Metastable δ-Bi12SiO20 and its effect on the quality of grown single crystals of γ-Bi12SiO20

1996 ◽  
Vol 11 (10) ◽  
pp. 2575-2582 ◽  
Author(s):  
Senlin Fu ◽  
Hiroyuki Ozoe
Keyword(s):  
Single Crystals ◽  
Melting Temperature ◽  
Room Temperature ◽  
Lattice Distortion ◽  
Grown Crystal ◽  
Growth Parameters ◽  
Cooling Process ◽  
Slow Cooling ◽  
Large Lattice

Metastable δ-Bi12SiO20 may crystallize from the overheated Bi12SiO20 melt and transform into stable γ-Bi12SiO20 at about 569.5 °C during the subsequent slow cooling process. The transition δ-Bi12SiO20 → γ-Bi12SiO20 is irreversible and the γ-Bi12SiO20 is stable up to the melting temperature. By quenching the Bi12SiO20 melt, pure δ-Bi12SiO20 can be obtained at room temperature. The quenched δ-Bi12SiO20 crystal is nontransparent and has a space group of Fm3m (225) and a lattice constant of 55.417 Å at 20 °C. The quenched metastable δ-Bi12SiO20 can transform into pure γ-Bi12SiO20 at 382.5–386.1 °C with an exothermic heat of 31.68–32.38 J/g. The transition-produced δ-Bi12SiO20 crystal is still nontransparent and has a large lattice distortion. The transition δ-Bi12SiO20 → γ-Bi12SiO20 causes about 6% volume contraction, which may result in cracking of the grown crystal. By controlling the growth parameters, this transition can be effectively avoided.

scholarly journals Growth and Characterization of Epsomite Single Crystals Doped with KCl from low Temperature Aqueous Solutions

1970 ◽  
Vol 33 (1) ◽  
pp. 47-54 ◽  
Author(s):  
S Ferdous ◽  
J Podder
Keyword(s):  
Aqueous Solutions ◽  
Single Crystals ◽  
Optical Quality ◽  
Dielectric Studies ◽  
Slow Cooling ◽  
Large Size ◽  
Isothermal Evaporation ◽  
Academy Of Sciences

Highly transparent and well faceted large size epsomite single crystals have been grown in pure form and doped with KCl from aqueous solutions by slow cooling and isothermal evaporation method. The optical quality of the epsomite improves on doping by KCl. Mass growth rates were found to increase with doping of lower concentrations of KCl and then decreases with the higher concentration of KCl. KCl doped epsomite crystal reveals that structures are slightly distorted due to adsorption of Cl- ion into the crystal lattice. DC conductivity along the growth axis for all of the grown crystals increases with temperature in the range of 25 to 70ºC and also increases with the KCl concentration. Dielectric constant is found to be almost independent of frequency up to range of 106Hz. The dielectric studies show the suitability of these grown crystals for optoelectronic applications. DOI: 10.3329/jbas.v33i1.2949 Journal of Bangladesh Academy of Sciences, Vol. 33, No. 1, 47-54, 2009

Crystal structure, dielectric, piezoelectric and elastic properties of (±)-tris(ethylenediamine)cobalt(III) nitrate, (±)–[Co(H2N(CH2)2NH2)3](NO3)3

1998 ◽  
Vol 213 (3) ◽  
Author(s):  
S. Haussühl ◽  
J. Schreuer
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Single Crystals ◽  
Elastic Properties ◽  
Structure Analysis ◽  
Elastic Constants ◽  
Room Temperature ◽  
Optical Quality ◽  
X Ray

AbstractLarge single crystals of optical quality of (±)-tris(ethylenediamine)cobalt(III) nitrate have been grown from aequeous solutions. An X-ray structure analysis yielded space groupPyroelectric, dieletric, piezoelectric and elastic constants have been determined at room temperature. Additionally, we have studied the coefficients of thermal expansion and the thermoelastic constants in the range between 270 K and 350 K. The structure exhibits a nearly trigonal symmetry around the [unk]

Growth and Characterization of Ti3PSe4 Single Crystals

1986 ◽  
Vol 90 ◽  
Author(s):  
N. B. Singh ◽  
R. H. Hopkins ◽  
R. Mazelsky ◽  
M. Gottlieb
Keyword(s):  
Single Crystals ◽  
Growth Parameters ◽  
Optical Transmittance ◽  
Etch Pit Density ◽  
Bridgman Technique ◽  
Absorption Bands ◽  
Cross Sectional ◽  
Etch Pit

ABSTRACTGood quality single crystals of Ti3PSe4 were grown from the melt by the Bridgman technique following improvements in the method of purifying the parent components, and optimization of growth parameters. Crack-free crystals 8 cm in length and 17 mm in diameter were produced.The quality of the crystals was evaluated by optical transmittance and metallographic techniques. In the range 0.7 to 14 μm the optical transmittance shows elimination of absorption bands exhibited in crystals grown without special purification steps. Etchpit studies showed that the crystals were free from inclusions and lamellar twins and that they show a uniform cross sectional etch pit density.

scholarly journals EVALUATION OF THE POTENTIAL INCLUSION OF MALAYSIAN RUBBER SEED, Hevea brasiliensis Muell. Arg. (EUPHORBIACEAE) ON THE TAMBACU DIET

2020 ◽  
Vol 9 ◽  
pp. 648
Author(s):  
Daiane Milhomem Araújo ◽  
Antonio Carlos Freitas Souza ◽  
Jociel Ferreira Costa ◽  
Francisco Eduardo Aragão Catunda Júnior ◽  
Diego Carvalho Viana
Keyword(s):  
Room Temperature ◽  
Production Systems ◽  
Growth Promotion ◽  
Growth Parameters ◽  
Fish Farming ◽  
Production Chain ◽  
Rubber Seed ◽  
Physical Chemical ◽  
Biometric Measurements

In intensive production systems, fish are exposed to stressful conditions, becoming more susceptible to diseases, which may reflect on their growth parameters. Alternative growth promotion methods without environmental impacts have become the target of researchers and fish farmers. For this reason, the objective of this work was to evaluate the potential of including Malaysian rubber seed in the feeding of tambacu raised in cages. The seeds were collected on a farm in the municipality of Imperatriz, Maranhão, a sample was sent for physical-chemical analysis of the fixed oil. For inoculation in the diet, the husks were removed, dried at room temperature, crushed and manually mixed with the commercial ration feed following the experimental design. The quality of the water was measured throughout the experiment. Biometric measurements were performed to infer growth gains with the tested diet. The results show an influence on the inclusion of 40% of the Malaysian rubber seed in the tambacu diet during rearing. In order to reduce costs resulting from the use of alternative ration feeds, we suggest the use of Malaysian rubber seed in an attempt to minimize barriers due to the high prices of commercial ration feeds within the fish farming production chain.

scholarly journals Effect of Cooling Methods on the Strength of Silico-ferrite of Calcium and Aluminum of Iron Ore Sinter during the Cooling Process

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 402
Author(s):  
Xu Zhang ◽  
Hao Bai ◽  
Xin Lu ◽  
Tian He ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Iron Ore ◽  
Cooling Process ◽  
Slow Cooling ◽  
Iron Ore Sinter ◽  
Mass Fractions ◽  
Mechanical Strengths ◽  
Biot Numbers ◽  
Cooling Methods

In the iron making process, a high mechanical strength is favorable for iron ore sinters in the blast furnace, and the bonding phase is regarded as one of the key components that determines the quality of the iron ore sinter, in which the silico-ferrite of calcium and aluminum (SFCA) is one of the typical phases. In this study, synthesized samples with different SFCA mass fractions were prepared to study the effect of different cooling methods on the strengths of the SFCA samples. The results showed that the strength of a sample could be improved by increasing the SFCA content during a temperature change. Further, the test results for the compressive strength suggested that the SFCA had a positive effect on the strength of the iron ore sinter during cooling, with slow cooling being significantly effective at preventing the generation of thermal stress. Moreover, the Biot number was introduced to normalize all of the cooling methods. The results showed that higher mechanical strengths for iron ore sinters will be obtained with higher SFCA content and lower Biot numbers, which will guide the evaluation of mechanical strength of iron ore sinter after the cooling process in industry.

scholarly journals Modulation of quartz-like GeO2structure by Si substitution: an X-ray diffraction study of Ge1−xSixO2(0 ≤x< 0.2) flux-grown single crystals

2012 ◽  
Vol 45 (2) ◽  
pp. 272-278 ◽  
Author(s):  
Adrien Lignie ◽  
Dominique Granier ◽  
Pascale Armand ◽  
Julien Haines ◽  
Philippe Papet
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Piezoelectric Materials ◽  
Structural Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spontaneous Nucleation ◽  
Tetrahedral Angle ◽  
Hydroxy Groups

The spontaneous nucleation by the high-temperature flux method of GeO2and SiO2-substituted GeO2(Ge1−xSixO2) compounds was improved to give single crystals free of hydroxy groups. The crystal structure and quality of these α-quartz-like piezoelectric materials were studied by single-crystal X-ray diffraction at room temperature. The refinements gave excellent final reliability factors, which are an indication of single crystals with a low level of defects. A good correlation was found between the silicon content in Ge1−xSixO2crystals determined through extrapolation from the inter-tetrahedral bridging angle and that found from energy-dispersive X-ray spectroscopy. The effect of germanium replacement by silicon on the distortion of the α-quartz-type GeO2structure was followed by the evolution of the intra-tetrahedral angle and other structural parameters. TheTO4(T= Si, Ge) distortion was found to be larger in α-GeO2than in α-SiO2and, as expected, the irregularity of theTO4tetrahedra decreased linearly as the substitution of Si for Ge increased.

Study of the influence of dopants on the crystalline perfection of ferroelectric glycine phosphite single crystals using high-resolution X-ray diffraction analysis

2011 ◽  
Vol 44 (2) ◽  
pp. 313-318 ◽  
Author(s):  
Krishnamurthy Senthil Kumar ◽  
Sridharan Moorthy Babu ◽  
G. Bhagavannarayana
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
Point Defects ◽  
Room Temperature ◽  
Rare Earth Metals ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
X Ray ◽  
Tilt Boundaries

Good quality and optically transparent single crystals of pure and doped glycine phosphite (GPI) were grown by both solvent-evaporation and temperature-cooling techniques. Dopants were chosen in different categories, namely transition metals (Cr, Mn, Co, Ni, Zn, Mg, Cd), rare-earth metals (Ce, Nd, La), dyes (rhodamine B, malachite green, fluorescein) and an amino acid (L-proline). The concentration of dopants was chosen depending on the category of dopants and the quality of crystallization during the growth process. The crystalline perfection of the as-grown pure and doped GPI crystals was investigated by high-resolution X-ray diffraction at room temperature. A multicrystal X-ray diffractometer employing a well collimated and highly monochromated Mo Kα1beam and set in the (+, −, −, +) configuration was employed. Most of the crystal specimens show excellent crystalline perfection. However, grain boundaries, low-angle tilt boundaries, and vacancy and interstitial point defects were observed in some crystal specimens.

scholarly journals Oxide Self-Flux in Optical Floating Zone Crystal Growth of Nickel Niobate (NiNb2O6)

2017 ◽  
Author(s):  
Timothy J. S. Munsie ◽  
Anna Millington ◽  
Graeme M. Luke ◽  
Hanna A. Dabkowska
Keyword(s):  
Phase Diagram ◽  
Crystal Growth ◽  
Melting Temperature ◽  
Niobium Oxide ◽  
Growth Parameters ◽  
Growth Conditions ◽  
Floating Zone ◽  
Liquid Zone ◽  
Small Excess

Growing crystals of nickel niobate (NiNb2O6), we noticed that changing growth conditions allowed our material to enter different areas of the phase diagram. In particular, we found that excess material accumulated within and above the liquid zone. Analysis showed that this was an unincorporated constituent. Changing the ratio of the constituent oxides - an excess of ~4% of either NiO or Nb2O5 gave us the opportunity to investigate changes in zone stability, melting temperature and quality of the resulting crystal. We found that a small excess of nickel oxide decreases the melting temperature significantly, and created the best pseudo-rutile NiNb2O6 crystal studied, while higher amounts of niobium oxide allowed us to stabilize the NiNb2O6 columbite phase. This research reinforces the idea that self-flux as a travelling solvent can significantly impact crystal growth parameters and quality.

scholarly journals Electronic nematicity in Sr2RuO4

2020 ◽  
Vol 117 (20) ◽  
pp. 10654-10659 ◽  
Author(s):  
Jie Wu ◽  
Hari P. Nair ◽  
Anthony T. Bollinger ◽  
Xi He ◽  
Ian Robinson ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Lattice Distortion ◽  
Sensitive Indicator ◽  
Crystallographic Axis ◽  
Unconventional Superconductor ◽  
High Quality ◽  
Large Lattice ◽  
Order Of Magnitude ◽  
Electronic Nematicity

We have measured the angle-resolved transverse resistivity (ARTR), a sensitive indicator of electronic anisotropy, in high-quality thin films of the unconventional superconductor Sr2RuO4 grown on various substrates. The ARTR signal, heralding the electronic nematicity or a large nematic susceptibility, is present and substantial already at room temperature and grows by an order of magnitude upon cooling down to 4 K. In Sr2RuO4 films deposited on tetragonal substrates the highest-conductivity direction does not coincide with any crystallographic axis. In films deposited on orthorhombic substrates it tends to align with the shorter axis; however, the magnitude of the anisotropy stays the same despite the large lattice distortion. These are strong indications of actual or incipient electronic nematicity in Sr2RuO4.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

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