Thermodynamic aspects of polymorphism in liquid crystals
Abstract
Materials Literature
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Mesomorphic Behaviour of Biphenyl Esters I: Biphenyl-4-Trans-p-n-Alkoxycinnamates
Many mesomorphic compounds undergo decomposition on repeated heating. In the search for compounds which are appreciably stable to heating cycles and which display mesophases over a wide range of temperatures, we have prepared some biphenyl-4-trans-p-n-alkoxycinnamates and have investigated their mesomorphic properties…
Use of Ion Bombardment to Study Irradiation Damage in Zirconium Alloys
Zircaloy-2 having several different microstructures, textures, and compositions has been bombarded with either 5 MeV or 46.5 MeV nickel ions at 300 to 600°C to achieve doses ranging from 0.65 to 87.0 displacements per atom (dpa). Similar material was reactor-irradiated near 320°C to neutron fluences between 0.8 and 3.…
The Plasticisation and Swelling of Acrilan under Dyebath conditions
Measurements have been made which show that there is no predictable connection between fibre swelling and the plasticisation of acrylic fibres. The diffusion of dyes into the fibres is controlled by the segmental mobility of the fibrous polymer chains and not by fibre swelling.
Lattice constant measurements on the 106 K transition of SrTiO3
The temperature dependence of the lattice constant of SrTiO3, in particular around the 106 K transition, has been measured by using a double-crystal X-ray diffraction method; a relative accuracy of 10−5 is attained. The results are compared with those of EPR in terms of static rotation ø of TiO6 octahedra around [001]…
A study of the dielectric properties of powdered BaTiO3
The anomalous behaviour of powdered barium titanate is confirmed by the use of the formula for mixtures. Systematic measurements of the dielectric properties of BaTiO 3 have been done for two cases: embedded grains and fine-grained pressed powder. The influence of the size and shape of the grains, and of the method of…
The effect of stress on the microstructure of neutron irradiated cold worked type 316 stainless steel
20% cold worked Type 316 stainless steel in the form of uniaxially stressed solid rod and pressurized tubes was irradiated at 450°C in the EBR-11. Five irradiated and three unirradiated specimens were examined by transmission electron microscopy to determine the effect of stress on microstructure and possible mechanis…
The Luminescence of Tb3+ in Borates of the Composition X[sub 2]Z(BO[sub 3])[sub 2] (X = Ba, Sr, Ca; Z = Ca, Mg)
Four new borates of the formula X 2 Z ( BO 3 ) 2 , with X = Ba , Sr , Ca , and Z = Ca , Mg , are described. Ca 2 Mg ( BO 3 ) 2 is tetragonal, and Ba 2 Mg ( BO 3 ) 2 is hexagonal and isomorphous with the mineral buetschliite. Ba 2 Mg ( BO 3 ) 2 and Sr 2 Mg ( BO 3 ) 2 are related to buetschliite but their diffraction pa…
Investigation of aqueous sodium metasilicate solutions by 29Si n.m.r. spectroscopy
The presence of a variety of polysilicates, including branched chain species, in aqueous sodium metasilicate solutions has been shown by 29Si n.m.r.
Galvanic Cells Containing Cathodes of Iron-Doped Beta-Alumina
Galvanic cells of the form where varied between 0.9 and 1.2 were operated at 120°C, and currents of 50 mA/cm 2 could be drawn. The cells were electrochemically regenerative, and the cathodes could be thermally regenerated. Initial open‐circuit voltages varied between 2.37 and 2.45V. Cells were discharged at constant c…
An electrooptic image storage device using field induced reversible transitions between AFE and FE phases of PLZT ceramics
Field induced reversible transitions between AFE and FE phases of PLZT ceramics are considered to realize a high contrast image storage and display device. The proposed field-induced phase transition takes the material from a non-scattering AFE phase to a scattering FE phase, and returns the material to the original A…
An x-ray diffraction investigation of sulphide spinels
Samples of the metallic spinels CuCr 2 S 4 and CuCo 2 S 4 have been prepared and examined by x-ray diffraction. In each case the spinel pattern was accompanied by a number of weak foreign reflections consistent with the presence of a single impurity phase, identified as γ-CuCrS 2- x and CoS 2 respectively. Careful str…
The Morphology of Anodic Films Formed on Aluminium in Oxalic Acid
SummaryElectron microscopy of carbon replicas taken from outer surfaces, sections and cell base patterns of anodic films, formed in oxalic acid, has enabled relationships between the main film parameters of barrier layer thickness, cell size and pore diameter to be quantified and related to the anodizing variables. In…
Aluminium corrosion studies. I. Potential-pH-temperature diagrams for aluminium
The potential-pH-temperature relationships for the aluminium-water system have been calculated by the methods of de Bethune, Khodakovskiy, Criss and Cobble, and Helgeson and a critical comparison made. The Criss and Cobble method produced the most consistent results and was used to construct a corrosion diagram for th…
Crystal structure of sodium tetratungstate, Na2W4O13
The structure of Na2W4O13 has been determined by Patterson and Fourier methods from 426 independent reflections measured photographically. The basic units, consisting of four edge-shared octahedra, are linked along two crystallographic directions by corner sharing to form octahedral layers, which are held together by…
The role of mosaic block structure on onset of deformation and fatigue of bulk crystallized polyethylene
The influence of the mosaic block structure of bulk-crystallized high-density polyethylene upon deformation within the elastic limit and upon fatigue phenomenon has been extensively studied in the temperature range of the α relaxation mechanism. The magnitude of elastic limit, estimated from two models involving a til…
Recent Survey of Catalysis by Solid Metal Sulfates
The relationships between the surface properties of ionic salts, in particular metal sulfates, and their catalytic activities have intrigued us for some time [l]. They offer a useful model for linking homogeneous to heterogeneous catalysis. A metal sulfate, for example NiSO4·7H2O, develops a significant degree of acid…
Covalent character of lithium compounds studied by X-ray photoelectron spectroscopy
Fifteen lithium compounds have been studied as powders and very thin films, and all of them have been found to undergo photoreduction to varying degrees. Photoreduction leads to the formation of lithium oxide and lithium metal which exhibit clear peaks in the X-ray photoelectron spectrum. The presence of lithium compo…
Solid/solution interface equilibria for aromatic molecules adsorbed from non-aromatic media. Part 2.—Aromatic carboxylic acids
Data have been obtained for benzoic acid, 1-naphthoic acid and 2-naphthoic acid adsorption on the carbon blacks Graphon and Spheron 6, and on the oxides Alcoa C730, Alon C, titanium dioxide and Cab–O–Sil using some or all of the solvents cyclohexane, carbon tetrachloride and cyclohexanone. Individual isotherms were ca…
Complex formation between 4,9-diazadodecane-1,12-diamine (spermine) and copper(II) ions and protons in aqueous solution
Equilibrium constants are reported for protonation of the linear tetra-amine 4,9-diazadodecane-1,12-diamine (4,9NH-ddd) and for formation of the complexes [CuL]2+ and [Cu(HL)]3+(L = 4,9NH-ddd) at I= 0·1M-NaCl and 25 °C. The bis(propane-1,3-diamine) complex, [Cu(prd)2]2+, and that formed by the title ligand are of simi…