ZfN: Search Results

1	Author	Hiroki Fujimori, Tetsuo Asaji	Requires cookie*
	Title	CI NQR in Glassy Crystal of 2-chlorothiophene
	Abstract	Stable crystalline 2-chlorothiophene has two glass transitions at 164 and 186 K. 35 CI NQR measurements were carried out between 77 and 200 K. Two NQR signals with full widths of about 100 kHz at half maximum were observed in this temperature range. The spin-lattice relaxation times Ti were measured at the two peak frequencies. The activation energy obtained from the results of the T\ measurements showed a fairly good agreement with those estimated from calorimetric measurements.
	Reference	Z. Naturforsch. 55a, 183—185 (2000); received October 13 1999
	Published	2000
	Keywords	NQR, 2-chlorothiophene, Glassy Crystal, Glass Transition
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	TEI-XML for	default:Reihe_A/55/ZNA-2000-55a-0183.pdf
	Identifier	ZNA-2000-55a-0183
	Volume	55

2	Author	J. Reuter, T. Brückert, A. Würflinger	Requires 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
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	TEI-XML for	default:Reihe_A/48/ZNA-1993-48a-0705.pdf
	Identifier	ZNA-1993-48a-0705
	Volume	48

3	Author	G. Herms, J. Sakowski, W. Gerike, Dörte Stachel	Requires cookie*
	Title	Structural Changes in Two Different Types of Oxide Glass Melts: Borates and Metaphosphates
	Abstract	X-ray diffraction experiments of molten oxide glasses, which give new insights into the structure of melts, were carried out. Using modern means (synchrotron radiation, image plates, container-less high-temperature technique) it could be shown that the short range order of melt and solid glass is often qual-itatively different. If vitreous B 2 0 3 or binary borate glasses with low content of network modifier are heated up above T & , the network topology begins to alter. With rising temperature more and more of the boroxol groups are replaced by independent B0 3 groups. While melting a metaphosphate glass, how-ever, structural changes of another kind take place. In solid glass the environment of the network mod-ifier ions is similar to the one found in crystalline modifications, and their distances to the surrounding P0 4 tetrahedra have narrow distributions. In the melt, however, these distances scarcely become evi-dent, probably owing to the increased thermal motion of the modifier ions.
	Reference	Z. Naturforsch. 53a, 874—882 (1998); received February 17 1997
	Published	1998
	Keywords	X-ray Diffraction, Short Range Order, Borate Glasses, Phosphate Glasses, Glass Transition
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	TEI-XML for	default:Reihe_A/53/ZNA-1998-53a-0874.pdf
	Identifier	ZNA-1998-53a-0874
	Volume	53