Synthesis and thermotropic properties of hydroxy and silyloxy axially substituted phthalocyanines

Novel boron(III) subphthalocyanines 5-8 with six lipophilic alkylthio chains at the peripheral sites, bearing hydroxy or triethylsilyloxy groups in the axial position, have been synthesized and their thermotropic properties have been studied. These compounds are gelatinous materials at room temperature and gradually soften as the temperature is raised up to a point at which high fluidity typical of classical liquids is observed. By the usual techniques employed for the study of thermotropic behaviour (polarizing microscopy, DSC and X-ray diffraction), no liquid crystalline properties have been found. Instead, the compounds have an amorphous structure (i.e. behave as isotropic materials) throughout the temperature range studied. They could be designated as liquid subphthalocyanines.

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New method for the production of bulk amorphous materials of Nd–Fe–B alloys

Journal of Materials Research ◽

10.1557/jmr.2005.0098 ◽

2005 ◽

Vol 20 (3) ◽

pp. 563-566 ◽

Cited By ~ 16

Author(s):

Tetsuji Saito ◽

Hiroyuku Takeishi ◽

Noboru Nakayama

Keyword(s):

Electron Microscopy ◽

Amorphous Materials ◽

Room Temperature ◽

Amorphous Structure ◽

X Ray Diffraction ◽

Bulk Materials ◽

X Ray ◽

Transmission Electron ◽

Melt Spun ◽

Melt Spun Ribbons

We report a new compression shearing method for the production of bulk amorphous materials. In this study, amorphous Nd–Fe–B melt-spun ribbons were successfully consolidated into bulk form at room temperature by the compression shearing method. X-ray diffraction and transmission electron microscopy studies revealed that the amorphous structure was well maintained in the bulk materials. The resultant bulk materials exhibited the same magnetic properties as the original amorphous Nd–Fe–B materials.

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Структурные, магнитные и тепловые свойства соединения Tb-=SUB=-0.8-=/SUB=-Sm-=SUB=-0.2-=/SUB=-Fe-=SUB=-2-=/SUB=- cо структурой фаз Лавеса

Физика твердого тела ◽

10.21883/ftt.2019.12.48603.551 ◽

2019 ◽

Vol 61 (12) ◽

pp. 2471

Author(s):

Т.А. Алероева ◽

И.С. Терешина ◽

Т.П. Каминская ◽

З.С. Умхаева ◽

А.В. Филимонов ◽

...

Keyword(s):

Thermal Expansion ◽

Wide Temperature Range ◽

Room Temperature ◽

Structural Features ◽

Surface Topology ◽

Magnetic Domains ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Range ◽

Comprehensive Study

A comprehensive study of the structure, phase composition, features of the surface topology, the magnetostrictive and thermal properties of the Tb0.8Sm0.2Fe2 compound are performed. The structural features were established at micro- and nanoscale levels, and information on the magnetic domains structure at room temperature was obtained. The results of x-ray diffraction studies in a wide temperature range of 90–760 K, including Curie temperature, are represented. Experimental data on thermal expansion and magnetostriction in magnetic fields up to 12 kOe were obtained and analyzed. Anomalies were found in the thermal expansion curves dl/l (T) and magnetostriction λ (T) at low temperatures. It is established that in compound under study the value of the magnetostrictive effect remains almost unchanged in a wide temperature range 100–300 K in fields up to 3.5 kOe.

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X-ray diffraction evidence for decreased lipid fluidity in senescent membranes from cotyledons

Canadian Journal of Botany ◽

10.1139/b76-114 ◽

1976 ◽

Vol 54 (10) ◽

pp. 1074-1078 ◽

Cited By ~ 52

Author(s):

B. D. McKersie ◽

J. E. Thompson ◽

J. K. Brandon

Keyword(s):

Crystalline State ◽

Liquid Crystalline ◽

Room Temperature ◽

X Ray Diffraction ◽

Membrane Function ◽

X Ray ◽

Hydrocarbon Chains ◽

Sharp Band ◽

Microsomal Membranes ◽

Diffraction Patterns

Smooth microsomal membranes were isolated from bean cotyledons at various intervals after planting. Wide-angle x-ray diffraction patterns were recorded at room temperature from oriented specimens of the membranes. Patterns for membranes from 2-day-old cotyledons featured a broad lipid reflection centered about a Bragg spacing of 4.6 Å. This diffraction band derives from the apolar hydrocarbon chains of the membrane phospholipid, and its diffuse nature indicates that these hydrocarbons are in a disordered liquid–crystalline state. By day 4 in the germination sequence a faint sharp band superimposed on the broad lipid reflection was discernable at a Bragg spacing of 4.15 Å. This sharp reflection represents lipid in an ordered, crystalline state and derives from a close hexagonal packing of the hydrocarbon chains. During the later stages of germination the 4.15-Å reflection intensified to the point of becoming very pronounced in patterns for membranes from 9-day-old cotyledons. These patterns also displayed a sharp but weaker reflection at 3.75 Å, which derives from an orthorhombic packing of the hydrocarbon chains in crystalline lipid. By 9 days of age the cotyledons were extensively senescent and beginning to abscise.The data indicate that senescence of membranes involves a phase change whereby the proportion of crystalline to liquid– crystalline lipid progressively increases. This changed physical state of the lipid represents a substantial decrease in membrane fluidity and may well contribute to loss of membrane function in senescing membranes.

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Oxidation kinetics of commercially pure titanium

Matéria (Rio de Janeiro) ◽

10.1590/s1517-70762007000300014 ◽

2007 ◽

Vol 12 (3) ◽

pp. 525-531 ◽

Cited By ~ 59

Author(s):

E. Gemelli ◽

N.H.A. Camargo

Keyword(s):

Oxidation Kinetics ◽

Room Temperature ◽

Thermal Analyses ◽

Pure Titanium ◽

Thermal Characterization ◽

Commercially Pure Titanium ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Range ◽

Commercially Pure

The aim of this work was to perform thermal characterization of commercially pure titanium in dry air to determine its oxidation kinetics and the structure of the oxide. The oxidation kinetics were determined thermogravimetrically under isothermal conditions in the temperature range 300 to 750 ºC for 48 hours and the structure of the oxides was determined by differential thermal analyses and X-ray diffraction in the temperature range room temperature - 1000ºC. The oxidation rate of titanium increased with increase in temperature. It was high in the initial stages of oxidation and then decreased rapidly with time, especially up to 600 ºC. The kinetic laws varied between inverse logarithmic at the lower temperatures (300 and 400 ºC) and parabolic at the higher temperatures (650, 700 and 750 ºC). Evidences from X-ray diffraction and differential thermal analyses data revealed that the passive oxide film formed at room temperature crystallized into anatase at about 276 ºC. The crystallized oxide formed in the range 276 - 457 ºC consisted of anatase, in the range 457 - 718 ºC consisted of anatase and rutile sublayers, and at temperatures beyond 718 ºC consisted of a layer of pure rutile. Scanning electron microscopy observations reveled that the oxidized surfaces were crack-free and the surface roughness increased steadily with oxidation temperature.

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Electrical and Structural Properties of Multioriented Thin Film PZT Deposited at Room Temperature by RF-PVD

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.464.89 ◽

2013 ◽

Vol 464 ◽

pp. 89-93 ◽

Cited By ~ 1

Author(s):

Mohammed Mahdi ◽

Mohammed Kadri

Keyword(s):

Cross Sections ◽

Room Temperature ◽

Perovskite Phase ◽

Phase Evolution ◽

Lead Zirconate ◽

Amorphous Structure ◽

X Ray Diffraction ◽

X Ray ◽

Si Substrates ◽

Crystallographic Characteristics

As PZT target are prepared from solid solution method. The perovskit phase evolution is investigated in this paper by DRX at different temperatures in order to show crystallization, morphology and structure of lead zirconate ceramics (PZT) target. Samples were deposited at room temperature on Aluminum (Al) and silicon (Si) substrates, and then heat-treated in a tabular furnace at 200 and 400°C during 30 min under atmospheric pressure. The films characterization were done glancing incidences X-ray diffraction (GIXRD) analysis with Fe Kα radiation (l=1.936Å ) at glancing angle of 1.5°for crystallographic characteristics; and Scanning Electron Microscopy (SEM-Zeiss ultra plus) in Ultra-High resolution imaging to observe surfaces morphology and cross-sections of thin films.We present in this paper a x-ray diffraction analysis, showing that as-deposited PZT films depend strongly on substrate nature, it presents an amorphous structure and nanocrystallizes in a pure perovskite phase PbZr0.44Ti0.56O3 when it was deposited on Al substrate (followed by thermal treatement at 400°C).Ferroelectrics and piezoelectric properties are showed using Sawyer Tower circuit and impulsionel test respectively.

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Synthesis and liquid crystal behavior of tris[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth complexes

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424607000138 ◽

2007 ◽

Vol 11 (02) ◽

pp. 100-108 ◽

Cited By ~ 16

Author(s):

Ying Zhang ◽

Weili Jiang ◽

Jianzhuang Jiang ◽

Qingbin Xue

Keyword(s):

Rare Earth ◽

Liquid Crystal ◽

Liquid Crystalline ◽

Optical Microscope ◽

Rare Earth Complexes ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Range ◽

Ionic Size ◽

Liquid Crystal Phase Transition

A series of tris[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth(III) complexes M 2[ Pc ( OC 8 H 17)8]3 [ M = Eu , Gd , Y , Lu ] has been prepared by the reaction of corresponding bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth complexes with M ( acac )3·n H 2 O in refluxing 1,2,4-trichlorobenzene. These liquid crystalline sandwich, triple-decker complexes were characterized by elemental analysis and various spectroscopic methods including 1 H NMR, UV-vis, IR and mass spectroscopies. Their liquid crystal phase transition behavior was studied by Polarized Optical Microscope, Differential Scanning Calorimeter and X-ray diffraction. The complexes, with octyloxy attached as side chains, showed rectangular columnar liquid crystal phases in a liquid crystal temperature range between 83 and 305°C. In addition to the rare earth contraction, both the transition temperature and the wide temperature range of the mesophase show a slight but obvious trend to decrease, respectively, in the same order. In contrast, the molecular packing of these complexes as revealed by X-ray diffraction was found to be almost independent of the ionic size of the central rare earth.

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Tilting structures ininverseperovskites,M3TtO (M= Ca, Sr, Ba, Eu;Tt= Si, Ge, Sn, Pb)

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520615006150 ◽

2015 ◽

Vol 71 (3) ◽

pp. 300-312 ◽

Cited By ~ 46

Author(s):

Jürgen Nuss ◽

Claus Mühle ◽

Kyouhei Hayama ◽

Vahideh Abdolazimi ◽

Hidenori Takagi

Keyword(s):

Phase Transitions ◽

Room Temperature ◽

Structural Changes ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Range ◽

Tolerance Factors ◽

Multiple Twinning ◽

Perovskite Type ◽

Perovskite Type Structure

Single-crystal X-ray diffraction experiments were performed for a series ofinverseperovskites,M3TtO (M= Ca, Sr, Ba, Eu;Tt= tetrel element: Si, Ge, Sn, Pb) in the temperature range 500–50 K. ForTt= Sn, Pb, they crystallize as an `ideal' perovskite-type structure (Pm\bar 3m,cP5); however, all of them show distinct anisotropies of the displacement ellipsoids of theMatoms at room temperature. This behavior vanishes on cooling forM= Ca, Sr, Eu, and the structures can be regarded as `ideal' cubic perovskites at 50 K. The anisotropies of the displacement ellipsoids are much more enhanced in the case of the Ba compounds. Finally, their structures undergo a phase transition at ∼ 150 K. They change from cubic to orthorhombic (Ibmm,oI20) upon cooling, with slightly tilted OBa6octahedra, and bonding angles O—Ba—O ≃ 174° (100 K). For the larger Ba2+cations, the structural changes are in agreement with smaller tolerance factors (t) as defined by Goldschmidt. Similar structural behavior is observed for Ca3TtO. SmallerTt4−anions (Si, Ge) introduce reduced tolerance factors. Both compounds Ca3SiO and Ca3GeO with cubic structures at 500 K, change into orthorhombic (Ibmm) at room temperature. Whereby, Ca3SiO is the only representative within theM3TtO family where three polymorphs can be found within the temperature range 500–50 K: Pm\bar 3m–Ibmm–Pbnm. They show tiny differences in the tilting of the OCa6octahedra, expressed by O—Ca—O bond angles of 180° (500 K), ∼ 174° (295 K) and 170° (100 K). For largerM(Sr, Eu, Ba), together with smallerTt(Si, Ge) atoms, pronounced tilting of the OM6octahedra, and bonding angles of O—M—O ≃ 160° (295 K) are observed. They crystallize in theanti-GdFeO3type of structure (Pbnm,oP20), and no phase transitions occur between 500 and 50 K. The observed phase transitions are all accompanied by multiple twinning, in terms of pseudo-merohedry or reticular pseudo-merohedry.

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Nonlinear thermal expansion in Li2NiMn3O8

Powder Diffraction ◽

10.1154/1.2959851 ◽

2008 ◽

Vol 23 (3) ◽

pp. 224-227

Author(s):

Lingmin Zeng ◽

Yeqing Chen ◽

Wei He ◽

Liangqin Nong

Keyword(s):

Thermal Expansion ◽

High Temperature ◽

Room Temperature ◽

Linear Thermal Expansion ◽

Lithium Ion ◽

Entire Temperature Range ◽

X Ray Diffraction ◽

Spinel Type ◽

X Ray ◽

Temperature Range

A lattice thermal expansion study on Li2NiMn3O8, a high-voltage cathode material for lithium-ion batteries, was carried out by high-temperature X-ray diffraction from room temperature to 973 K. Rietveld refinement of a high-quality room-temperature diffraction pattern confirmed that Li2NiMn3O8 has the cubic Al2MgO4 spinel type of crystal structure. The analysis of the high-temperature X-ray diffraction patterns showed that the Li2NiMn3O8 structure remained stable and no phase transition was detected over the temperature range from 298 to 973 K. As expected, the value of lattice parameter a or unit cell volume V increases with increasing temperature. The increase in a or V is linear only in the low-temperature region and nonlinear over the entire temperature range from 298 to 973 K. Least-squares analysis of the data for a or V showed the thermal expansion of a or V for Li2NiMn3O8 can best be fitted by a 3-degree polynomial function of temperature. The linear thermal expansion coefficients for a and V averaged over the entire temperature range from 298 to 973 K were also calculated, and αTa=1.10×10−5 K−1; αTV=3.29×10−5 K−1.

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Synthesis and Properties of Liquid Crystalline Polyurethanes from 4,4-bis (6-hydroxyhexoxy) Biphenyl and 3,3'-Dimethyl-4, 4’-Biphenylene Diisocyanate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.428-429.144 ◽

2010 ◽

Vol 428-429 ◽

pp. 144-149

Author(s):

Xiao Dong Chen ◽

Nan Qiao Zhou ◽

Hai Zhang

Keyword(s):

Nematic Phase ◽

Liquid Crystalline Polymer ◽

Liquid Crystalline ◽

Crystalline Polymer ◽

Decomposition Temperature ◽

Wide Angle ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Temperature Range

A thermotropic liquid crystalline polyurethane (LCPU) was synthesized by the polyaddition reaction of 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI) with 4,4-bis(6-hydroxyhexoxy)biphenyl (BHHBP). The liquid crystalline behavior of the polymer was investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide angle X-ray diffraction (WAXD). The LCPU exhibited a nematic phase with a threaded texture and had a wide mesophase temperature range. And thermogravimetric analysis (TGA) indicated the decomposition temperature of the LCPU was >300°C. The observation of POM showed that the LCPU was a thermotropic nematic liquid crystalline polymer at certain temperature range.

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Liquid-crystalline heterodimesogens and ABA-heterotrimesogens comprising a bent 3,5-diphenyl-1,2,4-oxadiazole central unit

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.8.54 ◽

2012 ◽

Vol 8 ◽

pp. 472-485 ◽

Cited By ~ 22

Author(s):

Govindaswamy Shanker ◽

Marko Prehm ◽

Carsten Tschierske

Keyword(s):

Liquid Crystalline ◽

Optical Observations ◽

Central Unit ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Polarizing Microscopy ◽

X Ray ◽

Nematic Phases ◽

Lower Temperature ◽

Optical Polarizing Microscopy

Three new types of terminally connected ABA-heterotrimesogens and heterodimesogens, composed of a bent 3,5-diphenyl-1,2,4-oxadiazole central unit and one or two rod-shaped 4-cyanobiphenyl cores or one 2-phenyl-1,3,4-thiadiazole core, connected by flexible spacers, have been synthesized, and their mesomorphic behavior was studied by optical polarizing microscopy (PM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All dimesogens exhibit broad ranges of cybotactic nematic phases (NcybA and NcybC), in some cases accompanied by additional mesophases (CybA or SmC) at lower temperature. The combination of the 3,5-diphenyl-1,2,4-oxadiazole unit with one cyanobiphenyl core leads to the removal of tilted smectic and cybotactic nematic phases (SmC, NcybC), which are replaced by the nontilted CybA phases and nematic phases composed of SmA-type clusters (NcybA). The orthogonal cybotactic nematic phases of bent-core mesogens are of special interest for achieving biaxial nematic phases of the orthorhombic type. The orthogonal (NcybA) and skewed (NcybC) cybotactic nematic phases were distinguished by XRD and optical observations.

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