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21Author    Hiroyuki Ishida, Hironobu Maeda, Akiko Hirano, Tamotsu Fujimoto, Yoshihiro Kubozono, Setsuo Kashino, Shuichi EmuraRequires cookie*
 Title    E X A F S S tu d y o n th e P h a s e T r a n s itio n ( P h a s e a ' -5) in C H 3 N H 3 I  
 Abstract    The local structure of CH3NH3I around the I" ion in Phase a 'and 8 was studied by iodine K-edge EXAFS. The crystal structure in Phase a ' was redetermined by single crystal X-ray diffraction. The Debye-Waller factor <r(2) derived from EXAFS spectra shows an anomalous behavior around the order-disorder transition temperature from Phase 8 to a '. The phase transition has been interpreted as the disordering process which involves not only the H atoms but also the C atoms in the cation. 
  Reference    Z. Naturforsch. 50a, 876—880 (1995); received June 16 1995 
  Published    1995 
  Keywords    Crystal structure, EXAFS, Phase transition, X-ray diffraction 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0876.pdf 
 Identifier    ZNA-1995-50a-0876 
 Volume    50 
22Author    Tetsuo Asaji, Masaki Ohkawa, Takehiko Chiba, Makoto KagaRequires cookie*
 Title    Successive Phase Transitions in Potassium Hexachloroselenate(IV) Revealed by 35 C1 NQR  
 Abstract    K 2 SeCl 6 undergoes structural phase transitions of first order at 35 K, 65 K, and 79 K. The temperature dependence of the ? C1 NQR spin-lattice relaxation time suggests that the phase transitions at 65 K and 79 K are displacive ones associated with a resonant soft mode. The presence of a precursor cluster is suggested by the temperature dependence of the signal intensity above 79 K. 
  Reference    Z. Naturforsch. 51a, 705—709 (1996); received October 20 1995 
  Published    1996 
  Keywords    Phase transition, Soft mode, NQR, Spin-lattice relaxation 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0705.pdf 
 Identifier    ZNA-1996-51a-0705 
 Volume    51 
23Author    M. Grottel, A. Kozak, Z. PająkRequires cookie*
 Title    *H and 19 F NMR Study of Cation and Anion Motions in Guanidinium Hexafluorozirconate  
 Abstract    Proton and fluorine NMR second moments and spin-lattice relaxation times of polycrystalline guanidinium hexafluorozirconate and its deuterated analogue were studied in laboratory (60 MHz) and rotating (H, = 20 G) frames over a wide range of temperature. An analysis of the experimental results enabled us to reveal a dynamical inequivalence of two crystallographically independent cations and an unexpected high mobility of nonspherical anion dimers. A comparison of the ions dynamics in 2:1 complex studied with the guanidinium 1:1 and 3:1 complexes has shown a significant contribution of the hydrogen bonds to the potential barriers hindering the anion reorien-tations. At low temperatures a proton motion in the hydrogen bond and at 400 K a solid-solid phase transition have been discerned. 
  Reference    Z. Naturforsch. 51a, 991—996 (1996); received May 14 1996 
  Published    1996 
  Keywords    NMR, Ion Motions, Hydrogen Bonds, Phase Transitions 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0991.pdf 
 Identifier    ZNA-1996-51a-0991 
 Volume    51 
24Author    Roman Goc, JanW. WąsickiRequires cookie*
 Title    Computer Simulation of the Order-Disorder Transition in Ammonium Chloride  
 Abstract    The phase transition at T c = 243 K in ammonium chloride is well established to be of the order-disorder type. The ammonium chloride has a CsCl-type cubic structure with hydrogen atoms pointing toward four of the eight chloride ions at the corners of the unit cell. This means that there are two possible orientations of ammonium tetrahedron; a and b. In the ordered phase below the T c temperature all ammonium ions have the same, let it be a, orientation. Above the T c temperature ions are randomly distributed among the two possible orientations a and b. An attempt was made to correlate such structural transition with the second moment of the proton NMR absorption line. This approach was chosen because the second moment is the parameter of the NMR line for which the exact theoretical formula exist, and which is mainly a function of the structure and the reorien-tational state of the studied material. It was found that the NMR second moments calculated for the described above model of the structural transition properly reflect the changes of the experimental NMR second moments measured at temperatures below and above this transition. 
  Reference    Z. Naturforsch. 52a, 609—613 (1997); received June 18 1997 
  Published    1997 
  Keywords    NMR, Ammonium chloride, Phase transition, Simulation 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0609.pdf 
 Identifier    ZNA-1997-52a-0609 
 Volume    52 
25Author    Hiroyuki Ishida, Hiroshi Ono, Ryuichi IkedaRequires cookie*
 Title    Crystal Structure of the High-temperature Solid Phases of Choline Tetrafluoroborate and Iodide  
 Abstract    The crystal structure of the highest-and second highest-temperature solid phases of choline tetrafluoroborate and iodide was determined by X-ray powder diffraction. The structure in the highest-temperature phase of both salts is NaCl-type cubic (a = 10.16(2) Ä, Z = 4 for tetrafluorobo-rate; a = 10.08(2) A, Z = 4 for iodide). The second highest-temperature phase of tetrafluoroborate and iodide is CsCl-type cubic (a = 6.198(6) Ä and Z = 1) and tetragonal (a = 8.706(2) A, c = 6.144(6) Ä, and Z = 2), respectively. DSC was carried out for the iodide, where the presence of three solid-solid phase transitions was confirmed. Enthalpy and entropy changes of these transitions were evaluated. 
  Reference    Z. Naturforsch. 52a, 679—680 (1997); received June 17 1997 
  Published    1997 
  Keywords    Crystal structure, Powder X-ray diffraction, Phase transition 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0679_n.pdf 
 Identifier    ZNA-1997-52a-0679_n 
 Volume    52 
26Author    J. Furtak, Z. Czapla, A. V. KitykRequires cookie*
 Title    Ultrasonic Studies of Ferroelectric Phase Transition in Gly-H 3 P0 3 Crystals  
 Abstract    The temperature behaviour of the longitudinal and transverse ultrasound wave velocities and attenuation in the region of the ferroelectric phase transition (T c — 225 K.) of the glycine phosphite (Gly-H 3 P0 3) crystals is studied. The obtained results are considered within the framework of phenomenological theory. 
  Reference    Z. Naturforsch. 52a, 778—782 (1997); received October 4 1997 
  Published    1997 
  Keywords    Ferroelectricity, Phase Transition, Ultrasonic Velocity, Attenuation 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0778.pdf 
 Identifier    ZNA-1997-52a-0778 
 Volume    52 
27Author    M. Windhaus, B. D. Mosel, W. Müller-WarmuthRequires cookie*
 Title    Mössbauer Studies of Fe 2+ in Iron Langbeinites and other Crystals with Langbeinite Structure  
 Abstract    57 Fe Mössbauer spectra have been measured at various temperatures between 4.2 K and 300 K for iron langbeinites A 2 Fe 2^04)3 with A = K, NH 4 , Rb, T1 and magnesium, manganese and cadmium lang-beinites doped with Fe" + . The spectra revealed several contributions whose isomer shifts and quadru-pole splittings have been obtained by fitting program routines. For the high-temperature cubic phases two crystallographically non-equivalent iron sites have been identified, characteristic of Fe 2+ in the high-spin state. Abrupt changes of the quadrupole couplings indicated phase transitions; in some cases, the spectra have also revealed several sites for Fe 2+ in low temperature phases. From the temperature de-pendences, phase transition temperatures, crystal field splittings and Debye temperatures have been de-rived. 
  Reference    Z. Naturforsch. 53a, 27—37 (1998); received January 21 1998 
  Published    1998 
  Keywords    57 Fe Mössbauer Spectroscopy, Inorganic Crystals, Structure, Phase Transitions 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0027.pdf 
 Identifier    ZNA-1998-53a-0027 
 Volume    53 
28Author    M. Sandmann, A. WürflingerRequires cookie*
 Title    PVT Measurements on 4'-w-Hexyl-Biphenyl-4-Carbonitrile (6CB) and 4 -w-Heptyl-Biphenyl-4-Carbonitrile (7CB) up to 300 MPa  
 Abstract    P, V m , 7" data were established for 4'-n-hexyl-biphenyl-4-carbonitrile (6CB) and 4'-n-heptyl-biphen-yl-4-carbonitrile (7CB) between 300 and 370 K up to 300 MPa, and specific volumes were determined for the liquid crystalline, isotropic, and also partly for the crystal phases. Volume and enthalpy chang-es at the phase transitions are also presented. In the case of 6CB, a new crystal phase has been detect-ed, corresponding to a triple point at 338 K and 196 MPa. The p, V m , T data enabled us to separate the entropy change into a volume-dependent part and configurational part. From the molar volumes along the nematic-isotropic phase transition T Nl (p), the molecular field parameter y= 3lnT NI /3ln V NI was deter-mined. 
  Reference    Z. Naturforsch. 53a, 233—238 (1998); received March 11 1998 
  Published    1998 
  Keywords    6CB, 7CB, High Pressure, pVT, Phase transitions, Thermodynamics 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0233.pdf 
 Identifier    ZNA-1998-53a-0233 
 Volume    53 
29Author    Tetsuo Asaji, Keizo Horiuchi, Takehiko Chiba, Takashige Shimizu, Ryuichi IkedaRequires cookie*
 Title    NMR * NQR and DTA * DSC Studies of Phase Transitions in Pyridinium Tetrachloropalladate(II) and Pyridinium Tetrachloroplatinate(II)  
 Abstract    From the measurements of DTA • DSC and the temperature dependences of 35 C1 NQR frequen-cies, phase transitions were detected at 150 K, 168 K, and 172 K for (pyH) 2 [PtCl 4 ], and at 241 K for (P yH) 2 [PdCl 4 ], In order to elucidate the motional state of the constituent ions in the crystals in connec-tion with the structural phase transitions, the 35 C1 NQR and 'H NMR spin-lattice relaxation times and the second moment of the 'H NMR line were measured as functions of temperature. For both com-pounds, the potential wells for the cationic reorientation are suggested to be highly nonequivalent at low temperatures. Above 168 K, the pyridinium ions in (pyH) 2 [PtCl 4 ] are expected to reorient between almost equivalent potential wells. As for (pyH) 2 [PdCl 4 j, it is expected that the orientational order of the cation still remains even above the second order transition at 241 K. A change of the potential curve from two-unequal to three-unequal wells is proposed as a possible mechanism of the second order tran-sition. The activation energies for the cationic motion in the respective model potential are derived for both compounds at high and low temperatures. 
  Reference    Z. Naturforsch. 53a, 419—426 (1998); received December 30 1997 
  Published    1998 
  Keywords    Phase transition, NQR, NMR, Spin-lattice relaxation, DSC 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0419.pdf 
 Identifier    ZNA-1998-53a-0419 
 Volume    53 
30Author    Masao Hashimoto, Yuko Monobe, Hiromitsu Terao, Haruo Niki, Koichi ManoRequires cookie*
 Title    Phase Transition and Crystal Dynamics of 4-Bromobenzyl Alcohol  
 Abstract    For the title compound a phase transition from Phase II to Phase I (low and room temperature phases, respectively) was found at ca. 217 K. The temperature dependence of the 8 'Br NQR frequency and that of the dielectric constant showed anomalies at ca. 195 K that were tentatively attributed to a higher order phase transition. A similar anomaly was found at ca. 218 K for 4-chlorobenzyl alcohol which showed a II-I transition at 236 K. The dielectric dispersion observed for both compounds at low temperatures indicates an excitation of a molecular motion with the dielectric relaxation rate of ca. 1 kHz. The temperature dependence of the sl Br NQR frequencies of 2-and 3-bromobenzyl alcohol, measured at T > 77 K, gave no evidence of phase transition in their crystals. 
  Reference    Z. Naturforsch. 53a, 436—441 (1998); received March 24 1998 
  Published    1998 
  Keywords    NQR, Phase Transition, Molecular Motion, Dielectric Dispersion 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0436.pdf 
 Identifier    ZNA-1998-53a-0436 
 Volume    53 
31Author    M. Sandmann, A. WürflingerRequires cookie*
 Title    PVT Measurements on 4'-/i-Octyl-Biphenyl-4-Carbonitrile (8CB) up to 300 MPa  
 Abstract    P, V m , Tdata have been measured for the smectic, nematic and isotropic phases of 4'-n-octyl-biphen-yl-4-carbonitrile (8CB) in the temperature range 300-370 K and pressures up to 300 MPa. At atmos-pheric pressure all phase transitions appear to be of first order due to a discontinuity in the density. The volume change at the smectic A -nematic transition is only a tenth of the volume change at the clear-ing temperature. At moderate pressures below 80 MPa the S A -N transition could be detected as a dis-continuity in the period of oscillation in measurements with a high-pressure vibrating tube densimeter. At higher pressures the discontinuity seems to die away, possibly indicating a change from first order to second order transition. From the volume changes and the slopes of the transition lines we calculate the enthalpy changes at the phase transition. The p, V m , T data enable us to calculate the volume part of the entropy and the molecular field parameter y=9ln 7 N i/3ln V NI . 
  Reference    Z. Naturforsch. 53a, 787—792 (1998); received July 10 1998 
  Published    1998 
  Keywords    8CB, High Pressure, pVT, Phase Transitions, Thermodynamics 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0787.pdf 
 Identifier    ZNA-1998-53a-0787 
 Volume    53 
32Author    Hiroyuki IshidaRequires cookie*
 Title    H and 19 F NMR Studies on Molecular Motions in Two Solid Phases of t-Butylammonium Tetrafluoroborate  
 Abstract    Differential thermal analysis (DTA), differential scanning calorimetry (DSC), and the temperature dependence of the spin-lattice relaxation time (T {) and the second moment (M 2) of 1 H and F NMR were studied in (CH3) 3 CNH 3 BF4 and (CH 3) 3 CND 3 BF 4 . DTA and DSC revealed a solid-solid phase transition at 219 K for (CH 3) 3 CNH3BF4 and at 221 K for (CH 3) 3 CND 3 BF 4 . The motions of cations and anions in the two solid phases were studied by T x and M 2 experiments. The motional modes of the ions and their motional parameters were determined. 
  Reference    Z. Naturforsch. 53a, 796—800 (1998); received May 30 1998 
  Published    1998 
  Keywords    Molecular motion, Phase transition, Nuclear magnetic resonance 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0796.pdf 
 Identifier    ZNA-1998-53a-0796 
 Volume    53 
33Author    E. Mikuli, A. Migdał-Mikuli, S. WróbelRequires cookie*
 Title    Phase Transitions in Crystalline [Me(H 2 0) 6 ](BF 4 ) 2 . Part I (Me = Mn, Fe, Co, Ni and Zn)  
 Abstract    Solid polymorphism in five compounds of the type [Me(H 2 0) 6 ](BF 4) 2 , where Me = Mn, Fe, Co, Ni and Zn, have been studied in the temperature range 120 -330 K by DSC. For each substance at least three solid modifications have been found. In addition, for compounds with Me = Mn, Fe and Zn some new low temperature phase transitions have been observed. The transition temperatures for the [Me(H 2 0) 6 ](BF 4) 2 compounds are distinctly lower than those for the [Me(H 2 0) 6 ](C10 4) 2 compounds. The entropy-and enthalpy-changes at the phase transitions of the hexaaquametal(II) tetrafluoroborates are significantly lower than those for the corresponding chlorates(VII). Linear correlations between the highest transition temperature and the crystal density are found for both series of these isomorphous compounds. 
  Reference    Z. Naturforsch. 54a, 225—228 (1999); received December 12 1998 
  Published    1999 
  Keywords    Hexaaquametal(II) tetrafluoroborates, Phase Transitions, DSC Method 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0225.pdf 
 Identifier    ZNA-1999-54a-0225 
 Volume    54 
34Author    M. Sandmann, F. Hamann, A. WürflingerRequires cookie*
 Title    PVT and DTA Measurements on trans-4-w-Hexyl- (4'-CyanophenyI)-Cyclohexane (6PCH) up to 300 MPa  
 Abstract    The phase diagram of trans-4-n-hexyl-(4'-cyanophenyl)-cyclohexane, (6PCH) has been estab-lished by high-pressure differential thermal analysis. Specific volumes are presented for temper-atures between 300 and 370 K up to 300 MPa. The p,V m ,T data have been determined for the nematic, isotropic, and (partly, in the neighbourhood to the melting curve) solid phases. Volume and enthalpy changes along the phase transitions have also been calculated. As previously, the p,Vm,T data were used to calculate the volume entropy for the nematic-isotropic transition. The molar volumes along the clearing line T NI (p) enabled us to calculate the molecular field parameter 7 = ain T NI /3ln V NI , being 4.1. 
  Reference    Z. Naturforsch. 54a, 281—286 (1999); received March 13 1999 
  Published    1999 
  Keywords    6PCH, High Pressure, pVT, Phase Transitions, Thermodynamics 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0281.pdf 
 Identifier    ZNA-1999-54a-0281 
 Volume    54 
35Author    M. Massalska-Arodź, A. Würflinger, D. BüsingRequires cookie*
 Title    High-pressure DTA Studies of the Phase Behaviors of 4-n -butyl-thiocyanobiphenyl (4TCB) and 4-w-pentyl-4'-n-phenyl-cyanocyclohexane (5HCP)  
 Abstract    DTA measurements of 4-/i-butyl-thiocyanobiphenyl (4TCB) and/?-cyano-/?'-pentylphenyl-cyclohex-ane (5HCP) have been performed in the temperature range 220 K-390 K and pressures up to 400 MPa. For 4TCP a transition from a crystalline to a liquid crystal phase (probably smectic E) could be detect-ed at higher pressures > 90 MPa. The pressure dependence of the transition temperature has been estab-lished. At pressures lower than 88.7 MPa no transition of SmE into a crystal or into a glass has been found. For 5HCP only the melting curve was observed, in contrast to 5PCH, which displays a liquid crystalline nematic phase. 
  Reference    Z. Naturforsch. 54a, 675—678 (1999); received November 5 1999 
  Published    1999 
  Keywords    DTA, High Pressures, Phase Transitions, Liquid Crystals 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0675.pdf 
 Identifier    ZNA-1999-54a-0675 
 Volume    54 
36Author    Tetsuo Asaji, Tomohiro IshizakaRequires cookie*
 Title    Effect of Deuteration on Ammonium Motion and Structural Phase Transition Studied by Nuclear Quadrupole Resonance  
 Abstract    35 C1 NQR measurements revealed two phase transitions at 14.5 K and 70 K in NH4ICI4. By deuteration of the ammonium ions, the respective transition temperature increased to 27 K and 74 K. In the lowest-temperature phase of NH4ICI4, by the deuteration a remarkable change of the temperature dependence of the 35 C1 NQR frequencies was observed. The NQR spin-lattice relaxation-time minimum, ascribable to the modulation effect of the electric field gradient (EFG) due to a motion of the ammonium ions, was observed at 7 K and 11 K in NH4ICI4 and ND4ICI4, respectively. The activation energy of the ammonium motion and the fluctuation fraction q /q of the EFG were determined to be 0.32 kJ moP 1 and 1.3xlO~ 3 for NH4ICI4, and 0.30 kJ mol -1 and 0.88xl0~ 3 for ND4ICI4. The experimental result suggests that the inter-ionic interaction between the ammonium ion and the ICl^ complex anion is weakened by the deuteration. However, the frequency shift observed in the lowest-temperature phase is much larger in ND4ICI4 than in NH4ICI4. This suggests that the lattice distortion in NH4ICI4 is suppressed to a great deal by the tunneling rotation of NH4 ions. The effective inter-ionic interaction responsible for the lattice distortion, the transition temperature and the enhancement of tunneling of NH4 as compared with ND4 is discussed for NH4ICI4 as well as for previously reported NH4AUCI4 and ct-N^HgCb. 
  Reference    Z. Naturforsch. 55a, 83—89 (2000); received August 26 1999 
  Published    2000 
  Keywords    Isotope Effect, Tunneling, Phase Transition, Ammonium, NQR 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0083.pdf 
 Identifier    ZNA-2000-55a-0083 
 Volume    55 
37Author    Y. M. Seo, S. K. Song, J. PelzpRequires cookie*
 Title    Impurity Effects on the Local Structure in the Mixed Hexachlorometallate (A 2 BC1 6 : A = K, Rb, B = Sn, Re, and Pb) Studied by the Chlorine NQR  
 Abstract    Chlorine NQR was studied for the isostructural hexachlorometallate mixed system. The study shows that Isomorphic hexachlorometallate solid solutions exhibit often impurity induced local structural order because of their relatively clear local site symmetry. This is manifested in the formation of a few satellite lines near the original resonance line and results from the random distribution of impurities on the lattice sites of the corresponding counterpart ions. Using the point charge model and a simple binomial function for the occupation probability of the guest ions on the host lattice sites, the position and the line intensity could be determined, the results of which are in good agreement with the NQR-observation. The temperature region of lattice dynamics in the crystal seems to shift in proportion to the impurity content. This fact explains the gradual change of the transition temperature in the mixed crystal between two starting materials. 
  Reference    Z. Naturforsch. 55a, 207—211 (2000); received August 23 1999 
  Published    2000 
  Keywords    NQR, Hexahalmetallates, Phase Transition, Mixed Crystals 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0207.pdf 
 Identifier    ZNA-2000-55a-0207 
 Volume    55 
38Author    Hideta Ishihara, Keizo Horiuchi, ThorstenM. Gesing, Shi-Qi Dou, J.-Christian Buhl, Hiromitsu TeraoRequires cookie*
 Title    I NQR and Crystal Structure Studies of [N(CH 3 ) 4 ] 2 CdI 4  
 Abstract    The temperature dependence of 127 1 NQR and DSC as well as the crystal structure at room temperature of the title compound were determined. This compound shows a first-order phase transition of an order-disorder type at 245 K. Eight 127 I(i^i: m = ±5 <-+ ±|) NQR lines of 79. corresponding eight 127 I(^ 2 : m = ±| <-» • ±|) NQR lines were observed at liquid nitrogen temperature. Three 127 I(^i) NQR lines wfth an intensity ratio of 1:1:2 in the order of decreasing frequency were observed just above the transition point and two NQR lines except for the middle-frequency line disappeared around room temperature. This temperature behavior of NQR lines is very similar to that observed in [N(CH 3)4] 2 Hgl4. Another first-order phase transition takes place at 527 K. The structure of the room-temperature phase was redetermined: orthorhombic, Pnma, Z = 4, a = 1342.8(3), b = 975.7(2), c = 1696.5(3) pm. The NQR result of three lines with an intensity ratio of 1:1:2 is in agreement with this structure. The thermal displacement parameters of atoms in both cations and anions are large. 
  Reference    Z. Naturforsch. 55a, 225—229 (2000); received October 13 1999 
  Published    2000 
  Keywords    NQR, DSC, Crystal Structure, Phase Transition 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0225.pdf 
 Identifier    ZNA-2000-55a-0225 
 Volume    55 
39Author    Maciej Bujak, Jacek ZaleskiRequires cookie*
 Title    Structure and Phase Transition in (C 2 H 5 NH 3 ) 3 Sb 2 CI 9 (C 2 H 5 NH 3 )SbCl 4 ; X-ray, DSC and Dielectric Studies  
 Abstract    The structure of (C 2 H 5 NH 3) 3 Sb 2 Cl 9 • (C 2 H 5 NH 3)SbCl 4 at 295 K has been determined. The crystals are orthorhombic, space group Pna2! (a -16.925(3), b = 24.703(5), c = 7.956(2) A, V = 3326.4(12) A 3 , Z = 4, d c = 2.018, d m = 2.01(1) Mg m -3). They consist of an anionic sublattice composed of two different polymeric zig-zag chains. One is built of Sb 2 Cl 9 3-units (corner sharing octahedra) and the other one is made of corner sharing SbCl^ 2-square pyramids. In the cavites between the polyanionic chains four non-equivalent ethylammonium cations are located. Three of them are disordered. The cations are connected to the anions by weak N-H...C1 hydrogen bonds. A first order phase transition of the order-disorder type was found at 274 K. It was studied by DSC, dielectric and X-ray diffraction methods. The mechanism of the phase transition is attributed to the ordering of at least one of the ethylammonium cations. 
  Reference    Z. Naturforsch. 55a, 526—532 (2000); received January 10 2000 
  Published    2000 
  Keywords    Ethylamine, Chloroantimonate(III), Structure, Phase Transition 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0526.pdf 
 Identifier    ZNA-2000-55a-0526 
 Volume    55 
40Author    A. Wiirflinger, M. SandmannRequires cookie*
 Title    Thermodynamic Measurements on w-Hexadecane (C 16 H 34 ) and /z-Heptadecane (C 17 H 36 ) at Elevated Pressures  
 Abstract    Specific volumes of/7-hexadecane (H-Ci 6 H 34) and n-heptadecane (fl-C 17 H 36) are presented for tem-peratures between 298 and 348 K and pressures up to 280 MPa. The melting curve for /7-C j6 H 34 was determined with differential thermal analysis. ThepVTdata are established for the liquid, solid and (in the case of J?-C| 7 H 36) rotator phases. Forn-C 16 H 34 the density immediately below the freezing temper-ature is larger than for n-Ci 7 H 36 immediately below the rotational transition temperature. Changes of volume, enthalpy, and entropy along the phase transitions are reported. The volume change of melting decreases distinctly with increasing pressure, whereas the volume change at the rotational transition is much less pressure-dependent. Enthalpy and entropy changes have been calculated with the aid of the Clausius-Clapeyron equation. 
  Reference    Z. Naturforsch. 55a, 533—538 (2000); received February 16 2000 
  Published    2000 
  Keywords    Hexadecane, Heptadecane, DTA, /?V7, High Pressure, Phase Transitions 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0533.pdf 
 Identifier    ZNA-2000-55a-0533 
 Volume    55 
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