Vibrational study of various crystalline phases of thallium dihydrogen phosphate TlH2PO4 and its deuterated analog TlD2PO4

H1NMR study of proton motions in thallium-deficientTlHKim1, Lee2, Lee3 1996Phys. Rev. B9040View full textAdd to dashboardCite

“…2 TDP undergoes two major structural phase transitions and three more complex phase transitions. [3][4][5][6][7] The roomtemperature phase ͑phase II͒ is known to be paraelectric and ferroelastic, while the low-temperature phase ͑phase III͒ is believed to be antiferroelectric from the polarization-electric field double hysteresis loops of its deuterated analog TlD 2 PO 4 . 8 Thus, the antiferroelectric phase transition in TDP corresponds to the ferroelectric phase transition in KDP.…”

Phonon dynamics simulation of TlH2PO4 crystal

“…A comparison between the calculated near the BZ centre and experimental phonon frequencies taken in Raman and IR [18] measurements in prototype phase is presented in Table 1. The mode assignment performed basing on the eigenvector analysis is also presented there.…”

“…Hanazawa et al [7] suggested that the acoustic phonon softening is caused by the bilinear coupling with the Q transition parameter transforming in the Brillouin zone Since an X-ray study showed that a slight rotation of PO 4 groups appeared after phase transition into ferroelastic phase [5], Hanazawa et al [7] suggested that the Q transition parameter may be related to the rotational mode of PO 4 groups. However, a temperature-dependent Raman study revealed no visible softening of the optical mode in the vicinity of the ferroelastic phase transition [18]. Moreover, based on the examination of the isotope effect in the partly deuterated Tl(H 1Àx D x ) 2 PO 4 compound, Matsuo et al [5] arrived at a conclusion that the hydrogen bonds play no significant role in the ferroelastic phase transition.…”

“…Therefore, their symmetry assignment suggested in Ref. [18] is of a rather approximate character. Moreover, it should be taken into account that the current simulation was done assuming a few requirements imposed by symmetry.…”

“…Careful structural research was carried out by different investigators in all temperature phases [1][2][3][4][5]. An exhaustive set of Brillouin scattering [6], elastic [7], resonance [8][9][10][11][12], dielectric [13][14][15][16] and spectroscopic [17,18] measurements have been performed over the last three decades. However, despite the extensive bibliography devoted to the investigation of TDP crystal, one cannot claim that all the aspects of physical properties of this crystal are properly understood.…”