The modulated structure of θ-(BEDT-TTF)2RbM'(SCN) 4; (M'=Zn, Co) were investigated by X-ray diffraction method. θ-(BEDT-TTF)2RbM'(SCN)4 are two-dimensional organic conductors which exhibit metal-insulator transition at 210 K. The insulating phase is known as a charge ordered state. Above TMI= 210 K, diffuse rod of q=(1/3 k 1/4) was found. Below TMI, there are some differences depending on the sample cooling speed. In the slow-cooled-state (0.2 K/min), the diffuse rod of q=(1/3 k 1/4) disappears and is replaced by superlattice of c*/2. In the rapid-cooled-state (5-6 K/min), the structural phase transition at TI becomes imperfect. The diffuse rod of q remains below TMI and the lattice modulation of c*/2 is disordered in the direction of inter-conducting-layer.
- Metal-insulator phase transition
- Organic conductors based on radical cation and/or anion.
- Structural phase transition
- X-ray emission diffraction and scattering
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry