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1Author    R. Jakubas, G. Bator, M. Foulon, J. Lefebvre, J. MatuszewskiRequires cookie*
 Title    Structural Phase Transitions in (/i-C 3 H 7 NH3) 2 SbBr 5  
 Abstract    Dielectric, DSC, thermal expansion and preliminary X-ray diffraction studies on (/i-C 3 H 7 NH3) 2 SbBr 5 are reported. It was found that this crystal undergoes a complex sequence of phase transitions. On cooling: phase I phase II at 188.7 K (continuous), II -» • III at 165 K (1st order, z!S = 26.8 J/mol K), III IV at 137 K (1st order, 1.6 J/mol K). On heating: IV III at 154 K, III II' at 168 K, II' -> II at 177 K (1st order, 2.8 J/mol K), II I at 189 K. All 1st order phase transitions are likely due to the motion of the n-C 3 H 7 NH3 cations. The dielectric dispersion studies between 100 Hz-1 MHz within the phases I and II indicate a fast reorientational motion of dipoles with T < 10" 7 s. 
  Reference    Z. Naturforsch. 48a, 529—534 (1993); received October 7 1992 
  Published    1993 
  Keywords    Alkylammonium halogenoantimonates, Phase transition, Dielectric, DSC, Thermal expansion 
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 TEI-XML for    default:Reihe_A/48/ZNA-1993-48a-0529.pdf 
 Identifier    ZNA-1993-48a-0529 
 Volume    48 
2Author    Jacek ZaleskiRequires cookie*
 Title    Crystal Structure and Phase Transitions of [C(NH2)3]3Sb2C l9 * 0.9 H 20 A dam Pietraszko  
 Abstract    The room temperature structure of [C(NH2)3]3Sb2C l9 ■ 0.9 H 20 (GNCA) was solved. It crystal­ lizes in the monoclinic C2/c space group with a = 15.275, b = 8.794, c = 17.904 (in Ä), ß = 96.40°, V = 2390 Ä 3, Z = 4. Refinement of the atomic parameters by a least squares methods gave R = 0.042, wR = 0.039 for 1958 reflections with F>4ct(F). The structure consists of polyanionic (Sb2Cl|_)n layers built of deformed corner connected SbX^-octahedra. Two crystallographically inequivalent guanidinium cations are present, one situated between polyanionic layers, the other one together with a disordered water molecule inside cavities formed by polyanions. Temperature X-ray scattering experiments together with DSC studies were carried out above room temperature. Temperature dependence of the lattice parameters between 300 K and 380 K was determined and a phase transition of mixed order at 364 K was revealed. 
  Reference    Z. Naturforsch. 49a, 895—901 (1994); received June 7 1994 
  Published    1994 
  Keywords    Guanidinium, Chloroantimonate, Crystal structure, Phase transition, DSC 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0895.pdf 
 Identifier    ZNA-1994-49a-0895 
 Volume    49 
3Author    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 
4Author    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 
5Author    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 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0390.pdf 
 Identifier    ZNA-2000-55a-0390 
 Volume    55 
6Author    H. Schmalfuss, W. Weissflog, A. Würflinger3, S. Masberg3, G. M. Schneider3Requires cookie*
 Title    Thermodynamic Measurements on Selected Liquid Crystals at Normal and Elevated Pressures  
 Abstract    Densities have been determined for two 5-n-alkyl-2-(4-isothiocyanatophenyl)-l,3-dioxanes (6DBT, 10DBT), 4-n-tetradecyl-4'-cyanobiphenyl (14CB), 4-n-octyl-4'-thiocyanatobiphenyl (8BT) and two laterally aryl-branched mesogens 4-cyanobenzyl 5-(4-n-octyloxybenzoyloxy)-2-undecyloxybenzoate (4CNOUB), 3-cyanobenzyl 2,5-bis(4-n-octyloxybenzoyloxy)benzoate (3CN-BOB). The densities have been measured in the isotropic, nematic (only 3CNBOB) and smectic phases with a vibrating tube densimeter. The densities decrease with increasing alkyl chain length within a homologous series. Furthermore the enthalpy changes accompanying the phase transitions have been determined by DSC. 
  Reference    Z. Naturforsch. 56a, 262—266 (2001); received December 5 2000 
  Published    2001 
  Keywords    Specific Volumes, Density, DSC, Liquid Crystals, Thermodynamics 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0262.pdf 
 Identifier    ZNA-2001-56a-0262 
 Volume    56 
7Author    R. Zaleski, Z. Jakubas, L. Galewski, SobczykRequires cookie*
 Abstract    Dielectric. DSC and preliminary X-ray diffraction studies on [(C2H5)4N]3Sb2Br9 (TEABA) and [(C2H5)4N]3Bi2Br9 (TEABB) are reported. The compounds are isomorphous, space group P6322. The static electric permittivity measurements on single crystals in the temperature range 220 290 K revealed that both compounds show two distinct dielectric anomalies; TEABA at Tcl = 258 K and Tc2 = 252 K, while TEABB at Tcl= 265 K and Tcl = 248 K. The DSC studies show only one anomaly of first order at TcX =258 K for TEABA, and TcX =266 K for TEABB. These transitions are pre­ sumably related to a freezing of the reorientational motion of the tetraethylammonium cations. S tr u c tu r a l P h a s e T ra n s itio n s in |(C 2H 5)4N ] 3S b 2B r 9 a n d |(C 2H 5) 4N |3B i2B r 9 
  Reference    Z. Naturforsch. 44a, 1102 (1989); received May 11 1989 
  Published    1989 
  Keywords    Alkylammonium halogenoantimonates, Bismuthates, Phase transition Dielectric, DSC, Single crystals 
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 TEI-XML for    default:Reihe_A/44/ZNA-1989-44a-1102.pdf 
 Identifier    ZNA-1989-44a-1102 
 Volume    44 
8Author    G. H., C. A., J. Zaleskia, G. Batorb, R. JakubasbRequires cookie*
 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 
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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0888.pdf 
 Identifier    ZNA-1995-50a-0888 
 Volume    50 
9Author    E. Mikuli, A. Migdał-Mikuli, I. Natkaniec, J. MayerRequires cookie*
 Title    Phase Transitions and Water Dynamics of [Mn(H 2 0) 6 ](C10 4 ) 2 Studied by Differential Scanning Calorimetry and Neutron Scattering Methods  
 Abstract    DSC measurements performed at 95 -290 K have shown that [Mn(H 2 0) 6 ](C10 4) 2 possesses, besides a high-temperature phase, existing above 323 K, four low-temperature solid phases. The inelastic incoherent neutron scattering (IINS) spectra and neutron powder diffraction (NPD) pat-terns registered at 20 -290 K have supported the DSC results and provided evidence that the investigated substance possesses even more than five solid phases. The IINS spectra have shown that in the room-temperature phase, water molecules perform fast stochastic reorientation at the picosecond scale. The orientational disorder characteristic for the room-temperature phase can be easily overcooled and frozen. Even by relatively slow cooling at ca. 40 K/hour a metastable, orientational (protonic) glass phase is formed below ca. 160 K. Below ca. 100 K, a structural phase transition was observed by the NPD, however the IINS spectra indicate existence of the pure ordered low-temperature phase only after annealing the sample for a few hours at 100 K. On heating, a structural phase transition takes place at ca. 120 K, and at ca. 225 K water molecules begin fast reorientation. 
  Reference    Z. Naturforsch. 55a, 759—764 (2000); received July 7 2000 
  Published    2000 
  Keywords    Hexaaquamanganese(II) chlorate(VII), Phase Transitions, DSC, Neutron Scattering 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0759.pdf 
 Identifier    ZNA-2000-55a-0759 
 Volume    55 
10Author    V. Berbenni, A. Marini, D. CapsoniRequires cookie*
 Title    Solid State Reaction Study of the System Li 2 C03/Fe 2 03  
 Abstract    A thermoanalytical (TGA/DSC) and diffractometric (XRD) study has been performed on the solid state reaction system Li 2 C0 3 -Fe 2 0 3 in the x Li range 0.10-^0.50. A detailed analysis of the results shows that the data are in agreement with a reaction model where the carbonate decomposition is regulated by the formation of both LiFe0 2 and LiFe 5 0 8 , and the relative amount of the two phases depends on the initial composition. The DSC evidence offers the possibility to directly quantify the LiFe 5 O x phase. Fur-thermore it allows one to obtain the enthalpies of formation of both LiFe0 2 and LiFe 5 0 8 . 
  Reference    Z. Naturforsch. 53a, 997—1003 (1998) 
  Published    1998 
  Keywords    Lithium Ferrites, Solid State Reaction, Iron (III) Oxide, Lithium Carbonate, TGA, DSC 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0997.pdf 
 Identifier    ZNA-1998-53a-0997 
 Volume    53 
11Author    M. M. Ahmad, M. A. HefniaRequires cookie*
 Title    Effect of Li Content on the DSC and Electrical Conductivity of (Li1_J C Kx)2S 0 4 Mixed Crystals  
 Abstract    Differential scanning calorimetry on (Li1_J(K (.)2S 04 mixed crystals, where x = 0.01, 0.1, 0.3 and 0.5, revealed that, as the potassium content increases, the first high temperature phase of the intermediate LiKS04 phase at T -432 °C grows and shifts to higher temperature, and a double-phase mixture con­ sisting of LiKS04 and Li2S 04 exists for x< 0.5. Ionic conductivity measurements on (Li|_xK;t)2S 04 mixed crystals for x < 0.5 did show that the electrical conductivity increases as the Li2S 04 concentra­ tion increases, with an average activation energy of 0.9 eV. The enhanced electrical conductivity is pri­ marily a result of the increase in the Li+ ion (charge carriers) concentration and/or the formation of a diffuse space charge layer at the interface between the two phases. 
  Reference    Z. Naturforsch. 56a, 677—680 (2001) 
  Published    2001 
  Keywords    (Li)_^KJ()2S 04 Crystals, DSC, Ionic Conductivity, Diffuse Space Charge Layer 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0677.pdf 
 Identifier    ZNA-2001-56a-0677 
 Volume    56