Sodium Metasilicate Gel Research Articles

Crystallization and thermal characterization of calcium hydrogen phosphate dihydrate crystals

Calcium hydrogen phosphate dihydrate (CHPD) is found quite frequently in urinary calculi (stones). The CHPD crystals were grown by the single diffusion gel growth technique in sodium metasilicate gel. The crystals were found to be having platelet and broad needle type morphologies. The crystals were analyzed by FTIR spectroscopy. The thermal properties were studied by employing the thermogravimetric analysis (TG). Various kinetic and thermodynamic parameters for dehydration were estimated from the TG curve. The selected platelet was studied by scanning electron microscope (SEM) for the growth morphologies indicating that the crystals grew in the form of leaflets having prominent (010) faces. This was in agreement with earlier reported studies.

Effect of fluorides (KF and NaF) on the growth of dicalcium phosphate dihydrate (DCPD) crystal

Dicalcium phosphate dihydrate (CaHPO 4·2H 2O, DCPD also known as brushite) is the major component of hard tissues like bone, teeth and a medicine for calcium supply. The effect of sodium fluoride and potassium fluoride on the crystallization of DCPD in sodium meta silicate gel has been studied at room temperature under the physiological pH (7.4). Addition of fluorides reduces the crystal size and the number of crystals grown when compared to pure system. Among the two fluorides, the KF suppresses the crystal formation more drastically than that of NaF. In both the cases, the ‘Ca’ content in the DCPD crystals was found to be less when compared to its pure form. The crystal morphology, elemental composition and properties of the grown crystals were analyzed using SEM-EDAX, powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermal analysis (TG-DSC).

Self-assembled right handed helical ribbons of the bone mineral hydroxyapatite

A self-assembled right handed helical ribbon of bone mineral, hydroxyapatite (HAp) was crystallized in sodium meta silicate gel matrix at 27 degrees C and the physiological pH (7.4). At temperatures 37 and 47 degrees C, helical structures were followed by many Liesegang rings. The samples were characterized by FT-IR, XRD, SEM, ICP-OES and TG-DTA techniques. The helical ribbon consisted of platy Ca-deficient apatite crystals of size 2.8 microm. Liesegang ring had a continuous network of fibers with interconnected pores. The samples exhibited bioactivity when soaked in SBF.

Characterization of L‐aspartate crystals grown in gel medium

AbstractL‐Aspartate [C4H7NO4], also called as 2‐aminobutanedoioic acid, an organic amino acid was crystallized with the aid of sodium metasilicate gel. Diffusion of the supersaturated solutions in porous gel network by solubility reduction method in silica gel was carried out in our laboratory. The crystals were characterized using powder X‐ray diffraction technique. Fourier transform infrared spectroscopy reveals the presence of functional groups in the crystals. Optical absorbance of the crystals was studied by UV – Visible spectroscopy and the thermal properties were studied by thermo gravimetric analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Laser irradiation of BaMgHPO 4 crystals in silica gel media at different growth environments (nucleation reduction strategy) and its characterization studies

The Barium magnesium hydrogen phosphate (BMHP) crystals were grown in sodium meta silicate gel media. The growth processes were done by single diffusion method and double diffusion for different physical and chemical parameters, such as using different gel densities, various concentrations of phosphoric acid and supernatant solutions. The gel pH plays an important role in the formation of different HPO 4 species in the phosphoric system. The pH range in which HPO 4 2− ions dominates were considered which in turn is necessary for the growth of BMHP crystals. In the present investigation, BMHP crystals optimum growth parameters were identified. The laser light exposure medium of growth gave better nucleation reduction. The grown crystals were analyzed by XRD, FTIR, TGA, SEM and etching. The results are discussed in detail.

Growth and characterization of nonlinear optical zinc hydrogen phosphate single crystal grown in silica gel

AbstractGood optical quality single crystals of zinc hydrogen phosphate (ZnHPO4) having dimensions up to 8×2×2 mm3 have been grown with the aid of sodium meta silicate gel. Single crystal XRD studies confirm that the crystal belongs to the orthorhombic system with space group P212121. The functional groups present in the crystals were confirmed using FTIR technique. Optical absorbance shows very low absorption in the entire visible region. Differential thermal and thermo gravimetric analysis confirmed that the crystal is stable up to 193°C. Photoconductivity study reveals positive photoconductivity in the presence of photo active centers formed by trap energy levels. The NLO activity of the crystal was confirmed by Kurtz powder technique. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of magnetic field on the gel growth of PbBr 2

Effect of a magnetic field on the gel growth of PbBr 2 was studied by observing nanocrystallites in silica gel. The control of the reaction between the Pb(NO 3) 2 and KBr solutions by the diffusion process in a sodium metasilicate gel was used for the growth of PbBr 2 crystals. The nanocrystallites formed in the gel prepared with and without the magnetic field have been examined by transmission electron microscopy. The following results were obtained. (1) Oriented PbBr 2 nanocrystallites were obtained in the gel prepared with magnetic field. (2) The size of these nanocrystallites was four times larger than that of crystallites grown in the gel prepared without magnetic field (25 nm).

Growth of single crystals of PbBr 2 in silica gel

The conditions for the gel growth of PbBr 2 were studied in this paper. The controlled reaction between the Pb(NO 3) 2 and KBr solutions by the diffusion process in a sodium metasilicate gel was used for growing PbBr 2 crystals. The following results were obtained: (1) Transparent PbBr 2 single crystals were obtained in a high-acidic gel. (2) Sizable single crystals of PbBr 2 were also grown in the liquid placed over a gel because the gel barrier had the task of slowing down the diffusion rate of reacting ions.

FTIR spectroscopic, thermal and growth morphological studies of calcium hydrogen phosphate dihydrate crystals

AbstractCalcium hydrogen phosphate dihydrate (CHPD or DCPD) is found quite frequently in urinary calculi (stones). The CHPD crystals were grown by the single diffusion gel growth technique in sodium metasilicate gel. The crystals were found to be having platelet and broad needle type morphologies. The crystals were analyzed by FTIR spectroscopy. The thermal properties were studied by employing the thermogravimetric analysis. Various kinetic and thermodynamic parameters for dehydration were estimated. The selected platelet was studied by SEM for the growth morphologies indicating that the crystals grew in the form of leaflets having prominent (010) faces. This was in agreement with earlier reported studies. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Coupling medium for microwave medical imaging applications

Sodium meta silicate gel is proposed as a novel coupling medium with a better coupling and a lesser dielectric loss than the conventionally used media. Dielectric constants between 8 and 20 exhibited for various relative density and pH, makes the material in perfect match with that of the various tissues. It is also useful as a phantom model material in microwave medical imaging.

Thermal behaviour of strontium tartrate single crystals grown in gel

Thermal behaviour of strontium tartrate crystals grown with the aid of sodium metasilicate gel is investigated using thermogravimetry (TG) and differential thermal analysis (DTA). Effect of magnetic field and dopant (Pb)2+ on the crystal stability is also studied using thermal analysis. This study reveals that water molecules are locked up in the lattice with different strengths in the grown crystals.

A new polymorph of barium chloroanilate trihydrate.

Single crystals of a new polymorph of the title compound, barium(II) 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone trihydrate, Ba2+.C6Cl2O4(2-).3H2O, have been grown in sodium metasilicate gel. Each Ba2+ cation is coordinated by eight O atoms. The Ba2+ cations are bridged by an O atom of a ligand around the centre of symmetry at Wyckoff position 4a and by the O atom of a water molecule around the centre of symmetry at Wyckoff position 4b, forming a sheet parallel to the (100) plane. Loose contacts are found around one of the water molecules, as observed in the Cmca form.

Growth of Lead Tungstate Single Crystals from Gel and Their Luminescence

Lead tungstate PbWO4 single crystals were grown from sodium metasilicate gel and water solutions of lead acetate and sodium tungstate as the reagents. Crystals grown were several micrometer in size and by X-ray diffraction measurements it was determined that they are only of the scheelite structure. No evidence of lead tungstate low temperature modification – raspite – was found. The emission properties of crystals were measured over the temperature interval 80 to 300 K and it was found that they are similar to those in PbWO4 crystals grown by the Czochralski method.

Spectral characterization of lanthanum heptamolybdate single crystals

Using sodium metasilicate gel, lanthanum heptamolybdate (La 2Mo 7O 24· nH 2O) single crystals are grown by the diffusion of lanthanum nitrate into the set gel embedded with a mixture of molybdenum trioxide, ammonium hydroxide and concentrated nitric acid. The infrared (IR) absorption spectrum of lanthanum heptamolybdate (LHM) single crystals identifies the presence of molybdate (MoO 4) 2− groups and water of crystallization, while energy dispersive X-ray analysis (EDAX) confirms the presence of heavy elements (La and Mo) in LHM. X-ray photoelectron spectroscopic (XPS) studies of LHM re-establish the presence of lanthanum and molybdenum besides their chemical states as their respective oxides. It is shown that the oxygens in the sample are present in three different environments as terminal oxygen (MoO), bridging oxygen (MoOLa) and oxygen of lattice water (HOH). The implications are discussed.

Growth and physico chemical characterization of lanthanum neodymium oxalate single crystals

Single crystals of lanthanum neodymium oxalate (LNO) are grown in sodium meta silicate gels, by the diffusion of a mixture of aqueous solutions of lanthanum nitrate and neodymium nitrate into the test tube having the set gel containing oxalic acid. The bluish pink coloured tabular crystals of LNO having well defined hexagonal basal planes appear either as ‘foggy’ or ‘clear’, the latter at the greater depths inside the gel. The colouration of LNO visually observed is evidenced in UV-visible spectrum, by the revelation of well pronounced characteristic peaks in the visible region (500–900 nm). X-ray diffraction (XRD) of powdered LNO is ordered, meaning crystalline in nature, besides its ‘isostructurality’ with similarly grown lanthanum samarium oxalate crystals. The single crystallinity of LNO is established by its oscillation XRD pattern. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) support that LNO loses water of crystallization around 120°C and CO and CO2 around 350–450°C, while the infrared absorption (IR) spectrum of LNO establishes the presence of oxalate (C2O4)2− ions. Energy dispersive X-ray analysis (EDAX) confirms the presence of La and Nd in the sample. X-ray photoelectron spectroscopic (XPS) studies of LNO establish the presence of La and Nd in their respective oxide states. An empirical structure for LNO has been proposed on the basis of these findings. The ‘smokiness’ in the foggy LNO crystal has been attributed due to the ‘gel inclusion’ during the growth process.

Crystal growth and characterization of antimony thiourea bromide

Antimony thiourea bromide (ATB) single crystals were grown in sodium meta silicate gel at ambient temperature. The conditions of the growth of large ATB single crystals in gel were obtained. The morphology of the crystals was indexed. The grown crystals were characterized by chemical analysis, EDX, X-ray diffraction and IR techniques. ATB crystallizes in the orthorhombic system with space group Cmc2 1 . The dielectric constant and refractive indices of the ATB single crystals were determined.

Physico-chemical characterization of calcium strontium tartrate crystals

Mixed single crystals of calcium strontium tartrate (CST) of high optical quality and morphological perfection have been grown from light irradiated sodium meta silicate gel medium at ambient temperature. The results obtained on characterization of CST crystals using EDX, chemical analysis, X-ray diffraction and infra-red spectral techniques are reported. A thermogravimetric study is carried out in order to study the kinetic parameters and associated mechanism of dehydration process. The two dimensional diffusion mechanism is suggested for the solid state nonisothermal dehydration step in CST crystals. The CST crystals turn out to be a tetrahydrate and the crystals are thermally unstable. The chemical composition was thus established as Ca 0.5Sr 0.5C 4H 4O 6.4H 2O.

Infrared Spectroscopic and Thermal Studies of Gel Grown Spherulitic Crystals of Iron Tartrate

AbstractGrowth of spherulitic crystals of iron tartrate by controlled diffusion in sodium metasilicate gels has been described. Infrared spectroscopic, thermogravimetric and elemental analysis have been conducted to characterize the crystals. The results are interpreted and explained.

Growth and characterization of calcium pyrophosphate dihydrate grown in silica gel

Calcium pyrophosphate dihydrate crystals, which are responsible for various arthritic diseases, were grown in sodium metasilicate gel. Variations in gel density, pH value and concentration of the reactants were found to have profound effect on the growth of the crystals. The grown crystals were characterized using IR, XRD, TGA and optical microscopy.

Microhardness studies of doped and undoped strontium tartrate tetrahydrate single crystals

The study of the microhardness of undoped and doped crystals and the way in which this parameter is connected with the dislocation density is of great interest for transducer applications involving mechanical vibrations [1, 2]. Microhardness gives information about the deformation resistance near the surface, anisotropy in the crystals, evidence for multiphase in the crystals, etc. Tartrates of calcium and strontium crystallize in the orthorhombic system with space group P212121 [3-5] showing ferroelectric properties [6]. Growth of these crystals doped with cobalt, nickel, etc., has drawn considerable interest recently [7, 8]. We carried out microhardness studies on both doped and undoped strontium tartrate tetrahydrate single crystals, using a diamond pyramid indentor. Crystals of strontium tartrate tetrahydrate were grown in silica gel medium [9, 10] in pure form and with chromium, iron, cobalt, nickel and cadmium as dopants. Sodium metasilicate gel of density 1.04 gem -3 was prepared and acidified with tartaric acid. The gel was allowed to set in test tubes of length 20 cm and diameter 2.5 cm. After gelation, 1 M aqueous solution of SrC12 was poured on top and allowed to diffuse into the gel. Strontium tartrate tetrahydrate crystals were found to grow in the gel. The best results were obtained for a gel density of 1.04 gcm -3, pH 4.2, 1 M tartaric acid and 1 ~ SrC12. To grow the doped crystals, an aqueous solution of the chloride of the dopant was used together with the outer reactant SrCI2. The detailed experimental procedure was reported elsewhere [11]. Doped and undoped crystals of strontium tartrate tetrahydrate of size about 8 m m × 4 mm × 2 mm (Fig. 1) were used for microhardness study. Before indentation the crystals were carefully lapped and polished to avoid surface effects which influence the hardness value strongly. Indentations were made using a Vickers pyramidal indentor for various loads from 5 to 100 g. The distance between two indentation points were more than three times the pit diagonal length, in order to avoid any mutual influence of the indentations. The diagonals of the impressions were measured using a Leitz Metallux II microscope with a calibrated ocular at magnification ×500. The measurements were made at room temperature and the indentation time was 10 s. To maintain uniformity between samples, the microhardness was measured on the dominant (1 1 0) face