1994 Fiscal Year Final Research Report Summary
Homogeneity range and some physical properties of newly synthesized intercalation compounds of layred tanlalum disulfide.
| Project/Area Number |
05650631
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
HINODE Hirofumi Tokyo Institute of Technlogy, Faculty of Engineering Lecturer, 工学部, 講師 (50165130)
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| Project Period (FY) |
1993 – 1994
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| Keywords | tantalum disulfide / intercalation / single phase region / superlattice / metalic conduction / paramagnetic / Curie-Weiss law |
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| Research Abstract |
The intercalation compounds of M_xTaS_2(M=Ni and Mn)were synthesized by heating the mixture of TaS_2 and metal M in an evacuated silica tube. TaS_2 was synthesized from Ta foil and pure sulfur powder. By using powder x-ray diffraction method and EDAX analysis, the single phase region was determined as 0.11<less than or equal>x<less than or equal>0.40 in Ni_xTaS_2 and 0.20<less than or equal>x<less than or equal>0.50 in Mn_x TaS_2 at 1000ﾟC,respectively. In Ni_xTaS_2 the hexagonal a-axis and c-axis both decreased with increasing Ni content x and became minimum at x=0.25. Then lattice parameters in creased with increasing x. The electron diffraction patterns of Ni_<0.25>TaS_2 showed the 2a_0*2a_0 superlattice spots (a_0 : host TaS_2 lattice parameter).In Mn_xTaS_2 the hexagonal c-axis increased simply with increasing Mn content x, while a-axis had anomalies at x=1/4 and 1/3where different superlattices(2a_0*2a_0 and ROO<3>a_0*ROO<3>a_0 superlattice spots, respectively)are observed. The temperature dependence of electrical resistivity showed metallic behavior in both Ni_xTaS_2. In the case of N_xTaS_2 the rigid band model was not valid. The temperature variation of magnetic susceptibility obeyed a Curie-Weiss law also in both case. In Ni_xTaS_2 The values of the Weiss constant(paramagnetic Curie temperature)rheta were all negative indicating the antiferromagnetic exchange interactions. In Mn_xTaS_2 rheta decteased with x and changed the value from poseteve to negative at x=0.50 suggesting the change of exchange interactions from ferromagnetic to antiferromagnetic. The valence state of Ni in Ni_xTaS_2 was evaluated as +3 divalent at x=0.33 and the +2 and +3 mixed state at other Ni content x by P_<eff>(effective Bohr magneton)calculated from the Curie constant.The valence state of Mn in Mn_xTaS_2 was evaluated as +2 also by P_<eff>.
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