A. WANIC (a), and W. WOLSKI (d) Neutron spectrometric investigations are made of goethite (a-FeOOH) of mineralogical and synthetic origin (a-FeOOH of natural isotopic composition) and also of a-FeOOD using a monochromatic neutron beam of I = 1.12 A. Some powder diffraction patterns in the temperature range from -190 to +120 "C are measured. The obtained coordinates for all atoms (including those for hydrogen) in the unit cell are given. The existence of antiferromagnetic spin ordering a t temperatures below +SO "C is observed. A model is proposed in which the spins are aligned parallel to the b-axis. EbIn EICCJIeHOBaH reTIIT (cc-FeOOH) MuHepanora4ecKoro IIPOMCXOmAeHHR EI CEIH-TeTElseCHIlfi (eCTeCTBeHHOr0 E130TOnWleCKOrO COCTaBa) a TaKme AefiTepEI3OBaHHbIfi W T H T a-FeOOD. kICCJIeAOBaHHfI BeJIEICb B B m s a (~rOCJIaBEIH) IIpH peaKTope PA. ,&JIH M3MepeHHn HCIZOJI3OBPHO KPaKOBCKllfi HefiTpOHHblfi KpEICTNIJlEI~eCKEl~ CIIeK-TpOMeTp EI IIyuOK HefiTpOHOB C AJIUHOfi BOJlHbI A = 1,12 A. TeMnepaTypa o6paaua U3MeHIIJIaCb B IIpeAeJlaX OT -190 HO +I20 "c. YTOYHeHO HOOPAEIHaTbI aTOMOB BbInO 06HapymeHO CyrrleCTBOBaHIIe aHTEl-meneaa II wicnopona B s n e~e~~a p~o t m e h e , a TaKme B nepwfi pa3 6b1no onpe-#eppoMarHmHoro ynopHAoseHm CIIEIHOB EIOHOB meneaa B TeMnepaTypax HHme +80 "C. ~P M B O A E I T C R MoAen C~E~H O B O~~ peluema B KOTOPOP C~E I H~I napanenmb1 OCM b.HeJIeHO IIOJIOmeHEIe aTOMOB BOAOpOAa.
International audienceThe concept of the vibratory energy transfer between a linear master DOF and a nonsmooth nonlinear energy sink (NES) in the presence of gravity forces is studied. Different invariant manifolds of the system at different time scales are revealed and necessary conditions for leading the behavior of the system to strongly modulated response (SMR) are enlightened
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