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41.
Recent structure analyses of crystals with different compositions in the Ca2Fe2?xAlxO5 system have led to a reinterpretation of the magnetic ‘phase diagram’ of this system. In the composition range 0 ? x ? 1, there are at least three and possibly four different magnetic structures. At room temperature, and between x = 0·00 and x less than but near 0·60 (the exact boundary is not known), the magnetic structure belongs to magnetic space group Pcm′n′; in a narrower range, approximately 0·57 ? x ? 0·65, the magnetic space group is Ipb′m′2; for x greater than about 0·80, the magnetic space group is Ipbm′2′. There is a substantial region of x and T (at room temperature 0·65 ? x ? 0·80), for which our experimental results cannot distinguish between two possibilities: either both the Ipb′m′2 and Ipbm′2′ structures coexist with spin-flipping as x or T changes or there is a continuous rotation of the spins with changing x or T. In the latter case, the most probable single magnetic space group in this region is Cpm′; with increasing x or T the transitions occur by way of Ipb′m′2 → Cpm′ → Ipbm′2′. 相似文献
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It was found that a polycrystalline gadolinium sample forming part of a closed magnetic loop threading a coil induced substantial coil noise when its temperature corresponded to the transition temperature of gadolinium. 相似文献
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The , and , ground vibrational state transitions of 35ClO and 37ClO and the , excited vibrational state transitions of 35ClO have been observed in the 164–167 GHz region. Additional measurements have also been made on the and transitions of both the ground and excited vibrational states. All measurements were made using millimeter oscillators which were phase locked to harmonics of a Hewlett-Packard microwave spectrometer's X-band source. Λ-doubling splitting of a few transitions was resolved.When magnetic and nuclear quadrupole hyperfine terms off-diagonal in J and in the Hund's case (a) representation were included in addition to the usual diagonal terms, an excellent fit to all of our observed transitions resulted. The most significant change from previously determined parameters is the centrifugal distortion constant D for which the values, D0 = 0.03972(26) MHz for 35ClO, D0 = 0.03888(32) MHz for 37ClO and D1 = 0.0395(21) MHz for 35ClO are obtained. Values of 1.56959(1) Å for the equilibrium bond length and 854(7) cm?1 for the equilibrium vibrational frequency are derived from the measured spectra. In addition, values for the Λ-doubling constant βp and the quadrupole coupling constant eQq2 were derived from the measured spectra for the first time. 相似文献
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