LiHo(PO3)4

Lithium holmium(III) polyphosphate(V), LiHo(PO3)4, belongs to the type I of polyphosphates with general formula ALn(PO3)4, where A is a monovalent cation and Ln is a trivalent rare earth cation. In the crystal structure, the polyphosphate chains spread along the b-axis direction, with a repeat period of four tetra­hedra and 21 inter­nal symmetry. The Li and Ho atoms are both located on twofold rotation axes and are surrounded by four and eight O atoms, leading to a distorted tetra­hedral and dodeca­hedral coordination, respectively. The HoO8 polyhedra are isolated from each other, the closest Ho⋯Ho distance being 5.570 (1) Å

Bis(imidazole-κN 3)bis­(nitrato-κO)zinc(II)

The title complex, [Zn(NO3)2(C3H4N2)2], contains a ZnII centre with a slightly distorted tetra­hedral coordination environment, involving two N atoms from imidazole ligands and two O atoms from nitrate anions. The imino NH groups participate in inter­molecular N—H⋯O hydrogen bonds

2-[(4-Benzhydrylpipérazin-1-yl)méthyl]acrylonitrile

In the title compound, 2-[(4-benz­hydryl­piperazin-1-yl)­methyl]­acrylo­nitrile, C21H23N3, the substituted piperazine ring adopts a chair conformation and the dihedral angle between the mean planes of the aromatic rings is 71.61 (8)°

Non-centrosymmetric Na3Nb4As3O19

A new non-centrosymmetric compound, tris­odium tetra­niobium triarsenic nona­deca­oxide, Na3Nb4As3O19, has been synthesized by a solid-state reaction at 1123 K. The structure consists of AsO4 tetra­hedra and NbO6 octa­hedra sharing corners to form a three-dimensional framework containing two types of tunnels running along the c axis, in which the sodium ions are located. Na+ cations occupying statistically several sites, respectively, are surrounded by seven, six and four O atoms at distances ranging from 2.08 (1) to 2.88 (4) Å. The title structure is compared with those containing the same groups, viz. M 2XO13 and M 2 X 2O17 (M = transition metal, and X = As or P)

Disodium tris­(dioxidomolybdenum) bis­(diarsenate)

The asymmetric unit of the title compound, Na2(MoO2)3(As2O7)2, is composed of two cyclic MoAs2O11 units and an MoO6 corner-sharing octa­hedron. The anionic framework can be decomposed into two types of layers, viz. MoO2As2O7 and Mo2As2O14, which use mixed Mo—O—As and As—O—Mo bridges to achieve a new three-dimensional structure with two types of large channels in which the Na+ cations are located. Two O atoms are disordered and are located in two positions close to their initial positions with occupancy ratios of 0.612 (17):0.388 (17) and 0.703 (12):0.298 (12)

K0.8Ag0.2Nb4O9AsO4

The title compound, potassium silver tetra­niobium nona­oxide arsenate, K0.8Ag0.2Nb4O9AsO4, was prepared by a solid-state reaction at 1183 K. The structure consists of infinite (Nb2AsO14)n chains parallel to the b axis and cross-linked by corner sharing via pairs of edge-sharing octa­hedra. Each pair links together four infinite chains to form a three-dimensional framework. The K+ and Ag+ ions partially occupy several independent close positions in the inter­connected cavities delimited by the framework. K0.8Ag0.2Nb4O9AsO4 is likely to exhibit fast alkali-ion mobility and ion-exchange properties. The Wyckoff symbols of special positions are as follows: one Nb 8e, one Nb 8g, As 4c, two K 8f, one Ag 8f, one Ag 4c, one O 8g, one O 4c

AgNa2Mo3O9AsO4

The title compound, silver disodium trimolybdenum(VI) nonaoxide arsenate, AgNa2Mo3O9AsO4, was prepared by a solid-state reaction at 808 K. The structure consists of an infinite (Mo3AsO13)n ribbon, parallel to the c axis, composed of AsO4 tetra­hedra and MoO6 octa­hedra sharing edges and corners. The Na and Ag ions partially occupy several independent close positions, with various occupancies, in the inter-ribbon space delimited by the one-dimensional framework. The composition was refined to Ag1.06(1)Na1.94(1)Mo3O9AsO4

A novel hybrid numerical with analytical approach for parameter extraction of photovoltaic modules

Building an accurate mathematical model of photovoltaic modules is an essential issue for providing reasonable analysis, control and optimization of photovoltaic energy systems. Therefore, this study provides a new accurate model of photovoltaic Panels based on single diode Model. In this case, the proposed model is the link between two models which are the ideal model and the resistance network. All parameters are estimated based on hybrid Analytical/Numerical approach: three parameters photocurrent, reverse saturation current and ideality factor are obtained using an Analytical approach based on the datasheet provided by the manufacturer under Standard Test Conditions. The series and shunt resistances are obtained by using a Numerical approach similar to the Villalva's method in order to achieve the purpose of modeling the resistance network part. Our model is tested with data from the manufacturer of three different technologies namely polycrystalline, Mono-crystalline silicon modules and thin-film based on Copper Indium Diselenide, and for more accurate performance evaluation we are introducing the Average Relative Error and the Root Mean Square Error. The simulated Current-Voltage and Power-Voltage curves are in accordance with experimental characteristics, and there is a strong agreement between the proposed model and the experimental characteristics. The computation time is 0.23 s lower than those obtained using others approach, and all obtained results under real environment conditions are also compared with different models and indicated that the proposed model outperforms the others approach such as villalva's and kashif's method

K3VO2(V2As2O12)

A new potassium vanadium arsenate, tripotassium trivanadium bis­(arsenate) hexa­oxide, K3VO2(V2As2O12), was synthesized by a solid-state reaction at 743 K. The structure is built up from VO5 pyramids, VO4 tetra­hedra (.m. symmetry) and AsO4 tetra­hedra linked together by corner-sharing to form a three-dimensional framework. The two crystallographically independent K+ cations, one of which has .m. symmetry, are located in the inter­connected tunnels running along the a and b directions