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Synthesis and Characterization of KMo 4 O 6
M. Andrade, M. L. Maffei, L. M. S. Alves, C. A. M dos Santos, B. Ferreira and A. F. Sartori.
Escola de Engenharia de Lorena – USP, P. O. Box 116, Lorena, SP 12602-810, Brazil
ma@ppgem.eel.usp.br
The KMo 4 O 6 compound is an important molybdate that shows interesting physical
properties such as high anisotropy, structure with infinites chains with Mo 6 octahedra,
metal–insulator transition (MIT) near 120 K, and quasi-one-dimensional electrical
behavior [1]. This compound crystallizes into two phases. One has tetragonal structure
with space group P4/mbm, lattice parameters a = 9.612 Å and, c = 2.950 Å. The
synthesis of KMo 4 O 6 is commonly carried out by electrolysis of molten salts [2, 3]. One
the biggest issue in studying high anisotropic conductors and MIT is due to these
behaviors appear closed related to the superconductivity [4].
The crystals grew in the form of black square prisms with dimensions of 1.0 x
0.2 x 0.2 mm³. They were obtained from a mixture of K 2 MoO 4 and MoO 3 in the molar
ratio of 6:1, dried at 160 ° C and 450 ° C. The synthesis occurred with a current of 20 –
25 mA at 930 °C for 52 h. X- ray diffractometry confirmed that the crystals obtained
were due to the KMo 4 O 6 phase with the same characteristics reported previously [2,3].
Electrical resistances measurements were done by standard four-probe method using a
PPMS from 2 to 300 K. The results show metallic behavior with a MIT near 120 K.
Magnetic measurements were done parallel and perpendicular to the field in the range 2
– 300 K using a VSM coupled in a PPMS. The MxT curves agree with the magnetic
anisotropy reported previously. MxH curves display non-linear behavior at high
temperatures which suggest that the KMo 4 O 6 compound does not show a Pauli
paramagnetism as reported previously. The results also suggest magnetic ordering
which happens near the metal–insulator transition temperature.
Acknowledgement: FAPESP (2010/06637-2 and 2009/54001-2), CNPq (490182/2009-
7 and 309084/2010-5) and CAPES.
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State Chem. 102, 69 (1993).
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Solid State Chem. 117, 217 (1995).
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(1990).
[4] C. A. M. dos Santos, B. D. White, Yi-Kuo Yu, J. J. Neumeier, and J. A. Souza,
Physical Review Letters 98, 266405 (2007).
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