1 edition of Crystallization and devitrification studies 1970-1978. Edited by Gary E. Lofgren found in the catalog.
Crystallization and devitrification studies 1970-1978. Edited by Gary E. Lofgren
|Contributions||Lofgren, G.E., NASA|
|LC Classifications||QE 421 C957 1979|
|The Physical Object|
|Pagination||432 p. ill.|
|Number of Pages||432|
The electron paramagnetic resonance of Mn 2+ in both the crystal and glass form of ZnCl 2 has been studied at 9 and 35 GHz. The spectra are found to fit the same spin Hamiltonian but with different values of D and to crystal and crystal to glass transformations were induced by heat treatment and neutron irradiation, respectively. The changes of the crystal field parameters and of their. perturbation of the crystallization media, e.g. by external electric or ultrasonic ﬁelds (Nanev & Penkova, ; Kakinouchi et al., ), by continuous light irradiation (Veesler et al.,
Separation and purification - Separation and purification - Exclusion and clathration: Differences in the sizes of molecules can also be the basis for separations. An example of these techniques is the use of molecular sieves in gas-solid chromatography. Size-exclusion chromatography (SEC) has proved effective for the separation and analysis of mixtures of polymers. The ZBLAN glass (53ZrF 4 ‐20BaF 2 ‐4LaF 3 ‐3AlF 3 ‐20NaF) is the most promising of these materials since its fiber‐drawing region lies on the edge, or possibly just outside its crystallization region. It is believed that additional research into understanding the nucleation mechanics involved in the devitrification of fluoride glasses.
At room temperature (i.e. no microwave heating), for a fixed volume of 20 μL solution of glycine at pH 4, 6 and 9, the total crystallization time (i.e., complete evaporation of solvent) on MUDA-modified SIFs 17 and 20 min, respectively. Glycine crystals grown on MUDA-modified SIFs were mostly α-form (Fig. 1). The total evaporation. Devitrification and recrystallization of nanoparticle-containing glycerol and PEG solutions. Lv F(1), Liu B(2), Li W(1), Jaganathan GK(1). Author information: (1)Institute of Biothermal Science and Technology, University of Shanghai for Science and Technology, Shanghai, China.
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Inoue, D.V. Louzguine, in Nanostructured Metals and Alloys, The formation of nano-quasicrystals. Nanoscale quasicrystals are formed on devitrification in various metallic glassy alloys. An icosahedral quasicrystalline phase (a 3-dimensional quasicrystal while 2- and 1-dimensional quasiperiodic structures also exist) having a long-range quasiperiodic translational and an.
Lofgren also provided most of available evidence on these processes but his study did not include SEM studies of devitrified samples. Several authors have recently used SEM studies to obtain information on crystallization and devitrification processes in natural rhyolitic glasses , .Cited by: A number of studies have examined the behavior of crystallization or vitrification, devitrification and recrystallization of aqueous solutions.
As early asDiller and his co-workers ,  developed cryomicroscopy to investigate the growth of ice-crystals during cryopreservation by tracking the ice by: Quantifying crystallization and devitrification of rhyolites by means of X-ray diffraction and potassic feldspar (e.g., Lofgren ). The inte- The purpose of this study is to construct a.
ELSEVIER Journal of Non-Crystalline Solids () IOURNAL OF ltllgl mWtM Kinetic analyses of crystallization and devitrification: Comparison of activation energies in aqueous solutions of glycerol and dimethyl sulphoxide J.M. Hey, D.R. MacFarlane Department of Chemistr3, Monash Uni~ersi~', Wellington Rd, Cla,on Vic., Australia Received 9 November Cited by: For the Zr 70 Pd 20 Cu 10 alloy the transition from the quasicrystalline to crystalline phases differs dramatically from the Zr 70 Pd 30 alloy.
The quasicrystalline phase disappears over a temperature range of less than 2 K, forming the Zr 2 Si type (I4/mcm) structure (), which is stable over only a 2 K range as indicated by the arrow on Fig.
1(b).This phase exhibits a second rapid. Unwanted crystallization occurring in a glaze during cool-down in the firing is called devitrification, it spoils gloss surfaces and can be a real plague to industry.
It can be dealt with by faster cooling or adjustments to chemistry (e.g. higher Al 2 O 3, switching some CaO for MgO, reducing B 2 O 3). Devitrification leads to the formation of secondary minerals from a silicate glass and, given that this process most commonly occurs in more evolved compositions, the secondary minerals typically include quartz (or SiO 2 polymorphs cristobalite and tridymite) and potassic feldspar (e.g., Lofgren.
The crystallization of pure tellurite glass during various heating rates was studied. The activation energy for crystallization was × eV mol−1. The glass transformation, T g, starting crystallization, T x, crystallization, T c and melting temperatures, T m, have been reported for binary tellurite glasses of the form (1 − x) TeO2−xAnOm [AnOm = MnO2, Co3O4 and MoO3].
crystal nucleation and growth in lithium diborate glass by thermal analysis j. ceram. soc., 83  –60 () j. sestak the role of thernal annealing in the processing of metallic glasses thermochimica acta () j.
Šesták, e. illekova jmayk- and ngg- crystallization kinetics of. Q: What is devitrification, how does it happen, and how can it be prevented.
A glass is by definition a liquid at all temperatures. Compositionally a typical glass consists of the 'glass (or network) formers' (SiO 2 and B 2 O 3), fluxes (also called alkaline metals, K 2 O and Na 2 O), and the network (or matrix) modifying alkaline earths (CaO, BaO, PbO, ZnO).
crystallization as well as the mutual interference of down-stream processes with the crystallization are also treated. Finally, techniques to characterize the crop are discussed. The third part of the book is dedicated to accounts of actual developments and of carried-out crystallizations.
Engaging Crystallization in Qualitative Research, the first "how to" book to both explain and demonstrate crystallization methodology, offers a framework for blending grounded theory and other social scientific analyses with creative representations of data, such as narratives, poetry, and film.
Author Laura L. Ellingson explores relevant. The Study of Devitrification Processes in Heavy‐Metal Fluoride Glasses. IAN R. DUNKLEY. The Development of a Heated-Stage Optical Microscope for ZBLAN Microgravity Crystallization Studies, Microgravity Science and Technology, /s.
Kinetics of thermal devitrification (crystallization) of some iron-based amorphous alloys Milenko V. Šušić 1 Journal of Materials Science Letters volume 5, pages – () Cite this article.
The surface crystallization mechanism is predominant at the beginning of the devitrification process; however, the volume crystallization acquires importance with an increase in the fluorine content. Nanoparticles in solution offer unique electrical, mechanical and thermal properties due to their physical presence and interaction with the state of dispersion.
This work aimed to study the effects of hydroxyapatite (HA) nanoparticles on the behavior of devitrification and recrystallization of glycerol (60% w/w) and PEG (50% w/w) solutions during warming. The value of Avrami’s exponent n lay between 1 andcorresponding to a diffusion-controlled growth of crystals.
The apparent activation energy for crystallization, E, varied from 45 to 50 kcal mol−1. These values of n and E are low by comparison with those of other fluoride glasses, which suggests high stability against devitrification. The ability of electrolytic glasses to control the ice crystallization is presented with an analysis of ice transformation in terms of polymorphism.
During the devitrification of such glasses, an intermediate disordered water phase is always present until the stable ice I h is formed. Process Engineering Laboratory II Spring d c dt = r k gA cn k n cm (1) where c= c c s is the di erence between actual and saturation concentration (sometimes called supersaturation as well) and ris the increase in the supersaturation due to the decreasing.
Marshall, R. R., Devitrification of natural glass, Geol. Soc. Am. Bull., 72, – Google Scholar. Up to a volume fraction = the equilibrium state is a fluid, while for > the equilibrium state is a crystal. For crystal states coexist. This phase behaviour has indeed been observed in concentrated suspensions of nearly hard .Ore-metal focused experimental studies have been complemented by numerous advances in our understanding of arc magma generation (e.g., Annen et al.
; Cashman and .