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Single crystals of the langbeinite-type phosphates K1.65Na0.35TiFe(PO4)3 and K0.97Na1.03Ti1.26Fe0.74(PO4)3 were grown by crystallization from high-temperature self-fluxes in the system Na2O–K2O–P2O5–TiO2–Fe2O3 using fixed molar ratios of (Na+K):P = 1.0, Ti:P = 0.20 and Na:K = 1.0 or 2.0 over the temperature range 1273–953 K. The three-dimensional framework of the two isotypic phosphates are built up from [(Ti/Fe)2(PO4)3] structure units containing two mixed [(Ti/Fe)O6] octa­hedra (site symmetry 3) connected via three bridging PO4 tetra­hedra. The potassium and sodium cations share two different sites in the structure that are located in the cavities of the framework. One of these sites has nine and the other twelve surrounding O atoms. [ABSTRACT FROM AUTHOR]

Cubic crystals of tripotassium aluminium (or gallium) nitridotriphosphate, K3MIII(PO3)3N (MIII = Al, Ga), were grown by application of the self-flux method. In their isostructural crystal structures, all metal cations and the N atom occupy special positions with site symmetry 3, while the P and O atoms are situated in general positions. The three-dimensional framework of these oxidonitridophosphates is built up from [MIIIO6] octa­hedra linked together via (PO3)3N groups. The latter are formed from three PO3N tetra­hedra sharing a common N atom. The coordination environments of the three potassium cations are represented by two types of polyhedra, viz. KO9 for one and KO9N for the other two cations. An unusual tetra­dentate type of coordination for the latter potassium cations by the (PO3)3N6– anion is observed. These K3MIII(PO3)3N (MIII = Al, Ga) compounds are isostructural with the Na3MIII(PO3)3N (MIII = Al, V, Ti) compounds. [ABSTRACT FROM AUTHOR]

Synergistic integration between carbon matrix and 2D MXene brings up great creativity towards more opportunity of versatile serving scenario for MXene-based hybrid materials, especially in realms like electrochemical energy storage, photo-/electrocatalysis water splitting, electromagnetic waves adsorption, sensing and so on. Multidimensional carbonaceous matrix, from zero-dimension (0D) to larger scales of 3D counterparts, building various heterostructure configuration with 2D MXene, could cultivate personas for different targets and further maximizing MXene intrinsic strength of in terms of layered structure and unique properties. In our review, we present a comprehensive discussion on miscellaneous structural integration of carbon matrix and MXene, including designing principles, synthetic routes, as well as internal correlation between two components. Meanwhile, we analyze and elaborate the textural features and structure–property relationships of 2D MXene-based composites with 0D, 1D, 2D and 3D multidimensional carbon matrix. At last, to fulfill future development and application foreground, we put forward subsistent challenge and noteworthy research perspectives of MXene-based and corresponding hybridization with carbonaceous matrix with different dimensionalities. [ABSTRACT FROM AUTHOR]

Abstract: The interaction of TiN with Na2O–K2O–P2O5 melts was investigated at (Na+K)/P molar ratios of 0.9, 1.0, and 1.2 and at Na/K molar ratios of 1.0 and 2.0. Interactions in the system led to the loss of nitrogen and the partial loss of phosphorus and resulted in the formation of KTiP2O7 and langbeinite‐type K2−xNaxTi2(PO4)3 (x=0.22–0.26) solid solutions over the temperature range of 1173 to 1053 K. The phase compositions of the obtained samples were determined by using X‐ray diffraction (including Rietveld refinement), scanning electron microscopy (using energy‐dispersive X‐ray spectroscopy and element mapping), FTIR spectroscopy, and thermogravimetric analysis/differential thermal analysis. K1.75Na0.25Ti2(PO4)3 was characterized by single‐crystal X‐ray diffraction [P213 space group, a=9.851(5) Å]. The 3D framework is built up by TiO6 octahedra and PO4 tetrahedra sharing all the oxygen vertices with the formation of cavities occupied by K(Na) cations. Only one of the two crystallographically inequivalent potassium sites is partially substituted by sodium, and this was confirmed by calculating the bond‐valence sum. The thermodynamic stability of K1.75Na0.25Ti2(PO4)3 crystals and the preferable occupation sites of NaK cationic substitutions were investigated by DFT‐based electronic structure calculations performed by the plane‐wave pseudopotential method. [ABSTRACT FROM AUTHOR]

Herein, the peculiarities of complex phosphate formation in self-fluxes of Cs–MII–Bi–P–O (MII = Ca, Sr, Ba and Pb) systems with Cs/P = 0.7–1.3 at fixed ratios of Bi/P = 0.2 and Bi/MII = 1.0 were studied and discussed. Three novel isostructural diphosphates with the general composition Cs3MIIBi(P2O7)2 (MII = Ca, Sr and Pb) and the original framework topology were synthesized and characterized via single-crystal and powder X-ray diffraction, SEM, DTA, and FTIR- and UV-VIS-spectroscopy. In addition, electronic structure (DFT) and Voronoi–Dirichlet polyhedra (VDP) characteristics calculations and crystallochemical analysis were performed. In the structure of the new compounds, the MIIO7 and BiO6 polyhedra are connected via common oxygen vertices forming infinite helical-like chains, which are linked by P2O7 groups into a 3D-framework with pentagonal tunnels, where the Cs+ cations are located. The structural peculiarities are discussed considering perspectives for the creation of new luminescent materials. The dielectric bandgaps, Eg, of the Cs3MIIBi(P2O7)2 crystals reveal an ∼0.2 eV low-energy shift in the Ca–Sr–Pb sequence of MII cations, which reveals the possibility to tune the optical absorbance spectra of the crystals via the synthesis of solid solutions with various contents of MII cations. The glass-ceramic synthetic approach is also proposed as a convenient method for the creation of new diphosphates, and the applicability of this method is verified for Cs3CaBi(P2O7)2. [ABSTRACT FROM AUTHOR]

Solid solutions KTi1-XHfXOPO4 (х = 0.008 - 0.107) possessing the KTiOPO4 structure, have been synthesized in molten system K2O-P2O5-TiO2-HfF4. The crystal growth experiment of Hf-doped KTP crystal has been reported. The X-ray powder diffraction data and chemical analysis are also presented. It has been shown that KTiOPO4 crystal structure slightly changes when Hf incorporates into the framework. Transmission/absorption spectra of KTi0.974Hf0.026OPO4 crystals have been recorded. The incorporation of Hf ions shifts the optical absorption edge in the UV-visible spectrum towards the long-wavelength region with absorption near 387 nm. [ABSTRACT FROM AUTHOR]

The solid solution KNi0.93FeII0.07FeIII(PO4)2 {potassium [nickel(II)/iron(II)] iron(III) bis(orthophosphate)} has been prepared by the flux method. The compound shows a new type of structure for a phosphate with the general composition MI MII MIII(PO4)2. The framework is formed by [(Ni/Fe)O6] polyhedra [Fe site occupancy = 0.069 (14)] linked via shared oxygen vertices forming a cis-like parallel chain stretching along a and [FeO5] polyhedra (located on alternate sides of the chains) connected via two types of PO4 groups into a three-dimensional structure. The K atoms are disordered between two sites, denoted K1 A and K1 B, with occupancies of 0.930 (9) and 0.070 (9), respectively, and reside inside channels along the a axis. Calculations of the Voronoi-Dirichlet polyhedra of the K atoms give a coordination scheme for K1 A of [9 + 3] and for K1 B of [10 + 2]. The most remarkable feature of the structure is the splitting of the K-atom site and the population of the K1 A and K1 B positions due to substitution of Ni by Fe in the (Ni/Fe) position. [ABSTRACT FROM AUTHOR]

Abstract: The crystallization of complex phosphates from the melts of Cs2O–P2O5–CaO–M III 2O3 (M III—Al, Fe, Cr) systems have been investigated at fixed value Cs/P molar ratios equal to 0.7, 1.0 and 1.3 and Са/Р=0.2 and Ca/М III=1. The fields of crystallization of CsCaP3O9, β-Ca2P2O7, Cs2CaP2O7, Cs3CaFe(P2O7)2, Ca9 M III(PO4)7 (M III—Fe, Cr), Cs0.63Ca9.63Fe0.37(PO4)7 and CsCa10(PO4)7 were determined. Obtained phosphates were investigated using powder X-ray diffraction and FTIR spectroscopy. Novel whitlockite-related phases CsCa10(PO4)7 and Cs0.63Ca9.63Fe0.37(PO4)7 have been characterized by single crystal X-ray diffraction: space group R3c, a=10.5536(5) and 10.5221(4)Å, с=37.2283(19) and 37.2405(17)Å, respectively. [Copyright &y& Elsevier]

Abstract: Phase equilibrium in the pseudo-quaternary system K2O–MoO3–P2O5–Bi2O3 was studied as three-component solvent K2MoO4–KPO3–MoO3 containing 15mol% Bi2O3 during slow cooling and spontaneous crystallization. The results of the investigation were shown on a composition diagram, which indicates the crystallization fields of K2Bi(PO4)(MoO4), K5Bi(MoO4)4, BiPO4 and K3Bi5(PO4)6. New phosphate K3Bi5(PO4)6 was characterized by single-crystal X-ray diffraction (space group C2/c, a=17.680(4), b=6.9370(14), c=18.700(4)Å, β=113.79(3)°) and FTIR spectroscopy. The possibility of lone electron pair stereoactivity of bismuth was suggested using the calculations of characteristics of the Voronoi–Dirichlet polyhedra for K3Bi5(PO4)6 and K2Bi(PO4)(MoO4). [Copyright &y& Elsevier]

Crystals of dipotassium iron(III) tin(IV) tris(orthophosphate) were grown from a self-flux in the system K2O-P2O5-Fe2O3-SnO2. The title compound is isotypic with the mineral langbeinite, K2Mg2(SO4)3. Its three-dimensional [M2(PO4)3]∞ framework is composed of [MO6] (M = Sn, Fe) octahedra and [PO4] tetrahedra interlinked via vertices. In comparison with the previous refinement from X-ray powder data [Aatiq, Haggouch, Bakri, Lakhdar & Saadoune. (2006). Powder Diffr. 21, 214-219], the present reinvestigation from single-crystal data allows a more precise determination of the distribution of the Fe and Sn atoms over two crystallographic positions and a revision of the P-O and M-O [M = K, (Fe, Sn)] bond lengths. For the two K+ cations, two different polyhedra with coordination numbers of 9 and 12 are observed. The (Fe, Sn) and K atoms are located on three-fold axes. [ABSTRACT FROM AUTHOR]

Abstract: Two new mixed valence manganese-containing orthophosphates with a langbeinite structure have been obtained from the complex fluoride–phosphate melts using the high-temperature flux technique. M IVF4 and K2 M IVF6 (M IV—Zr, Hf) were used as fluoride and polyvalent metal precursors. Obtained langbeinites were investigated using a single-crystal X-ray diffraction, FTIR-, UV–VIS- and electron paramagnetic resonance (EPR)-spectroscopy. Both compounds crystallize in a cubic system (sp. gr. P213) with cell parameters a=10.2106(12) and 10.1896(9)Å for K1.96Mn0.57Zr1.43(PO4)3 and K1.93Mn0.53Hf1.47(PO4)3, respectively. The rigid langbeinite-like framework is built up from the isolated [MO6] octahedra and [PO4] tetrahedra interlinked via oxygen vertices. Potassium cations occupy positions in the large closed cavities of the framework. Statistical distribution of manganese and tetravalent metal over two crystallographic positions in octahedral oxygen environment can be observed. The presence of the mixed valence manganese in the reported phosphates was confirmed using UV–VIS and EPR-spectroscopy. [Copyright &y& Elsevier]

Abstract: The single crystals of caesium magnesium titanium (IV) tri-oxo-tetrakis-diphosphate bis-monophosphate, Cs3.70Mg0.60Ti2.78(TiO)3(P2O7)4(PO4)2, crystallize in sp. gr. P-1 (No. 2) with cell parameters a=6.3245(4), b=9.5470(4), c=15.1892(9)Å, α=72.760(4), β=85.689(5), γ=73.717(4), z=1. The titled compound possesses a three-dimensional tunnel structure built by the corner-sharing of distorted [TiO6] octahedra, [Ti2O11] bioctahedra, [PO4] monophosphate and [P2O7] pyrophosphate groups. The Cs+ cations are located in the tunnels. The partial substitution of Ti positions with Mg atoms is observed. The negative charge of the framework is balanced by Cs cations and Mg atoms leading to pronounced concurrency and orientation disorder in the [P2O7] groups, which coordinate both. [Copyright &y& Elsevier]

Abstract: A new potassium bismuth phosphate-molybdate K2Bi(PO4)(MoO4) has been synthesized by the flux method and characterized by single-crystal and powder X-ray diffraction, IR spectroscopic studies. The compound crystallizes in the orthorhombic system with the space group Ibca and the cell parameters: a=19.7037(10), b=12.4752(10), c=7.0261(10). This phase exhibits an original layered structure, in which the [Bi(PO4)(MoO4)]∞ layers consist of [Bi2Mo2O18]∞ chains linked through single PO4 tetrahedra. The K+ cations interleaved between these layers exhibit a monocapped distorted cubic coordination. [Copyright &y& Elsevier]

Abstract: New complex phosphates of the general formula K2 M 0.5Ti1.5(PO4)3 (M=Mn, Co) have been obtained from the melting mixture of KPO3, K4P2O7, TiO2 and CoCO3·mCo(OH)2 or Mn(H2PO4)2 by means of a flux technique. The synthesized phosphates have been characterized by the single-crystal X-ray diffraction and the FTIR-spectroscopy. The compounds crystallize in the cubic system with the space group P213 and cell parameters a=9.9030(14)Å for K2Mn0.5Ti1.5(PO4)3 and a=9.8445(12)Å for K2Co0.5Ti1.5(PO4)3. Both phosphates are isostructural with the langbeinite mineral and contain four formula unit K2 M 0.5Ti1.5(PO4)3 per unit cell. The structure can be described using [M 2(PO4)3] framework composed of two [MO6] octahedra interlinked via three [PO4] tetrahedra. The Curie–Weiss-type behavior is observed in the magnetic susceptibility. [Copyright &y& Elsevier]

Tetra­potassium cerium(IV) zirconium tetra­kis­(mono­phos­phate) crystallizes in the tetra­gonal system (space group I41/ amd). A complex disorder in K4CeZr(PO4)4 involves the mixing of Ce and Zr atoms on a single site with m2 symmetry and the splitting of P- and O-atom positions, equivalent to a rotation of the phosphate groups, to yield eight- and sixfold coordination environments around Ce and Zr, respectively. The K atoms are located in tunnels running parallel to the a and b axes. [ABSTRACT FROM AUTHOR]

Crystals of the title compound, CsCd(P3O9), were grown from a melt. The structure is isotypic with CsCdP3O9. The three-dimensional framework is built up from [CaO6] octa­hedra linked together via corner-sharing to cyclic [P3O9]3− anions. The Cs cations are situated in large cavities in the [CaP3O9]∞− anion framework. Except for one P and three O atoms, all other atoms (one Cs, one Ca, one P and three O atoms) are located on mirror planes. [ABSTRACT FROM AUTHOR]

Aliovalent KTP isomorphic compounds potassium chromium niobium oxide phosphate, KCr0.5Nb0.5OPO4, and potassium iron niobium oxide phosphate, KFe0.5Nb0.5OPO4, exhibit structures that differ from that of the non-centrosymmetric KTiOPO4. There are two crystallographically independent octa­hedral sites, M1 and M2, statistically occupied by Nb and Cr (or Fe) atoms. The M1O6 and M2O6 octa­hedra are connected alternately to form a chain with a cis– trans arrangement. The Nb atoms prefer the M2 sites arranged in a cis-like configuration. Each PO4 tetra­hedon has the P atom on a twofold axis. Site-splitting at the K-atom position is observed in both compounds. In the isomorphous structures, one Nb atom lies on an inversion centre and the other on a twofold axis. Similarly with the pairs of Fe/Cr sites, one is on an inversion centre and the other on a twofold axis. [ABSTRACT FROM AUTHOR]

Dipotassium bismuth phosphate tungstate has been synthesized using the flux technique. It crystallizes in the space group Ibca and is isotypic with Na2Y(PO4)(MoO4). It exhibits a layered structure, which is built up from [Bi(PO4)(WO4)]∞2- layers. Each layer is composed of [BiO8]∞ zigzag chains, which are connected via PO4 and WO4 tetrahedra. The parallel anionic [Bi(PO4)(WO4)]∞2- layers are stacked along [100] and are held together by K+ counter-cations which occupy sites in the interlayer space. Bi, W and P atoms are all located on twofold axes. [ABSTRACT FROM AUTHOR]

As one of the most likely alternatives to traditional vapor compression refrigeration technology, solid refrigeration technology based on the barocaloric effect (BCE) has attracted extensive attention in recent years. Spin-crossover (SCO) compounds are considered suitable for working at low driving pressures due to high-pressure sensitivity and small hysteresis width. However, the entropy change (ΔSSCO) of the SCO compound is smaller than that of other excellent barocaloric materials (plastic crystals and two-dimensional perovskites). Here, we report the BCE of the SCO compound {Fe(pz)2(BH3CN)2} (pz = pyrazine) with a smaller molar mass and a third source of entropy change besides electron and vibrational entropy changes. Compound {Fe(pz)2(BH3CN)2} exhibits high pressure sensitivity ( d T 1 / 2 d P = 20.2 K kbar−1) as well as entropy change (Δ S SCO = 202 J kg−1 K−1). The maximum values of reversible isothermal entropy change (ΔSit,rev,max) and adiabatic temperature change (ΔTad,rev,max) at 1 kbar are only 103 J kg−1 K−1 and ∼0 K, respectively, due to the hysteresis behavior. However, at sufficiently high driving pressures, ΔSit,rev,max exceeds 200 J kg−1 K−1, and ΔTad,rev,max can reach ∼47 K, which exceeds all SCO compounds reported in BCE studies and is comparable to some plastic-crystalline and two-dimensional perovskite barocaloric materials. The excellent BCE of the SCO compound {Fe(pz)2(BH3CN)2} is mainly due to its small molar mass, which makes the unit mass compound exhibit higher ΔSSCO, while the introduction of the third source of entropy change—the reorientation entropy change (ΔSreo), only plays a small role. This is expected to promote the practical application of SCO compounds as barocaloric refrigerants. [ABSTRACT FROM AUTHOR]

During multivalent ions insertion processes, intense electrostatic interaction between charge carriers and host makes the high‐performance reversible Al3+ storage remains an elusive target. On account of the strong electrostatic repulsion and poor robustness, Prussian Blue analogues (PBAs) suffer severely from the inevitable and large strain and phase change during reversible Al3+ insertion. Herein, we demonstrate an entropy‐driven strategy to realize ultralong life aqueous Al‐ion batteries (AIBs) based on medium entropy PBAs (ME‐PBAs) host. By multiple redox active centers introduction, the intrinsic poor conductivity can be enhanced simultaneously, resulting in outstanding capabilities of electrochemical Al3+ storage. Meanwhile, the co‐occupation at metal sites in PBA frameworks can also increase the M−N bond intensity, which is beneficial for constraining the phase change during consecutive Al3+ reversible insertion, to realize an extended lifespan over 10,000 cycles. Based on the calculation at different operation states, the fluctuation of ME‐PBA lattice parameters is only 1.2 %. Assembled with MoO3 anodes, the full cells can also deliver outstanding electrochemical properties. The findings highlight that, the entropy regulation strategy could uncover the isochronous constraint on both strain and phase transition for long‐term reversible Al3+ storage, providing a promising design for advanced electrode materials for aqueous multivalent ions batteries. [ABSTRACT FROM AUTHOR]

During multivalent ions insertion processes, intense electrostatic interaction between charge carriers and host makes the high‐performance reversible Al3+ storage remains an elusive target. On account of the strong electrostatic repulsion and poor robustness, Prussian Blue analogues (PBAs) suffer severely from the inevitable and large strain and phase change during reversible Al3+ insertion. Herein, we demonstrate an entropy‐driven strategy to realize ultralong life aqueous Al‐ion batteries (AIBs) based on medium entropy PBAs (ME‐PBAs) host. By multiple redox active centers introduction, the intrinsic poor conductivity can be enhanced simultaneously, resulting in outstanding capabilities of electrochemical Al3+ storage. Meanwhile, the co‐occupation at metal sites in PBA frameworks can also increase the M−N bond intensity, which is beneficial for constraining the phase change during consecutive Al3+ reversible insertion, to realize an extended lifespan over 10,000 cycles. Based on the calculation at different operation states, the fluctuation of ME‐PBA lattice parameters is only 1.2 %. Assembled with MoO3 anodes, the full cells can also deliver outstanding electrochemical properties. The findings highlight that, the entropy regulation strategy could uncover the isochronous constraint on both strain and phase transition for long‐term reversible Al3+ storage, providing a promising design for advanced electrode materials for aqueous multivalent ions batteries. [ABSTRACT FROM AUTHOR]

An optimal performance of bone implants with bioceramic coatings is closely related to the surface modification technology. For the first time, we have evaluated a gas detonation deposition (GDD) approach to obtain biocompatible ceramic coatings based on bioglass (BG) and calcium phosphates on Ti-based alloys as prospective materials towards their application for the development of bone implants. For the production of the coatings, hydroxyapatite (HA), HA metal-substituted (containing Ag+, Cu2+, or Zn2+) and tricalcium phosphate (TCP) were synthesized and characterized. Pure powders and their combination with BG were used to obtain coatings on a Ti–6Al–4V alloy using the developed automatized GDD setup. The microstructure, phase and chemical composition of the produced coatings were studied using XRD, SEM-EDS and Raman spectroscopy. The produced coated materials were evaluated in vivo in Wistar rats to analyze a reparative osteogenesis over a period of 12 weeks. The results regarding the optimization of the GDD method indicate its high productivity, as confirmed by high deposition rates. The highest deposition rate was observed for the coatings obtained from the HA metal-substituted powders. The results revealed a partial transformation of a HA phase to an α-TCP phase during the deposition, with a prevalence of the HA-phase in the coatings. According to the histological evaluation, the reparative osteogenesis occurs through the perimeter of the titanium implants, whereas the regeneration level increases from the 4th to the 12th week. The highest osteointegration level was detected for the implants coated with a biocomposite consisting of BG, HA and TCP. The results of the current study demonstrate an effectiveness of the GDD method to produce biocompatible coatings on Ti-based alloys. This provides excellent prerequisites towards the application and standardization of the GDD technology to manufacture bone implants for bone fixation and defect replacement, as well as the development of dental implants. [ABSTRACT FROM AUTHOR]

The evolution of high-performance and stable electrode materials for supercapacitors plays a vital role in the next generation of energy storage devices. In this work we present a simple method for preparing Bi(nanoparticles)/CNx(nanosheets) nanocomposites as electrode materials for supercapacitors, which were synthesized by thermally treating bismuth citrate and urea at 550–700 °C under an Ar atmosphere. According to physicochemical studies (XRD, SEM, TG-DTA, XPS, FTIR, and BET), a "smeared" bismuth formation or the formation of nanoparticles on the CNx surface of interwoven 2D-nanosheets at different calcination temperatures was observed. Electrochemical measurements show that the specific capacity of the composites can reach 1251 F g−1 (more than 90% of the theoretical value) at a current density of 500 mA g−1 in a 6 M KOH electrolyte, and most two-dimensional CNx-based nanostructures remain intact after multiple galvanostatic charge–discharge processes, which is promising for the development of highly efficient supercapacitors. A supercapacitor composed of Bi/CNx nanocomposites for the negative electrode and Ni-layered hydroxide for the positive electrode demonstrates a high energy density of 58 W h kg−1 with a power density of 800 W kg−1 accompanied by a good cycle life (the parameters decreased down to only 78% after 1000 charge–discharge cycles). Our current results indicate that the addition of urea not only determines the morphology of the composites, but also lays the foundation for the development of new types of nanocomposites for the power industry. [ABSTRACT FROM AUTHOR]

The title compound is prepared from KPO3 and NiO (Pt crucible, 1173 K) as a self-flux to which K2ZrF6 is added. [ABSTRACT FROM AUTHOR]

Polycrystalline AgCa10(PO4)7 is obtained by solid state reaction of a stoichiometric mixture of Ag3PO4, CaCO3, and CaHPO4 (porcelain crucible, calcination at 873 K, annealing at 1173 K, 20 h). [ABSTRACT FROM AUTHOR]

Aliovalent K0.92In0.46Nb0.54OPO4 (KINP, potassium indium niobium oxide phosphate) features a chain structure involving corner-sharing [ MO6] octahedra ( M = In/Nb), which allows this compound to be recognized as a member of the KTiOPO4 (KTP) family. However, its crystallization in the polar space group P41 belonging to the 4/ m Laue group generates its own subclass of KTP-related compounds. The unit cell contains 18 symmetry-independent atoms occupying general positions. The cis– cis principle of octahedral arrangement is observed for each of the separate [ MO6]∞ chains. The observed variations in the cis– cis linkage are critically important for nonlinear optical properties and distinguish the present compound from other KTP-related structures. The anionic framework adopts one-dimensional tunnels running orthogonal to the ab plane. The K+ ions are arranged in the [001] direction at a distance of c. Merohedral twinning was detected during the structure refinement. [ABSTRACT FROM AUTHOR]

Nonacalcium chromium(III) heptakis(orthophosphate) has been obtained from a melt in the system Cs2O–CaO–Cr2O3 using a polyphosphate flux. The three-dimensional framework is related to the whitlockite structure [β-Ca3(PO4)3] and is built up from CaO8 and CaO9 polyhedra sharing vertices, edges and faces, further connected by PO4 tetrahedra and CrO6 octahedra. The Cr, one P and one O atom are located on threefold rotation axes. Ca9Cr(PO4)7 is isotypic with Ca9Fe(PO4)7. The crystal studied was an inversion twin. [ABSTRACT FROM AUTHOR]

The title compound, tris­odium titanium nitride tris­(phos­phate), is built up from TiIIIO6 octa­hedra linked together via [N(PO3)3] groups, the latter arising from three PO3N tetra­hedra sharing an N vertex. Three sodium cations complete the structure, which is also found for Na3AlN(PO3)3. All the metal cations and the N atom occupy special positions with site symmetry 3. [ABSTRACT FROM AUTHOR]

The particularities of the chemical interaction in systems MIPO3 -MIIO(or Mn2O3)- MICl ( MI - Na, K; MII - Mg, Co, Ni, Zn) have been investigated at the temperature 1073 K and molar ratios P/ Mx = 1 or 2 and MICl/( MIPO3 + MIIO(or Mn2O3)) = 30. The conditions of formation of complex phosphates MІMIIPO4 and Na4Ni3(PO4)2P2O7 have been found. Influences of the nature of alkali and bivalent metals on the products composition were discussed. The advantages of chloride melts using (synthesis time reduction and temperature reducing) for preparing of complex phosphates were shown. The synthesized compounds have been characterized using the powder X-ray diffraction, Fourier transform infrared and diffuse reflectance spectroscopies. [ABSTRACT FROM AUTHOR]

Nine novel phosphates, based upon a combination of caesium, zirconium and lanthanide ions, were obtained from fluoride-containing fluxes using high-temperature crystallization. The structures of Cs1.80Eu0.80Zr1.20(PO4)3 (CsEuZrP), Cs1.79Gd0.79Zr1.21(PO4)3 (CsGdZrP), Cs1.87Tb0.87Zr1.13(PO4)3 (CsTbZrP), Cs1.67Dy0.67Zr1.33(PO4)3 (CsDyZrP), Cs1.75Ho0.75Zr1.25(PO4)3 (CsHoZrP), Cs1.78Er0.78Zr1.22(PO4)3 (CsErZrP), Cs1.70Tm0.70Zr1.30(PO4)3 (CsTmZrP), Cs1.52Yb0.52Zr1.48(PO4)3 (CsYbZrP) and Cs1.63Lu0.63Zr1.37(PO4)3 (CsLuZrP) were solved using single-crystal X-ray diffraction. All compounds are isostructural to the mineral langbeinite (cubic system, space group P213). Their framework structures originate from the cross-linking of metal octahedra [ MO6] ( M = Zr, Ln) by phosphate tetrahedra. Cs+ cations are located in the closed cavities of the framework and preferentially occupy one of the two available sites. The principles of crystallization of the equilibrium langbeinite-related phosphates in the fluxes of the system Cs2O–P2O5–LnF3–ZrF4 (Ln = La–Nd, Sm–Lu) are discussed based on their crystal structures. [ABSTRACT FROM AUTHOR]

The creation of carbon matrices with a high surface area for effective catalytic activity is an urgent task today, especially in the field of electrocatalysis. In this study, microporous carbon (MPS) with a surface area of about 1300 m2 g−1 was produced from raw plant waste (apricot pit shells) by successive thermal carbonation and chemical treatment. The MPS was impregnated with H 2 PdCl 6 and calcined at various temperatures under a H 2 –Ar flux. The obtained Pd-NP@MPC (nanoparticle size from 1 to 25 nm) catalysts were characterized in detail by XRD, SEM, TEM and BET methods. Electrochemical tests show that the prepared composites exhibit high electrocatalytic activity and remarkable stability over time (over 50 h) for the HER process and overall water splitting performance. The electrodes have very low overpotentials (η) of 95–117 mV for HER in 1 M KOH at a current density of 100 mA cm−2. Furthermore, the Pd-NP@MPC-300 electrode can reach a high current density of 300 mA cm−2 at η merely of 170 mV and shows excellent electrocatalytic stability in prolonged water electrolysis. The relationships between MPC matrix characteristics, Pd NPs size and electrocatalytic properties are discussed in this paper. [Display omitted] • Microporous carbon (surface area ~1300 m2 g−1) was produced from apricot pit shells. • The Pd-NP@MPC composites (NPs 1–25 nm) exhibited superior HER in alkaline media. • The overpotentials of 95–117 mV for HER at a current density of 100 mA cm−2. • High catalytic activity remains well even after 50 h of continuous electrolysis. [ABSTRACT FROM AUTHOR]

Polycrystalline potassium nickel(II) hafnium(IV) tris(orthophosphate), a langbeinite-type phosphate, was synthesized by a solid-state method and refers to langbeinite-type phosphates. The three-dimensional framework of the title compound is built up from two types of [MO6] octahedra [the M sites are occupied by Hf:Ni in ratios of 0.754 (8):0.246 (8) and 0.746 (8):0.254 (8), respectively] and [PO4] tetrahedra are connected via O vertices. The K+ cations are located in two positions within large cavities of the framework, having coordination numbers of 9 and 12. The Hf, Ni and K sites lie on threefold rotation axes, while the P and O atoms are situated in general positions. [ABSTRACT FROM AUTHOR]

The article discusses the intermolecular structure of Bis{1-methyl-5-[3-(1-methyl-1H-tetrazolo[5,1-a]-isoindol-5-yI)allylidene]-5H-tetrazolo[5,1 -a]iso-indol-1 -ium} tetracyanonickelate(II). The molecular structure consists of two organic cations, C21H17N8+ or [MTIT]+, and a centrosymmetric inorganic dianion, [Ni(CN)4]2-. The ions stack along the b axis and are connected by a number of C-H...N hydrogen bonds. These cations are positioned axial to the Ni atoms. One more pair of N...H contacts is formed with two dye cations that are almost perpendicular to the plane of the [Ni(CN)4]2-.

The great interest in developing efficient and stable bifunctional electrodes for electrocatalytic water splitting is due to the rapid growth in demand for sustainable and renewable energy sources. Here, we present an original electrode design strategy which can be used for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). This strategy is based on the direct formation of active catalytic material on the electrode surface during electrolysis. In our case, cobalt hydroxides (β-Co(OH)2 and CoO(OH) for HER and OER, respectively) in a carbon matrix are produced by the chemical and electrochemical transformation of various forms (glass, glass-ceramic and polycrystalline) of Na4Co3(PO4)2P2O7 during electrolysis in 1 M NaOH solution. The CoOx(OH)y/C composites demonstrate remarkable stability over time (more than 50 h), and bifunctional catalytic activity with an overall water splitting potential close to 1.8 V at a current density of 10 mA cm−2. The range of overpotentials for OER and HER is 346–365 and 326–369 mV, respectively. These electrodes can invert the OER and HER processes with a total overpotential of 0.6 V in the cell. This remarkable CoO(OH) ↑ Co(OH)2 inversion in the carbon matrix its further utility for creating bifunctional electrodes for long-life water splitting cells. [ABSTRACT FROM AUTHOR]

Two simple pathways using metallic copper or copper salts are proposed for the synthesis of hybrid compounds under mild conditions. A variety of Strandberg- and mixed-metal Keggin-based products, namely, (NH4)5 n{[Cu(en)2][PMo8V4O40]} n ·9 nH2O ( 1), (NH4)4 n{[Cu(en)(H2O)][P2Mo5O23]} n ·3.5 nH2O ( 2), (NH4)7[PMo8V4O40] ·17H2O ( 3) and (NH4)2 n{[Cu(en)2][Cu(en)(H2O)][P2Mo5O23]} n ·3 nH2O ( 4), were isolated upon the variation of the composition of the reaction system. A rare four-substituted [PMo8V4O40]7- Keggin anion was obtained. The influence of the vanadium source [V2O5, NH4VO3 or (NH4)2V6O16] and the copper precursor (copper powder vs. copper salts) on the nature of the resulting products was studied. An ex situ electron paramagnetic resonance (EPR) spectroscopy study revealed the formation of VIV and CuII centres in the reaction mixture during Cu0 dissolution. The obtained compounds possess electrocatalytic activity in the reduction of iodate and nitrite anions, and a carbon-paste electrode modified with 4 exhibited a linear current response to l-cysteine. Furthermore, 4 demonstrated rapid and almost complete adsorption of a cationic dye. [ABSTRACT FROM AUTHOR]

Interactions in the systems MIPO3-MIIO (or Mn2O3)-MICl (MI: Na, K; MII: Mg, Co, Ni, Zn) are investigated at molar ratios P/Mx = 1 or 2, and MICl/(MIPO3 + MIIO) = 30 (porcelain crucibles, 1073 K, 3-5 h). [ABSTRACT FROM AUTHOR]

A very broad vibrational band ranging from 1000 up to 4000 cm−1 and two relatively sharp bands at 5000 and 5027 cm−1 are found in the Raman scattering spectrum of hydroxyapatite-containing films obtained by gas detonation spray method. We developed a theoretical model that interprets the broad band as a result of strong interaction between the high-frequency hydrogen bond vibrations and lattice phonons. Both sharp bands around 5000 cm−1 are assigned to the overtones of v-OH vibrations. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The interaction in the molten system Rb2O-P2O5-TiO2-NiO was investigated at different molar ratios Rb/P = 0.5-1.3, fixed Ti/P = 0.15, Ti/Ni = 1.0 at temperature range 1073-953 K. The conditions of formation of complex phosphates RbTi2(PO4)3, Rb2Ni0.5Ti1.5(PO4)3 and RbNiPO4 have been determined. The new phosphate Rb2Ni0.5Ti1.5(PO4)3 (space group P213, a = 9.9386(2) Å) has been obtained and investigated by the single crystal X-ray diffraction and FTIR-spectroscopy. It has langbeinite-like structure, that is built up from mixed (Ni/Ti)O6-octahedra and РО4-tetrahedra. Rubidium atoms are located in closed cavities of 3D-framework. [ABSTRACT FROM AUTHOR]

The possibility of PO43- for MoO42- partial substitution in the langbeinite framework has been studied by exploration of the K-Fe(Sc)-Mo(W)-P-O systems using the high-temperature solution method. It was shown that 1/3PO43- for MoO42- substitution leads to formation of three novel compounds K2Fe(MoO4)(PO4)2, K2Sc(MoO4)(PO4)2, and K2Sc(WO4)(PO4)2 with slightly increased lattice parameters and significant distortion of the anion tetrahedra without structure changes. In contrast, the antiferromagnetic structure is modified by substitution in the low-temperature region. The structural peculiarities are discussed in light of bond-valence sums calculations. [ABSTRACT FROM AUTHOR]

Powder samples of Cr3+-doped δ*-Al 2 O 3 with particles sizes of 10–70 nm were obtained by combustion method. It is shown for the first time that Cr3+ ions in the δ*-Al 2 O 3 occupy octahedral sites in the bulk and at the surface of the nanosized particles. The photoluminescence spectra of Cr3+ in δ*-Al 2 O 3 consist of several relatively narrow lines (R-lines luminescence) in the 680–720 nm range, which are due to the 2E g → 4A 2g transitions. The local structure around Cr3+ ions inside the nanoparticles is shown to differ from that of Cr3+ located in the surface layer, which results in essential differences in the full width at half maximum values (14 cm−1 vs. 39 cm−1 at 77 K) and in red shift of the R-lines with increasing temperature from 77 to 293 K (20 cm−1 vs. ~11 cm−1). It was found that the Cr3+-doped δ*-Al 2 O 3 exhibits some striking features, including an unexpectedly high crystal-field strength at the interior Cr3+ site and an unusually high concentration of surface Cr3+ centers. Possible reasons for these features are discussed. The results obtained are anticipated to be useful for the monitoring of processes involved in the preparation of ceramics and composites based on Al 2 O 3 :Cr3+. [Display omitted] • The luminescent properties of Сr3+ in nanosized δ*-Al 2 O 3 are analyzed. • Two types of Сr3+ related centers (regular and surface) are observed. • In the 77–293 K range, all the Cr3+centers show emissions of the 2E g.→4A 2g type. • Structural disorder degree as a notable characteristic of Al 2 O 3 polymorphs. [ABSTRACT FROM AUTHOR]

A controlled bioleaching strategy to embed Ni 3 S 2 nanocrystals into 1D hollow carbonaceous fibers derived from renewable biomass was designed with enough inner voids as well as abundant natural pyridinic and pyrrolic nitrogen. The hollow fiber-based electrode can prevent the large volume expansion, improve the electronic conductivity and enhance the diffusion rate of Li+/Na+ ion. As a result, the synthesized Ni 3 S 2 /hollow carbonaceous fiber electrodes deliver excellent reversible capacity and outstanding cycle stability, i.e., 673.4 mAh g−1 at 0.1 A g−1 after 100 cycles for lithium-ion batteries (LIBs), 378.4 mAh g−1 at 1 A g−1 after 100 cycles for sodium-ion batteries (SIBs), in electrochemical half-cells. More importantly, a superior electrochemical performance is obtained in a full-cell when employing Na 3 V 2 (PO 4) 3 as cathode (i.e., 218.9 mAh g−1 after 100 cycles at 0.5 A g−1). Image 1 • A novel controlled bioleaching template-free approach to synthesize tunable hollow Ni 3 S 2 carbonaceous fibers. • 1D hollow carbonaceous fibers provide enough inner voids, abundant natural pyridinic and pyrrolic nitrogen. • The composites exhibit excellent lithium/sodium-ion storage performance for Half/Full Cell Applications. [ABSTRACT FROM AUTHOR]

The formation of complex phosphates is investigated in melts containing Rb2CO3, H3PO4, TiO2, and NiO at different molar ratios of Rb:P = 0.5-1.3, Ti:P = 0.15, Ti:Ni = 1.0 at 1073-953 K (Pt crucible, 1273 K, 3 h). [ABSTRACT FROM AUTHOR]