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Structural phase transitions in K 2 CO 3 (Raman scattering study)

1981; IOP Publishing; Volume: 14; Issue: 11 Linguagem: Inglês

10.1088/0022-3719/14/11/021

1747-3802

A. C. Maciel, John F. Ryan, P.J. Walker,

Nonlinear Optical Materials Research

Structural phase transitions in K 2 CO 3 have been investigated using light scattering techniques. The Raman spectrum of the high-temperature hexagonal phase consists of a very broad structureless band which suggests that the system is highly anharmonic. Below the hexagonal-monoclinic transition at T cl =693K the authors observe a soft mode which is assigned to librational motion of the CO 3 groups. Evidence of a cell doubling transition at T c2 =526K is found in the number of Raman active modes observed at low temperature, although a soft mode is not observed at the transition.