On the Formation of AlPO4-Based Molecular-Sieves in the Presence of Cyclohexylamine

1993 ◽  
Vol 46 (2) ◽  
pp. 171 ◽  
Author(s):  
J Batista ◽  
V Kaucic ◽  
S Hocevar
Keyword(s):  
Crystal Structure ◽  
Hydrothermal Synthesis ◽  
Crystallization Temperature ◽  
Molecular Sieves ◽  
Chemical Compositions ◽  
Crystalline Phases ◽  
Complete Breakdown ◽  
Solid Phases ◽  
Synthesized Materials

The hydrothermal synthesis of the AlPO4-17, SAPO-44, MnAPSO-44 and intermediate solid phases [samples (APO)N, (APSO)N and Mn (APSO)N] in the presence of cyclohexylamine (cha) is described. (APO)N, (APSO)N and Mn (APSO)N represent unknown, layer-type, crystalline phases with different chemical compositions. These phases are predominantly formed at a high cha concentration and low crystallization temperature. All synthesized materials contain protonated cha in their structure, but only in AlPO4-17, (APO)N,(APSO)N and Mn (APSO)N is the -OH group also found. The calcination of the unknown phases leads to the loss of crystallinity and causes a complete breakdown of the crystal structure above 270°C.

Hydrothermal Synthesis of SnO2 Structures with Various Morphologies in the Presence of Different Alcoholic Co-Solvents

2016 ◽  
Vol 721 ◽  
pp. 87-91
Author(s):  
Kristaps Rubenis ◽  
Janis Locs
Keyword(s):  
Crystal Structure ◽  
Hydrothermal Synthesis ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Solvothermal Process ◽  
Starting Solution ◽  
Structure Morphology ◽  
Synthesized Materials

The addition of certain co-solvents to the hydrothermal synthesis starting solution can greatly alter morphology and enhance different morphology dependent properties of the synthesized material. While ethanol is the most common co-solvent used for the synthesis of various SnO2 nano/microstructures by hydro/solvothermal process, it is not clear how the use of some other alcoholic co-solvents (for example, methanol or isopropanol) affect morphology and properties of SnO2, especially if synthesis is done under similar conditions as in the case of ethanol co-solvent. In the present study, we investigated how the use of various alcoholic co-solvents (methanol, ethanol, 2-propanol, ethylene glycol and glycerol) affects crystal structure, morphology and specific surface area of the hydrothermally synthesized SnO2. Additionally, sensitivity towards 100 ppm ethanol of the synthesized materials was tested. The formation of nanoparticles, rod-cluster structures and spherical SnO2 structures were observed depending on the alcoholic co-solvent used. The highest sensitivity (~22 at 250 °C) showed the material that was synthesized in the presence of ethanol co-solvent.

Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium Lutetium Fluoride (KLF) Microcrystals

2020 ◽  
Author(s):  
Xiaojing Xia ◽  
Anupum Pant ◽  
Xuezhe Zhou ◽  
Elena Dobretsova ◽  
Alex Bard ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Solid State ◽  
Information Science ◽  
Point Group ◽  
Solid State Laser ◽  
Lanthanide Ions ◽  
Group Symmetry ◽  
Luminescence Spectra ◽  
Crystalline Phases ◽  
State Laser

Fluoride crystals, due to their low phonon energies, are attractive hosts of trivalent lanthanide ions for applications in upconverting phosphors, quantum information science, and solid-state laser refrigeration. In this article, we report the rapid, low-cost hydrothermal synthesis of potassium lutetium fluoride (KLF) microcrystals for applications in solid-state laser refrigeration. Four crystalline phases were synthesized, namely orthorhombic K<sub>2</sub>LuF<sub>5</sub> (Pnma), trigonal KLuF<sub>4</sub> (P3<sub>1</sub>21), orthorhombic KLu<sub>2</sub>F<sub>7</sub> (Pna2<sub>1</sub>), and cubic KLu<sub>3</sub>F<sub>10</sub> (Fm3m), with each phase exhibiting unique microcrystalline morphologies. Luminescence spectra and emission lifetimes of the four crystalline phases were characterized based on the point-group symmetry of trivalent cations. Laser refrigeration was measured by observing both the optomechanical eigenfrequencies of microcrystals on cantilevers in vacuum, and also the Brownian dynamics of optically trapped microcrystals in water. Among all four crystalline phases, the most significant cooling was observed for 10%Yb:KLuF<sub>4</sub> with cooling of 8.6 $\pm$ 2.1 K below room temperature. Reduced heating was observed with 10%Yb:K<sub>2</sub>LuF<sub>5</sub>

scholarly journals Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

The first proof of protonated anion tetrahedra in the tsumcorite-type compounds

2004 ◽  
Vol 68 (5) ◽  
pp. 757-767 ◽  
Author(s):  
T. Mihajlović ◽  
H. Effenberger
Keyword(s):  
Crystal Structure ◽  
Hydrothermal Synthesis ◽  
Single Crystal ◽  
Diffraction Data ◽  
Title Compound ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
Synthetic Compounds ◽  
X Ray

AbstractHydrothermal synthesis produced the new compound SrCo2(AsO4)(AsO3OH)(OH)(H2O). The compound belongs to the tsumcorite group (natural and synthetic compounds with the general formula M(1)M(2)2(XO4)2(H2O,OH)2; M(1)1+,2+,3+ = Na, K, Rb, Ag, NH4, Ca, Pb, Bi, Tl; M(2)2+,3+ = Al, Mn3+, Fe3+, Co, Ni, Cu, Zn; and X5+,6+ = P, As, V, S, Se, Mo). It represents (1) the first Sr member, (2) the until now unknown [7]-coordination for the M(1) position, (3) the first proof of (partially) protonated arsenate groups in this group of compounds, and (4) a new structure variant.The crystal structure of the title compound was determined using single-crystal X-ray diffraction data. The compound is monoclinic, space group P21/a, with a = 9.139(2), b = 12.829(3), c = 7.522(2) Å, β = 114.33(3)°, V = 803.6(3) Å3, Z = 4 [wR2 = 0.065 for 3530 unique reflections]. The hydrogen atoms were located experimentally.

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