Go toArchive
Browse byFacets
Bookbag ( 0 )
'Phase Transition' in keywords Facet   section ZfN Section A  [X]
Results  84 Items
Sorted by   
Publication Year
2001 (4)
2000 (19)
1999 (4)
1998 (9)
1997 (5)
1996 (5)
1995 (6)
1994 (10)
1993 (4)
1992 (4)
41Author    M. F. Mostafa, S. S. ArafatRequires cookie*
 Title    Dielectric Dispersion of New Ferroelectric Cobalt Halide Dimers: Bis-ethanolammonium-hexahalocobaltate, (C 2 H 8 NO) 2 Co 2 X 6 , X = CI/Br  
 Abstract    The AC conductivity in the frequency range 5.0 Hz -10.0 kHz, the magnetic susceptibility in a field of 14.7 and 17.810 4 A/m, and differential thermal analysis at 78 K up to room temperature for bis-(ethanolammonium)Co 2 X 6 ,X = CI and Br are reported. The bromide dimer undergoes an order-disorder transition at 302 K and a displacive type ferroelectric transition at T ~ 220 K. The chloride dimer shows two transitions, the first being in a displacive ferroelectric one at T ~ 210 K showing critical slowing down. The second phase transition, occuring at 282 K, is found to be inactive in the electric measurements. PACS: #76. 74 
  Reference    Z. Naturforsch. 55a, 595—604 (2000); received February 29 2000 
  Published    2000 
  Keywords    Dielectric Permittivity, Phase Transition, Ferroelctric Transition 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0595.pdf 
 Identifier    ZNA-2000-55a-0595 
 Volume    55 
42Author    Z. Czapla, S. Dacko, B. KosturekRequires cookie*
 Title    Ferroelectricity and Phase Transitions in Pyridinium Periodate Single Crystal  
 Abstract    Single crystals of pyridinium periodate were grown, and their physical properties were studied. Anomalies of the electric permittivity and birefringence were observed at T CL = 321 K and T C2 = 211 K. These observations gave evidences for the existence of three phases denoted as I, II, and III. Hysteresis loops were observed both in phase II and III. Pyroelectric measurements showed two anomalies at T CL and T C2 . The anomaly at T CL is related to the transition between a para-and ferroelectric phase, and the anomaly at T cl to the transition between two ferroelectric phases. 
  Reference    Z. Naturforsch. 55a, 891—894 (2000); received August 8 2000 
  Published    2000 
  Keywords    Phase Transitions, Ferroelecticity, Dielectric Properties, Birefringence 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0891.pdf 
 Identifier    ZNA-2000-55a-0891 
 Volume    55 
43Author    Albert Würflinger, M. Massalska-Arodż3, S. Urbanb, W. Weissflogc, S. EmstcRequires cookie*
 Title    Thermodynamic Measurements on the Binary System Bis{[2,2-di(w- hexyloxycarbonyl)ethenyl]phenyl} Biphenyl-4,4'-dicarboxylate and 4-w-Octyloxyphenyl 4-/i-Pentyloxybenzoate at Elevated Pressures  
 Abstract    Thermodynamic measurements have been carried out on the binary system of a swallow-tailed liquid crystal A = bis{[2,2-di(n-hexyloxycarbonyl)ethenyl]phenyl} biphenyl-4,4'-dicarboxylate (4DS6) and B = 4-n-octyloxyphenyl 4-rc-pentyloxybenzoate (5 0 /0 8). A filled smectic A phase is induced in the concentration range 0.11 < xA < 0.75. The maximum of the SmA-N transition temperature (365 K) is observed for xA = 0.33. Dilatometric measurements show that the packing density in the filled phases is increased. High-pressure DTA is employed in order to investigate the coexistence range of the liquid crystalline phases and the slopes of the transition lines. The slopes of the melting curves for the mixtures are significantly smaller than those for the pure components. The slopes for the smectic -nematic -isotropic transitions are considerably larger. The coexistence range for the (smectic + nematic) phases does not seem to be pressure-limited, rather it increases with pressure. 
  Reference    Z. Naturforsch. 56a, 658—662 (2001); received July 18 2001 
  Published    2001 
  Keywords    Phase Transitions, DTA, High Pressure, Swallow-tailed Liquid Crystals 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0658.pdf 
 Identifier    ZNA-2001-56a-0658 
 Volume    56 
44Author    Hideta Ishihara, Keizo Horiuchi, V. G. Krishnan, Ingrid Svoboda, Hartmut FuessRequires cookie*
 Title    Isolated versus Condensed Anion Structure VI: X-ray Structure Analysis and 81 Br NQR of Guanidinium Pentabromodicadmate(II), [C(NH 2 ) 3 ]Cd 2 Br 5 , fns-Hydrazinium Pentabromocadmate(II), [H 2 NNH 3 ] 3 CdBr 5 , and fo's-Hydrazinium Tetrabromocadmate(II)-Tetra Hydrate, [H 2 NNH 3 ] 2 CdBr 4 -4H 2 0  
 Abstract    The structure of the condensed bromocadmate anions in [C(NH 2) 3 ]Cd 2 Br 5 (1) and [H 2 NNH 3 ] 3 CdBr 5 (2) were studied at room temperature by X-ray diffraction. (1) crystallizes with double-chains bridged by Br atoms (orthorhombic, Pmmn, Z= 2, a = 1394.0(5), b = 394.5(1), c = 1086.9(5) pm). This chain structure was not described previously. (1) shows three 8 'Br NQR lines at temperatures between 77 and 323 K. Structural phase transitions take place at 283 K and at 535 K. (2) crystallizes with Br bridged zigzag-chains (monoclinic, P2[, Z=2,a = 943.1(1), b = 778.8(2), c = 942.0(2) pm, ß = 102.10(2)°) and shows a first-order phase transition around 304 K with a large thermal hysteresis. Below the transition point five 81 Br NQR lines are observed at temperatures between 122 and 304 K, and above the transition point four 81 Br NQR lines at tem-peratures between 288 and 353 K. Two 81 Br NQR lines are observed in [H 2 NNH 3 ] 2 CdBr 4 -4H 2 0 (3) at temperatures between 77 and around 320 K with positive temperature coefficients. 
  Reference    Z. Naturforsch. 55a, 390—396 (2000); received November 19 1999 
  Published    2000 
  Keywords    NQR, DSC, Crystal Structure, Phase Transition, Bromocadmate 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0390.pdf 
 Identifier    ZNA-2000-55a-0390 
 Volume    55 
45Author    Z. NaturforschRequires cookie*
 Title    An ESR Study of Structural Phase Transitions o f(N H ,)2Pb|C u(N 02)6|  
 Abstract    T etsuo Asaji, Laxm an S hrikrishna P ra b h u m irash i *, and D aiy u N ak a m u ra The structural changes o f (N H 4) 2P b [C u (N 0 2)6] crystals during the phase transitions at 316, 287, and 95 K were studied by means o f a single crystal ESR technique. Anisotropic g values [9 > 9±) were obtained in the lowest temperature phase IV, whereas the ESR spectra recorded in the intermediate phases III and II, in which the crystal is known to be tetragonally compressed along the c axis, could be interpreted by use o f effective g values [g (c) < g (_L c)]. In the highest temperature phase I an isotropic g value was obtained. The phases I, II, and III o f the present complex can be assumed to be very similar to the corresponding phases observed above ~ 250 K for the com pounds R2P b [C u (N 0 2) 6] with R = K, Rb, Cs, and Tl. However, the lowest temperature phase transition transforms the phase III with an antiferrodistortive order o f the elongated [C u (N 0 2)6]4_ octahedra into the phase IV with a ferrodistortive one. This occurs only for the complex with R = N H 4 and is very unusual. The results o f the 14N N Q R experiments already reported for the phases III and IV could be well explained by the present newly proposed model. 
  Reference    Z. Naturforsch. 41a, 1154—1158 (1986); received May 3 1986 
  Published    1986 
  Keywords    Magnetic Resonance (ESR, N Q R ), Phase Transition, Crystal Structure 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-1154.pdf 
 Identifier    ZNA-1986-41a-1154 
 Volume    41 
46Author    G. Schmitz, H. Klein, D. WoermannRequires cookie*
 Title    Spinodal Decomposition in a Polystyren/ Cyclohexane Solution of Critical Composition  
 Abstract    Results of experiments are reported demonstrating spi-noidal decomposition in a critical mixture of polystyrene and cyclohexane. If time and length are properly scaled using data obtained from static and dynamic light scattering exper­ iments, the time evolution of the "spinodal ring" is repre­ sented to a good approximation by an empirical equation proposed by Snyder and Meakin which describes spinodal decomposition for various types of systems. 
  Reference    Z. Naturforsch. 43a, 825—827 (1988); received June 24 1988 
  Published    1988 
  Keywords    Phase transition, spinodal decomposition, criti­ cal phenomena, polymer solution 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/43/ZNA-1988-43a-0825_n.pdf 
 Identifier    ZNA-1988-43a-0825_n 
 Volume    43 
47Author    Taro Eguchi, Koichi Mano, Nobuo NakamuraRequires cookie*
 Title     
 Abstract    p p lic a tio n o f M a x im u m E n tro p y M e th o d (M E M) f o r P r e c is e D e te r m in a tio n o f N Q R F re q u e n c ie s The maximum entropy method (MEM) is applied to the analysis of the closely spaced nuclear quadrupole resonance spectra of 35C1 in hexachlorobenzene and 14N in frarts-azobenzene. The superiority of the MEM to usual FFT spectra is discussed with respect to the precision of frequency measurements and the noise characteristics in broad and noisy NQR spectra. 
  Reference    Z. Naturforsch. 44a, 15—18 (1989); received November 3 1988 
  Published    1989 
  Keywords    Maximum Entropy Method, Nuclear Quadrupole Resonance, Phase Transition, Spec­ tral Analysis 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/44/ZNA-1989-44a-0015.pdf 
 Identifier    ZNA-1989-44a-0015 
 Volume    44 
48Author    Koji Yamada, Takashi Matsui, Tomoko Tsuritani, Tsutomu Okuda, Sumio IchibaRequires cookie*
 Title    I-NQR, 119 Sn Mössbauer Effect, and Electrical Conductivity of MSnI 3 (M = K, NH 4 , Rb, Cs, and CH 3 NH 3 )  
 Abstract    In a series of MSnI 3 compounds (M = K, NH 4 , Rb, Cs, CH 3 NH 3) two types of coordination around the central Sn(II) were found by 127 I-NQR and powder X-ray diffraction techniques. They are square pyramidal (for M = NH 4 , Rb) and octahedral (for M = CH 3 NH 3). CsSnI 3 , on the other hand, showed a drastic structural change of the anion at 425 K from a square pyramid to a regular octahedron. Associated with this phase transition, the electrical conductivity increased from 4xlO~ 3 Scm _1 to about 10 2 S cm" 1 . This metallic modification was characterized by 127 I-NQR and 119 Sn Mössbauer spectroscopy. 
  Reference    Z. Naturforsch. 45a, 307—312 (1990); received August 24 1989 in revised form October 28 1989 
  Published    1990 
  Keywords    NQR, Mössbauer effect, Perovskite compound, Phase transition, Electrical conductivity 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0307.pdf 
 Identifier    ZNA-1990-45a-0307 
 Volume    45 
49Author    V. P. Tarasov, G. A. Kirakosyan, K. E. German, Acad Sei, UssrRequires cookie*
 Title    Anomalous Temperature Dependence of the "Tc Quadrupole Coupling and Disordering of Cesium Positions in CsTc0 4  
 Abstract    A "Tc and 133 Cs solid-state NMR study of polycrystalline CsTc04 at a field of 7.04 T and temperatures from 90 to 430 K revealed first-order quadrupole effects. "Tc quadrupole coupling constant, Cq, shows anomalous positive temperature coefficients and decreases from 2.0 MHz at 430 K to 0.45 MHz at 90 K. The asymmetry parameter, rj ("Tc), is zero at 430 K and at 210 K. The high-temperature minimum of rj is associated with a phase transition from orthorhombic to tetrag-onal and the second minimum reflects an orientational change of the principal axes q xx and q yy of the EFG-tensor. The 133 Cs NMR spectra are characterised by a superposition of the two powder multiplets from the first-order couplings which arise from magnetically and crystallographically nonequivalent cesium sites, Cs (1) and Cs (2); the population ratio of Cs (2) and Cs (1), p2/p1, varies from 2.0 at 120 K to 6.5 at 373 K. The nonequivalence and population changes are attributed to the temperature change of the crystal field potential in the vicinity of the cations. 
  Reference    Z. Naturforsch. 47a, 325—329 (1992); received July 26 1991 
  Published    1992 
  Keywords    Technetium, Cesium, Solid State NMR, Quadrupole Effects, Phase Transitions 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0325.pdf 
 Identifier    ZNA-1992-47a-0325 
 Volume    47 
50Author    H. G. Kreul, R. Waldinger, A. WürflingerRequires cookie*
 Title    Differential Thermal Analysis and Dielectric Studies on Neopentanol under Pressure  
 Abstract    Differential thermal analysis (DTA) and dielectric measurements have been performed on 2,2-di-methyl-l-propanol (neopentanol) up to 200 MPa. Neopentanol exhibits at least one orientationally disordered (ODIC) phase (solid I) that transforms at lower temperatures to a non-plastic phase (solid II). There is evidence of a further ODIC phase denoted as solid I'. The pressure dependence of the phase transitions and the dielectric behaviour up to frequencies of 13 MHz are described. Activation enthalpies and volumes are derived from the dielectric relaxation time and compared with results for other alcohols. 
  Reference    Z. Naturforsch. 47a, 1127—1134 (1992); received July 27 1992 
  Published    1992 
  Keywords    High pressure, DTA, Phase transitions, Dielectric constant, and relaxation 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-1127.pdf 
 Identifier    ZNA-1992-47a-1127 
 Volume    47 
51Author    J. Reuter, T. Brückert, A. WürflingerRequires cookie*
 Title    Differential Thermal Analysis under Pressure on Cyanocyclohexane, 1,2,3,4-Tetrahydro-5,6-dimethyl-1,4-methanonaphthalene, and 2-Methyl-2-propanol  
 Abstract    Differential thermal analysis has been performed on cyanocyclohexane (CCH), 1,2,3,4-tetrahydro-5,6-dimethyl-1,4-methanonaphthalene (TDMN), and 2-methyl-2-propanol (t-butanol) up to 300 MPa. The latter compound was also investigated dielectrically. CCH displays an ODIC phase that transforms only reluctantly to the low-temperature stable phase II. Annealing under pressure can appreciably accelerate this transformation. For all three compounds the phase diagrams were established. For CCH and TDMN also the pressure dependence of the glass transition has been determined. 
  Reference    Z. Naturforsch. 48a, 705—708 (1993); received March 10 1993 
  Published    1993 
  Keywords    High pressure, DTA, Phase transitions, Glass transition, Dielectric constant 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0705.pdf 
 Identifier    ZNA-1993-48a-0705 
 Volume    48 
52Author    W. Medycki, R. Jakubas, N. Piślewski, J. LefebvreRequires cookie*
 Title    NMR and Dilatometric Studies on [N(CH 3 ) 4 1 3 M 2 X 9 (M = Sb, Bi; X = C1, Br)  
 Abstract    Thermal expansion studies on [N(CH 3) 4 ] 3 Sb-,Cl 9 and [N(CH 3) 4 ] 3 Sb 2 Br 9 are reported. The relax-ation times 'H T, were measured for [N(CH 3) 4 ] 3 Bi 2 Cl 9 , [N(CH 3) 4 ] 3 Sb 2 Br 9 , and [N(CH 3) 4 ] 3 Bi 2 Br 9 in the temperature range 100-290 K. To interpret the 7\ data on [N(CH 3) 4 ] 3 Bi 2 Cl 9 the method of Tj calculation reported by Takeda et al. has been applied successfully. Two different, inequivalent types of [N(CH 3) 4 ] 3 cations for all tetramethylammonium crystals are found. 
  Reference    Z. Naturforsch. 48a, 748—752 (1993); received January 31 1993 
  Published    1993 
  Keywords    Tetramethylammonium crystals, Phase transitions, Thermal expansion, 'H spin-lattice relaxation time 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0748.pdf 
 Identifier    ZNA-1993-48a-0748 
 Volume    48 
53Author    Günter RadonsRequires cookie*
 Title    Mechanisms for Phase Transitions in the Multifractal Analysis of Invariant Densities of Correlated Random Maps  
 Abstract    Multifractal properties of the invariant densities of correlated random maps are analyzed. It is proven that within the thermodynamical formalism phase transitions for finite correlations may be due to transients. For systems with infinite correlations we show analytically that phase transitions can occur as a consequence of localization-delocalization transitions of relevant eigenfunctions. 
  Reference    Z. Naturforsch. 49a, 1219—1222 (1994); received October 12 1994 
  Published    1994 
  Keywords    Fractals, Dynamical systems, Phase transitions, Stochastic automata, Random walk 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-1219.pdf 
 Identifier    ZNA-1994-49a-1219 
 Volume    49 
54Author    M. Ohga, F. M. Ostafa, A. Hmed, A. A. YoussefRequires cookie*
 Title    Dielectric Permittivity and AC Conductivity Investigation for the New Model Lipid Bilayer Material: (CH2)io(NH3)2CdCl4  
 Abstract    Differential thermal scanning of the new lipid-like bilayer material (CH2)io(NH3)2CdCl4 showed two structural phase transitions, with onset temperatures at T2 = (359 ± 2) K and 7, = (415± 1) K. Permittiv­ ity measurements were performed between room temperature and 450 K at 60-100 kHz. A step-like rise in permittivity at T2, associated with an order-disorder transition, is attributed to chain melting. Two anomalies at (413 ± 1) K and (430 ± 3) K, showing thermal hysteresis of -8 and 10 K, respectively, in­ dicate first order transitions which are associated with crystalline phase change. The AC conductivity follows an Arrhenius-type relation with the activation energy A£ varying with the frequency / according to the relation AE = A£0 [1 -exp where AE0,f0 and a are 0.95 eV, 52 Hz and 0.11, respectively. The frequency dependent conductivity follows the power law a= C 7dc + ßcov, with 0.3 <s < 1.5 for hopping conduction of hydrogen and/or chloride ions in the high temperature range, and localized hopping and/or orientational motion predominating temperatures lower than 413 K. Variations of B and s with temperature are discussed. PACS No. 76, 77 
  Reference    Z. Naturforsch. 56a, 568—578 (2001); received April 26 2001 
  Published    2001 
  Keywords    Phase Transitions, AC Dielectric Permittivity, Two-dimensional Materials, Lipid Bilayers 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0568.pdf 
 Identifier    ZNA-2001-56a-0568 
 Volume    56 
55Author    G. H., C. A., J. Zaleskia, G. Batorb, R. JakubasbRequires cookie*
 Title     
 Abstract    ie le c tr ic P r o p e r tie s a n d C h a r a c te r is a tio n o f th e S u p e rio n ic P h a s e o f [ C (N H 2) 3]2S b C l 5* [ C (N H 2) 3]C l (GHCA undergoes four phase transitions at Tcl = 402 K, Tc2 = 373 K, Ta = 162 K, and TcA = 146 K. Below Tc3 it possesses pyroelectric properties with the spontaneous polarization vector (Ps) in the ac plane and the maximum along the c axis equal to 8 pC/m2. Dielectric dispersion studies of GHCA show that the main dielectric dispersion connected probably with collective motions of chlorine ions is above 1GHz. For the phase transition at Tc2 to a superionic phase the thermal dilatation and electric conductivity were measured. The anomalies of the electric conductivity at Tc2 and T x were observed with large values of <j(10"3 S/m) above Tcl. The guanidinium cations above Tc2, besides reorientational motions, undergo slow self diffusion. 
  Reference    Z. Naturforsch. 50a, 888—892 (1995); received February 20 1995 
  Published    1995 
  Keywords    Guanidinium, chloroantimonate, phase transition, DSC, dilatometric, pyroelectric, electric conductivity 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0888.pdf 
 Identifier    ZNA-1995-50a-0888 
 Volume    50 
56Author    T. Brückert, D. Büsing, A. Würflinger, S. UrbanRequires cookie*
 Title      
 Abstract    h e r m a l A n a ly s is (D T A) a n d D ie le c tr ic S tu d ie s o f 4 -(tra n s -4 -H e p ty l-C y c lo h e x y l) -b e n z o n itr ile (7 P C H) u n d e r H ig h P r e s s u r e With the aid of DTA the phase diagram of 4-(trans-4-heptyl-cyclohexyl)-benzonitrile, 7PCH, was redetermined. Dielectric studies on the static and complex permittivity have been performed on 7PCH in the pressure range 0.1 -220 MPa, the frequency range 1 kHz-13 MHz and the temperature range 290-380 K. For the slow relaxation process in the nematic phase, characterized by the relaxa­ tion time Tjj , we have calculated the activation volume, A* V u, of about 80 to 60 cm3/mol (decreasing with increasing temperature), and the activation enthalpy, A *Hn, of approximately 70 kJ/mol. The isochoric activation energy, A* Un, amounts to about 36 kJ/mol. The pressure dependence of A * Hu is less pronounced compared with previous findings for 5PCH and 7CB. Estimates of t 0 (extrapo­ lated from the relaxation time in the isotropic phase) allow the calculation of the retardation factor gu = Tn/t0 that is analysed in terms of theories of Martin-Meier-Saupe and Coffey in order to evalu­ ate the nematic potential q. Using data for the order parameter 5 from NMR studies it was possible to determine the strength of the interaction potential in the nematic phase and to check the relation q~S which is valid at p = const., but not at V= const. The results are compared with recent findings for other homologous series. 
  Reference    Z. Naturforsch. 50a, 977—983 (1995); received August 25 1995 
  Published    1995 
  Keywords    Dielectric Relaxation, High Pressure, Liquid Crystals, Activation Parameters, Phase Transitions 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0977.pdf 
 Identifier    ZNA-1995-50a-0977 
 Volume    50 
57Author    GaryL. Catchen, EdwardF. Hollinger, ToddM. RearickRequires cookie*
 Title    Characterizing Phase Transitions in the Perovskites PbTi0 3 and BaTi0 3 Using Perturbed-Angular-Correlation Spectroscopy  
 Abstract    Perturbed-angular-correlation (PAC) spectroscopy was used to measure in ceramic samples of PbTi0 3 and BaTi0 3 the temperature dependence of the Ti-site electric-field gradients (EFGs) at temperatures very close to the ferroelectric-to-paraelectric transition temperatures T c . The samples were doped with small amounts of Hf that carried the 181 Hf — l8l Ta probe radioactivity. A high-frequency nuclear quadrupole interaction that decreases very little as the temperature approaches T c , characterizes the PbTi0 3 transition. The tetragonal and cubic phases for PbTi0 3 appear to coexist over a temperature interval of 8 ± 1 K, and the transition shows a thermal hysteresis of about 4 K. In contrast, a lower-frequency interaction that decreases rapidly as temperature approaches T c , characterizes the BaTiO, transition. Both phases of BaTi0 3 appear to coexist over an interval of about 2 K, and the thermal hysteresis is about 1 K. At temperatures above T c , both PbTi0 3 and BaTi0 3 show weak, non-vanishing Ti-site EFGs. Although, for BaTi0 3 , this effect limits the accuracy with which critical effects can be measured, we estimate a power-law exponent ß = 0.21 ± 0.05, which most likely is somewhat lower in magnitude than the actual critical exponent. For the explanation of our observations we assume the existence of a distribution of T c -values. This distribution would arise because the crystals could have spatially non-uniform distributions of nucleation sites, which for PbTi0 3 and BaTi0 3 could be point defects. 
  Reference    Z. Naturforsch. 51a, 411—421 (1996); received November 20 1995 
  Published    1996 
  Keywords    Ferroelectric, perovskite, nuclear electric-quadrupole, perturbed-angular-correlations, phase transition 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0411.pdf 
 Identifier    ZNA-1996-51a-0411 
 Volume    51 
58Author    M. Sandmann, F. Hamann, A. WürflingerRequires cookie*
 Title    PVT Measurements on 4-/i-Pentyl-4'-Cyano-Biphenyl (5CB) and trans-4-(4'-Octyl-Cyclohexyl)-Benzonitrile (8PCH) up to 300 MPa  
 Abstract    Specific volumes are presented for 4-n-pentyl-4'-cyanobiphenyl (5CB) and trans-4-(4'-octyl-cyclo-hexyl)-benzonitrile (8PCH) for temperatures between 300 and 370 K up to 300 MPa. The p,V m ,T data were determined for the liquid crystalline and isotropic phases, and partly also for the solid phase adjacent to the melting curve. Stable and metastable crystal phases can be distinguished. The density and melting temperature of the metastable form are lower than for the stable one. Volume and enthalpy changes accompanying the phase transitions are reported as well. The p,V m ,T data allow to calculate the entropy change for a hypothetical transition at constant volume. The molar volumes along the nematic-isotropic phase transition T NI (p) allow to determine the molecular field parameter y = S In T NI /0 In F N ,. 
  Reference    Z. Naturforsch. 52a, 739—747 (1997); received August 13 1997 
  Published    1997 
  Keywords    5CB, 8PCH, High pressure, pVT, Phase transitions, Thermodynamics, DTA 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0739.pdf 
 Identifier    ZNA-1997-52a-0739 
 Volume    52 
59Author    E. Mikuli, A. Migdał-Mikuli, S. Wróbel, B. GradRequires cookie*
 Title    DSC Investigations of the Phase Transitions of [M(H 2 0) 6 ](N0 3 ) 2 , where M = Mn, Co, Ni, Cu and Zn  
 Abstract    The phase transitions of [M(H 2 0) 6 ](N0 3) 2 , where M = Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ or Zn 2+ have been studied at 100 -400 K by DSC. Two phase transitions connected with a two-stage melting process have been found for these five compounds. For the compound with M = Co, besides the two melting points a solid-solid phase transition at 272 K has been found. 
  Reference    Z. Naturforsch. 54a, 595—598 (1999); received August 13 1999 
  Published    1999 
  Keywords    Hexaaquametal(II) nitrates, Phase Transitions, Melting Points, DSC Method 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0595.pdf 
 Identifier    ZNA-1999-54a-0595 
 Volume    54 
60Author    Michael Uhrmacher, Klaus-Peter LiebRequires cookie*
 Title    Phase Transitions in Oxides Studied by Perturbed Angular Correlation Spectroscopy  
 Abstract    Radioactive atoms located on cation sites in oxide matrices can be used to monitor phase transitions by measuring the electric or magnetic hyperfine interactions by means of Perturbed Angular Correlations spectroscopy. The article illustrates three types of phase transitions studied with 11 'in tracers and their daughter nuclei m Cd, namely magnetic, structural and REDOX phase transitions in binary and ternary polycrystalline or single-crystalline oxides. In this context, we also discuss the question of identifying the probes' lattice site(s), the scaling of the Electric Field Gradients in oxides, the influence of the (impurity) probes themselves on the phase transitions, and the occurrence and mechanisms of dynamic interactions. Recent results on " 1 In in pure and Li-doped In 2 S 3 will also be presented. 
  Reference    Z. Naturforsch. 55a, 90—104 (2000); received August 26 1999 
  Published    2000 
  Keywords    Phase Transitions, Oxides, Perturbed Angular Correlations, 111 In, Point Charge Model 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0090.pdf 
 Identifier    ZNA-2000-55a-0090 
 Volume    55 
Prev
1
2
3
4
5
Next