Metals Rb Research Articles

Dynamic and Static Assembly of Sulfated Cellulose Nanocrystals with Alkali Metal Counter Cations.

Sulfate groups on cellulose particles such as cellulose nanocrystals (CNCs) provide colloidal stability credit to electrostatic repulsion between the like-charged particles. The introduction of sodium counter cations on the sulfate groups enables drying of the CNC suspensions without irreversible aggregation. Less is known about the effect of other counter cations than sodium on extending the properties of the CNC particles. Here, we introduce the alkali metal counter cations, Li+, Na+, K+, Rb+, and Cs+, on sulfated CNCs without an ion exchange resin, which, so far, has been a common practice. We demonstrate that the facile ion exchange is an efficient method to exchange to any alkali metal cation of sulfate half esters, with exchange rates between 76 and 89%. The ability to form liquid crystalline order in rest was observed by the presence of birefringence patterns and followed the Hofmeister series prediction of a decreasing ability to form anisotropy with an increasing element number. However, we observed the K-CNC rheology and birefringence as a stand-out case within the series of alkali metal modifications, with dynamic moduli and loss tangent indicating a network disruptive effect compared to the other counter cations, whereas observation of the development of birefringence patterns in flow showed the absence of self- or dynamically-assembled liquid crystalline order.

Elemental Profiling for Discrimination of Geographical Origin of Tea (Camellia sinensis) in north-east region of India by ICP-MS coupled with Chemometric techniques

The study aimed to discriminate the teas originated from eight north-east region of India using 67 elemental profiling through the use of ICP-MS and process the large data with chemometric software. Among the 67 elements, concentrations of 18 elements were significantly different in the eight regions (Darjeeling, Tripura, Upper Assam, South Bank, Terai, North Bank, Dooars and Cachar). Selected 18 elements belongs to alkali metal (Rb, Cs), alkaline earth metal (Mg, Sr, Ba), transition metal (V, Cr, Mn, Co, Ni, Zn, Mo), basic metal (Al), metalloid (B), non-metal (Se) and lanthanide (La, Ce, Nd). Multivariate chemometric analysis with PCA, LDA, SVM & OPLS DA were performed on the concentration of 18 elements on 307 authentic sample set. The correct classification rate for the training set (307) and test set (24) tea samples were 100% for SVM, LDA and OPLS DA model and confidence measure for SVM and LDA model were 99.4% and 88.97%, respectively. Variable importance in projection (VIP) values ranged between 1.04-1.51 for five elements (Cr, Mo, Rb, Mn and Ni), which can be considered as significant parameter for discrimination. The results demonstrated that ICP-MS with chemometric software could be used to discriminate the geographical origin of tea.

Regulating electronic environment on alkali metal-doped Cu@NS-SiO2 for selective anisole hydrodeoxygenation

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure. Herein, we synthesized a series of novel Cu-based catalysts, Cu@NS-SiO2 (NS = nano sphere) and alkali metals (Na, K, Rb, and Cs) doped Cu@NS-SiO2, and applied them in hydrodeoxygenation reaction of anisole. High Cu dispersion was presented on all catalysts. The modification of alkali metals on Cu@NS-SiO2 significantly enhanced the electron density of Cu sites in the following order: Cs > Rb > K > Na, among which Cs decreased the Cu 2p3/2 binding energy most (by 0.7 eV). Moreover, the modification did not substantially affect the geometric structure of Cu species. This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole, and thus promoted the selectivity of benzene. Compared with Cu@NS-SiO2 (∼59%), the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO2 at ∼83%.

Formation of the Lened W-(Be) Skarn Deposit by Neutralization of a Magmatic Fluid—Evidence from H3BO3-Rich Fluids

Magmatic-hydrothermal systems, especially those causing the formation of tungsten deposits, may be enriched in boron, as is suggested by the presence of hydrothermal tourmaline. This study examines the boron and metal (including tungsten) concentrations of quartz-hosted fluid inclusions in the Lened W-(Be) deposit of the Canadian Cordillera and resolves (i) the analytical challenges involved during fluid salinity calculations of B-rich fluids and (ii) the relationship between fluid chemical composition and ore-forming processes involved at Lened. The aqueous fluid inclusions from this study have high CO2 and boron contents, indicated by the presence of a carbonic phase and sassolite crystals (H3BO3) in fluid inclusions. The boron content of the aqueous liquid phase (0.5 wt. %) was determined using microthermometric and Raman spectroscopic analyses. Boron was judged the most appropriate internal standard for quantifying the LA-ICP-MS data from these inclusions after calculation of salinity in the H2O-NaCl-H3BO3 system (3.5 to 5 wt. % NaCleq). Trace element data of the fluids show relatively high concentrations of Li (40 to 474 ppm), Al (56 to 1003 ppm), As (36 to 490 ppm) and Cs (68 to 296 ppm); and lower concentrations of Rb (3.6 to 77 ppm), Sr (0.4 to 23 ppm), Sb (1 to 32 ppm), Ba (0.6 to 163 ppm), Mg (6.9 to 7.6 ppm) and other metals, such as Be (2.4 to 10.2 ppm), W (2.4 to 27 ppm) and Cu (5.1 to 73 ppm). The high Cs and Li concentrations suggest a magmatic origin of the metals, while the moderate concentrations in Sr and Ba are indicative of fluid–rock interaction with the surrounding limestone. The presence of sassolite suggests that these fluids were highly acidic. The neutralization of this fluid through interaction with the surrounding limestone is the most probable trigger for scheelite precipitation. The presence of such high boron content in the magmatic fluid at Lened indicates the potential role in the enrichment of the source melt before fluid exsolution.

Unveiling the Origin of Alkali Metal (Na, K, Rb, and Cs) Promotion in CO2 Dissociation over Mo2C Catalysts.

Molybdenum carbide (Mo2C) is a promising and low-cost catalyst for the reverse water−gas shift (RWGS) reaction. Doping the Mo2C surface with alkali metals can improve the activity of CO2 conversion, but the effect of these metals on CO2 conversion to CO remains poorly understood. In this study, the energies of CO2 dissociation and CO desorption on the Mo2C surface in the presence of different alkali metals (Na, K, Rb, and Cs) are calculated using density functional theory (DFT). Alkali metal doping results in increasing electron density on the Mo atoms and promotes the adsorption and activation of CO2 on Mo2C; the dissociation barrier of CO2 is decreased from 12.51 on Mo2C surfaces to 9.51–11.21 Kcal/mol on alkali metal-modified Mo2C surfaces. Energetic and electronic analyses reveal that although the alkali metals directly bond with oxygen atoms of the oxides, the reduction in the energy of CO2 dissociation can be attributed to the increased interaction between CO/O fragments and Mo in the transition states. The abilities of four alkali metals (Na, K, Rb, and Cs) to promote CO2 dissociation increase in the order Na (11.21 Kcal/mol) < Rb (10.54 Kcal/mol) < Cs (10.41 Kcal/mol) < K (9.51 Kcal/mol). Through electronic analysis, it is found that the increased electron density on the Mo atoms is a result of the alkali metal, and a greater negative charge on Mo results in a lower energy barrier for CO2 dissociation.

USING MODERN INSTRUMENTAL METHODS FOR COFFEE IDENTIFICATION

The article provides an analysis of published works devoted to authentication of the place of origin of coffee beans, as well as the research of the main components that can be identification parameters when authenticating coffee. Based on the analysis of scientific literature, the authors noted the most significant works aimed at confirming the authenticity of the place of origin for coffee beans from Ethiopia, Kenya, Hawaii, Costa Rica, Jamaica, Brazil, Guatemala, Mexico and other countries. It was shown that the most widespread studies were aimed at analyzing the values of isotopic ratios of carbon ( 13 C/ 12 C), hydrogen ( 2 H/ 1 H), oxygen ( 18 O/ 16 O) and nitrogen ( 15 N/ 14 N) in compounds contained in coffee beans, which reflect the distribution of “light” and “heavy” isotopes during biological and geochemical processes within the boundaries of a particular region. The authors analyzed the works aimed at studying the qualitative and quantitative composition of trace elements and rare earth metals (Na, Mg, Al, Mn, Ga, Rb, Ba, Pb, Y, La, Ce, Pr, Sm, Nd, Eu, Dy, Gd and others), as well as the research of the values of isotopic ratios ( 87 Sr/ 86 Sr) in product samples and soils of the studied region. Based on the presented materials, it is concluded that the use of the isotope mass spectrometry method in combination with statistical processing of the results makes it possible to determine with a high degree of reliability the product belonging to a certain geographical region, as well as to authenticate the botanical origin of the beans. The advantages of comprehensive research of several indicators using various methods of mathematical statistics and modeling in determining the geographical place of coffee origin are shown.

Chemical signature and fractionation of trace elements in fine particles from anthropogenic and natural sources

The health effects of trace metal elements in atmospheric fine particulate matter (PM2.5) are widely recognized, however, the emission factor profiles and chemical fractionation of metal elements in different sources were poorly understand. In this study, sixteen metal elements, including Cd, Pb, V, Zn, Ba, Sb, As, Fe, Sr, Cr, Rb, Co, Mn, Cu, Ni and Sn from biomass burning, bituminite and anthracite combustion, as well as dust, were quantified. The results show different emission sources were associated with distinct emission profiles, holding important implications for source apportionment of ambient particulate metals. Specifically, Fe was the dominant metal species (28-1922 mg/kg) for all samples, and was followed by different metals for different samples. For dust, Mn (39.9 mg/kgdust) had the second-highest emission factor, while for biomass burning, it was Cr and Ba (7.5 and 7.4 mg/kgbiomass, respectively). For bituminous coal combustion, the emission factor of Zn and Ba was 6.2 and 6.0 mg/kgbituminous, respectively, while for anthracite combustion the corresponding emission factor was 5.6 and 4.3 mg/kganthracite, respectively. Moreover, chemical fractionation (i.e., the exchangeable, reducible fraction, oxidizable, and residual fraction) and the bioavailability index (BI) values of the metal elements from different sources were further investigated to reveal the link between different emission sources and the potential health risk. The findings from this study hold important implications for source apportionment and source-specific particulate metal-associated health effects.

Rücktitelbild: Site‐Specific Reduction‐Induced Hydrogenation of a Helical Bilayer Nanographene with K and Rb Metals: Electron Multiaddition and Selective Rb+ Complexation (Angew. Chem. 10/2022)

Die reduktionsinduzierte Hydrierung eines helikalen Doppelschicht-Nanographen (C138H120) mit K oder Rb in 18-Krone-6 wird im Forschungsartikel von Israel Fernández, Marina A. Petrukhina, Nazario Martín et al. vorgestellt (e202115747). Laut DFT-Rechnungen führt die Lokalisierung der ersten beiden Elektronen im Helicen-Teil zu einer regiospezifischen Hydrierung an den C-Atomen am Rand des zentralen [6]Helicen-Rückgrats (rosa H-Atome). Das dritte Elektron bildet ein radikalisches Trianion am HBC, das zum finalen Rb-Komplex führt.

Back Cover: Site‐Specific Reduction‐Induced Hydrogenation of a Helical Bilayer Nanographene with K and Rb Metals: Electron Multiaddition and Selective Rb+ Complexation (Angew. Chem. Int. Ed. 10/2022)

A reduction-induced hydrogenation of a helical bilayer nanographene (C138H120) with K or Rb in 18-crown-6 is reported by Israel Fernández, Marina A. Petrukhina, Nazario Martín et al. in their Research Article (DOI: 10.1002/anie.202115747). DFT calculations predict that localization of the first two electrons in the helicene moiety leads to a site-specific hydrogenation at the carbon atoms located on the edge of the central [6]helicene backbone (pink hydrogens). The third electron forms a radical trianion on the HBC leading to a final Rb-complex.

Antioxidant potential and mineral content of medicinal plants grown in urban area of India

AbstractMedicinal plants accumulate minerals and synthesize phytochemicals valuable for treating human diseases. The objective of this work has been to characterize the polyphenol and mineral contents of 25 medicinal plant leaves grown in the urban environment of India to know their antioxidant, nutritional potentiality, and ease of contamination with toxic elements. Total polyphenol (TPh) and flavonoid (Fla), and mineral concentrations were determined spectrophotometrically and by X‐ray fluorescence spectroscopy, respectively. The leaves under study were found to be rich in polyphenols, nutrients (P, S, Cl, K, Mg, Ca, Mn, Fe, Cu, Zn, and Mo), and other metals (Rb, Sr, Ba, Al, Ti, V, Cr, Co, As, Se, and Pb), with concentrations ranging from 1.28 to 3.96 g 100 g−1, from 219.8 to 7159.9 mg 100 g−1, and from 4.3 to 334.0 mg 100 g−1, respectively. Maximum polyphenol and mineral (nutrient and other elements) concentrations were detected in Melia azadirachta L. and Solanum lycopersicum L. leaves. Enrichment factors, correlations among elements, sources, health hazards associated with heavy metals, and potential applications of plant leaves are also discussed.

Alkali metal influences in aluminyl complexes.

The previously reported potassium aluminyl complex [(BDI-H)Al-K+]2 was converted in Li+ or Na+ salts by a salt metathesis reaction with Li(BPh4) or Na(BPh4), respectively; BDI-H = dianionic [(DIPP)N-C(Me)C(H)-C(CH2)-N(DIPP)2-] and DIPP = 2,6-diisopropylphenyl. The Rb and Cs aluminyl complexes were obtained by reaction of (BDI)Al with RbC8 or CsC8; BDI = HC[C(Me)N(DIPP)]2. Crystal structures of two monomers, (BDI-H)Al-Li+·(Et2O)2 and (BDI-H)Al-Na+·(Et2O)(TMEDA), and four dimers [(BDI-H)Al-M+]2 (M = Li, Na, Rb, Cs) are discussed. Lewis base-free dimers [(BDI-H)Al-M+]2 crystallize either as slipped dimers (Li+, Na+) in which each Al center features only one Al-M contact or as a symmetric dimer (K+, Rb+, Cs+) in which the cation bridges both Al centers. The dimer with the largest cation (Cs+) shows Cs⋯CH2C interactions between dimers, resulting in a coordination polymer. AIM and charge analysis reveal highly ionic Al-M bonds with strong polarization of the Al lone-pair towards the smaller cation Li+ and Na+. The Al-M bonds become weaker from Li to Cs. Calculated dimerization energies suggest that in apolar solvents only complexes with the heavier metals Rb and Cs may be in a monomer-dimer equilibrium. This is confirmed by DOSY measurements in benzene. Dimeric aluminyl complexes with heavier alkali metals (K-Cs) react with benzene to give a double C-H activation in para-positions.

Site-Specific Reduction-Induced Hydrogenation of a Helical Bilayer Nanographene with K and Rb Metals: Electron Multiaddition and Selective Rb+ Complexation.

The chemical reduction of π‐conjugated bilayer nanographene 1 (C138H120) with K and Rb in the presence of 18‐crown‐6 affords [K+(18‐crown‐6)(THF)2][{K+(18‐crown‐6)}2(THF)0.5][C138H122 3−] (2) and [Rb+(18‐crown‐6)2][{Rb+(18‐crown‐6)}2(C138H122 3−)] (3). Whereas K+ cations are fully solvent‐separated from the trianionic core thus affording a “naked” 1.3 − anion, Rb+ cations are coordinated to the negatively charged layers of 1.3 −. According to DFT calculations, the localization of the first two electrons in the helicene moiety leads to an unprecedented site‐specific hydrogenation process at the carbon atoms located on the edge of the helicene backbone. This uncommon reduction‐induced site‐specific hydrogenation provokes dramatic changes in the (electronic) structure of 1 as the helicene backbone becomes more compressed and twisted upon chemical reduction, which results in a clear slippage of the bilayers.

Site‐Specific Reduction‐Induced Hydrogenation of a Helical Bilayer Nanographene with K and Rb Metals: Electron Multiaddition and Selective Rb+ Complexation

AbstractThe chemical reduction of π‐conjugated bilayer nanographene 1 (C138H120) with K and Rb in the presence of 18‐crown‐6 affords [K+(18‐crown‐6)(THF)2][{K+(18‐crown‐6)}2(THF)0.5][C138H1223−] (2) and [Rb+(18‐crown‐6)2][{Rb+(18‐crown‐6)}2(C138H1223−)] (3). Whereas K+ cations are fully solvent‐separated from the trianionic core thus affording a “naked” 1.3− anion, Rb+ cations are coordinated to the negatively charged layers of 1.3−. According to DFT calculations, the localization of the first two electrons in the helicene moiety leads to an unprecedented site‐specific hydrogenation process at the carbon atoms located on the edge of the helicene backbone. This uncommon reduction‐induced site‐specific hydrogenation provokes dramatic changes in the (electronic) structure of 1 as the helicene backbone becomes more compressed and twisted upon chemical reduction, which results in a clear slippage of the bilayers.

The Role of Different Alkali Metals in the A15Tl27 Type Structure and the Synthesis and X-ray Structure Analysis of a New Substitutional Variant Cs14.53Tl28.4.

Alkali metal thallides have been known since the report of E. Zintl on NaTl in 1932. Subsequently, binary and ternary thallides of alkali metals have been characterized. At an alkali metal proportion of approximately 33% (A:Tl~1:2, A = alkali metal), three different unique type structures are reported: K49Tl108, Rb17Tl41 and A15Tl27 (A = Rb, Cs). Whereas Rb17Tl41 and K49Tl108 feature a three-dimensional sublattice of Tl atoms, the A15Tl27 structure type includes isolated Tl11 clusters as well as two-dimensional Tl-layers. This unique arrangement is only known so far when the heavier alkali metals Rb and Cs are included. In our contribution, we present single-crystal X-ray structure analyses of new ternary and quaternary compounds of the A15Tl27 type structure, which include different amounts of potassium. The crystal structures allow for the discussion of the favored alkali metal for each of the four Wyckoff positions and clearly demonstrate alkali metal dependent site preferences. Thereby, the compound Cs2.27K12.73Tl27 unambiguously proves the possibility of a potassium-rich A15Tl27 phase, even though a small amount of cesium appears to be needed for the stabilization of the latter structure type. Furthermore, we also present two compounds that show an embedding of Tl instead of alkali metal into the two-dimensional substructure, being equivalent to the formal oxidation of the latter. Cs14.53Tl28.4 represents the binary compound with the so far largest proportion of incorporated Tl in the structure type A15Tl27.

A Transferable Force Field for Predicting Adsorption and Diffusion of Small Molecules in Alkali Metal Exchanged Zeolites with Coupled Cluster Accuracy

We present a transferable force field for small adsorbates (CH4, CO2, O2, and N2) in alkali metal (Li, Na, K, Rb, and Cs) exchanged zeolites. The fitting procedure is based on adsorbate–adsorbent interaction energies obtained from periodic density functional theory calculations and corrected using coupled-cluster methods applied to small clusters. The fitting approach aims at accurate prediction of both adsorption and diffusion properties by using sets of configurations that sample adsorption sites and intracrystalline hopping transition states. The quality of the force field is assessed for a wide range of adsorbates in zeolites with different chemical composition and topologies, showing good agreement between theoretical predictions and experimental measurements of adsorption and diffusion.

Tuning Magnetic Interactions Between Triphenylene Radicals by Variation of Crystal Packing in Structures with Alkali Metal Counterions.

The monoanion of triphenylene (C18H12, 1) was generated in THF using several alkali metals (Na, K, Rb, and Cs) as reducing agents and crystallized with the corresponding cations in the presence of 18-crown-6 ether. The UV-vis spectroscopy points to the metal-dependent coordination environment of the triphenylene monoanion-radicals, 1·-, in solution. The X-ray diffraction characterization confirmed the formation of a solvent-separated ion pair (SSIP) with sodium ions, [{Na+(18-crown-6)(THF)2}(1·-)] (2), and three contact-ion pair (CIP) complexes formed by larger alkali metal ions, [{K+(18-crown-6)}(1·-)] (3), [{Rb+(18-crown-6)}(1·-)] (4), and [{Cs+(18-crown-6)}(1·-)] (5). Structural analysis of the series reveals a notable geometry perturbation of the triphenylene framework in 2 caused by one-electron acquisition, which is further enhanced by direct metal binding in 3-5. This has been correlated with the aromaticity changes and charge redistribution upon one-electron reduction of 1, as revealed by the computational studies. The EPR spectroscopy and magnetic susceptibility measurements confirm antiferromagnetic interactions corresponding to an S = 1/2 system in the solid state. The magnetic behavior of 3-5 correlates with the arrangement of triphenylene radicals in the crystal structures. All three compounds exhibit antiferromagnetic (AFM) interactions between S = 1/2 radicals in the solid state, but the exchange coupling in 4 and 5 is notably stronger than that in 3, which leads to AFM ordering at 3.8 K in 4 and at 2.0 K in 5. The magnetic phase transitions in 4 and 5 can be interpreted as originating from interactions between the chains of the AFM-coupled S = 1/2 radicals.

Computation of thermophysical properties of liquid metals and alloys on the basis of generalized version of hole theory

• Modification of Frenkel’s hole theory has been applied to liquid metals and alloys. • Liquid metals Na, K, Rb, Cs, Sn and Pb and four alloys K-Rb, Na-Cs, Sn-Pb and Na-K. • Various expressions for r h ,V h , α, β T , P int , E h , ∆E V , ced, α vdw and u were derived. • Interaction study of alkali metal alloys with the help of hole theory. • The calculated and experimental values show excellent. A generalized version of hole theory, recently developed as a modification of Frenkel’s hole theory has been applied successfully, for the first time, to six pure liquid metals (K, Rb, Na, Cs, Pb and Sn) and four liquid metal alloys (K-Rb, Na-Cs, Sn-Pb and Na-K) at different temperatures. Various expressions for r h ,V h , α, β T , P int , E h , ΔE V , ced, α vdw and u were derived for the pure liquid metals and alloys. The calculated and experimental values show excellent agreement demonstrating the success of the theory to the pure liquid metals and alloys.

Tuning the surface and optical properties of graphitic carbon nitride by incorporation of alkali metals (Na, K, Cs and Rb): Effect on photocatalytic removal of organic pollutants

Alkali metals have been known for their intercalation properties and can be employed for the separation of stacking in sheet-like materials. In this work, alkali metals (Na, K, Rb and Cs) have been systematically incorporated in varying concentrations in g-C3N4 sheets and their effect on resulting optical, surface and photocatalytic properties have been explored in detail. It was observed that the optical, electronic and surface properties of g-C3N4 were altered upon the incorporation of different alkali metal ions. The band gap and specific surface area of resulting materials were decreased as compared to the pristine g-C3N4. In addition, the alkali metal incorporation in g-C3N4 sheets showed the formation of cyanide groups and nitrogen vacancies in the resulted materials. Further, the photocatalytic activity of g-C3N4 and alkali metal incorporated g-C3N4 was calculated by studying the degradation of acid red 94 dye under visible light irradiation. It was observed that the photocatalytic activity of pristine g-C3N4 sheets was decreased with an increase in the concentration of alkali salt used during the synthesis of alkali metal incorporated g-C3N4. This decrease in the activity could arise due to the decreased surface area, detrimental amount of nitrogen vacancies and high concentration of alkali metal ions incorporated in the structural framework of g-C3N4 sheets. This work provides a unique example of the adverse effect of alkali metal ions on photocatalytic activity of g-C3N4 and paves future directions for the improvement of the performance of g-C3N4 based materials.

Büyük Kuluncak (Malatya) Nb-U-NYE-Zr-Li Yatağının Cevherleşme Özellikleri ile Alterasyon ilişkisi

Rare Earth Elements (REE) + Niobium (Nb) + Uranium (U) + Zircon (Zr) + Lithium (Li) formations are investigated which are related with alkaline Upper Cretaceous - Lower Paleocene Kuluncak Syenitoid that settled by cutting the Kuluncak ophiolite in the north of Kuluncak (Malatya) town. The alkaline magma-related Büyük Kuluncak REE - Nb - U deposit, which is enriched with regard to rare metals (Nb, Zr, and Rb), is the first economic deposit of our country. The deposit formed related to alkaline characterized foid syenite, sodalite syenite, syenite, alkaline feldspar syenite rocks which intruded into Triassic - Lower Cretaceous limestones of the Domuzdağı Nappe. The REE and fluorites with related elements formed in magmatic rocks, the contact zone of these rocks with limestones, in pegmatitic intrusions and in fluorites formed with the effect of the contact metasomatism. The purpose of this study is to interpret ore properties and the alteration grade of the rocks which formed the deposit. The REE are enriched in argillized and highly argillized samples. However, the REE composition of fresh samples are relatively low. Therefore, the REE are enriched twice or three times due to the effects of alteration and argillization of the hydrothermal fluids in the parent rock and contact metasomatism and alterations that occur both syn- and post-emplacement of syenite.

Effect of alkali metals doping on the properties of ZTS crystals (tris(thiourea)zinc(II)sulphate)

The influence of alkali metals (Na, K, Cs, Li and Rb) doping on the properties and crystal growth of tris(thiourea)zinc(II)sulphate crystals by slow evaporation solution growth technique at 30 °C has been investigated. Each metals as dopant incorporate into the crystal lattice even at its low concentrations is well confirmed by energy dispersive X – ray spectroscopy (EDS). In the powder X –ray diffraction (XRD), high intense peaks are observed for all doped specimens due to stress developed in the crystal because of doping when compared to pure one. Single crystal XRD reveals a nominal increase in the cell parameter values of the doped samples compared to pure. Presence of each alkali metal quantitatively is confirmed by inductively coupled plasma (ICP) technique. It is interesting to observe the enhancement of fluorescence intensity of pure ZTS by the dopant in the photoluminescence (PL) spectra. The grown crystals are also characterized by FT-IR, UV-V is and TG/DSC methods. The second harmonic generation (SHG) efficiency, an essential character required for the single crystals to identify the non-linear optical (NLO) property, was performed by kurtz powder technique.