Peculiar Crystal Growth of the Trivalent Titanium Derived TiO2–SnO2 Precursor under Hydrothermal Conditions

2016 ◽  
Vol 45 (3) ◽  
pp. 318-320 ◽  
Author(s):  
Go Sakai ◽  
Ayano Tanaka ◽  
Takuma Sueda ◽  
Tsubasa Ogata ◽  
Yuji Okuyama ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Hydrothermal Conditions ◽  
Trivalent Titanium

Phase evolution and crystal growth of VO2 nanostructures under hydrothermal reactions

RSC Advances ◽  
2016 ◽  
Vol 6 (9) ◽  
pp. 7113-7120 ◽  
Author(s):  
Weilai Yu ◽  
Shuai Li ◽  
Chi Huang
Keyword(s):  
Crystal Growth ◽  
Phase Evolution ◽  
Hydrothermal Conditions ◽  
Hydrothermal Reactions ◽  
First Time

The phase evolution and crystal growth of VO2 nanostructures under hydrothermal conditions was comprehensively investigated and the feasibility of the Ostwald's step rules towards VO2 polymorph evolution was for the first time demonstrated.

Crystal growth and morphology of Nd:YVO4 under hydrothermal conditions

2006 ◽  
Vol 41 (5) ◽  
pp. 1415-1421 ◽  
Author(s):  
K. Byrappa Ramaningaiah ◽  
C. K. Chandrashekar ◽  
K. M. Lokanatharai ◽  
B. Basavalingu ◽  
K. Soga
Keyword(s):  
Crystal Growth ◽  
Hydrothermal Conditions

Hydrothermal Crystal Growth and Crystal Structures of the Mercury(II) Chromates(VI) α-HgCrO4, β-HgCrO4, and HgCrO4·H2O

2006 ◽  
Vol 61 (6) ◽  
pp. 708-714 ◽  
Author(s):  
Berthold Stöger ◽  
Matthias Weil
Keyword(s):  
Crystal Growth ◽  
Single Crystal ◽  
Single Crystals ◽  
Crystal Structures ◽  
Chromic Acid ◽  
Structure Type ◽  
Data Sets ◽  
Hydrothermal Conditions ◽  
Hydrothermal Crystal Growth ◽  
Structure Factors

Single crystals of α-HgCrO4, β -HgCrO4 and HgCrO4 ・ H2O were obtained by reacting yellow HgO in chromic acid of various concentrations under hydrothermal conditions at 200 °C (4 d). All crystal structures were solved and refined from single crystal diffractometer data sets [α-HgCrO4: P21/n, Z = 4, a = 5.5079(8), b = 8.5266(12), c = 7.3503(10) Å , β = 94.022(3)°, 955 structure factors, R[F2 > 2σ (F2)] = 0.0296; β -HgCrO4: Cmcm, Z = 4, a = 5.7187(9), b = 9.0169(14), c = 7.0114(11) Å, 361 structure factors, R[F2 > 2σ (F2)] = 0.0275; HgCrO4 ・ H2O: P1̅, Z = 2, a=5.6157(15), b =6.1115(16), c= 7.590(2) Å , α =108.850(5), β =91.666(5), γ =116.569(5)°, 1235 structure factors, R[F2 > 2σ (F2)] = 0.0316]. The previously reported structure of α-HgCrO4 has been re-determined. It contains distorted [HgO7] pentagonal bipyramids in which the short bonds are directed towards the apices. The new polymorph β -HgCrO4 adopts the CrVO4 (β -CrPO4) structure type and is composed of slightly distorted [HgO6] octahedra. The previously unknown monohydrate HgCrO4 ・ H2O crystallizes in an unique structure and is composed of one nearly regular [HgO4(H2O)2] octahedron and one considerably distorted [HgO6] octahedron. All three structures contain tetrahedral chromate anions CrO42− as the second building units with average Cr-O distances of ca. 1.65 Å

Synthesis of clay-sized iron oxides under marine hydrothermal conditions

Clay Minerals ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 719-731 ◽  
Author(s):  
N. Taitel-Goldman ◽  
A. Singer
Keyword(s):  
Crystal Growth ◽  
Short Range ◽  
Elevated Temperatures ◽  
Complete Oxidation ◽  
Alkaline Ph ◽  
Hydrothermal Conditions ◽  
Atlantis Ii Deep ◽  
Pure Phase ◽  
Acidic Conditions ◽  
Morphology Changes

AbstractGoethite, lepidocrocite, magnetite and akaganeite were synthesized in 0.8 M, 2 M and 5 M NaCl solutions at various temperatures (25, 40, 60°C) under slightly acidic to slightly alkaline pH with or without Si additions. Elevated temperatures prevent complete oxidation of initial Fe2+ solutions and magnetite and siderite precipitate, accompanied by goethite and lepidocrocite. At higher salinity, O2 solubility is reduced and its distribution is limited, leading to coprecipitation of lepidocrocite, akaganeite and goethite.Lepidocrocite morphology changes from plates at pH 5.5 through rods at pH 7 to multi-domainic crystals at pH 8.2, due to enhanced crystal growth along the c axis. Salinity and temperature have opposite effects on lepidocrocite crystallinity.Goethite crystals are multi-domainic and twinning appears only at elevated temperatures. Increases in temperature and salinity improve goethite crystallinity as observed by IR spectra. Addition of Si up to Si/Fe = 0.1 retards crystal growth and Si-OH-stretching bands appear. At Si/Fe = 1 most of the precipitate is short range ordered.Platy and rod-shaped lepidocrocite from the Thetis and Atlantis II Deeps, were probably formed under the slightly acidic conditions of the hydrothermal brines. The Si concentration was greater in Atlantis II Deep than in Thetis Deep, leading to larger lepidocrocite and goethite crystals in the latter.Multi-domainic goethite could have precipitated throughout. Pure phase goethite might have precipitated in the less concentrated brine, whereas mixtures of goethite and lepidocrocite might have precipitated in the more concentrated brine, depending mainly on oxidation rate and oxygen mobility within the brine.

Crystal Growth of Nd:RVO4 (where R=Y, Gd) under Mild Hydrothermal Conditions

1999 ◽  
Vol 315-317 ◽  
pp. 506-513 ◽  
Author(s):  
K. Byrappa ◽  
B. Nirmala ◽  
M. Yoshimura
Keyword(s):  
Crystal Growth ◽  
Hydrothermal Conditions

Organic-ligand-assisted hydrothermal synthesis of ultrafine and hydrophobic ZnO nanoparticles

2010 ◽  
Vol 25 (2) ◽  
pp. 219-223 ◽  
Author(s):  
Tahereh Mousavand ◽  
Satoshi Ohara ◽  
Takashi Naka ◽  
Mitsuo Umetsu ◽  
Seiichi Takami ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Hydrothermal Synthesis ◽  
Carboxylic Acids ◽  
Functional Groups ◽  
Zno Nanoparticles ◽  
Organic Ligand ◽  
Polymer Matrices ◽  
Organic Modifiers ◽  
Hydrothermal Conditions ◽  
Zno Particles

In this study, we report the synthesis of uniform and narrowly size-distributed ZnO nanoparticles with sizes of approximately 3 nm; the nanoparticles were prepared by means of organic-ligand-assisted hydrothermal conditions with various organic modifiers. The results obtained herein revealed that among the various functional groups tested (alcohols, aldehydes, carboxylic acids, and amines), only hexanol effectively controlled the nucleation and crystal growth of spherical ZnO nanoparticles. The use of hexanol also caused the surface of the ZnO particles to change from hydrophilic to hydrophobic, which would enhance the dispersion of these particles in polymer matrices, paints, cosmetics, and other organic application media.

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