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1

Selective crystallization of gamma glycine for NLO applications using magnesium sulfate (MgSO4) as an additive

Anbu Chudar Azhagan S., Kathiravan V. S.

Materials Science Poland

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2019

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Vol. 37, No. 2

265--279

EN

Crystallization of γ-glycine in the presence of selected concentration (9 g/mL) of tailor-made additive magnesium sulfate heptahydrate salt (MgSO4·7H2O) has been studied at ambient temperature by adopting slow solvent evaporation procedure. The morphological modifications of glycine crystals grown from pure aqueous solutions of glycine and from glycine solutions containing magnesium species in the amount of 0.1 g/mL to 16 g/mL have been investigated thoroughly. The crystalline nature and phase identification of the crystalline material were confirmed by X-ray powder diffraction and SXRD studies. NMR studies revealed the information about the molecular conformation in solution, phase changes, functional groups and chemical environment. FT-IR spectra revealed distinct difference between α and γ-glycine polymorphs in the region around 880 cm−1 to 930 cm−1. The grown γ-glycine crystal had a lower cut-off value at 200 nm and the bandgap value evaluated from the Tauc plot was found to be 5.83 eV. The marked differences between α and γ-polymorphs of glycine were also revealed by DSC thermograms. The mechanical strength of the γ-glycine crystal was studied with the help of Vickers microhardness instrument. Kurtz-powder NLO study proved the generation of second harmonics (i.e. green light emission) in the grown γ-glycine crystal and its efficiency was calculated as 1.44 times better than that of the reference material potassium dihydrogen phosphate.

2

Crystallization, habit modification and control of nucleation of glycine polymorphs from aqueous solutions doped with magnesium sulfate impurity

Azhagan S. A. C., Kathiravan V. S., Priya N. S.

Materials Science Poland

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2018

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Vol. 36, No. 3

483--493

EN

The influence of magnesium sulfate as an additive in the nucleation of α and γ-polymorphs of glycine crystallized from aqueous solutions has been explored for the first time. Based on crystallization experiments, it was concluded that lower concentration of magnesium sulfate, say less than 2 g/mL, favors α-nucleation sites, whereas the optimized concentration of magnesium sulfate impurity to yield γ-nucleation sites is 2 g/mL and above. The nucleation time span (in days), solubility and pH were measured for α- and γ-nucleation sites in the aqueous solutions doped with magnesium sulfate. The glycine polymorphs α- and γ-single crystals were grown by slow solvent evaporation technique at ambient temperature. Crystal habit of glycine polymorphs was investigated and analyzed using goniometry. The unit cell dimensions and space group of the as-grown crystal were identified by single crystal XRD analysis. Both α- and γ-polymorphs of glycine were characterized structurally by powder XRD studies. The percentage of magnesium present in the grown glycine crystals was estimated by inductively coupled plasma optical emission spectrometry elemental analysis (ICP-OES). The nonlinear optical properties of the γ-glycine crystals were examined by Q-switched high energy Nd:YAG laser. The second harmonic generation output efficiency of the as-grown gamma glycine single crystals was computed to be 1.31 times superior than that of the reference material potassium dihydrogen phosphate (KDP).

3

Two-phase synthesis of olive-like NiS particles and chain-like Bi2S3 nanowires

Yuan Y., Xu H., Meng X., Han Q.

Materials Science Poland

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2015

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Vol. 33, No. 1

1--5

EN

Highly dispersed olive-like NiS particles were synthesized in a liquid-liquid biphasic system at room temperature, where nickel xanthate in organic solvents (toluene and benzene) and sodium sulfide in water solution were used as nickel and sulfide sources, respectively. NiS particles were formed at the stabilized phase interface. The structures, chemical composition and optical characteristics of the products were investigated by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. The organic solvents obviously influenced the morphology of the NiS particles. The olive-like NiS with smooth surface and sharp ends was obtained at benzene/water interface, while spindle-like NiS particles with rough surface and circle ends were formed when using toluene as a solvent. Analogously, chainlike Bi2S3 nanowires were produced at chloroform/water interface. The effect of the experiment parameters including reaction time, solvent and concentration of reactants on the size and morphology of the products was discussed in detail and a possible formation mechanism was suggested.

4

Predicted Crystal Structures, Analysis, Impact Sensitivities and Morphology of Solid High-Energy Complexes: Alkaline-Earth Carbohydrazide Perchlorates

Liu Y., Zhang R., Feng C.-G., Yang L., Zhang T.-L.

Central European Journal of Energetic Materials

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2015

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Vol. 12, no. 2

229--248

EN

The crystal structures, density of states, energy gap, thermodynamic properties, impact sensitivities and morphology of beryllium carbohydrazide perchlorate ([Be(CHZ)3](ClO4)2), magnesium carbohydrazide perchlorate ([Mg(CHZ)3](ClO4)2), calcium carbohydrazide perchlorate ([Ca(CHZ)3] (ClO4)2), strontium carbohydrazide perchlorate ([Sr(CHZ)3](ClO4)2) and barium carbohydrazide perchlorate ([Ba(CHZ)3](ClO4)2) were investigated using the density functional theory (DFT) and crystal morphology theory. The results show that all of the complexes have six-coordinated distorted octahedra, which is different from previous works. This was rationalised by consideration of the intermolecular interactions in the crystal structures. Hence the crystal structure is now more reliable. The chemical reactions of the whole molecule may be triggered by an electron transition of CHZ or ClO4 −. Furthermore the energy gaps were observed, and the values of the impact sensitivities were inferred to have the following sequence: [Be(CHZ)3](ClO4)2 > [Mg(CHZ)3](ClO4)2 > [Sr(CHZ)3](ClO4)2 > [Ca(CHZ)3](ClO4)2 > [Ba(CHZ)3](ClO4)2. In addition, the thermodynamic equations at 25-1000 K were obtained. The positive values of the standard molar free enthalpies shows that carbohydrazide perchlorates are stable at 298.15 K. The (1 0 -1) and (0 0 2) faces are the most important growth directions of the crystal morphologies, and have the minimum growth rates. From the cleaved main growth faces, it can be deduced that surface active agents with active hydrogen atoms in the functional groups could be used as crystal-control reagents to control the crystal morphology for alkaline-earth carbohydrazide perchlorates.

5

Czochralski growth of SrLaAlO4 and SrLaGaO 4 single crystals and its implications for the crystal morphology

Pajaczkowska A., Gloubokov A., Klos A., Woensdregt C. F.

Zeszyty Historyczne Politechniki Warszawskiej

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2014

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z. 16

85--89

EN

Single crystals of SrLaAlO4 (SLA) and SrLaGaO4 (SLG) have been grown from nonstoichiometric melts by the Czochralski method making use of different seed orientations, [100] (SLA, SLG), [110] (SLA) and [001] (SLG). The anisotropic properties of the crystal structure are reflected in the growth morphology of the crystals. In the case of (SLA) {101} facets appear at the crystal/melt interface and in that of [100] SLG {101} and {103} facets occur, while for [001] SLG {001} and {103} facets are present. SLA crystals are very similar to the theoretical growth forms computed according to the Hartman-Perdok theory for models with an effective charge on oxygen, qO −2|e|. However the habit of SLG crystals corresponds better to the theoretical growth forms based on an effective charge qO = −1.5|e| due to the presence of oxygen vacancies.

6

Preparation and Characterization of Desensitized ?-HNIW in Solvent-Antisolvent Recrystallizations

Jiang X., Guo X., Ren H., Jiao Q.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 3

219-236

EN

The solubility of hexanitrohexaazaisowurtzitane (HNIW) in solvent and solvent-antisolvent mixtures, and the temperature at which the HNIW's polymorph transforms were studied. The solubility of HNIW in solvent-antisolvent mixtures was measured at 30 C and these data were fitted to a generalized solubility curve. Recrystallization experiments were conducted at 30 C in the case of saturation with the volume ratio of ethyl acetate to petroleum ether (chloroform) ranging from 0:1 to 4:1. Desensitized HNIW was obtained by ethyl acetate and petroleum ether crystallization and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), High Performance Liquid Chromatography (HPLC) and Scanning Electron Microscopy (SEM). The FTIR and XRD spectra confirmed the structural features of ε-HNIW. The blocklike ε-HNIW grains had an average particle size of 160 ?m and high purity (98.52%). The decomposition of ε-HNIW was observed in the temperature range of 225-246 C by Differential Scanning Calorimetry (DSC). Furthermore, the impact and friction sensitivity tests suggested that the desensitized ε-HNIW was less sensitive than raw HNIW. Small scale gap tests with desensitized ε-HNIW showed that these crystals are less sensitive to shock initiation.

7

Second phase morphology in the Zn-Ti0.1-Cu0.1 single crystals obtained at different growth rates

Boczkal G.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 2

479-484

EN

The influence of growth rate on a morphology, distribution and crystallographic relationship of the intermetallic phase Zn16Ti in Zn-Ti0.1-Cu0.1 single crystals were investigated. The crystals obtained at rates in range of from 1.8mm/h to 16mm/h were tested. In all cases a strong elongation of the Zn16Ti particles along the [11-20] direction is observed. Moreover, it is found that a lamellar phase existing in the crystals develop in range of the growth rate from 6 to 10 mm/h and grows in the f10-11gplanes. In the case of the growth rate of 16mm/h oval-shaped areas of α phase (solid solution of zinc and 0.1wt.% of copper with trace content of titanium) elongated along [10-10] direction and surrounded by needle shaped precipitations are formed in the structure.

PL

W pracy badano wpływ szybkości wzrostu monokryształów Zn-Ti0.1-Cu0.1 na morfologię, rozkład i zależności krystalograficzne fazy międzymetalicznej Zn16Ti. Do testów użyto kryształów wyhodowanych z prędkościami z zakresu od 1.8mm/h do 16mm/h. We wszystkich przypadkach zaobserwowano istnienie cząstek tylko jednej fazy Zn,sub>16Ti, wydłużonych na kierunku [11-20]. Ponadto stwierdzono, że przy szybkości wzrostu z zakresu 6 do 10mm/h, obserwowana faza międzymetaliczna ma postać płytkowa, preferująca płaszczyzny wzrostu f10-11g. W przypadku szybkości wzrostu 16mm/h zaobserwowano tworzenie się fazy iglastej, która otacza obszary czystej osnowy (roztwór stały cynku z dodatkiem 0.1% miedzi oraz niewielką zawartością tytanu) tworzące owale wydłużone na kierunku [10-10].

8

Transformations in liquid state and microstructure analysis in immiscible Fe60Cu20P10Si5B5 alloy

Ziewiec K., Malczewski P., Prusik K.

Inżynieria Materiałowa

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2011

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Vol. 32, nr 1

26-29

EN

The microstructure and chemical composition of the arc-melt ingot and melt-spun ribbons ejected at different temperature were analysed using light microscope (LM) and scanning electron microscope SEM/EDS (Fig. 1, 3). The melt-spun ribbon was investigated by transmission electron microscope (TEM) (Fig. 4). The melting range of the alloy was investigated by means of differential thermal analysis (DTA) (Fig. 2). The alloy processed at the slow cooling rate during cooling after arc-melting, formed the fractal surface structures consisting of the Fe-rich regions and Cu-rich regions (Fig. 1). The melt-spun ribbon microstructure was found to depend on the value of ejection temperature (Fig. 3, 5). The lower ejection temperatures (below Ts) applied during melt spinning process resulted in the formation of the non-homogeneous lamellar structures separated into Fe-rich and Cu-rich regions. This was due to the rapid cooling within the miscibility gap. High-temperature ejection above the miscibility gap resulted in the formation of a amorphous/crystalline composite with a uniform fine particle distribution.

PL

Przeprowadzono badania mikrostruktury oraz składu chemicznego stopu Fe60Cu20P10Si5B5 po przetapianiu łukowym oraz po odlewaniu na wirujący bęben dla różnych wartości temperatury wypychania ciekłego metalu. Do badań zastosowano mikroskop świetlny, skaningowy mikroskop elektronowy wyposażony w EDS oraz transmisyjny mikroskop elektronowy. Zakres temperatury związany ze stanem ciekłym badano za pomocą różnicowej analizy termicznej. W stopie chłodzonym z małą szybkością, występującą w trakcie chłodzenia po przetapianiu łukowym, zaobserwowano tworzenie mikrostruktury fraktalnej składającej się z obszarów wzbogaconych w żelazo oraz obszarów wzbogaconych w miedź. Stwierdzono, że mikrostruktura taśmy odlewanej na wirujący bęben zależy od wartości temperatury wypychania ciekłego stopu. Zastosowanie niskiej wartości temperatury wypychania ciekłego stopu (poniżej Ts) w trakcie procesu odlewania na wirujący bęben spowodowało powstanie niejednorodnych struktur warstwowych zawierających obszary bogate w żelazo oraz obszary bogate w miedź. Struktury te wytworzyły się w wyniku szybkiego chłodzenia w zakresie niemieszalności w stanie ciekłym. Wypychanie ciekłego stopu powyżej zakresu występowania niemieszalności w stanie ciekłym spowodowało tworzenie się kompozytu amorficzno-krystalicznego o jednorodnym rozkładzie drobnodyspersyjnych cząstek.

9

Analysis of the processes of silicon epitaxial lateral overgrowth in Ar ambient gas

Jóźwik I., Olchowik J. M.

Materials Science Poland

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2006

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Vol. 24, No. 4

967--973

EN

Liquid phase epitaxy (LPE) and, in particular, epitaxial lateral overgrowth (ELO) is an attractive method of thin film deposition, owing to the simplicity of its technology and a reduced growth temperature. In this paper, we present recent results of the ELO of silicon layers carried out by means of LPE using Ar as an ambient gas, without any addition of hydrogen, potentially explosive gas, which makes this deposition technique a very safe process. The aim of the this work focused on the silicon ELO growth on partially masked substrates was to determine optimal conditions of growth resulting in ELO layers of the maximum aspect ratio and minimum defect density. Data presented herein clearly show that the epitaxial layers characterized by the maximum value of the aspect ratio can be obtained by application of the 0.25°C/min cooling rate. Noteworthy is the fact that in the same conditions the defect density achieves the minimum value of 1.07×104 cm-2, which is the amount smaller by the factor of 10 than the defect density of Si substrates used (1.7×105 cm-2). It confirms the ELO technique as a promising tool for the fabrication of low-defect density silicon layers of good morphology.

10

On the interrelation between crystal morphology and its geometry

Prywer J.

Scientific Bulletin. Physics / Lodz University of Technology

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2003

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Vol. 23

43-57

EN

The morphological variety of crystal habits is due to differences in relative growth rates of faces of which the crystal is composed. However, if the faces grow equally fast, the sizes of faces are not the same. The sizes of faces, in such a case, are determined by crystal geometry represented by interfacial angles. The largest crystal faces are those, which form interfacial angles α + γ close to Π. The results show that the crystal geometry plays a big role, bigger than it was thought so far, in the formation of final crystal habit.

PL

Zróżnicowanie morfologiczne kryształu jest funkcją względnych prędkości wzrostu ścian, które tworzą ten kryształ. W przypadku, gdy wszystkie ściany rosną jednakowo szybko, wielkości poszczególnych ścian nie są takie same i zależą od kątów dwuściennych, czyli od geometrii kryształu. W takim przypadku ścianami morfologicznie najważniejszymi są ściany, dla których suma kątów dwuściennych α + γ jest bliska Π. Jeśli ściany kryształu rosną z różnymi prędkościami, ścianami najważniejszymi morfologicznie nie zawsze są ściany wolno rosnące. Ściany, dla których suma kątów dwuściennych α + γ jest bliska Π mogą istnieć w pokroju nawet, jeśli rosną szybciej niż ściany sąsiednie. Natomiast ściany, które rosną wolniej od jednej ze ścian sąsiednich mogą nie pojawiać się w pokroju w ogóle. Wyniki przedstawionej w pracy analizy wskazują, że ścianami tworzącymi kryształ nie koniecznie muszą być ściany wolno rosnące oraz, że geometria kryształu odgrywa ważną rolę w kształtowaniu się ich morfologii.