In Situ Synchrotron Radiation Small-angle X-ray Scattering Study Of The Kinetics Of Growth Of Cdte Nanocrystals In Borosilicate Glass

A number of isolator-semiconductor nanocrystal composites exhibit quantum confinement effects and nonlinear optical properties. In this work, the formation and growth of CdTe and CdTe0.9S0.1 nanocrystals immersed in a borosilicate glass host matrix were studied by small-angle x-ray scattering using synchrotron radiation during in situ annealing in the 560-580°C temperature range. The values of the average radii of the CdTe nanocrystals determined by using Guinier plots for different annealing times (20-30 Å) agree with those obtained from optical absorption spectroscopy measurements. The nanocrystal size distribution depends on the thermal history and composition of the samples. The existence of other structural heterogeneities having an average size of several hundred ångstroms was detected. © 1995 American Institute of Physics.6621338134

SAXS study of nucleation and growth of CdTe1-xSx semiconductor nanocrystals in borosilicate glass

Previous investigations demonstrated that borosilicate glasses containing CdTeS nanocrystals exhibit quantum confinement effects. In this paper nucleation and growth of CdTe1-xSx (x=0, 0.40 and 0.70) spheroidal nanocrystals (with radii of a few nanometers) were studied during isothermal annealing at 580 C using the SAXS technique. The time evolutions of the averages of nanocrystal radii and width of the size distribution depend on the crystal stoichiometry. Smaller crystals are formed when sulfur content is lower. The rate of growth increases with sulfur content. The geometrical standard deviation of the radii of ternary crystals exhibits a minimum at annealing times of 15-20 min. These results provide useful hints which can help to obtain glass-CdTeS nanocrystal composites having a controlled average crystal size and a narrow size distribution

SAXS AND TEM STUDIES OF PHASE SEPARATION IN BaO-SiO2 GLASSES

La séparation de phases amorphes des verres de BaO-SiO2 a été étudiée par diffusion de rayons X aux petits angles et microscopie électronique de transmission, dans la région de germination et croissance de la lacune de miscibilité. Les diamètres des particules sphéroïdales précipitées, déterminés avec la loi de Guinier et par microscopie électronique, sont en accord. La cinétique de croissance des particules est bien décrite par la théorie classique de "coarsening". Les intégrales des courbes de diffusion de rayons X ont permis de déterminer la frontière de la lacune de miscibilité et le temps nécessaire pour que la matrice atteigne sa composition d'équilibre. La germination se produit pendant le refroidissement du liquide ou dans les tous premiers stades du traitement thermique. La processus de "coarsening" commence avant que la matrice atteigne la composition d'équilibre.Amorphous phase separation was studied in the nucleation and growth region of the BaO-SiO2 miscibility gap. Nearly spherical droplets were precipitated, the diameters obtained from SAXS and TEM being in reasonable agreement. The growth kinetics of the droplets were well described by the classical theory of coarsening. From the integrated SAXS intensities the times to reach the equilibrium matrix compositions at 743 and 760°C were determined, and the binodal boundary located. Nucleation occurred during quenching from the melt or within a very short time of heat treatment. Coarsening began well before the attainment of the equilibrium matrix composition

Nucleation And Growth Of Cdte1-xsx Nanocrystals Embedded In A Borosilicate Glass. Effects Of Sulfur Content And Two-step Thermal Annealing

Nucleation and growth of CdTe1-xSx nanocrystals embedded in a borosilicate glass matrix and submitted to isothermal annealing were studied by small-angle X-ray scattering (SAXS). Two different sulfur contents (x=0.3 and x=0.7) were investigated. The formation and growth of the nanocrystals was studied in situ, maintaining the samples at a constant temperature (560 °C) inside a high-temperature cell. The effect of a nucleation pretreatment at 460 °C on the characteristics of nanocrystal formation and growth was also studied. The experimental results demonstrate that, in composites with high sulfur content (x=0.7), nanocrystals grow during the isothermal annealing by coarsening of preformed small crystals. In glasses with low sulfur content (x=0.3), nanocrystals grow by progressive diffusion of Cd, Te and S atoms initially dispersed in the glass matrix. © 2001 Elsevier Science B.V. All rights reserved.293-2951517526Neto, J.A.M., Barbosa, L.C., Cesar, C.L., Alves, O.L., Galembeck, F., (1991) Appl. Phys. Lett., 59, p. 2715Craievich, A.F., Alves, O.L., Barbosa, L.C., (1993) J. Phys., 3, p. 373Craievich, A.F., Alves, O.L., Barbosa, L.C., (1995) Rev. Sci. Instrum., 66, p. 1338Bernardes, A., Tolentino, H., Rodrigues, A.R.D., Craievich, A.F., Torriani, I., (1992) Rev. Sci. Instrum., 63, p. 1065Kellermann, G., Vicentin, F., Tamura, E., Rocha, M., Tolentino, H., Barbosa, A., Craievich, A.F., Torriani, I., (1997) J. Appl. Cryst., 30, p. 880Potter B.G., Jr., Simmons, J.H., (1991) Phys. Rev. B, 43, p. 2234Glatter, O., Kratky, O., (1982) Small Angle X-ray Scattering, , Academic Press, LondonGuinier, A., Fournet, G., (1955) Small-angle Scattering of X-rays, , Wiley, New YorkSvergun, D.I., Semenyuk, A.V., Feigin, L.A., (1988) Acta Crystallogr. A, 44, p. 244Svergun, D.I., (1992) J. Appl. Cryst., 25, p. 495Christian, J.W., (1975) The Theory of Transformations in Metals and Alloys, , Pergamon, New YorkLifshitz, I.M., Slyozov, V.V., (1961) J. Phys. Chem. Solids, 19, p. 35Liu, Y., Reynoso, V.C.S., Royas, R.F.C., Brito Cruz, C.H., Cesar, C.L., Alves, O.L., (1996) J. Mater. Sci. Lett., 15, p. 98

Polymorphisme du dipalmitoyl 1,2 glycéride

Transformations of dipalmitoyl 1,2 glyceride have been studied by thermal differential analysis and X ray diffraction patterns. The crystalline phase C transforms by successive melting and cooling to a metastable form Lβ in which the molecules are perpendicular to the layers. Two supplementary metastable forms have been detected and the kinetics of their transformations has been studied.Les transformations du dipalmitoyl 1,2 glycéride ont été étudiées par analyse thermique différentielle et diagrammes de rayons X. La phase cristalline C se transforme par fusion et refroidissement en une phase métastable Lβ où les molécules sont perpendiculaires aux couches. Deux autres phases métastables ont été décelées et leurs cinétiques de transformation étudiées

Clay-containing Block Copolymer Nanocomposites With Aligned Morphology Prepared By Extrusion

Clay-containing nanocomposites of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) copolymers having cylindrical domains were obtained by melt extrusion using a tape die. One type of sample (SEBS-MA) had maleic anhydride attached to the middle block. Two types of organoclays were added, namely Cloisite 20A and Cloisite 30B. Small angle X-ray scattering and transmission electron microscopy (TEM) analyses showed that the addition of 20A clay to SEBS and SEBS-MA resulted in nanocomposites with intercalated and partially exfoliated structures, respectively. The addition of 30B clay to SEBS and SEBS-MA promoted the formation of composites containing relatively large micron-sized and partially exfoliated clay particles, respectively. Our TEM analysis revealed that clay particles embedded in SEBS are preferably in contact with the polystyrene cylindrical domains, while in SEBS-MA they are in contact with the maleated matrix. The extrusion processing promoted alignment of the axes of the polystyrene cylinders along the extrusion direction in all samples, and the basal planes of the clay particles were mostly parallel to the main external surfaces of the extruded tapes. © 2013 Society of Chemical Industry.632184194Hamley, I.W., (1998) The Physics of Block Copolymers, , Oxford University Press, OxfordLaus, M., Francescangeli, O., Sandrolini, F., (1997) J Mater Res, 12, pp. 3134-3139. , andMauritz, K.A., Blackwell, R.I., Beyer, F.L., (2004) Polymer, 45, pp. 3001-3016. , andHa, Y.-H., Thomas, E.L., (2002) Macromolecules, 35, pp. 4419-4428. , andGanguly, A., Bhowmick, A.K., Li, Y., (2008) Macromolecules, 41, pp. 6246-6253. , andLai, S.-M., Chen, C.-M., (2007) Eur Polym J, 43, pp. 2254-2264. , andDrazkowski, D.B., Lee, A., Haddad, T.S., (2007) Macromolecules, 40, pp. 2798-2805. , andLee, K.M., Han, C.D., (2003) Macromolecules, 36, pp. 804-815. , andGroenewold, J., Fredrickson, G.H., Eur Phys, J., (2001) E, 5, pp. 171-182. , andHa, Y.-H., Kwon, Y., Breiner, T., Chan, E.P., Tzianetopoulou, T., Cohen, R.E., (2005) Macromolecules, 38, pp. 5170-5179Carastan, D.J., Demarquette, N.R., Vermogen, A., Masenelli-Varlot, K., (2008) Rheol Acta, 47, pp. 521-536. , andHasegawa, N., Usuki, A., (2003) Polym Bull, 51, pp. 77-83. , andSilva, A.S., Mitchell, C.A., Tse, M.F., Wang, H.-C., Krishnamoorti, R., (2001) J Chem Phys, 115, pp. 7166-7174. , andCarastan, D.J., Vermogen, A., Masenelli-Varlot, K., Demarquette, N.R., (2010) Polym Eng Sci, 50, pp. 257-267. , andVaia, R.A., Maguire, J.F., (2007) Chem Mater, 19, pp. 2736-2751. , andLee, J.Y., Park, M.S., Yang, H.C., Cho, K., Kim, J.K., (2003) Polymer, 44, pp. 1705-1710. , andDaniel, C., Hamley, I.W., Mortensen, K., (2000) Polymer, 41, pp. 9239-9247. , andPark, S.-Y., Cho, Y.-H., Vaia, R.A., (2005) Macromolecules, 38, pp. 1729-1735. , andKoerner, H., Jacobs, J.D., Tomlin, D.W., Busbee, J., Vaia, R., (2004) Adv Mater, 16, pp. 297-302. , andKoerner, H., Hampton, E., Dean, D., Turgut, Z., Drummy, L., Mirau, P., (2005) Chem Mater, 17, pp. 1990-1996Wiesner, U., (1997) Macromol Chem Phys, 198, pp. 3319-3352Folkes, M.J., Keller, A., (1976) J Polym Sci B: Polym Phys, 14, pp. 833-846. , andPakula, T., Saijo, K., Kawai, H., Hashimoto, T., (1985) Macromolecules, 18, pp. 1294-1302. , andKobori, Y., Kwon, Y.K., Okamoto, M., Kotaka, T., (2003) Macromolecules, 36, pp. 1656-1664. , andHoneker, C.C., Thomas, E.L., Albalak, R.J., Hajduk, D.A., Gruner, S.M., Capel, M.C., (2000) Macromolecules, 33, pp. 9395-9406. , andFerry, J.D., (1980) Viscoelastic Properties of Polymers, , Wiley, New YorkCarastan, D.J., Demarquette, N.R., (2007) Int Mater Rev, 52, pp. 345-380. , andJang, B.N., Wang, D., Wilkie, C.A., (2005) Macromolecules, 38, pp. 6533-6543. , andCui, L., Ma, X., Paul, D.R., (2007) Polymer, 48, pp. 6325-6339. , andKim, K.N., Kim, H., Lee, J.W., (2001) Polym Eng Sci, 41, pp. 1963-1969. , andFilippi, S., Paci, M., Polacco, G., Dintcheva, N.T., Magagnini, P., (2011) Polym Degrad Stab, 96, pp. 823-832. , andPark, C.I., Park, O.O., Lim, J.G., Kim, H.J., (2001) Polymer, 42, pp. 7465-7475. , andRen, J., Silva, A.S., Krishnamoorti, R., (2000) Macromolecules, 37, pp. 3739-3746. , andVermogen, A., Masenelli-Varlot, K., Séguéla, R., Duchet-Rumeau, J., Boucard, S., Prele, P., (2005) Macromolecules, 38, pp. 9661-9669. , andChoi, S., Lee, K.M., Han, C.D., (2004) Macromolecules, 37, pp. 7649-7662. , andVaia, R.A., Giannelis, E.P., (1997) Macromolecules, 30, pp. 8000-8009. , andJang, B.N., Wang, D., Wilkie, C.A., (2005) Macromolecules, 38, pp. 6533-6543. , andLee, J.Y., Park, M.S., Yang, H.C., Cho, K., Kim, J.K., (2003) Polymer, 44, pp. 1705-1710. , andVaia, R.A., Ishii, H., Giannelis, E.P., (1993) Chem Mater, 5, pp. 1694-1696. , andVaia, R.A., Jandt, K.D., Kramer, E.J., Giannelis, E.P., (1996) Chem Mater, 8, pp. 2628-2635. , andBousmina, M., (2006) Macromolecules, 39, pp. 4259-4263Lee, J.Y., Baljon, A.R.C., Sogah, D.Y., Loring, R.F., (2000) Chem Phys, 112, pp. 9112-9119. , an