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Elastic and thermal properties of CaSrAl 2 SiO 7 crystal have been simulated theoretically. Mechanical and thermal properties of the crystal have been found better than those of Ca 2 Al 2 SiO 7 with the same crystal structure. An Yb3+:CaSrAl 2 SiO 7 single crystal has been grown by the micro-pulling-down method. Detailed spectral properties of the Yb3+:CaSrAl 2 SiO 7 have been investigated. All the results indicate that the Yb3+:CaSrAl 2 SiO 7 is a potential material for Yb3+ laser, especially for tunable and ultrashort lasers. • An Yb3 + :CaSrAl 2 SiO 7 has been grown by the micro-pulling-down method. • Mechanical and thermal properties of CaSrAl 2 SiO 7 are higher than those of Ca 2 Al 2 SiO 7. • The splitting of the 2F 7/2 multiplet in Yb3+:CaSrAl 2 SiO 7 is up to 1002 cm−1. [ABSTRACT FROM AUTHOR]

Monoclinic Cu 4 O(SeO3) 3 has been prepared hydrothermally with subsequent heating in evacuated silica tubes. It has been characterized in measurements of dc and ac magnetic susceptibility χ and specific heat C p. The title compound orders magnetically at T 1 = 13.2 K and evidences a pre-transitional anomaly at T 2 = 17.2 K. In the range T 1 < T < T 2 , the application of external magnetic field rapidly suppresses excessive magnetization of this intermediate phase, but the hump in specific heat appears. The magnetic system of the title compound is constituted by the layered network of isolated Cu atoms and O 2 Cu 6 units composed by edge-sharing anion-centered OCu 4 tetrahedra. First principles calculations provided values of both ferromagnetic and antiferromagnetic exchange interactions within O 2 Cu 6 units J 1 – J 11 and J 12 – J 22 , and antiferromagnetic intralayer J 23 – J 30 and interlayer J 31 – J 32 exchange interactions. Basing on signs and values of these interactions a magnetic model of monoclinic Cu 4 O(SeO3) 3 is suggested. • O 2 Cu 6 units of edge-sharing OCu 4 tetrahedra are the building blocks of Cu 4 O(SeO3) 3. • It orders magnetically at T 1 = 13.2 K and shows a pre-transitional anomaly at T 2 = 16.5 K. • Basing on signs and values of exchange interactions a magnetic model is suggested. [ABSTRACT FROM AUTHOR]

Abstract The thermoelectric transport properties of artificially textured polycrystalline CrSiTe 3 samples have been investigated for elucidating their correlations with a crystal structure and the corresponding charge density distribution. We verified that the low mobility of 13–27 cm2 V−1 s−1 attributing poor electronic transport properties is originated from the discrete charge density distribution in the covalently bonded layer. Also, the modulation of thermal conductivity values from 3.5 to 5.4 W m−1 K−1 with varying the texture was confirmed in pristine CrSiTe 3. Thus, we suggest that the electronic and thermal transport properties of layer structured CrSiTe 3 are strongly correlated with crystallographic features. Graphical abstract Image 1 Highlights • Thermoelectric transport properties of CrSiTe 3 compounds. • Strong correlation between structure and thermoelectric properties. • The charge density distributions are strongly localized without no overlaps. • In-plane electronic transport properties depend on charge density distributions. • Anisotropy in thermal conductivity inherited from crystal structure. [ABSTRACT FROM AUTHOR]

Abstract The features of electronic structure of La 0.7 Sr 0.3 MnO 3, Pr 0.8 Sr 0.2 MnO 3 , and Pr 0.6 Sr 0.4 MnO 3 polycrystalline films of different thickness have been investigated using magnetic circular dichroism (MCD) in the range of 1.1–4.2 eV. The temperature behavior of the samples electrical resistance were also has been studied. It was found that films with high Sr content (0.3 and 0.4) act as high-temperature semiconductors, while the maximum in the temperature dependences of resistivity these films indicates the transition of the samples to the metallic state at some temperature T M-S , which is different for different sample thickness. The films with the lower Sr content (0.2) act as insulators in the used temperature range. The MCD spectra have been decomposed to the Gaussian-shaped lines, and the temperature dependence of intensity of each line has been analyzed in comparison with temperature dependence of the films magnetization and with their electric conductivity type. Different temperature behavior of the intensity of four specified Gaussian-lines was revealed for semiconductor films. In the case of insulating Pr 0.8 Sr 0.2 MnO 3 samples, the intensity of three specified Gaussian lines changes with the temperature in the same way as the magnetization changed. It was established that the lanthanide (La, Pr) type does not affect the MCD spectra shape for the films with the same electrical conductivity type. Besides, the correlation between the MCD data of the films and their conductivity type was revealed. Due to the detailed analysis of the specified Gaussian lines with taking into account the well-known in the literature absorption bands, lying outside the studied spectral region, the MCD bands for the studied manganite films have been identified with electronic transitions of a different nature. Highlights • La 0.7 Sr 0.3 MnO 3, Pr 0.8 Sr 0.2 MnO 3 , and Pr 0.6 Sr 0.4 MnO 3 films act as objects of research. • Magnetic circular dichroism (MCD) and electrical resistance of the films are studied. • Lanthanide type does not affect the MCD spectra shape for the films with the same electrical conductivity type. • MCD band of the positive sign near 2.3–2.4 eV is typical for the metallic films only. • Revealed MCD bands are identified with electronic transitions of a different nature. [ABSTRACT FROM AUTHOR]

The optical and electrical characteristics of copper oxide thin films are greatly dependent on the preparation procedure, which determines the crystallite size and the density of native defects. Minimization of the synthesis temperature is in general desirable to reduce the thermal budget and extend the deposition on sensitive substrates. Here, copper oxide layers have been prepared by heating evaporated copper in air at low temperatures (≤350 °C). The crystalline structure, optical and electrical properties of the oxidized films have been analyzed as a function of the evaporated copper thickness and the heating temperature. Single-phase Cu 2 O and CuO layers have been obtained by adjusting the preparation parameters, which allow to change the visible transmittance and gap energy of the films according to the specific application. Both copper oxide phases exhibit p-type conduction and photosensitivity. The analysis of photoconductivity transients and the optical absorption coefficients made possible to identify the sub-gap defect levels present in these compounds. [ABSTRACT FROM AUTHOR]

Са 3 (VO 4 ) 2 -based compositions are considered as promising multifunctional materials combining ferroelectric, optical nonlinear, and Ca 2+ -ion conductive properties. Their ferroelectric Curie points stretch from minimal for β -Ca 3 (PO 4 ) 2 -type compounds temperatures of about 800 K to very high. Investigated in this paper lead substitution for calcium is as a factor controlling ferroelectricity, ionic-conductivity and non-linear optical activity in Ca 3 (VO 4 ) 2 -based materials. Polar phase containing powders and ceramics in Ca 10.5- x Pb x (VO 4 ) 7 system are synthesized for 0 ≤ x ≤ 9.5 by the solid state method, and structurally characterized with X-ray powder diffraction and transmission electron microscopy. Dielectric properties, differential thermal analysis and second harmonic generation (SHG) evidence that Ca 10.5- x Pb x (VO 4 ) 7 solid solution (0 ≤ x ≤ 4.5) belongs to whitlockite-type ferroelectrics. SHG activity strongly increases with x up to its maximum at x = 4.5, where it has a record value among all studied before Ca 3 ( X O 4 ) 2 -related compounds ( X = P,V). Ferroelectric Curie temperatures of Ca 3 (VO 4 ) 2 drops from its known value T c = 1368 K ( x = 0) to 770 K ( x = 4.5). Crystal symmetry at T c changes from R 3 c to R 3 ¯ c . After this, one more phase transition to the symmetry R 3 ¯ m takes place, its temperature bringing down from 1387 K ( x = 0) to 804 K ( x = 4.5). Ferroelectric and non-ferroelectric phase transitions in the Са 10.5- x Pb x (VO 4 ) 7 are separated by a broad interval Δ T = 20–50 K and both classified as first-order transformations going in the sequence: R 3 c ↔ R 3 ¯ c ↔ R 3 ¯ m . Structures of Са 10.5- x Pb x (VO 4 ) 7 compositions with x = 0.5–4 were refined by the Rietveld method and peculiarities of the Pb 2+ cations distribution in the M 1 - M 3 and M 4 sites of β -Ca 3 (PO 4 ) 2 -type structure are discussed regarding the optical nonlinear, ferroelectric and ion-conductive properties. Manifold increased Ca 2+ - ion conductivity of Са 10.5- x Pb x (VO 4 ) 7 in vicinity of 1000 K at x = 4–4.5 in combination with their ferroelectric and optical nonlinear properties extends applicability of ion-exchange technologies to new promising materials. [ABSTRACT FROM AUTHOR]

Cu and Ni substitutions are investigated at spinel MFCO (Manganese Iron Cobalt Oxide) components using a variety of characterization techniques, including XRD, XPS, RAMAN spectroscopy, SEM, TGA, dilatometer measurements, and electrochemical investigations. MnCu 0.25 Fe 0.25 Ni 0.5 CoO 4 and MnCu 0.5 Fe 0.25 Ni 0.25 CoO 4 spinel oxides were prepared and evaluated as a copper-nickel MFCO protective coating layer on the commercially available 316 L stainless steel interconnect for intermediate temperature solid oxide fuel cells (IT-SOFCs). XRD analysis indicates that both powder samples contain a single phase with a cubic structure. In both compounds, mixed Mn3+/Mn4+, Co2+/Co3+, and Cu+/Cu2+ couples are found, showing that co-doping of Ni and Cu into the MFCO spinel resulted in the redistribution of Mn and Co ions (Mn3+, Mn4+, Co2+, and Co3+) into the octahedral sites, which contributed to the increase in electrical conductivity. MnCu 0.5 Fe 0.25 Ni 0.25 CoO 4 exhibited a maximum conductivity of 54 S cm−1 at 750 °C. Following the area-specific resistance (ASR) of the scale/coating during heating and cooling cycles was used to evaluate the protective action of the coating applied to 316 L stainless steel. Postmortem microstructural analysis of the screen-printed coatings showed good protection against chromium diffusion. [Display omitted] • New MnFe 1−x-y Cu x Ni y CoO 4 spinel protective layers fabricated by sol-gel auto-combustion and screen printing technology. • The crystal structures and morphologies of the bulk and film materials were deeply investigated. • Thermogravimetric and thermal expansion analysis confirmed the higher stability of Ni-rich spinel compounds. • The electrical performances for the coated films on metallic interconnects were evaluated by ASR and DC measurements. [ABSTRACT FROM AUTHOR]

We determined the crystalline characteristics of the hexagonal α-alumina phase by X-ray diffraction at high temperatures between 293 and 2308 K under dynamic vacuum then under constant flow of nitrogen. The experimental values obtained under dynamic vacuum allow to deduce, an anisotropy of the ‘c’ direction compared to the ‘a’ direction of approximately 12% in the range of 293 K–1760 K. On the other side, no anisotropy remains above 1765 K. This anisotropy reflects the fact that aluminum atoms occupy 2/3 of the octahedral sites in the compact hexagonal sublattice formed by the oxygen atoms. We have also reacted alumina when heated under a constant flow of nitrogen. Nitriding alumina occurs around 1765 K and then forms aluminum mononitride, AlN, ZnS-Wurtzite type hexagonal structure. The thermal expansion of this mononitride cell is linear and is characterized by an anisotropy of the direction 'a' in comparison to the direction 'c' of about 17%. [ABSTRACT FROM AUTHOR]

A molybdenum trioxide micropowder (МоО 3 MP) with an average crystallite size of 821 nm was obtained by the thermal treatment of an initial molybdenum nanopowder (Mo NP) with an average crystallite size of 150 nm. The structure of these powders and their resistance to carbon monoxide action at an increased temperature were studied by X-ray diffraction, X-ray fluorescence, and IR spectroscopy. The Mo NP sample contained 88.25% molybdenum and 11.51% oxygen and, as a whole, showed resistance to CO action at 200 °C. However, its crystallites were observed to grow under the specified conditions, and their final average size exceeded 1000 nm. The obtained MoO 3 MP sample contained 67.50% molybdenum and 32.34% oxygen. Мо 2 С, Мо and Мо 4 О 11 were identified in addition to МоО 3 after a treatment with CO at 200 °C. It is concluded that the МоО 3 MP is unstable under the action of carbon monoxide at the indicated temperature. It is suggested that a dissociative sorption of CO involving МоО 3 occurs. [ABSTRACT FROM AUTHOR]

● AAl 3 P 6 O 20 (A = Rb, Cs) were designed from Ba 5 P 6 O 20 by aliovalent substitution. ● They exhibit the shortest cutoff edges (<190 nm) among Al-based phosphates. ● Flexible P 3 O 10 groups are favorable for designing NCS crystal structures. We obtained two Al-based triphosphates AAl 3 P 6 O 20 (A = Rb, Cs) by aliovalent substitution and they have the shortest cutoff edges (<190 nm) among Al-based phosphates. [Display omitted] Two deep-ultraviolet (DUV) transparent nonlinear optical (NLO) materials, AAl 3 P 6 O 20 (A = Rb, Cs) (I, II), have been elaborately designed from Ba 5 P 6 O 20 by aliovalent substitution strategy. Both of compounds crystallize in noncentrosymmetric (NCS) C222 1 (No. 20) space group with three-dimensional (3D) ∞ 3 Al 3 P 6 O 20 skeleton. The cutoff edges of I and II are lower than 190 nm, which are the shortest ones among the reported Al-based phosphates. In addition, their syntheses, thermal properties, NLO performances are discussed and the first-principles calculation elucidates the origin of the optical properties. This study shows that aliovalent substitution is an effective synthetic route for designing DUV transparent Al-based phosphates NLO materials. [ABSTRACT FROM AUTHOR]

• The Sr 3- x Ca x La(VO 4) 3 : Sm3+ and Sr 2 CaLa(VO 4) 3 : y Sm3+ were synthesized by citric-assisted sol-combustion method. • SCLVO: Sm3+ has a hexagonal structure with space group R-3 m (166). • The replacement of Sr2+ by Ca2+ improves the emission intensity of Sr 3 La(VO 4) 3 : Sm3+ phosphor. • Phase structure, luminescent behaviors and thermal stability were systematically studied. Sr 3- x Ca x La(VO 4) 3 : Sm3+ (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5) and novel Sr 2 CaLa(VO 4) 3 : y Sm3+ (SCLVO: y Sm3+, y = 0.01, 0.03, 0.05, 0.07, 0.09) phosphors were synthesized by the citric acid-assisted sol-combustion method. The crystal structure, morphology, concentration-dependent emission spectrum, decay time, and thermal stability of phosphors were studied. These synthesized phosphors have a hexagonal structure with a space group of R-3 m (166). High-purity Sr 3- x Ca x La(VO 4) 3 : Sm3+ phosphors were obtained when x < 2.5. The change in particle shape and unit cell parameters of the Sr 3- x Ca x La(VO 4) 3 : Sm3+ phosphors led to reduced luminescence performance when the Ca2+ concentration was x > 1. The optimal doping concentration of Sm3+ in the SCLVO host is 3 mol%. Under the excitation of 402 nm near-ultraviolet (NUV) light, all phosphors in this series emit orange–red light at 603 nm, which is attributed to the 4G 5/2 →6H 7/2 transition of Sm3+. The SCLVO: 0.03Sm3+ phosphor exhibits a double exponential decay time of 0.872 ms, excellent thermal stability with an activation energy E a of 0.232 eV, a chromaticity coordinate of (0.5817, 0.4136), and a high color purity of 98.48%. These experimental results demonstrate the potential application of phosphor SCLVO: 0.03Sm3+ in the red component of white light-emitting diodes (WLEDs). [ABSTRACT FROM AUTHOR]

• High P-T method is proved to be the simplest for ZnCO 3 synthesis. • The crystal structure of impurity-free ZnCO3 was determined by single crystal X-ray diffraction. • Accurate thermal expansion of ZnCO 3 was quantified by single crystal X-ray diffraction at different temperatures. Carbonate materials have been increasingly favoured in terms of the development of flame retardants because of the eternal subject of inorganic carbon sequestration. In this regard, anhydrous zinc carbonate (ZnCO 3) has been deemed as suitable candidate thanks to its excellent flame retardancy compared to traditional hydroxid flame retardant. However, the single crystals growth, accurate characterizations of structural and thermal properties are still not entirely clear from previous studies. With this in mind, ZnCO 3 single crystals were synthesized under high-pressure-temperature conditions (high P-T; 3 GPa and 973 K). The crystal structure of impurity-free ZnCO 3 was determined by means of single crystal X-ray diffraction (XRD). The symmetry was identified as R 3 ¯ c , while the unit cell parameters were a= 4.6463(3) Å and c= 15.0015(11) Å with a final R value of 0.0229. The quantitative analyses of Raman spectrum and infrared absorption indicate that the as-synthesized ZnCO 3 is anhydrous phase. Using Thermogravimetric (TG) / Differential Scanning Calorimeter (DSC) measurements, ZnCO 3 was decomposed in the temperature range of 593–773 K, whereas the heat capacity and the endothermic peak were determined. According to the single crystal XRD from 150 K to 383 K, the thermal expansion coefficients were quantified as α a = 7.90 × 10−6 K−1 and α c = 22.8 × 10–6 K−1, as well as α Vunit cell = 38.8 × 10–6 K−1. These findings provide a precise characterisation and obtain important thermal parameters for the evaluation of its flame retardant properties. [ABSTRACT FROM AUTHOR]

A series of Dy3+ activated Ba(YLu) 2 Si 3 O 10 samples were prepared by high temperature solid-phase method. The purity of the phase was determined and the structural changes were analyzed. Under excitation at 350 nm, the BaY 2 Si 3 O 10 : Dy3+ phosphor shows two stronger luminescence peaks at 486 nm and 572 nm and weaker emission peak at 668 nm. In addition, with the continuous replacement of Y3+ in the matrix by Lu3+ ions, the chromaticity coordinates of samples in the system can be adjusted from the cold white region to the warm white region, and the luminescence performance of phosphors can be effectively improved. It was observed that the thermal stability of the phosphor was gradually enhanced with Lu3+ concentration increases, and the emission intensity of the BaLu 2 Si 3 O 10 : 0.04Dy3+ phosphor at 453 K could still maintain 83.78% of that at room temperature, which was discussed in conjunction with the Debye temperature and the rigid structure model to provide a reference for the improvement of the thermal stability performance. In addition, the increase of the concentration of Lu3+ ions doping will shorten the lifetime of phosphors due to the non-radiative energy transfer caused by the shortening of the ion distance in the lattice. • Ba(YLu) 2 Si 3 O 10 : Dy3+ phosphors with weak thermal quenching were synthesized. • The emission intensity of phosphor increased by 23.23% with increasing Lu3+ content from 0 to 2. • The chromaticity coordinates of samples can be effectively adjusted from the cold white region to the warm white region. • The emission intensity of the BaLu 2 Si 3 O 10 : 0.04Dy3+ could still maintain 83.78%. [ABSTRACT FROM AUTHOR]

• Influence of doping in ferroelectric properties of multiferroics. • Holmium doped BiFeO 3 give rise to distorted rhombohedral phase. • Variation of dielectric values with temperature and frequency. • AC conductivity and Impedance analysis of doped Bismuth Ferrites. • Enhancement in ferroelectricity of Ho- BiFeO 3 samples with P-E hysteresis loop. Multiferroic holmium doped bismuth ferrite samples, prepared by solid-state route method are analyzed in this study to understand the effect of Ho3+ in the crystal structure, thermal properties, dielectric behavior, ferroelectricity, and AC conductivity of bismuth ferrites. Preliminary structural analysis using XRD and refinement characterize to see the distortion in the rhombohedral type of structure with doping. Effect of holmium on morphology, using FESEM and compositional analysis using EDAX show more uniform and dense distribution of well-developed grains as well as a better phase formation with lesser secondary phase, for 80% holmium doped sample. Dielectric, AC conductivity, and impedance parameters variation with frequency and temperature are studied to investigate the electrical behavior of Ho-BFO. Emphasis on the effect of holmium doping on the ferroelectric nature of the doped BFO is further analyzed in terms of P-E loops. The temperature effect on the dielectric properties exhibits an anomaly corresponding to magneto-electric coupling in the samples; all these results are discussed here in detail. [ABSTRACT FROM AUTHOR]

• CrSm x Fe 1- x O 3 pervoskite nanoparticles were prepared and investigated. • Their structural, crystalline structure, thermal properties were studied. • HTEM images showed large particles sizes giving the whole picture of the nanoparticles. • TGA showed decrease in sample weight giving largest weight loss around ≈ 31%. • Their electrochemical performance has been studied as well. Variation of the bulk density D , theoretical density D x , and porosity P with x. [Display omitted] CrSm x Fe 1- x O 3 pervoskite nanoparticles, (x = 0, 0.035, 0.07, 0.1 and 0.15) were prepared via auto-compassion strategy. XRD plots proved the complete emersion of the solitary-phase orthorhombic Nano-pervoskites. Samples' crystallite size R surged with x. FTIR confirmed the evolution of Orthorhombic Pervoskite phase. HTEM images showed relatively large particle size for all samples giving the whole picture of the nanoparticles. DTA/TGA showed decrease in sample weight giving largest weight loss around ≈31%. Cyclic voltammetry and galvanostatic charge/discharge measurements were adopted to investigate the electrochemical merits of CrSm 0.15 Fe 0.85 O 3 pervoskite nanoparticles in 1 M KOH electrolyte solution. CrSm 0.15 Fe 0.85 O 3 pervoskite nanoparticles exhibited specific capacitance of 1840 mF/g at 50 mV/s. Nearly, rectangular shape of cyclic voltammetry curve revealed that electric double layer capacitance was dominated. The study presents a promising application of CrSm 0.15 Fe 0.85 O 3 pervoskite nanoparticles as electrode materials for energy storage. Nyquist plots for CrSm 0.15 Fe 0.85 O 3 pervoskite nanoparticles appeared in the frequency range from 1.0 Hz to 20 kHz. CrSm 0.15 Fe 0.85 O 3 pervoskite nanoparticles retains low value of solution resistance (Rs) as 50 Ω. [ABSTRACT FROM AUTHOR]

In this manuscript the crystal structure of Li 3 UF 7 from powder X-ray and neutron diffraction studies is reported. The existence of Li 3 UF 7 has been debated for a long time, as it is often missed in a number of phase diagram studies. This study adopted a judicious composition of LiF and UF 4 , and an optimum cooling rate to prepare Li 3 UF 7. The Li 3 UF 7 phase could be obtained by cooling the molten LiF-UF 4 with large excess of LiF at a rate of 5 K/min while slower cooling tends to form LiUF 5. The crystal structures of Li 3 UF 7 and LiUF 5 in the temperature range of 300–10 K have been obtained from the powder neutron diffraction studies. At 300 K, Li 3 UF 7 has an orthorhombic lattice with unit cell parameters: a = 8.698(2) Å, b = 8.692(2) Å, c = 12.803(1) Å, V = 968.0(4) Å3; Z = 8 (Space group: C cca), and is isostructural to orthorhombic Li 3 ThF 7. On cooling, the orthorhombic distortion of Li 3 UF 7 increases but does not reveal any structural transition down to 10 K. The crystal structure of Li 3 UF 7 is built from the defective (Li-deficient) layers of edge shared octahedral LiF 6 and layers corner connected UF 9 polyhedra. Analogous studies on LiUF 5 have also been carried out, which has a tetragonal (Space Group: I 4 1 /a) lattice with unit cell parameters: a = 14.8882(8) Å, c = 6.5438(7) Å, V = 1450.5(2) Å3; Z = 16. The structure of LiUF 5 is built from the three-dimensional sub -lattice formed by U 4 F 30 units and the empty tunnels of the sublattice are occupied by Li 4 F 16 clusters formed by four edge shared LiF 6 octahedra. Also, the details of crystal chemistry of the compounds in LiF-UF 4 systems and their thermal stabilities are discussed. The complexity in the crystal chemistry in LiF-UF 4 system is manifested in multiple close by thermal events in the DTA runs which has also been discussed in the manuscript. ga1 • Synthesis and crystal structure of metastable Li 3 UF 7 in LiF-UF 4 are reported. • Conditions for formation of different phases in LiF-UF 4 system are delineated. • Crystal structures of Li 3 UF 7 and LiUF 5 down to 5 K are studied by LT-PND. • Anisotropic thermal expansion in Li 3 UF 7 is observed in between 5 and 300 K. • LiF-UF 4 phase diagram and comparative crystal chemistry phases in it are discussed. [ABSTRACT FROM AUTHOR]

Attempts to obtain Eu 5 Br[BO 3 ] 3 by the reaction of europium sesquioxide (Eu 2 O 3) and elemental boron (B) at 1323 K in the presence of sodium bromide (NaBr) acting as flux and bromine source for 72 h in a silica-jacketed niobium capsule yielded single crystals of Eu 3 [BO 3 ] 2 and the hitherto unknown bromide oxoborate Eu 6 Br[BO 3 ] 4 by serendipity. Optimizing the starting reactant ratios and variations of the fluxes gave access to isotypic Eu 6 X [BO 3 ] 4 representatives with X = Cl and Br. Their hexagonal crystal structures was determined by single-crystal X-ray diffraction and adopt the non-centrosymmetric space group P 6 3 mc with lattice parameters in the range of a = 1052–1061 pm and c = 681–685 pm at 298 K as well as a = 1050–1059 pm and c = 680–682 pm at 100 K for Z = 2. Eight- and nine-fold coordinated europium cations have planar [BO 3 ]3– triangles and one of these also two halide anions as neighbors. The Raman and IR spectra of both compounds were acquired and compared to literature data to confirm the presence of isolated [BO 3 ]3– anions. Additionally, Mößbauer spectra and magnetic susceptibility measurements confirmed the simultaneous presence of di- and trivalent europium cations according to (Eu2+) 5 (Eu3+)(X –)([BO 3 ]3–) 4 with X = Cl and Br. Image 1 • New synthesis route via borothermic reduction of europium(III) oxide with elemental boron in halide fluxes. • Structure description of the new europium(II,III) halide oxoborates Eu 6 Cl[BO 3 ] 4 and Eu 6 Br[BO 3 ] 4. • IR and Raman spectroscopy revealing the presence of only isolated [BO 3 ]3– anions. • Mößbauer spectroscopy and study of magnetism proving the europium mixed-valence according to (Eu2+) 5 (Eu3+)(X –)([BO 3 ]3–]) 4. • Diffuse reflectance spectroscopy showing the optical band gaps of Eu 6 Cl[BO 3 ] 4 and Eu 6 Br[BO 3 ] 4. [ABSTRACT FROM AUTHOR]

Copper tin sulphide (Cu 2 SnS 3, CTS) is a promising p-type thermoelectric material. In the present work, we have investigated the cation disorder in CTS disks made by sintering powders produced via high energy reactive ball-milling. The crystalline structures, electronic and thermal properties were systematically investigated. As-milled CTS shows a disordered cubic structure (c-CTS), preserved with thermal treatment up to 500 °C. By increasing the thermal treatment temperature, CTS gradually evolves towards the ordered monoclinic structure (m-CTS), reaching complete order at 650 °C. The disordered CTS has several times higher zT than the ordered CTS. In fact, ordered CTS has high thermopower, up to 700 μV/K, and high electrical resistivity leading to zT < 0.05 above 700K; whereas, disordered (c-CTS) has comparatively high zT ∼0.30 above 700K. This has been related to the lower electrical resistivity, and the ultra-low thermal conductivity (k ∼0.26 W/m-K), resulting from the disordered structure, promoting Phonon-Glass-Electron-Crystal (PGEC) characteristics. In our best knowledge, zT ∼0.30 above 700K is the highest in CTS samples without acting on the chemistry of the system. • An alternative approach to produced disordered CTS. • Ultra-low k with phonon-glass-electron-crystal characteristic. • Enhanced zT∼ 0.30 at 723K without acting on chemistry. [ABSTRACT FROM AUTHOR]

The quaternary rare-earth sulfide LaSnGa 3 S 7 was prepared by reaction of La, SnS, Ga 2 S 3 , and S at 1173 K. Single-crystal X-ray diffraction analysis revealed that it adopts a new monoclinic structure type (space group P 2 1 / n , a = 11.3555(9) Å, b = 9.6177(5) Å, c = 11.5137(8), β = 115.693(9)°, Z = 4) featuring a three-dimensional (3D) anionic framework built up of two-dimensional (2D) Ga–S layers formed by corner-sharing [GaS 4 ] tetrahedra and unique [Sn 2 S 8 ] dimers formed by edge-sharing [SnS 5 ] units, with the intervening voids filled by La cations. An optical band gap of 2.39 (2) eV, as deduced from the UV–vis–NIR diffuse reflectance spectrum, is consistent with the yellow colour of the crystals. Thermal analysis suggests that LaSnGa 3 S 7 melts incongruently. The electronic structure of LaSnGa 3 S 7 is obtained through the first-principle calculations. Image 1 • LaSnGa 3 S 7 is the first quaternary compound in the RE-Sn-Ga-S systems. • It adopts a new structure type containing 2D Ga–S layers and unique [Sn 2 S 8 ] dimers. • It melts incongruently indicated by thermal analysis. • It has an indirect optical band gap of 2.39 (2) eV, consistent with the yellow color of the crystals. [ABSTRACT FROM AUTHOR]

The effect of varying thickness on structure and thermal properties is investigated in Fe–B–Nb and Fe–B–Si–Nb glassy alloy systems with the addition of different Nb and Co content, respectively. Accordingly, four alloys with the nominal compositions of Fe 76-x B 18 Nb 6+x (x = 0, 2) and (Fe 1-y Co y) 72 B 12 Si 12 Nb 4 (y = 0, 0.5) are processed in the forms of ribbon and rod. All alloys of ribbons represent amorphous structure, while those of rods explain the crystalline structure with the exception of heteromorphous structure for Co added alloy. The Nb addition causes about same glass transition temperature (Tg) but increases crystallization onset (Tx), resulting in a wider supercooled liquid region (ΔTx = Tx-Tg). Moreover, Nb also improves glass forming ability (GFA) with more free volume generation and higher structural relaxation exothermic heat (ΔH 0). The Co addition also improves free volume generation and higher ΔH 0 for ribbon, but lower amount free volume generation in bulk alloys (rod) than ribbon. • Both composition and processing routes affect structure and thermal behaviours in Fe-B-Nb and Fe-B-Si-Nb alloy systems. • Nb and Co addition improve glass forming ability with more free volume generation. • Free volume generation in rod is lower than ribbon for a Co added alloy. [ABSTRACT FROM AUTHOR]