The structural states of Cu2O at pressures between ambient and 11 GPa were re-investigated, using angle-dispersive diffraction, an area detector and synchrotron radiation. Thanks to the latter’s naturally high collimation, a hitherto suspected transition from the parent cubic phase to a new tetragonal phase was experimentally confirmed at pressures between 0.7 and 2.2 GPa, depending on the hydrostaticity of the pressure medium used. The other transformation, into a pseudocubic phase, was detected at about 8.5 GPa. In the same pressure range, the application of pressure also resulted in a general and strong broadening of the diffraction peaks. This broadening is attributed to the presence of microscopic strains and a reduction in grain size down to the nanocrystalline scale.

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Investigation of the relaxation properties of the a-and p-modifications of poly (vinylidene fluoride) in the temperature range from -170°C t o melting point showed that there exist six relaxation transitions and one phase transition in this polymer. The classification of the observed relaxation transitions is the same as for other amorphous-crystalline polymers. The reasons for the higher temperature of relaxation transitions in p-PVDF are discussed. Relaxationsiibergange in Poly(vinylidenf1uorid)Eine Untersuchung des Relaxationsverhaltens der aund j3-Modifikationen von Poly(vinylidenf1uorid) im Temperaturbereich von -170 "C bis zum Schmelzpunkt zeigte, daB sechs Relaxationsprozesse und ein Phaseniibergang in dem Polymer auftreten. Die Klassifizierung der beobachteten Relaxationsubergange erfolgte nach dem gleichen Schema wie bei anderen amorph-kristallinen Polymeren. Die Grunde fur die hohere Temperatur der Relaxationsubergange im /3-PVDF werden diskutiert. Penamaquonnbte nepexoaai e nonueununudeng6mopudePe3YnbTaTbI HCCJIeAOBaHIIR PeJIaKCaqHOHHbIX CBOfiCTB nOJIHBHHIIJIIIAeH+TOpHna (nBA@) OL-H @-MOAH@HKaqMH B HHTepBaJIe TeMnepaTyp OTi 7 0°C A 0 TeMnepaTypM IIJIaBJIeHHtI IIPRBOART K 3aKJIIO9eHHIO 0 CyIUeCTBOBaHMH B 3TOM HbIX nepeXOJ(0H T a ?Ke, 9 T O II y ApyrHX aMOp@HO-KpHCTannHseCKHX IlOJIHMepOB. AHaJIHampymTcR IlpllWiHbI CMe-nonmiepe mecm peJIaKCaUHOHHbIX M OnHOrO @a30~0ro nepexoaoB. ICnaccn+maqm H~~J I I O A~~M~I X penaKcaqHoH-YeHm TeMnepaTyp penaKcaqHoHHbIx nepexoAoB y @-IIBJ(@ K 6onee BbIcoKmM TeMnepaTypaM.

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