ZfN: Search Results

1	Author	G. K. Semin, A. M. Raevsky, S. I. Kuznetsov, T. L. Khotsyanova, S. I. Gushchin	Requires cookie*
	Title	Br NQR Spectra of the Impurity Molecules of Tetrabromides of Group IV Elements in the Matrix Crystals of Group IV Element Halides
	Abstract	Changes in 79 Br NQR spectra of the impurity molecules EBr4 (2-5% mol) (E = C, Si, Ti, Ge, Sn) in the matrix crystals of group IV element tetrahalides EHal4 (E = Si. Ti, Ge, Sn; Hal = CI, Br) were studied at 77 K. The mixtures of these components are substitution solid solutions (SS), which was proved by the appearance of characteristic satellites in the NQR spectra of the matrix crystals. Changes in the Br NQR spectra of the impurity molecules were analyzed from the viewpoint of packing factors and the type of nearest environment. In the temperature range 77-270 K an abnormal temperature dependence of the 79 Br NQR frequencies of TiBr4 impurity in SiBr4 matrix was observed for both lines of the cubic phase. The temperature dependence of the 79 Br NQR frequencies of SiBr impurity in TiBr4 matrix is normal.
	Reference	Z. Naturforsch. 47a, 111—116 (1992); received December 18 1991
	Published	1992
	Keywords	79, 81 Br NQR, Solid solutions, Group IV element tetrahalides, Temperature depen-dence of NQR frequencies
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	TEI-XML for	default:Reihe_A/47/ZNA-1992-47a-0111.pdf
	Identifier	ZNA-1992-47a-0111
	Volume	47

2	Author	Tsutomu Okuda, Shusaku Gotou, Toshirou Takahashi, Hiromitsu Terao, Koji Yamada	Requires cookie*
	Title	Structure and Successive Phase Transitions of RGeBr 3 (R = Alkylammonium) Studied by Means of NQR
	Abstract	A series of tribromogermanate(II) complexes RGeBr 3 (R = CH 3 NH 3 , (CH 3) 2 NH 2 , (CH 3) 4 N, C 2 H 5 NH 3 , (C 2 H 5) 4 N) have been synthesized and characterized by 81 Br NQR, AC conductivity, DTA, and X-rax diffraction. These measurements revealed the presence of successive phase transi-tions in these complexes. The crystal structures of Phases I and II in (NH 3) 4 NGeBr 3 were derived from the Rietveld analysis of powder X-ray diffraction. The electric conductivity was considerably high in CH 3 NH 3 GeBr 3 and (NH 3) 4 NGeBr 3 . The conduction mechanism is discussed on the basis of 81 Br NQR spin-lattice relaxation times and crystal structures.
	Reference	Z. Naturforsch. 51a, 686—692 (1996); received October 10 1995
	Published	1996
	Keywords	81 Br NQR, T x, Phase Transition, Ionic Motion, Ionic Conductivity
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	TEI-XML for	default:Reihe_A/51/ZNA-1996-51a-0686.pdf
	Identifier	ZNA-1996-51a-0686
	Volume	51

3	Author	K. Yamada, T. Ohtani, S. Shirakawa, H. Ohki, T. Okuda, T. Kamiyama, K. Oikawa	Requires cookie*
	Title	Phase Transition of C 5 H 5 NHSbBr 4 Having a Hypervalent Bond: A 2 H NMR and X-Ray Diffraction Study* [Phase Transition of C 5 H 5 NHSbBr 4 l
	Abstract	The second order phase transition at 253 K of pyridinium tetrabromoantimonate(III), C 5 H 5 NHSbBr 4 , has been characterized by means of X-ray diffraction and 2 H NMR. As was suggested from the 81 Br NQR spectra, the Rietveld refinements of the X-ray diffraction patterns at 297 K and 116 K confirm the structural change of the anion from SbBr 4 to SbBr 3 • Br -. The line shape analysis of the 2 H NMR using the deuterated analog revealed that the librational amplitude of the pyridinium ring about the axis normal to the plane increased with temperature and its rms amplitude reaching ca. 25° at T c . The librational motion may induce the phase transition breaking the hydrogen bonds of the type N-H -Br. However, nearest-neighbor 2n/6 jump or reorientation such as seen in benzene were not observed even at 350 K.
	Reference	Z. Naturforsch. 51a, 739—744 (1996); received October 11 1995
	Published	1996
	Keywords	2 H NMR, 81 Br NQR, Rietveld analysis, Phase transition, Hypervalent bond
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	TEI-XML for	default:Reihe_A/51/ZNA-1996-51a-0739.pdf
	Identifier	ZNA-1996-51a-0739
	Volume	51

4	Author	Hiromitsu Terao, Tsutomu Okuda, Aya Minami, Takashi Matsumoto, Yoshio Takeda	Requires cookie*
	Title	Br and l27 I NQR Studies of (CH 3 NH 3 ) 2 HgBr 4 and (CH 3 NH 3 ) 2 HgI 4
	Abstract	The 81 Br and 127 I NQR frequencies in (CH 3 NH 3) 2 HgBr 4 and (CH 3 NH 3) 2 HgI 4 , respectively, have been recorded from above 77 K to around room temperature. The resonance lines exist in a wide range of frequencies. An unusual temperature dependence of the resonance frequencies has been observed. Small 1 H-2 D isotope effects have been observed between (CH 3 ND 3) 2 HgBr 4 and (CH 3 NH 3) 2 HgBr 4 . Both negative and positive frequency differences between the deuterated and the nondeuterated compound have been observed at 77 K. The relatively large asymmetry parameters in the iodine compound decrease with increasing temperature, indicating the existence of H-bonds. The present results are interpreted qualitatively by considering the effects of H-bonding, N-H • • • X, between the halogen atoms and the CH 3 NH 3 ions which may undergo large molecular motions. It is suggested that not only frequency-lowering but also frequency-rising effects may be produced, depending on the direction of the H-bond, i.e., the angle between the Hg-X bond and the X • • • H bond.
	Reference	Z. Naturforsch. 47a, 99—105 (1992); received October 8 1991
	Published	1992
	Keywords	81 Br NQR, 127 I NQR, Anomalous temperature dependence, r H-2 D isotope effect, H-bonding, Motions of CH 3 NH+
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	TEI-XML for	default:Reihe_A/47/ZNA-1992-47a-0099.pdf
	Identifier	ZNA-1992-47a-0099
	Volume	47