A dupla perovsquita Ca2MnReO6 na forma policristalina foi preparada utilizando o método do tubo de quartzo encapsulado. A pressão parcial de oxigênio dentro do tubo de quartzo mostrou-se ser um parâmetro crucial para a produção de uma amostra estrutural monofásica. Esse parâmetro foi controlado usando a relação entre o conteúdo dos precursores ReO2 e ReO3 e o parâmetro fator de preenchimento (razão entre a massa e o volume interno total do tubo de quartzo).A morfologia e a composição química foi investigada através da microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raios X . Os parâmetros de estrutura cristalina foram determinados através da análise do padrão de difração tomado com luz síncrotron de alta resolução. Finalmente, os parâmetros cristalinos foram comparados com os resultados oriundos dos cálculos de Bond-Valence Method oriundos do programa SPuDS. Como resumo, a análise indicou que a amostra é um composto monofásico com uma estrutura cristalina monoclínica (grupo espacial P21/c) com a=5,44445(2) Å; b=5,63957(3) Å; c=7,77524(3) Å; and β = 90,18(1)º.

The Ca2Mn1Re1O6 double perovskite has been prepared in polycrystalline form by using the encapsulated quartz tube method. The partial oxygen pressure inside the quartz tube revealed this to be a crucial synthesis parameter for the production of a single structural phase sample. This parameter was controlled using the ratio between ReO2 and ReO3 content and the filling factor parameter (ratio between mass and total inner volume of the quartz tube). The morphology and chemical composition was investigated by scanning electron microscopy and energy dispersive X-ray spectroscopy. The crystal structure parameters were determined by analysis of the synchrotron high-resolution X-ray powder diffraction pattern. The analysis indicates that the sample is an ideal single-phase compound with a monoclinic crystal structure (space group P2(1)/n) with a = 5.44445(2) Å; b = 5.63957(3) Å; c = 7.77524(3) Å; and β = 90.18(1)º. Computer simulations were performed considering two cation valence configurations, namely, (i) Mn2+Re6+ or (ii) Mn3+Re5+, for the Ca2Mn1Re1O6 compound. XANES analysis measurements indicated +2.3 for the average valence of Mn (a mixture of Mn2+ and Mn3+) and +5.7 for the effective valence of Re (an intermediate valence between Re4+ (ReO2) and Re6+ (ReO3)). As a summary, we concluded there is a mixed valence configuration for Mn and Re in Ca2Mn1Re1O6 , taken into account the oxygen content of 6.0±0.1.

We evaluate nucleon and delta sigma-terms and obtain the results 43 MeV < sigmaN < 49 MeV and 28 MeV < <FONT FACE=Symbol>sD</FONT> < 32 MeV, depending on the coupling constants used, which are compatible with values extracted from experiment and produced by other groups. We show that the decay <FONT FACE=Symbol>D ® p</FONT>N explains the relation <FONT FACE=Symbol>sD</FONT> < sigmaN.