Ryôiti Kiriyama

Nuclear Magnetic Resonance and X-Ray Studies of Potassium Ferrocyanide Trihydrate Crystal

The atomic coordinates of one previously unknown water oxygen in potassium ferrocyanide trihydrate are determined by X-ray structure analysis in the paraelectric phase at room temperature. In K 4 Fe(CN) 6 ·3H 2 O and its isomorphous K 4 Ru(CN) 6 ·3H 2 O proton magnetic resonance patterns start to narrow at about -140°C, and definite change in both spectra occurs in the same temperature region around -40°C, about twenty degrees below the respective Curie points. Angular dependence of peak separations has been measured at liquid nitrogen temperature where all water molecules are effectively rigid. Direction angles of three proton-proton vectors with respect to the crystallographic a , b and c axes are, respectively, α 0 =134°, β 0 =49°, γ 0 =73°; α 0 =90°, β 0 =90°, γ 0 =0° and α 0 =0°, β 0 =90°, γ 0 =90°. A possible molecular mechanism for the ferroelectric origin is discussed.

Electrical and Magnetic Properties of Cu3Se2 and Some Related Compounds

The electrical conductivity and magnetic susceptibility of binary compounds CuxSe (x=2.0, 1.8, 1.5, 1.0 and 0.5) and CuxS (x=1.8 and 1.0) were studied over the temperature range from -150°C to 150°C. These compounds are near metallic conductors with resistivities of 100 to 6000µΩcm. It is found that Cu3Se2 may be antiferromagnetic, while the others are diamagnetic or weakly paramagnetic. A qualitative discussion is presented on the basis of the valencies of constituents and coordination configurations in order to explain the physical properties of these substances.

Nuclear Magnetic Resonance Experiment on the Single Crystals of K2HgCl4·H2O and K2SnCl4·H2O. II, The resonance absorption due to four proton system and the revised determination of their crystal structures

The energy levels and the transition probabilities are calculated for four proton interaction. The result of calculation is applied to the case of the single crystals of K 2 HgCl 4 ·H 2 O and K 2 SnCl 4 ·H 2 O. Ten absorption lines are expected from the theoretical calculation, of which each five form a group. Since in general cases the separations between the lines belonging to one of these groups are small compared to the separation between these groups as a whole, the expected resonance figure roughly coincides with the case of two proton resonance. But the shapes of resonance peaks have further fine structures. The observed fine structures were analysed by the theoretical consideration, and it is shown that the agreement between the theory and the experiment is satisfactory, if we take the distance of main protons to be 1.607 A and the distance between the proton-proton lines for adjacent water molecules which are parallel with each other to be 3.60 A in the case of Hg-salt and 1.62 A and 3.90 A respe...

Nuclear Magnetic Resonance Experiment on the Single Crystals of K2HgCl4·H2O and K2SnCl4·H2O. Part I

Proton magnetic resonances of water molecules in the single crystals of K 2 HgCl 4 ·H 2 O and K 2 SnCl 4 H 2 O were observed, and the distance and the direction of proton-proton line in each of water molecules in the unit cell were determined. The absorption lines are generally composed of four component lines, of which the separation varies with the direction of the externally applied magnetic field. These results are fairly well explained with the Pakes formula for two-proton system and by the fact that there are two different p-p directions in these crystals. The p-p distance in a water molecule determined in this experiment is 1.607 A, and the angles between the a -axis and p-p lines which lie on the plane parallel to the c -plane are ±21.4° for Hg-salt, and 1.62 A and ±39.5° respectively for Sn-salt. Each component line has further fine structures when the external field is applied to some particular directions. This cannot be explained by the assumption of two-spin system only, but understood by in...

PROTON AND CHLORINE SPIN-LATTICE RELAXATION IN α-NH4HgCl3

The spin-lattice relaxation times of 1H and 35Cl as well as the 35Cl NQR frequencies in α-NH4HgCl3 are reported. The proton T1 data are explained in terms of C3 reorientation and S4 flip of NH4+ ions. The latter mode is also largely responsible for the 35Cl quadrupole relaxation rate. A marked change in the proton T1 at 55 K indicates a phase transition, ascribable to the ordering of the NH4+ ions.

Dielectric Phenomena of Low Quartz

Temperature and frequency dependences of the dielectric constant and loss of a transparent single crystal of Brazilian quartz were measured for both directions parallel and perpendicular to its c-axis from -70° up to 600°C. and in the frequency range between 0.3 kc and 3 Mc by a C.R. bridge and a Q meter. Direct current electric conductivity was also measured from temperature up to 500°C. The enthalpy of activation for the dielectric relaxation was 21.3 kcal/mole and the activation energy for the d.c. conduction was 17.84 kcal/mole.Infrared absorption spectra of the Brazilian quartz and a smoky quartz showed marked dichroism in the neighbourhood of O-H stretching vibration, 2.7-3μ in every case, but the absorption feature was distinctly different. To compare these data with those for other silicate minerals, electric measurements were carried out for smoky quartz, vein-quartz, beryl and cordierite.The most probable explanations for the molecular mechanism of such electric phenomena of quartz are deduced as follows :1) Water molecules or OH ions and Na ions are trapped in some lattice defects being surrounded certain anisotropic crystalline fields.2) When the temperature rised and an external electric field is applied, the water molecule can be orientated loosening the binding interactions due to O-H…O type hydrogen bonds and an ion-dipole interaction between Na-OH2. This energy of activationis about 21 kcal/mole.3) Just then the Na ion can be diffusible to the external field direction breaking away from the restriction. Therefore, the activation energy of diffusion is almost identical to that of the dielectric relaxation.4) Direct current conduction does not necessarily imply long-range diffusion of ions, but may appear as the result of successive, relative displacement of ions in the lattice. This activation energy must be smaller than that of diffusion. It may correspond to the activation energy of d. c. conduction of about 18 kcal.