Monoclinic–orthorhombic phase transition in Ba₂Cu(HCOO)₆ crystals: a Raman scattering study

Abstract

The monoclinic-orthorhombic phase transition in Ba 2 Cu.HCOO/ 6 crystals, which takes place when the temperature is raised from 300 to 317 K, was analysed in the light of Raman scattering measurements. The disappearance of two modes related to HCOO vibrations is interpreted as the signature of phase transformation which is characterized by slight modifications in the atomic positions of HCOO in the unit cell. For the sake of completeness, we also show the evolution of the Raman spectrum from 50 to 300 K, where no phase transformation is observed.

New double formates Na3M(HCOO)6 (M=Ga, In) with diamond-like metal framework: Synthesis, structure and coordination modes

“…One could also expect more diversified structure frameworks when the compounds contain different cations with different valence and/or coordination number. In fact, double formates, such as MM 0 (HCOO) 4 [27][28][29][30][31][32], M 2 M 0 (HCOO) 6 [27,30,[33][34][35], MM'(HCOO) 4 (H 2 O) 2 (M = Ca, Sr, and Ba, M 0 = Cu) [36], Ba 2 M(H-COO) 6 (H 2 O) 4 (M = Fe, Co, Ni, Cu, Zn) [37][38][39][40][41] and M x M 0 1Àx (HCOO) 2 Á2H 2 O (M = Mn, Co, Ni, Zn, Cd, Mg, and M 0 = Cu) [42][43][44][45][46], were known for many years. In the structure of SrCu(H-COO) 4 (H 2 O) 2 , for example, four different connection modes, 2.20, 2.11, 3.21 and 4.22 coexist.…”

Raman Spectroscopy of Rhombohedral P4O10

“…6 Previous Raman and infrared spectroscopic studies, performed on these and similar materials, have provided useful complementary structural information to that obtained from X-ray diffraction patterns. These studies have also been performed to characterize phase purity 7,8 and investigate changes in structure as a function of the degree of modification. 9 As such, the electronic structure and vibrational characteristics of these oxides in their vapor and solid forms are of interest.…”