also determine the mechanism of sodium diffusion in alluaudites, whether it is one-dimensional or two-dimensional. These findings may help a deeper understanding of sodium diffusion processes in alluaudite-type compounds and their development as materials for sodium-ion batteries. Image 1 • Sodium diffusion in Na 4–2x M 1+x (T O 4) 3 (M ​= ​Mg, Zn, Cd; T ​= ​Mo) depends on M and x. • The Na dynamics increases with the M -ion size. • Higher concentration and charge of M -cation enhance sodium mobility in alluaudites. • The occupancy of M site and type of T atom determine whether diffusion 1D or 2D. [ABSTRACT FROM AUTHOR]

The study of the phase composition of the SrCo 2 (VO 4) 2 – SrCo 2 (PO 4) 2 system showed that it belongs to pseudo binary equilibria. The new phosphate-vanadates Sr 2.4-x Co 2.6+x P 3 VO 15 , x ​= ​0–0.04, was found to crystallize in the Sr 2.36 Mg 2.64 P 4 O 15 structural type. The crystal structure of the Sr 2.4-х Co 2.6+x P 3 VO 15 (x ​= ​0.00, 0.02 and 0.04) consists of three types of tetrahedra, Co(1)O 4 , P/V(1)O 4 and P(2)O 4 , one octahedron, Sr/Co(2)O 6 , and ten-fold oxygen coordination around Sr(1) ions. There are two types of chains directed along c -axis, consisting of edge-sharing octahedra, Sr/Co(2)O 6 , and corner-sharing tetrahedra, Co(1)O 4 , respectively. These chains are connected through P/V(1)O 4 , that form P/V(1) 2 O 7 pyro-groups, and single P(2)O 4 groups. Magnetic susceptibility of Sr 2.4-х Co 2.6+x P 3 VO 15 (x ​= ​0.00, 0.02, 0.04) measured in the temperature range from 2 to 300 ​K is found to be determined by linear chains of tetrahedrally surrounded cobalt and by paramagnetic octahedral cobalt ions. Crystal structure, one-dimensional chains of tetrahedrally and octahedrally coordinated cobalt ions, magnetic susceptibility as a function of temperature, and magnetization vs field curve of the Sr 2.4-х Co 2.6+x P 3 VO 15. Image 1 • The phase composition of the system SrCo 2 (VO 4) 2 – SrCo 2 (PO 4) 2 has been studied. • The new Sr 2.4-x Co 2.6+x P 3 VO 15 , x ​= ​0–0.04, crystallized in the Sr 2.36 Mg 2.64 P 4 O 15 structural type has been established. • The magnetic susceptibility of Sr 2.4-х Co 2.6+x P 3 VO 15 (x ​= ​0.00, 0.02, 0.04) measured in the temperature range from 2 to 300 ​K. [ABSTRACT FROM AUTHOR]