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1Author    Robert Becker, Wolfgang Brockner, Brigitte EisenmannRequires cookie*
 Title    Kristallstruktur und Schwingungsspektrum des Thallium(I)-Zinn(II)-ortho-Thiophosphates TlSnPS4  
 Abstract    TlSnPS4 crystallizes in the orthorhombic system, space group P na21 (Nr. 33), Z = 4 with the lattice constants a = 1175.8 (5) pm, b = 890.1 (4) pm, c = 663.3 (4) pm. In the structure are sligthly distorted discrete PS4_ anions. The far infrared, infrared and Raman spectrum is assigned on the basis o f P S]-units with C 3v symmetry. According to the DTA data the m elting point for TlSnPS4 is 575 ± 5 °C. The title compound is not moisture sensitive and semi-conducting. 
  Reference    Z. Naturforsch. 42a, 1309—1312 (1987); received Septem ber 15 1987 
  Published    1987 
  Keywords    ortho-Thiophosphate, TlSnPS4, Crystal Structure, Vibration Spectrum 
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 TEI-XML for    default:Reihe_A/42/ZNA-1987-42a-1309.pdf 
 Identifier    ZNA-1987-42a-1309 
 Volume    42 
2Author    J. Pirnat, J. Lužnik, Z. Trontelj, P. K. KadabaRequires cookie*
 Title    Iodine NQR and Phase Transitions in [N(CH 3 ) 4 ] 2 ZnI 4 * a  
 Abstract    Using a superregenerative NQR spectrometer, the temperature dependence of 127 I NQR spectra in [N(CH 3) 4 ] 2 ZnI 4 was measured between 167 and 335 K. The measurements confirm two known structural phase transitions at 219 and 257.5 K. The correspondence between the distinct regions of iodine NQR spectra and the crystal structure is discussed. The relation of [N(CH 3) 4 ] 2 ZnI 4 to the incommensurate family with the general formula X 2 YZ 4 and the high temperature (paraphase) crystal space group D^ (Pmcn) is studied. 
  Reference    Z. Naturforsch. 45a, 349—352 (1990); received August 23 1989 in revised form 25 November 1989 
  Published    1990 
  Keywords    NQR, phase transitions, ferroelectric, crystal structure, displacement modulation 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0349.pdf 
 Identifier    ZNA-1990-45a-0349 
 Volume    45 
3Author    Tsutomu Okuda, Yoshihiro Kinoshita, Hiromitsu Terao, Koji YamadaRequires cookie*
 Title    Structure and Bonding of Bromoantimonate (III) Complexes with Unusual Valency by Means of NQR and Powder X-Ray Diffraction  
 Abstract    NQR and powder X-ray diffraction were observed for several bromoantimonate (III) complexes which contain C"H2n+ jNF^ (n = 1 -3) or (C"H2lt + 1)2N H 2 (n = 1 -4) as a cation. The bond character, anion structure, crystal structure, and phase transition are discussed on the basis of the three-center-four-electron bond. A good correlation was found between the halogen NQR frequency and the Sb-X bond length. 
  Reference    Z. Naturforsch. 49a, 185—192 (1994); received July 23 1993 
  Published    1994 
  Keywords    81Br NQR, Temperature dependence, Phase transition, Crystal structure 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0185.pdf 
 Identifier    ZNA-1994-49a-0185 
 Volume    49 
4Author    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 
5Author    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 
6Author    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 
7Author    J. Pirnat, Z. Trontelj, Z. Jagličić, K. Lutar, H. BorrmannRequires cookie*
 Title    Arsenic NQR in the Paramagnetic Complex Co(AsF 6 ) 2 -2AsF 3  
 Abstract    Arsenic NQR in Co(AsF 6) 2 .2AsF 3 reveals three lines: one near 122 MHz and two near 50 MHz. Relations of the spectral lines to the structure and to thermal vibrations are discussed. Possible influence of paramagnetic Co is examined. 
  Reference    Z. Naturforsch. 55a, 212—214 (2000); received October 13 1999 
  Published    2000 
  Keywords    Co(AsF 6 ) 2, Complex, NQR, Paramagnet, Crystal Structure 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0212.pdf 
 Identifier    ZNA-2000-55a-0212 
 Volume    55 
8Author    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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 Identifier    ZNA-2000-55a-0225 
 Volume    55 
9Author    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 
10Author    Hiroyuki Ishida, Setsuo Kashino, Ryuichi IkedaRequires cookie*
 Title    Crystal Structure of Trimethylammonium Tetrafluoroborate in Three Solid Phases  
 Abstract    The crystal structure of (CH 3) 3 NHBF 4 was studied in three solid phases by X-ray diffraction techniques. The structures of the ionic plastic phase (Phase I) stable above 453 K and Phase II between 384 and 453 K are CsCl-type cubic (a = 5.772(4) Ä) and tetragonal (a = 9.815(5) and c = 6.895(5) A), respectively. The room temperature phase (Phase III) forms a monoclinic lattice (space group P2,/m, a = 5.7017(8), b = 8.5724(9), c = 7.444(1) Ä, and ß = 102.76(1)°). BF 4 ~ ions in this phase were shown to be disordered in four orientations. 
  Reference    Z. Naturforsch. 55a, 765—768 (2000); received June 28 2000 
  Published    2000 
  Keywords    Crystal Structure, X-ray Diffraction, Ionic Plastic Phase, Disorder 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0765.pdf 
 Identifier    ZNA-2000-55a-0765 
 Volume    55 
11Author    Hideta Ishihara, Toshiya Okajima, Keizo Horiuchia, Ingrid Svobodab, Hartmut FuessbRequires cookie*
 Title    Isolated versus Condensed Anion Structure VII: X-ray Structure Analysis of 1,3-Propanediammonium Dibromodichlorocadmate(II), [H3N(CH2)3NH3]CdBr2Cl2, and Estimation of Stability of Five-coordinated Halide Anions, MXg3-(M = Cd, Zn; X = Cl, Br) by Means of Ab-initio MO Calculations  
 Abstract    The coordination capability of Cl and Br in halogenocadmate(II) complexes is estimated by a solution of the structure of 1,3-propanediammonium dibromodichlorocadmate(II). The compound crystallizes as a layered anion structure with Cl bridges and Br terminals at 293 K: Imma, a = 741.56(7), b = 1869.5(5), and c -771.55(8) pm, Z = 4. In order to explain the stronger tendency of halogenocadmate(II) complexes to form layered structures as compared to halogenozincate(II), ab-initio calculations were performed. The stability of MX53-(M = Cd, Zn; X = Cl, Br) is compared. Isolated ZnX53-and CdBr53-ions are not stable. On the other hand a trigonal bipyramid CdCl53-ion is considered to be subtly stable in the crystal mainly due to Coulomb attractive interactions between the positively charged metal cation Cd2+ in a CdCl3 " fragment and two Cl-ions. 
  Reference    Z. Naturforsch. 56a, 641—646 (2001); received June 16 2001 
  Published    2001 
  Keywords    Crystal Structure, Halogenocadmate(II), Ab-initio MO Calculations 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0641.pdf 
 Identifier    ZNA-2001-56a-0641 
 Volume    56 
12Author    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 
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 TEI-XML for    default:Reihe_A/41/ZNA-1986-41a-1154.pdf 
 Identifier    ZNA-1986-41a-1154 
 Volume    41 
13Author    J. Krzystek, H.J U C Von Schütz, Wolf, R.-D Stigler, J. J. StezowskiRequires cookie*
 Title    Characterization of the Phenanthrene-Tetrachlorophthalic Anhydride (P/TCPA) 1:1 Charge-Transfer Crystal: Spectroscopic and Structural Investigations  
 Abstract    The 1:1 phenanthrene-tetrachlorophthalic anhydride (P/TCPA) charge-transfer complex crystalizes with monoclinic symmetry, space group P2,, with two magnetically inequivalent stacks in the unit cell. The noncentrosymmetric space group is very unusual for CT-complexes. The optical emission spectra at low temperature are characterized by a strong CT phospho-rescence and a weak CT fluorescence and delayed fluorescence. The S, band lies at 22 800 ± 100 cm" 1 , the T, band at 21 200 ± 100 cm" 1 . Above 15 K triplet excitons, moving along the stacks are revealed by ESR. They have a CT character of about 30%, coinciding with that of the shallow X-traps found by ODMR at jow temperatures. A further trap, with zero-field-splitting (zfs) parameters of £> = ±0.0617, E = + 0.0116 cm" 1 has a much larger CT character of 50% as found in the isolated complex in low-temperature glass [1]. A structural model is proposed. 
  Reference    Z. Naturforsch. 42a, 622—630 (1987); received February 28 1987 
  Published    1987 
  Keywords    Charge-transfer crystal, crystal structure, fluorescence, phosphorescence, triplet excitons 
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 TEI-XML for    default:Reihe_A/42/ZNA-1987-42a-0622.pdf 
 Identifier    ZNA-1987-42a-0622 
 Volume    42 
14Author    Takeshi Kyan, Hamagawa, Takahiro Isono, Masao HashimotoRequires cookie*
 Title    Hiroshi  
 Abstract    The crystal structure of cyclohexylhemiacetal (cycHx-CH) was determined at 296 K: monoclinic, space group P2 Jc, a =1028.7 (9), b = 609.5 (1), c = 1811.9 (4) pm, and ß = 99.79 (3)°, Z -4, R = 0.0552. The three 5s Cl NQR lines in cycHx-CH, T., T2, and T2*, were measured by a pulsed method at 80-300 K. Below 200 K Tf 1 obeyed the T law well, indicating that the spin lattice relaxation is governed by lattice vibrations. The reorientation of CC13 seems to be responsible for the sharp T: drop observed above 250 K. Shoulders in the T { vs. 1/T curves indicate the presence of Ti minima at about 240 K. A fluctuation of the EFG due to a dynamic disorder of hydrogen atoms in the OH groups is assumed to explain the T x minima. 
  Reference    Z. Naturforsch. 47a, 299 (1992); received July 25 1991 
  Published    1992 
  Keywords    Chlorine NQR, Spin-lattice relaxation, Hydrogen bond, Crystal structure 
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 Identifier    ZNA-1992-47a-0299 
 Volume    47 
15Author    SundaraR. Am Aprabhu, EdwinA C Lucken, Gerald BernardinelliRequires cookie*
 Title    Crystal Structure and NQR of Two Copper (I) Complexes of 4,6-Dimethylpyrimidine-2-thione  
 Abstract    The crystal structure and 63Cu NQR spectra of two neutral hexanuclear Cu(I) complexes of 4,6-dimethylpyrimidine-2-thione, (Hdmpt); [dmptCu]6 6 CHCl3 (l) and [dmptCu]6 C2 H4 Cl2 (2), are reported. The number and relative intensities of the NQR resonances are in agreement with the results of the crystallographic study. The temperature-dependence of the resonances reveals that both compounds undergo a phase-change in the temperature range 77 K -3 0 0 K, both of which may be associated with the loss of a symmetry-element present in the high-temperature phase. The 3 5 C1 resonances of CHC13 in 1 could be observed in the low-temperature phase but the corresponding resonances for C2 H4 C12 in 2 were not detected. 
  Reference    Z. Naturforsch. 49a, 193—198 (1994); received August 30 1993 
  Published    1994 
  Keywords    6 3 Cu, 3 5 C1, Cu(I), Crystal structure 
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 Identifier    ZNA-1994-49a-0193 
 Volume    49 
16Author    Masao Hashimoto, Shuji Matsumoto, Masakazu Kunitomo, Haruo Niki, Hirotaka Odahara, Katsuji TamakiRequires cookie*
 Title    35C1 NQR Relaxation and Hydrogen Bond in Some Chloral Hemiacetals  
 Abstract    The crystal structure of chloral ethylhemiacetal has been determined at 291 K: monoclinic, space group C f -P 2 lt Z = 2, a = 854.5(1), b = 594.0(3), c = 853.3(1) pm, ß = 108.30(2)°, R = 0.0962. A sharp decrease of the spin lattice relaxation time 7i found for the 35C1 N Q R o f the CC13 groups in chloral methyl-, ethyl-and n-heptylhemiacetals is attributed to the onset of reorientation of the group over a potential barrier o f ca. 39, 37, and 32 kJ/m ol, respectively. An unusual vs. 1/T curve with a 7i minimum superimposed on the sharp decrease of 7\ due to the reorientation was observed for each of the three Cl N Q R lines of nH p-C H . This phenom enon is tentatively ascribed to a fluctuation of EFG caused by jum ping m otion o f the hydrogen atom s in the OH groups. 
  Reference    Z. Naturforsch. 49a, 279 (1994); received August 16 1993 
  Published    1994 
  Keywords    Crystal structure, Hydrogen bond, Chlorine N Q R, Spin lattice relaxation 
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 Identifier    ZNA-1994-49a-0279 
 Volume    49 
17Author    Hiroyuki Ishida, Yoshihiro Kubozono, Setsuo Kashino, Ryuichi IkedaRequires cookie*
 Title    Crystal Structure of Trimethylammonium Perchlorate in Three Solid Phases Including the Ionic Plastic Phase Obtainable above 480 K  
 Abstract    The crystal structures of (CH3)3NHC104 in three solid phases were studied by X-ray diffraction techniques. X-ray powder patterns taken at ca. 500 and 445 K revealed that the plastic phase (Phase I) attainable above 480 K crystallizes in a CsCl-type cubic structure with a = 5.845 (1) A, Z = 1, V = 199.7 (2) Ä3, and Dx = 1.327 gem -3, while Phase II, stable between 480 and 396 K, forms a tetragonal structure with a = 9.912 (4), c = 7.01 (2) Ä, Z = 4, V = 689 (3) A3, and Dx = 1.54 gem -3. The room temperature phase (Phase III) was studied by single crystal X-ray diffraction and found to form a monoclinic lattice with space group P2X , a = 5.749(1), b = 8.670(1), c = 7.5585 (9) A, ß = 102.66 (1)°, Z = 2, V = 367.6 (2) A , and Dx= 1.441 g em -3. Thermal measurements, differential thermal analysis and differential scanning calorimetry, were carried out on these solid phases, and the obtained results were compared with those observed for (CH3)3NHBF4. 
  Reference    Z. Naturforsch. 49a, 723—726 (1994); received March 12 1994 
  Published    1994 
  Keywords    Crystal structure, X-ray diffraction, Thermal measurements, Ionic plastic phase 
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 TEI-XML for    default:Reihe_A/49/ZNA-1994-49a-0723.pdf 
 Identifier    ZNA-1994-49a-0723 
 Volume    49 
18Author    Hiroyuki Ishida, Masakazu Kato, Hiroshi Ono, Ryuichi IkedaRequires cookie*
 Title    Cationic Self-diffusion in Solid Choline Perchlorate Studied by NMR  
 Abstract    The 1 H spin-lattice and spin-spin relaxation times, and the second moment of the 1 H NMR linewidth of choline Perchlorate, [(Cff^NCfFCHiOHJClC^, were measured in its highest-temperature solid phase, i. e. above 275 K. X-ray powder patterns taken at ca. 380 K revealed that in this phase the crystal has a CsCl-type cubic structure (a = 6.326(4) A and Z = 1). From *H NMR experiments it was found that the cations in this phase undergo isotropic rotation and translational self-diffusion. From the 1 H T, measurements, the activation energies of the cationic rotation and self-diffusion were evaluated to be 21.4 ± 0.4 and 62 ± 3 kJ mol -1 , respectively. 
  Reference    Z. Naturforsch. 52a, 637—639 (1997); received May 28 1997 
  Published    1997 
  Keywords    Ionic plastic phase, Self-diffusion, Crystal structure, Nuclear magnetic resonance 
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 Identifier    ZNA-1997-52a-0637 
 Volume    52 
19Author    Masao Hashimoto, Shinichi Hashimoto, Hiromitsu Terao, Masayuki Kuma, Haruo Niki, Hiroyuki InoRequires cookie*
 Title    Crystal Structure and Phase Transition of 4-Aminopyridinium Tetrabromoantimonate(III) as Studied by Bromine and Antimony NQR, Proton NMR, and Single Crystal X-Ray Diffraction  
 Abstract    The crystal structure of the room temperature phase (RTP) of the title compound was determined at 297 K (monoclinic, space group C2/c, a = 1384.2(2), b = 1377.8(3), c = 755.5(2) pm, ß = 121.58(1)°). A complicated disorder was found for the cation. A phase transition from the low-temperature phase (LTP) to the RTP was found at (224 ±1) K (T c). The 'H NMR spectra showed a sharp motional narrowing at ca. T=T C , indicating the occurrence of a reorientational motion of the cation in the RTP in accord with the disorder. It was found that another reorientational motion is excited in the LTP. Four 81 Br NQR lines (132.71, 115.38, 61.54 and 59.31 MHz at 77 K) and two Sb NQR lines (53.78 and 33.76 MHz at 77 K) were found in the LTP, while a single 81 Br NQR line was observed at T> 276 K (ca. 121.80 MHz at 300 K). Crystal dynamics are discussed on the basis of the temperature dependence of the NQR, *H NMR line width, and 'H NMR Tj. 
  Reference    Z. Naturforsch. 55a, 167—172 (2000); received August 24 1999 
  Published    2000 
  Keywords    4-NH 2 PyHSbBr 4, Crystal Structure, Phase Transition, NQR, 'H NMR 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0167.pdf 
 Identifier    ZNA-2000-55a-0167 
 Volume    55 
20Author    J. Pirnat, Z. Trontelj, J. Lužnik, D. KirinRequires cookie*
 Title    Halogen NQR and the Phase Transition in CH 3 Hg-Halide Family  
 Abstract    The temperature dependence of the 35 C1 NQR line and its relaxation has been measured from 77 K to room temperature. The known displacive phase transition near 162 K is reflected in the change of the slope of the temperature dependence of the quadrupole line, but not so in the chlorine or proton relaxation. The results are discussed in view of the proposed structural changes and thermal vibrations. 
  Reference    Z. Naturforsch. 55a, 215—218 (2000); received October 13 1999 
  Published    2000 
  Keywords    Methylmercury Chloride, NQR, Crystal Structure, Phase Transition, Thermal Vibrations 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0215.pdf 
 Identifier    ZNA-2000-55a-0215 
 Volume    55 
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