I. Pabst et al., PHASE SEQUENCE OF [CH3NH3]2CUCL4 STUDIED BY X-RAY-DIFFRACTION AND LOW-FREQUENCY RAMAN-SCATTERING, Physica status solidi. a, Applied research, 155(2), 1996, pp. 341-352
The phase sequence of [CH3NH3]2CuCl4 was determined by X-ray structure
analysis at T = 100, 297, and 363 K and temperature-dependent: low-fr
equency, Raman-scattering investigations cr ere performed. At temperat
ures below T-tr=348(2) K the structure is monoclinic, space group P2(1
)/a, lattice parameters a = 7.155(4) Angstrom, b = 7.424(4) Angstrom,
c = 9.814(3) Angstrom, beta = 109.18(7)degrees (for T = 100 K) and in
the range 348 K < T < 455 K an orthorhombic high-temperature phase exi
sts (space group Ccmb, lattice constants a = 7.34(2) Angstrom, b = 18.
71(1) Angstrom; c = 7.33(5) Angstrom). The coexistence of two phases f
or low temperatures and the tetragonal high-temperature structure, rep
orted previously for the title compound, are explained by twins and de
finitely discarded.