Mitsuo Machida

Crystal Structure of Deuterated Dicalcium Strontium Propionate, Ca2Sr(C2D5CO2)6 in the Paraelectric and Ferroelectric Phases

The absolute crystal structure of the deuterated dicalcium strontium propionate (DDSP) has been determined by the X-ray diffraction with a four-circle automatic diffractometer at three temperatures in each of the paraelectric and ferroelectric phases. The space group is determined to be D 4 4 -P4 1 2 1 2 or D 4 8 -P4 3 2 1 2 in the paraelectric phase with the R -factors less than 3% and to be C 4 2 -P4 1 or C 4 4 -P4 3 in the ferroelectric phase with the R -factors less than 5%. The molecular structure of the deuterated propionates is also elucidated and compared with that of the nondeuterated one. The comparison confirms the structure quite similar to each other, indicating no isotope effect on the molecular structure. The disordered arrangement of the propionate molecules on (001) plane is observed in the ferroelectric phase similarly to the nondeuterated DSP.

NMR Investigation on Isotope Effect of Glycinium Phosphite H3NCH2COOH·H2PO3

The motions of the phosphite anions and glycinium cations in H 3 NCH 2 COOH·H 2 PO 3 (GPI) and its deuterated analogue (DGPI) were investigated by 1 H, 13 C and 31 P spin–lattice relaxation times T 1 . For both GPI and DPGI, T 1 s of the 1 H, 13 C and 31 P nuclei reflect the amino rotation, methylene libration and motion of the phosphite anions, respectively. Activation energies obtained from T 1 s of 1 H, 13 C and 31 P nuclei are 28.6(2), 26.0(4) and 26.2(4) kJ/mol for GPI and are 34.9(6), 27(1), 47(2) kJ/mol for DGPI, respectively. The deuterium substitution increases E a for the motion influenced by the hydrogen bonding. In all the observed motions, correlation times of DGPI are larger than those of GPI.

Neutron Diffraction Study of Crystal Structures of Deuterated Glycinium Phosphite in Paraelectric and Ferroelectric Phases

Crystal structure of deuterated glycinium phosphite was studied in the paraelectric (P) phase at 348 K and in the ferroelectric (F) phase at 223 K by means of the single crystal neutron diffraction...

X-Ray diffraction and NMR studies on the crystal structures of MABB and MABA at room temperature

Abstract We have investigated the structures of (CH3NH3)3Bi2Br9 (MABB) and (CH3 NH3)3Sb2Br9 (MABA) crystals by X-ray Fourier method and high resolution 15N-NMR in their prototypic phases. A doublet with intensity ratio 2:1 was observed in the NMR spectrum of MABB. The methyl ammonium cations also showed different electron density distributions at two non-equivalent sites. The distribution was examined in connection with splitting of the Br atoms and the NMR results.

Neutron structural investigation of the isotope effect of KHCO3

Abstract The crystal structures of KHCO3 and KDCO3 have been analyzed from the three-dimensional neutron-diffraction data measured in the high-temperature phase. In the space group C2/m (Z = 4), both the structures are refined successfully with a disordered model. The final R-factors are 0.055 for KHCO3, and 0.047 for KDCO3, respectively. Fourier analysis also reveals that the proton of KHCO3 and deuteron of KDCO3 have two-equilibrium positions separated by 0.616(4) and 0.647(3) A, respectively.

31P-NMR Study of Phase Transition in Betaine Phosphate (CH3)3NCH2COO·H3PO4 at 365 K

The phase transition in (CH 3 ) 3 NCH 2 COO·H 3 PO 4 at T C1 =365 K was studied by 31 P-NMR. Spin–lattice relaxation time shows a sharp dip at T C1 due to the critical slowing down. The critical relaxation rate is reproduced by the quasi-one-dimensional Ising model with antiferroelectric interactions along both the intrachain and interchain directions. The interaction parameters for intrachain J || and interchain J ⊥ are determined to be 693(3) and 4.1(1) K, respectively.

NMR Study of Phase Transitions in Betaine Phosphite (CH3)3NCH2COOH·H2PO3

The phase transitions in (CH 3 ) 3 NCH 2 COOH·H 2 PO 3 at T C1 =355 K and at T C2 =216 K were studied by nuclear magnetic resonance. Spin–lattice relaxation time T 1 of the 13 C nucleus in the CH 3 group shows two-mode behavior without showing anomaly in the both phase transitions. Activation energies are determined to be 23.1(9) and 1.3(2) kJmol -1 for two modes. T 1 of the 13 C nucleus in the CH 2 group exhibits a shallow dip around T C1 , suggesting that the motion of the CH 2 group slows down more or less at T C1 . T 1 of the 31 P nucleus takes a minimum at 253 K and activation energy is obtained as 12.6(2) kJmol -1 . In addition to the T 1 minimum, this shows a sharp dip at T C1 due to the critical slowing-down of the HPO 3 2- motion. The incomplete slow-down of the CH 2 motion is considered to be induced by the coupling with the disorder of the HPO 3 2- anion. The critical relaxation rate of the 31 P nucleus is well reproduced by the quasi-one-dimensional Ising model. Interaction parameters for intr...

Observations of the Ferroelastic Domain Structure of MP5O14 (M: La-Tb) by means of Scanning Tunneling Microscope, Electron Spin Resonance and X-Ray Diffraction.

The ferroelasticity of rare earth pentaphosphate, MP5O14 (M: La-Tb) belonging to the species mmmF2/m is studied by scanning tunneling microscope (STM), electron spin resonance (ESR) and X-ray diffraction. The temperature dependence (from room temperature to 180°C) of ferroelastic domain structure and monoclinic β angle of EuP5O14 was obtained by STM and X-ray diffraction (ω scan technique). The spin Hamiltonian parameters of LaP5O14:Cr3+ at 150°C in the para phase obtained from the ESR spectra are gx= gy= gz=1.97, D = 0.45 cm-1 and E = 0.05 cm-1. The principal axes of one of the Cr3+ paramagnetic centers are given by the Eulerian angles =15°, θ=90° and ψ= 0°.

Isotope Effect of Glycinium Phosphite NH3CH2COOH·H2PO3 Studied by Neutron Diffraction

To study the isotope effect of glycinium phosphite (GPI), temperature dependences of the 5 0 \bar6 and 3 0 \bar10 structure factors of GPI and the 11 0 \bar3 and 9 0 \bar8 structure factors of deuterated GPI (DGPI) were analyzed in the ferroelectric phase by using the quasi-one-dimensional Ising model. The Ising model reproduces well the behavior of all the structure factors in the wide temperature region. The parameters for the intrachain and interchain interactions are determined to be 312 and 7.1 K for GPI, and 477 and 8.4 K for DGPI on average, respectively.

NMR study of ferroelectric liquid crystal DOBAMBC

Molecular rotational motion in ferroelectric liquid crystal DOBAMBC (p-decyloxybenzylidene p′-amino 2-methyl butyl cinnamate) was studied in the smectic A (SmA) and chiral smectic C (SmC*) phases by 13 C-NMR. Spin-lattice relaxation times T 1 of the aromatic carbons at the ortho-positions reflect the rotational motion about the long molecular axis in the liquid crystal phases. Obtained activation energy in the SmC* phase is smaller than that in the SmA phase, indicating that the rotational motion becomes less hindered in the SmC* phase.