Kunio Ozawa

Effect of Hydrostatic Pressure on the Phase Transitions in Ferroelectric Ca2Sr(C2H5COO)6 and Ca2Pb(C2H5COO)6

Effects of hydrostatic pressure on the phase transitions in ferroelectric Ca 2 Sr(C 2 H 5 COO) 6 and Ca 2 Pb(C 2 H 5 COO) 6 were studied by dielectric constant measurements in a temperature range of -100∼ +200°C and a pressure range up to about 8.5 kbar. The I-II transition temperatures (8.7°C in the Sr-salt, 60.4°C in the Pb-salt at 1 atm) monotonically increase with increasing pressure with initial slopes of 19.7 deg kbar -1 for the Sr-salt and 23.4 deg kbar -1 for the Pb-salt, respectively. The II-III transition temperatures (-173°C in the Sr-salt, -88°C in the Pb-salt at 1 atm) increase with increasing pressure, and the first order II-III phase boundaries terminate at critical points of p crit =3.35 kbar; T crit =-35°C in the Sr-salt, and p crit =1.73 kbar; T crit =-41°C in the Pb-salt, respectively. A sharp maximum of low frequency dielectric constant was found at the critical point of the Pb-salt.

Change in the Order of the Phase Transition in Ferroelectric Triglycine Selenate at High Pressures

Dielectric constant of ferroelectric triglycine selenate was measured at hydrostatic pressures around 5 kbar in the vicinity of the Curie temperature. A discontinuous charge of the dielectric constant at the Curie temperature and a thermal hysteresis of the transition (typically about 0.2°C at 5.28 kbar) were found. The result indicates that the order of the ferroelectric transition changes from second to first order by application of hydrostatic pressure. Unusual dielectric properties of TGSe at high pressures so far reported can be interpreted on the basis of the order-change in the transition.

Critical points of the II-III transitions in Ca2Pb(C2H5COO)6 and Ca2Sr(C2H5COO)6

Abstract Critical points at which the first order nature of the II–III transition completely disappears were found at −40.5°C, 1.75 kbar for Ca 2 Pb(C 2 H 5 COO) 6 and at −33°C, 3.4 kbar for Ca 2 Sr(C 2 H 5 COO) 6 .

Dielectric Study on the Effect of Hydrostatic Pressure on the Phase Transitions in the System of {(NH4)3H(SO4)2}1-x{(ND4)3D(SO4)2}x

The concentration-pressure-temperature three dimensional phase diagram of {(NH 4 ) 3 H(SO 4 ) 2 } 1- x {(ND 4 ) 3 D(SO 4 ) 2 } x system was studied by means of dielectric measurements in a pressure-temperature range of \(p{\lesssim}10\) kbar and -100^°\(C{\lesssim}T{ 0.90 show the ferroelectric VI phase even at atmospheric pressure. A good correspondence between the effects of hydrostatic pressure and deuterium-substitution was established as regards the stability of the ferroelectric phases. Two pressure-induced phases (Phases VIII, IX) were newly observed in the normal-deuterated mixed crystal system.

Pressure-Temperature Phase Diagram of Triammonium Hydrogen Disulfate (NH4)3H(SO4)2

The pressure-temperature phase diagram of (NH 4 ) 3 H(SO 4 ) 2 was studied by means of dielectric and differential thermal analysis measurements in a range of \(p{\lesssim}8.5\) kbar, –100°C \({\lesssim}T{\lesssim}\)150°C. The I-II transition point (140°C at 1 atm) linearly decreases with increasing hydrostatic pressure with a slope of -5.76 deg kbar -1 . The pressure dependence of the II-III transition point is expressed by a quadratic equatuon T c = T 0 c + K p +γ p 2 with parameters of T 0 c =-8.1^° C , K =-3.7 deg kbar -1 , and γ=-0.13 deg kbar -2 . Two pressure-induced ferroelectric phases (Phases VI, VII) are found above about 5 kbar. The II-III-VI triple point is found at p =7.0 kbar, T =-40.5^° C .

DEUTERIUM ENRICHMENT DURING ION BOMBARDMENT IN VD0.01 ALLOYS

Abstract The deuterium concentration near the surface of vanadium containing 1 at.% D is found to increase gradually during the bombardment of 300 ∼ 750 keV helium ions. The depth profile of deuterium is obtained by the energy analysis of α-particles emitted from the nuclear reaction D(3He, α)H. The depth profile of radiation induced defects is also obtained by analyzing the channelling behavior of 0.8 MeV deuterons. Both depth profiles exhibit good correspondence, indicating the trapping of deuterium by radiation induced defects. The change in deuterium concentration near surface with ageing after helium bombardment is measured at temperatures between room temperature and 100°C, being more or less reversible with the change in ageing temperature. The binding energy of deuterium with defects is estimated to be (0.11 ± 0.02) eV.

Channeling studies on the trapping of deuterium in vanadium by oxygen interstitials

Abstract Ion channeling studies using ion-induced nuclear reactions have been made on single crystals of VD 0.005 , VD 0.01 , VO 0.02 D 0.01 , VO 0.01 D 0.02 , VO 0.03 D 0.04 and VO 0.02 to examine deuterium-oxygen clustering. Channeling angular distribution measurements indicate that some deuterium atoms are trapped at the octahedral interstices in the host lattice when they coexist with oxygen atoms. The result contrasts with the tetrahedral occupancy of deuterium in pure vanadium. This is the first direct evidence of deuterium atoms being trapped by oxygen atoms in metal.

Pressure-Temperature Phase Diagram of Ferroelectric Ammonium Bisulfate NH4HSO4

The pressure-temperature phase diagram of ferroelectric NH 4 HSO 4 was studied by means of dielectric and differential thermal analysis (DTA) measurements in a pressure and temperature region of \(p{\lesssim}8\times10^{3}\) kg cm -2 , –120°C \({\lesssim}T{\lesssim}\)200°C. The high pressure phase found by Bridgman above about 1×10 3 kg cm -2 at room temperature is proven not to be identical with the low temperature non-ferroelectric phase (Phase III) at 1 atm. The liquidus line was newly determined by DTA. A new high pressure phase (Phase VI) was found above 4×10 3 kg cm -2 just below the melting point. A change in the order of the transition at the upper Curie point was found at about 0.6×10 3 kg cm -2 .

Effect of Hydrostatic Pressure on the Phase Transitions in Monoclinic and Tetragonal RbD2PO4 Crystals

The effect of hydrostatic pressure was studied for the phase transitions in the two forms of RbD 2 PO 4 ; monoclinic (ferrielectric) and tetragonal (ferroelectric) crystals. In monoclinic crystal, the I-II and II-III transition temperatures mono-tonically decrease with increasing pressure, and the phase boundaries are represented by a quadric form of T c = T 0 c + K p +γ p 2 with the parameters of T 0 c , K , and γ being 102.5°C, -50 deg GPa -1 , -39 deg GPa -2 for the I-II transition and 41.8°C, -24 deg GPa -1 , -15 deg GPa -2 for the II-III transition, respectively. A pressure-induced phase of IV was newly observed above about 0.7 GPa. The transition to phase IV shows marked first order character. In tetragonal RbD 2 PO 4 , the ferroelectric Curie temperature monotonically decreases with increasing pressure with the initial slope of -47 deg GPa - 1 . The slope of the Curie temperature against pressure seems to decrease as pressure increases above about 0.3 GPa.

Spectral data and grotrian diagrams for highly ionized titanium, Ti V–Ti XXII

Abstract Wavelengths, energy levels, level configurations, oscillator strengths, and radiative transition probabilities for the titanium ions Ti V to Ti XXII are critically reviewed and tabulated. Grotrian diagrams are also presented to provide a graphical overview.