Developments in Ceramic Materials Research

Intensity (a.u.)
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Synthesis, Spectroscopic and Magnetic Studies… 131
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a
2 Theta (deg.)
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b
2 Theta (deg.)
Figure 27. Refinement of D2B neutron diffraction profiles at 2 K of (a) Mo(PO 3) 3 (λ= 1.594 Å) and (b)
Fe(PO3) 3 (λ = 2.41 Å), The positions of the Bragg reflections for the nuclear (first row ) and magnetic
(second row) structures are presented. The differences curves are plotted at the botton of the figures.
In order to understand the nature of the magnetic anomalies in the Fe(PO3)3
metaphosphate, observed in both the magnetization and the specific heat data, a deeper study
using neutron diffraction measurements in the 1.5-2.0 K temperature range every 0.5 K was
carried out. The thermal evolution of the D1B diffraction patterns is shown in Figure 29(a).
The three-dimensional magnetic ordering begins at 9 K, being similar to that obtained from
the specific-heat measurements (TN= 7.8 K).
The intensity of the magnetic reflections continuously increases without reaching
saturation probably due to the low temperature at which the magnetic order is established.