Type-A AFM phase

Pro.5Sro.5Mn03 corresponds to phase IV with a type-A AFM phase appearing below a Ts = Too < Tc (Kawano et al., 1997 Damay et al., 1998 Llobet et al., 1999). In this phase,... 

The application of a magnetic field stabilizes the FM phase, moving the 0 -R boundary to the left and suppressing the Type-A AFM phase at x = 0.5. Asamitsu et al. [217, 218] have measured a shift of the 0 -R transition temperature for x = 0.17 from 280 K to 220 K in an applied field of 7 T to produce a field-induced structural change from O to R symmetry in this temperature range. Campbell et al. [219] have confirmed the field-induced transition on a single-crystal x = 0.165 sample with neutron diffraction. 

Substituting smaller rare-earth ions in R0.5 Sro.sMnOs increases the A-site varianee as well as reducing t. Whereas Lao.sSro.sMnOs is a phase V FMM, Pro.sSro.sMnOs corresponds to phase IV, stabilizing the type-A AFM phase below Tn = Too, and Ndo.sSro.sMnOs contains the eoexistence of phases III and IV below r>j = Too 150 K (Kajimoto et al., 1999 Kuwa-hara et al., 1995), but an insulator-metal transition to the FMM phase is still indueed by an... 

On lowering the temperature in the range 0.980 < f < 0.992, the FMM phase transforms completely, or partially, to a type-A antiferromagnetic metallic (A AFM) phase IV in which orbital order constrains itinerant a electrons and de Getmes double exchange to the (001) planes the interactions between (001) planes are antiferromagneticby t -O-t superexchange as occurs in LaMnOs where all the 3d electrons at Mn(III) remain localized. 

Figure 24. Variation in the percentage of the different phases of Ndo.5-SrasMnOj with temperature FMM phase (diamonds) orbitally ordered A-type AFM phase (circles) charge-ordered CE-type AFM phase (squares) (from Woodward et al.50),...

Tanaka et at. (T45) partially masked the surfaces of disks of slag glass with gold coatings the disks were then embedded in cement pastes for various periods, after which they were removed and examined by SEM. This showed that two layers of in situ product were formed. The innermost one had Si/Ca 0.64, Al/Ca 0.32 and Mg/Ca 0.34 the outer one had Si/Ca 0.61, Al/Ca 0.24, Mg/Ca 0.20. The product formed immediately outside the original boundary of the slag had Si/Ca 0.48, Al/Ca 0.09, Mg/Ca 0.17. The two layers of in situ product could have been mixtures in differing proportions of C-S-H. a hydrotalcite-type phase and possibly AFm phase. 

A modified type of AFM, called a friction-force microscope (FFM), has been described." " This method was shown to be able to distinguish between fluorocarbons and hydrocarbons on a phase-separated LB film. This shows that although AFM has proven useful for imaging organic thin films on an atomic scale, the technique can also provide useful information about the composition of molecules, as well as their conformation. 

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