Negative evidence for a proton-tunneling mechanism in the phase transition of KH 2 PO 4 </mml:mrow…
1987; American Physical Society; Volume: 36; Issue: 1 Linguagem: Inglês
10.1103/physrevb.36.874
ISSN1095-3795
AutoresM. Ichikawa, Kiyosi Motida, Noboru Yamada,
Tópico(s)Crystallography and molecular interactions
ResumoWe have found a linear relation between the transition temperature T sub c (in K) and the hydrogen-bond length R (in A\r{}) for tetragonal ${\mathrm{KH}}_{2}$${\mathrm{PO}}_{4}$-type crystals, ${T}_{c}$=2290(R-2.428), irrespective of whether the crystals are deuterated or undeuterated; this finding supplies negative evidence for the proton-tunneling mechanism in the phase transition. We deduce from this relation that the isotope effect in the initial pressure derivative of ${T}_{c}$, ${\mathrm{dT}}_{c}$/dp, reflects not the isotope effect in ${\mathrm{dT}}_{c}$/dR, so far regarded as supporting evidence of proton tunneling, but that of dR/dp. Some R and dR/dp values at ${T}_{c}$ are predicted.
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