Materials Literature
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Abstract The new hydrotalcite-like compounds which consist of divalent metal, trivalent metal and inorganic or organic anion were synthesized and it was found that they have many characteristic properties such as the formation of solid solutions, anion exchange and molecular sieving. Some of them were capable of separ…
Properties relating to the effects of thermal expansion anisotropy were measured as functions of grain size in hot‐pressed dense MgTi 2 O 5 . Samples with grains smaller than ∼3 μm exhibited none of the microcracking attributed to thermal expansion anisotropy, whereas those with larger grains had all the characteristi…
A mechanism is proposed to explain depolarization phenomena that have been observed in thin ferroelectric films and related multilayer devices. It is shown that, for a short-circuited electrode-ferroelectric structure, incomplete compensation of the ferroelectric polarization charge results when the center of gravity…
The concept of crystal ionicity has proved to be a useful unifying concept for understanding chemical trends in diverse problems in chemistry and solid state physics. In particular, the dielectric description of ionicity developed by Phillips and Van Vechten (PV) has been successfully employed in a wide variety of are…
Polymers containing bulky side groups linked in ring form to the main chain are distinguished by a specific set of properties (cardopolymers). The review deals with the characteristics of the synthesis and with the physicochemical properties of cardopolycarbonates, cardopolyarylates, cardopolyamides, cardopolyimides,…
Factors which determine localisation and autolocalisation in topochemical processes are considered systematically in this review. The specific features of the formation and growth of nuclei in topochemical reactions, the role of the anisotropy of the properties of the initial crystal, and various versions of the catal…
We report here evidence for the first paraferroelectric transition observed in a pure molecular solid (without H bonds); we present results from x-ray diffraction, calorimetric and dielectric measurements, and direct optical observation of domain-wall displacement under an applied electric field.
By using LEED and workfunction measurements it has been found that a previously reported c(2*2) structure for Cs on W(100) was due to a small amount of H accumulated on the surface at the beginning of Cs deposition. These H atoms, in the presence of Cs, form patches of c(2*2).
PrAlO 3 has the cubic perovskite structure at high temperatures but is trigonally distorted at room temperature. At about 200 K it undergoes a first-order phase transition to an orthogonal phase, and there is a further phase transition to a triclinic phase at about 150 K. The authors have studied this system by Raman…
An anomaly in the electrical resistivity is observed in the vicinity of the order-disorder transition in an alloy of composition near ${\mathrm{Fe}}_{3}$Al, which is of the form predicted by Suezaki and Mori for antiferromagnets and, hence, order-disorder systems. The anomaly is qualitatively different from the "ferro…
A full spherical retarding-field energy analyser with three grids was made to measure the total secondary electron yield σ, the backscattering coefficient η, and the secondary electron spectrum N(E) as a function of angle of incidence and primary energy in UHV. The instrumental effects of the grid meshes in the measur…
Abstract The synthesis of 2‐oxa‐6‐aza‐adamantane ( 21 ) and several of its derivatives ( 13–20 , 22 , 23 , 25–34 , 37 , and 38 ) was achieved starting from the 9‐azabicyclo[3.3.1]nona‐2,6‐ dienes 2 , and 3 , and 9‐oxabicyclo[3.3.1]nona‐2,6‐diene ( 1 ).
Abstract Acenaphthylene, C12H8, occurs in space group Pbam (or Pba2) at room temperatures (23 °C) with a = 7.705 (5), b = 7.865 (5), c = 14.071 (5) Å and Z = 4, and is disordered. At about 130 K it undergoes a reversible transition to space group P21 nm with a = 7.588 (13), b = 7.549 (10), c = 27.822 (2) Å and Z = 8 (…
Single crystals of synthetic quartz, plastically deformed at atmospheric pressure and at high temperatures, have been examined in the electron microscope at 100 and 200 kV respectively. Tangles of dislocations are revealed in specimens compressed at temperatures below 800°C. Above this temperature, the dislocations pr…
Values for the ionization energies of the neutral actinides have been derived by utilizing interpolated spectral properties of these atoms. The results in electron volts are Ac: 5.17(12); Th: 6.08(12); Pa: 5.89(12); U: 6.05(7); Np: 6.20(12); Pu: 6.06(2); Am: 5.993(10); Cm: 6.09(2); Bk: 6.30(9); Cf: 6.41(10); Es: 6.52(…
The effect of uniaxial stress on the first-order Raman spectra of the cubic crystals, Ca${\mathrm{F}}_{2}$, Ba${\mathrm{F}}_{2}$, and ${\mathrm{Bi}}_{12}$Ge${\mathrm{O}}_{20}$ is studied at $\ensuremath{\sim}15$ \ifmmode^\circ\else\textdegree\fi{}K using a quantitative-stress cryostat. Both Ca${\mathrm{F}}_{2}$ and Ba…
The polarized light scattering spectrum from a dilute solution of spherical macromolecules is customarily interpreted on the basis of independent particle diffusion. However, it is known that diffusion in such a system is governed by a many particle diffusion equation with cross-diffusion coefficients Dij that depend…
We have observed the EPR spectra of As acceptors in both natural Mo${\mathrm{S}}_{2}$ crystals ($2H$ polytype) and in synthetic Mo${\mathrm{S}}_{2}$ crystals ($3R$ polytype). The $g$ values of the resonance signals show that the As acceptors are associated with a band that has ${d}_{{z}^{2}}$ orbital character. Energy…
Luminescence studies are reported on compounds M(IV)X2P: M is Si, Ge, Sn, Pb; X is F, Cl, Br, I, OH, benzoate; P is etioporphyrin or octaethylporphin. (One tetraphenylporphin is reported for comparison.) We find fluorescence yields 2 × 10−1 ≥slant φf ≥slant 2 × 10−4; phosphorescence yields 7 × 10−2 ≥slant φp ≥slant 3…
X-ray photoelectron spectra (XPS) of the valence bands of crystalline and amorphous As, Sb, and Bi have been measured. The results are compared with band-structure calculations for the crystalline materials. A splitting, $\ensuremath{\Delta}E$, of the "$s$-like" peak for the crystalline phase disappears in the amorpho…