Zinc Selenate Research Articles

Selenate precursor for synthesis of CZTSSe: Performance as thinfilm solar cell

Copper and Zinc selenates were synthesized by wetchemical method employing selenic acid. The selenates were mixed with SnS2 in the ratio of 1:1:1 and annealed at 350˚and 450 °C to obtain CZTSSe. The synthesized CZTSSe possess absorption coefficient as high as 105 cm−1. The obtained band gap of the samples are 1.62 and 2.69 eV. Hall measurements on the thin film of CZTSSe indicate high mobility (∼104 cm2 V−1 s−1). As a proof of concept, I-V characterization of SLG/FTO/ZnO/CZTSSe/Ag heterojunction device is studied at 1.5AM illumination. The photovoltaic efficiency of the device based on CZTSSe-350 °C and CZTSSe-450 °C is found to be 1.24% and 0.64% respectively. Thus, the synthetic procedure of sulfo-selenization via selenates and sulfides can act as an option to scale up CZTSSe for photovoltaic applications.

Atom Efficient Preparation of Zinc Selenates for the Synthesis of Selenol Esters under "On Water" Conditions.

We describe here an atom efficient procedure to prepare selenol esters in good to excellent yields by reacting [(PhSe)2Zn] or [(PhSe)2Zn]TMEDA with acyl chlorides under “on water” conditions. The method is applicable to a series of aromatic and aliphatic acyl chlorides and tolerates the presence of other functionalities in the starting material.

Synthesis, Characterization, Nucleation Kinetics, Mechanical, Photo Conductivity, Birefringence and DFT Studies of Tris(thiourea) Zinc Selenate as Potential NLO Material

Semi-organic single crystals of pure tris(thiourea) zinc selenate (TTZS) were grown from aqueous solution by slow evaporation method. Nucleation kinetics of grown TTZS was extensively studied through which important nucleation parameters were calculated. Further, the fair agreement between the experimental and theoretical interfacial energy values was successfully established. X-ray diffraction studies revealed the orthorhombic nature and Pca21 space group of the title crystal. Theoretically calculated bond lengths and bond angles were found to be in accordance with that of experimental XRD values but with minor deviations. The sharp peak in the HRXRD pattern indicated the higher degree of crystallinity of the sample. The micro hardness analysis was carried out to ascertain the mechanical strength of the TTZS crystal. The mechanical studies also helped to deduce Meyer’s index, elastic modulus, yield strength, fracture toughness, elastic stiffness coefficient and brittleness index. Kurtz-Perry powder technique suggested the phase matching nature of TTZS crystal and it further indicated that the SHG efficiency of TTZS is 1.12 times as that of standard KDP. The photoconductivity analysis resulted in the higher magnitude of dark currents than the photo current which suggested the negative photo conductivity nature of the TTZS crystal. The sample showed low value of birefringence (0.0483 at 532 nm). The laser damage threshold value of TTZS was found to be 2.60 GW/cm2. The charge distribution of Mulliken atomic charges, non-linear optical (NLO) and natural bond orbital (NBO) analyses were calculated by ab-initio method. The Frontier orbital analysis was employed to arrive at the values of global chemical molecular reactivity descriptors.

A systematic approach to physico-chemical analysis of tris (thiourea) zinc selenate — A semi-organic nonlinear optical crystal

Semi-organic single crystals of pure tris (thiourea) zinc selenate (TTZS) were grown from aqueous solution by slow evaporation method. X-ray diffraction studies inferred the orthorhombic nature and Pca21 space group of the title crystal. The elemental analysis has been performed to ascertain the purity and stoichiometry of TTZS crystals. UV spectral analysis has been conducted in order to figure out the values of transmittance, band gap energy, Urbach’s energy, nature of electronic transitions, reflectance, refractive index, optical and electrical conductivities, extinction coefficient and electrical susceptibility. Single oscillator parameters have also been calculated from the UV analysis. The dielectric response of the grown crystals has been thoroughly analyzed at different temperature values with varying frequencies. The ac conductivity studies are used to bring out the activation energy values of the electrical process. A theoretical approach has been adopted to unveil the solid state parameters of the crystal which include valence electron plasma energy, Penn gap, Fermi energy and polarisability. The second harmonic generation (SHG) efficiency of the title crystal has been evaluated by Kurtz-Perry technique. The correlation between the spectral and electrical properties with the non linear second harmonic generating efficiency of TTZS has been successfully substantiated.

Coefficients, D 2/1 of cocrystallization of M 2+ ions with ZnSeO 4·5H 2O at 40 °C and ZnSeO 4·H 2O at 50 °C and their dependences on various physicochemical and crystal-chemical factors

Coefficients, D 2/1 (Henderson, Kraček, Chlopin) of cocrystallization of low amounts of M 2+ ions (M 2+={Ni 2+, Cu 2+, Co 2+, Mg 2+, Mn 2+, Cd 2+}) with ZnSeO 4·5H 2O at 40 °C and ZnSeO 4·H 2O at 50 °C have been determined. Their values are very diverse, ranging from 0.12 (for Cu 2+ at 50 °C) to 1.87 (for Co 2+ at 50 °C) and generally differ significantly from those obtained at 25 °C. Apart from the change of the solubility ratio of cocrystallizing selenates ( m 01/ m 02) they are very strongly affected by crystal structure of selenate hydrates forming at the investigated temperatures. The dependence of the coefficients D 2/1, obtained at 40 °C on the radii of M 2+ ions permits to derive an empirical formula for their estimation. The results obtained show that it is possible to remove most of the investigated M 2+ ions by the crystallization of zinc selenate at various temperatures in order to achieve its purification.

Syntheses, characterizations and crystal structures of three new organically templated or organically bonded zinc selenates

Three new organically templated or organically bonded zinc selenates, namely, {H2bipy}Zn(SeO4)2(H2O)21 (bipy=4,4′-bipyridine), {H2pip}{Zn(SeO4)2(H2O)4}·2H2O 2 (pip=piprazine), and Zn(SeO4)(phen)(H2O)23 (phen=1,10-phenanthroline) have been synthesized by hydrothermal reactions. The structure of compound 1 features a 1D chain composed of [Zn(SeO4)2(H2O)2]2− anions. Compound 2 has a 2D layer structure built from {Zn(SeO4)2(H2O)4}2− anions that are cross-linked by doubly protonated piperazine cations via N–H⋯O hydrogen bonds. The structure of compound 3 contains a 1D chain of Zn(SeO4)(phen)(H2O)2, such chains are further interlinked by hydrogen bonds and π⋯π interactions to form a 〈200〉 layer. The different roles the templates played have also been discussed.

DTA, DSC, and X‐ray Powder Diffraction Studies on Some Zinc Selenate Hydrates

AbstractThe thermal dehydration of ZnSeO4 · 6 H2O, ZnSeO4 · 5 H2O, and ZnSeO4 · 3 H2O has been studied by TG, DTA, and DSC‐analyses. It has been established that the dehydration of ZnSeO4 · 6 H2O occurs stepwise and as intermidiate hydrates ZnSeO4 · 5 H2O, ZnSeO4 · 3 H2O and ZnSeO4 · H2O are produced. The enthalpy of dehydration of the observed phase transitions has been determined. The enthalpy of formation of ZnSeO4 · 6 H2O, ZnSeO4 · 5 H2O, ZnSeO4 · 3 H2O, and ZnSeO4 · H2O has been calculated on the basis of the DSC‐data. ZnSeO4 · 5 H2O and ZnSeO4 · 3 H2O have been studied rentgenographically: ZnSeO4 · 5 H2O crystallizes in triclinic system with lattice parameters: a = 6.387(2) Å; b = 10.706(3) Å; c = 6.167(3) Å; α = 98.66(2)°; β = 109.32(3)° γ = 75.52(3)° V = 384.3(2) Å3; SG P1. ZnSeO4 · 3 H2O forms orthorhombic crystals with lattice constants: a = 8.165(4)Å; b = 11.314(5) Å; c = 12.465(7) Å; V = 1151.5(7) Å3; SG Pbca.

Phase Interaction in the Systems Sodium Selenate – Copper Selenate – Water and Sodium Selenate – Zinc Selenate – Water at 25 °C

AbstractThe phase equilibrium in the systems Na2SeO4–CuSeO4–H2O and Na2SeO4–ZnSeO4–H2O were studied and it was established that new phases were obtained – double salts with a composition: Na2Cu(SeO4)2 · 2 H2O and Na2Zn(SeO4)2 · 2 H2O. The fields of phase equilibrium of the double salts in the triple systems were determined. The composition of the new phases was investigated by the Schreinemackers' method of physico‐chemical analysis, and the number of the water molecules of crystallization – by thermogravimetrical analysis. An X‐ray diffraction analysis of the new phases obtained was done.

Structure and absolute optical chirality of zinc selenate hexahydrate

The crystal structure and absolute optical chirality of ZnSeO4.6H20 (Mr= 316.42) have been determined. For a crystal that was found to be optically laevo over the wavelength range 0.3655 to 0.6328 grn, the space group was determined to be P4~2~2 (D4), with a =6.947(1), c=18.592(1)A, V= 897.3 (3) A 3, Z =4, D,n=2.343(2), D x=2.342Mgm -3, MoKa, ), = 0.71069 A, ~ = 685 mm -~, F(000) = 624, T297 K. The structure was refined to R =0.0216 and wR = 0.0272 for 688 unique reflections. The optical rotatory dispersion has been determined and the relationship between optical rotation and structural chirality is compared with earlier work on the related compound ct-NiSO4.6H20. The refractive indices and rotatory power are calculated by the program of Devarajan & Glazer [Acta Cryst. (1986), A42, 560569]. It is shown that the calculated anisotropic polarizability ellipsoids are roughly perpendicular to the thermal ellipsoids of the O atoms.

Thermal decomposition of some divalent metal selenates

Thermogravimetry, differential thermal analysis and differential thermogravimetry have been used to study the decomposition of hydrated selenates of manganese(II), cobalt, nickel, copper(II), zinc and cadmium. Based on the results obtained, mechanisms of decomposition have been proposed. The decomposition temperatures of non-hydrates show a gradual increase from manganese(II) selenate to zinc selenate and then a sudden drop for cadmium selenate.

Quenchable High-Pressure Polymorph of Zinc Selenate

A new quenchable high-pressure form of zinc selenate (ZnSeO(4)) was produced by subjecting the low-pressure modification to 40 kilobars at 400 degrees C for 30 minutes. The new form is orthorhombic, space group D(2h),(17)-Cmcm. The cell constants at 29 degrees C are: a, 5.511 angstroms; b, 8.110 angstroms; and c, 6.585 angstroms. The calculated density is 4.70 grams per cubic centimeter in comparison with 4.61 grams per cubic centimeter for the low-pressure modification. This implies a volume change of 2 percent at the transition.

I. The monoclinic double sulphates containing ammonium. Completion of the double sulphate series

In this communication are described the five remaining double sulphates of the series R 2 M(SO 4 ) 2 . 6H 2 O, in which R is ammonium and M is nickel, cobalt, manganese, copper, and cadmium. The ammonium salts, in which M is magnesium, zinc, and iron, have been described in two previous communications, in the latter of which (that concerning ammonium ferrous sulphate) a number of general questions concerning the whole series were also discussed. The present contribution completes the author’s work, commenced in the year 1890, on the double sulphates of this important monoclinic series, in all 31 salts, of which the It bases have been potassium rubidium, cæsium, ammonium, and thallium. Excluding thallium—of which only the zinc double sulphate has been included, the other double salts containing thallium not having yet been obtained in crystals of the perfection necessary for detailed accurate work of the character regarded as essential by the author—the four bases, potassium, rubidium, cæsium, and ammonium should give rise, with the eight several dyad bases above enumerated, to 32 double sulphates. All these have been obtained in excellent crystals, and fully described, with the two exceptions of potassium manganese and potassium cadmium sulphates, which, for some as yet undiscovered reason, are incapable of preparation. Yet so thoroughly are the relations between the various salts, and the rules governing the replacement of any one alkali base by any other, now understood, that it has been found possible to predict the constants of the two missing salts. Of the isomorphous double selenates, nine salts (including thallium zinc selenate) containing magnesium and zinc as M metals have already been described by the author, and it is intended that the remaining double selenates, those containing the other dyad metals, shall form the subject of the author’s next communication. Morphology . The first measurements of the crystals of this salt were made 60 years ago by Marignac, and the salt was included four years later by Murmann and Rotter in their comprehensive crystallographic investigation. The forms observed in both investigations were the same as those given in the list below, except a {100} and o {111}, and the values observed for the principal angles will be found quoted in the two last columns of the table of angles.