K2NiF4-type compounds

Table 5. Magnetic parameters of K2NiF4-type compounds...

Both symmetry and unit cell constants are similar to the corresponding values of K2NiF4 type compounds, as is shown in Table II. Indeed, we have found that a reasonable structure can be derived for Sr2Pd03 which is closely related to the K2NiF4 structure. In this proposed structure, the space group D2h25-Zmmm is assumed and the atoms are placed as follows ... 

Galasso and Darby [220] prepared and investigated the oxyfluoride K2NbC>3F, which has crystal structure similar to K2Ta02F and crystallizes in a K2NiF4 type structure. The structure of the compound consists of infinite layers of octahedrons, Nb04F2, that are oriented perpendicular to the c axis, as shown in Fig. 34. 

It has been found that Cs2CaF4 is a compound with K2NiF4-type structure. 

Cr + ions may be stabilized in the K2NiF4 structure type also A CrCl4 (A K, NH4, Rb, Cs). For the Rb and Cs compounds tetragonally compressed CrClg" octa-hedia are reported as the result of powder neutron diffraction studies with the rather approximate values Rb2(Cs2)CrCl4 243 (240) pm (2 x), 257 (261) pm (4 x)S3). The observed low-temperature ferromagnetism is not consistent with this... 

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