Optical Study on the Phase Transitions in KH2PO4 and KD2PO4

The infrared spectra of the PO4 stretching vibrations have been studied on KH2PO4 and KD2PO4 over a wide range of temperature. A trend of the intensity variation with temperature for these bands is similar in each compound, but is very different between both compounds. An inspection of the intensity behaviors indicates that each PO4 group is attached equivalently by four hydrogen atoms in KH2PO4, and by two deuterium atoms in KD2PO4, above the respective transition points. Namely, each of the hydrogen and phosphorus atoms in KH2PO4 moves in a single‐minimum potential well with a flattened bottom, while each of the corresponding atoms in KD2PO4 moves in a double‐minimum potential well. Further, non‐existence is evidenced for a Slater configuration connected with an energy parameter e0 in his model. As a result, it is concluded that the displacive and pseudospin models are the most relevant in describing the phase transition mechanisms in KH2PO4 and KD2PO4, respectively.

[1]  R. Blinc,et al.  As 75 Electric-Field-Gradient Fluctuations in K H 2 P O 4 -Type Ferroelectrics , 1969 .

[2]  T. Plesser,et al.  Experimental proof for proton tunneling in KH2 PO4 , 1969 .

[3]  Yoshiki Sato,et al.  Potentials for the hydrogen atoms in normal and deuterated KH2PO4 , 1969 .

[4]  J. Wood,et al.  Isotope Effect on the Hydrogen-Bond Length , 1969 .

[5]  H. Thomas,et al.  Critical Behavior of the Pseudospin Model of Order-Disorder Type Ferroelectrics , 1968 .

[6]  H. Cummins,et al.  Brillouin-Scattering Study of the Ferroelectric Transition in KH2PO4 , 1968 .

[7]  R. Blinc,et al.  Spin-Lattice Relaxation by the Ferroelectric Mode in KH 2 PO 4 , 1968 .

[8]  R. Blinc,et al.  Electron paramagnetic resonance study of proton dynamics in KH2PO4 - KH2AsO4 mixed crystals , 1968 .

[9]  T. C. Damen,et al.  Temperature Dependence of the Ferroelectric Mode in KH2PO4 , 1968 .

[10]  Kenji K. Kobayashi.  Dynamical Theory of the Phase Transition in KH2PO4-Type Ferroelectric Crystals , 1968 .

[11]  W. Reese,et al.  Studies of phase transitions in order-disorder ferroelectrics. II. Calorimetric investigation of KD(2)PO(4) , 1968 .

[12]  R. Hill,et al.  Infrared Absorption by Hydrogen Bonds in Single Crystal KH2PO4, KD2PO4, and KH2AsO4 , 1968 .

[13]  N. Fuson,et al.  Infra-red investigation of dicalcium phosphates , 1967 .

[14]  Y. Imry,et al.  Anisotropy and phase transition effects in neutron scattering from KH2PO4 , 1967 .

[15]  M. Tokunaga.  Theory of Ferroelectric Phase Transition in KH2PO4 Type Crystals. II: Dynamical Properties , 1966 .

[16]  Yoshiki Sato.  Optical Study of X‐Ray Irradiation Effect on the Phase Transition in Triglycine Sulfate and Diglycine Nitrate , 1966 .

[17]  T. Matsubara,et al.  Theory of Ferroelectric Phase Transition in KHzP04 Type Crystals. I , 1966 .

[18]  J. Villain,et al.  Atomic Motion in Hydrogen‐Bond Ferroelectrics , 1966 .

[19]  N. V. Cohan,et al.  Molecular Orbital Study of the Hydrogen Bond in Ice , 1965 .

[20]  R. Blinc,et al.  Low-frequency hydrogen modes in KH2PO4 type ferroelectric crystals , 1965 .

[21]  J. Kumamoto.  Vibrational frequencies of phosphate derivatives , 1965 .

[22]  A. Chapman,et al.  Spectra of phosphorus compounds—I the infra-red spectra of orthophosphates , 1964 .

[23]  P. D. Gennes,et al.  Collective motions of hydrogen bonds , 1963 .

[24]  M. Tinkham,et al.  Far‐Infrared Dielectric Measurements on Potassium Dihydrogen Phosphate, Triglycine Sulfate, and Rutile , 1963 .

[25]  E. A. Uehling,et al.  Random Motion of Deuterons in KD2PO4 , 1962 .

[26]  W. Cochran,et al.  Crystal stability and the theory of ferroelectricity part II. Piezoelectric crystals , 1961 .

[27]  R. Blinc.  On the isotopic effects in the ferroelectric behaviour of crystals with short hydrogen bonds , 1960 .

[28]  C. Reid.  Semiempirical Treatment of the Hydrogen Bond , 1959 .

[29]  R. Blinc,et al.  The infra-red spectra of some ferroelectric compounds with short hydrogen bonds , 1958 .

[30]  R. S. Pease,et al.  A neutron-diffraction study of the ferroelectric transition of potassium dihydrogen phosphate , 1955, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[31]  A. Ubbelohde,et al.  Acid-base effects in hydrogen bonds in crystals , 1955 .

[32]  G. M. Murphy,et al.  Infrared Reflection Spectra of Phosphate and Arsenate Crystals , 1954 .

[33]  Yutaka Takagi,et al.  Theory of the Transition in KH2PO4. (I) , 1948 .

[34]  A. Ubbelohde,et al.  Structure and thermal properties associated with some hydrogen bonds in crystals. IV. Isotope effects in some acid phosphates , 1942, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[35]  John C. Slater,et al.  Theory of the Transition in KH2PO4 , 1941 .