55 research outputs found
A Neutron Elastic Diffuse Scattering Study of PMN
We have performed elastic diffuse neutron scattering studies on the relaxor
Pb(MgNb)O (PMN). The measured intensity distribution near a
(100) Bragg peak in the (hk0) scattering plane assumes the shape of a butterfly
with extended intensity in the (110) and (10) directions. The
temperature dependence of the diffuse scattering shows that both the size of
the polar nanoregions (PNR) and the integrated diffuse intensity increase with
cooling even for temperatures below the Curie temperature K.Comment: Submitted to PR
Neutron scattering study of PbMgTaO and BaMgTaO complex perovskites
Neutron scattering investigations were carried out in
PbMgTaO and BaMgTaO complex
perovskites. The crystal structure of both compounds does not show any phase
transition in the temperature range 1.5 -- 730 K. Whereas the temperature
dependence of the lattice parameter of BaMgTaO follows the
classical expectations, the lattice parameter of relaxor ferroelectric
PbMgTaO exhibits anomalies. One of these anomalies is
observed in the same temperature range as the peak in the dielectric
susceptibility. We find that in PbMgTaO, lead ions are
displaced from the ideal positions in the perovskite structure at all
temperatures. Consequently short-range order is present. This induces strong
diffuse scattering with an anisotropic shape in wavevector space. The
temperature dependences of the diffuse neutron scattering intensity and of the
amplitude of the lead displacements are similar
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
Modelisation numerique de la mise en forme des produits plastiques realises par soufflage
Available at INIST (FR), Document Supply Service, under shelf-number : AR 15035 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc
Analyse comparee de l'evolution de la demande d'energie dans six pays industrialises
SIGLECNRS RP 400 (548) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Integration des dimensions energie et transport dans la construction d'un scenario de developpement durable en France
SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RP 185 (3498) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
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