Akio Miyazaki

Acoustic Phonon Softening and Spontaneous Strains in KD3(SeO3)2

Ultrasonic velocities at 5 and 10 MHz and spontaneous strains of KD 3 (SeO 3 ) 2 were measured and the results were compared with those for KH 3 (SeO 3 ) 2 . Elastic constants were obtained from the velocity data. The phase transition of KD 3 (SeO 3 ) 2 accompanies an instability of the soft s 44 mode alone, as in the case of KH 3 (SeO 3 ) 2 . Deuteration yields no significant isotope effect in the Curie-Weiss constant C s , although it gives large isotope effect in the transition temperature T c .

Ferroelastic Domain of (CH3NH3)4InCl7 and Its Phase Transitions

Optical observation of domain structure, differential thermal analysis, dielectric and dilatometric measurements of (CH 3 NH 3 ) 4 InCl 7 have been carried out over a temperature range from 25°C to 200°C. It has been found that the crystal undergoes phase transitions at 194°C ( T 1 ) and 190°C ( T 2 ), and is ferroelastic below T 1 . Taking account of the strain-compatibility relations for domain boundaries, it is suggested from the result of optical observation that the crystal symmetry is m m m , 2/ m and 2/ m in order of descending temperature.

Dielectric, Dilatometric and AC Calorimetric Studies of a New Phase Transition in (CH3NH3)NaSO4·6H2O

Dielectric, dilatometric and AC calorimetric properties of (CH 3 NH 3 )NaSO 4 ·6H 2 O in addition to a preliminary X-ray examination were investigated. The crystal at room temperature belongs to 6 mm with the unit cell parameters: a =7.25 A, c =12.93 A and Z =2. It was found that the crystal undergoes a phase transition of the second order at -133.8°C ( T c ). The dielectric constant along the a axis shows an anomalous break at T c , while the dielectric constant along the c axis does not show a remarkable anomaly near T c . Both the anomalous linear thermal expansion coefficient and the relative specific heat observed in the critical temperature region were discussed shortly.

Dielectric and Elastic Studies of the Phase Transition in NaNH4SeO4·2H2O

The dielectric constant of NaNH 4 SeO 4 ·2H 2 O along the c axis under stress-free and clamped conditions, e 33 f and e 33 c , were experimentally determined, and its elastic stiffnesses under constant electric field and constant electric polarization conditions, c 66 E and c 66 P , and other elastic stiffnesses were also determined experimentally. It was clarified that both e 33 c and 1/ c 66 P ( s 66 P ) follow the Curie-Weiss law, but the phase transition in NaNH 4 SeO 4 ·2H 2 O is caused by predominant dielectric instability more than elastic instability. It was predicted basing on the Landau theory that one of three elastic shear stiffnesses, c 66 E , shows discontinuous behaviour at the Curie temperature T c , but the other two, c 44 E and c 55 E , show continuous behaviours at T c , if the phase transition is of first order. The prediction was confirmed to be the case by the experimental results.

First report of bacterial leaf blight on cosmos (Cosmos bipinnatus Cav.) caused by Pseudomonas cichorii in Japan

Since 2006, a commercial grower in Japan has noted a leaf blight symptom on potted cosmos plants grown in a field. In August 2012, a Pseudomonas-like bacterium was isolated from the symptomatic leaves and found to cause the same symptom on cosmos seedlings after inoculation. On the basis of bacteriological and phylogenetic analyses, the causative bacterium was identified as Pseudomonas cichorii. This is the first report of bacterial leaf blight on cosmos caused by P. cichorii in Japan.

Dielectric and Elastic Properties of NaNH4SO4·2H2O above Its Curie Temperatute

The dielectric constant of NaNH 4 SO 4 ·2H 2 O at 10 kHz and 9.4 GHz, and its elastic stiffnesses at constant electric field (1/ s 66 E ) and at constant electric polarization (1/ s 66 P ) have been measured as functions of temperature above the Curie temperature ( T c ). It is observed that both the dielectric constant of a clamped crystal e 33 c . and the elastic compliance s 66 P follow the Curie-Weiss law, as in the cases of the dielectric constant of a stress-free crystal e 33 f and the elastic compliance s 66 E . It is found that the extrapolated Curie temperature T 0 is -300 K for s 66 P and 6 K for e 33 c . The experimental results are discussed shortly on the basis of the Landau theory.

Dielectric, Elastic and Thermal Properties on a New Phase Transition in (CH3NH3)NaSeO4·6H2O

Dielectric, ultrasonic, AC calorimetric and dilatometric measurements for (CH 3 NH 3 )NaSeO 4 ·6H 2 O in addition to an X-ray examination were made. It was found that the crystal undergoes a phase transition of the second order at 136.9 K ( T c ). The crystal at room temperature belongs to a point group 6 m m with the unit cell parameters: a =7.36 A, c =13.0 A and Z =2. Both the specific heat C p and the linear thermal expansion coefficients along the a and c axes, α 11 and α 33 , show λ-type anomalies with anomalous tails near T c . The dielectric constant along the a axis shows an anomalous break at T c . The dielectric constant along the c axis and the elastic stiffnesses c E 33 , c E 44 and c 66 do not show remarkable anomaly at T c , while c E 11 shows a small anomaly near T c , which corresponds to the λ-type anomalies observed in both C p and α i i ( i =1, 3) near T c .

Dielectric and elastic properties of NaNH4 XO4 ˙ 2H2O (X=S,Se) near the Curie temperatures

Abstract The dielectric constants of NaNH4XO4 · 2H2O (X=S,Se) under stress-free and clamped conditions ϵf 33 and ϵC 33, and the elastic stiffnesses at constant electric field and constant electric polarization CE 66 and CP 66 were determined experimentally. It was shown that the phase transitions in both crystals are caused by predominant dielectric instability more than elastic instability, although both ϵC 33 and sP 66 (1/cP 66) follow the Curie-Weiss law. The phase transitions in both crystals are confirmed to be of first order.

First report of ‘Candidatus Phytoplasma malaysianum’ associated with Elaeocarpus yellows of Elaeocarpus zollingeri

Abstract“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma.

Dielectric Studies of NaNH4(SO4)1-x(SeO4)x·2H2O on the Phase Transition

Dielectric constants of a NaNH 4 (SO 4 ) 1- x (SeO 4 ) x ·2H 2 O system along the c axis under stress-free and clamped conditions were measured in a temperature range from -210°C to 30°C. Examinations of the pyroelectric current were also carried out. The dielectric constants under stress-free and clamped conditions followed the Curie-Weiss law above the phase transition temperature. It was therefore suggested that the phase transition of the NaNH 4 (SO 4 ) 1- x (SeO 4 ) x ·2H 2 O system is caused predominantly by dielectric instability. A phase diagram of the NaNH 4 (SO 4 ) 1- x (SeO 4 ) x ·2H 2 O system was established from the results of dielectric measurements. It was found that the phase transition temperature of the NaNH 4 (SO 4 ) 1- x (SeO 4 ) x ·2H 2 O system exhibits a minimum value of -200°C at x =0.3. The space group in the ferroelectric phase of NaNH 4 SO 4 ·2H 2 O was identified to be P 2 1 from the phase diagram.