The peculiarities of glass state formation and the role of random elastic fields in mixed crystals of the KH₂PO₄family

Abstract

The source of random static electrical fields, which is determined by both the piezoelectric coupling and the static elastic deformations induced by substitutional disorder of ions with different ionic radii has been considered for mixed crystals of the KH2PO4 family. It is shown that the random electrical fields act mainly on the lattice polarization along the c axis and up-down proton configurations. The short-range interactions of four acid protons surrounding a PO4 group are represented as the random local uniaxial anisotropy for the mixed crystals provided the ice rule condition is fulfilled. It is also shown that the distinction of symmetry between the up-down and lateral proton configuration, and the peculiarities of proton-lattice interaction can lead to the coexistence of long-range order (for up-down/lateral configuration) with the glass or paraelectric (for lateral/up-down configuration) state.

Growth and electro-elastic properties of K(H1−xDx)2PO4single crystals

“…It is observed that d 36 increases with the increase in deuterium content, and this trend for d 14 is slight. In mixed crystals of the KDP family, the piezoelectric coupling of polarization and elastic strain u 6 is the source of the random electric fields along the c axis which play an essential role in these crystals (Smolyaninov & Glinchuk, 1994;Levitskii & Lisnii, 2004). To clarify the deformation of the PO 4 tetrahedron due to substitution of D for H, the structures of some crystals were resolved by single-crystal X-ray diffraction.…”

Thermodynamics, dielectric permittivity and phase diagrams of the Rb_{1-x}(NH_{4})_{x}H_{2}PO_{4} type proton glasses

“…The chaotic static electric fields governed by the piezoelectric interactions and static elastic strains are believed [27] to be formed by chaotic substitutional disorder of ions of different radii. It has been shown that these fields act, mainly, on the lattice polarization along the c-axis and on the configurations with two protons near the "upper" or "lower" (with respect to the c-axis) oxygen atoms.…”

Spin-glass model with essential short-range competing interactions

“…Цi поля викли-канi структурним безладом завдяки рiзницi мiж iонними радiусами iонiв Rb i NH 4 [11]. В [6] показано, що в присутностi гаусових ви-падкових полiв з нульовим середнiм значенням перехiд в протонне скло є розмитий, тобто сприйнятливiсть є згладжена, а параметр по-ICMP-05-01U 2 рядку протонного скла залишається скiнченним при температурах, вищих вiд номiнальної температури заморожування (межа стабiль-ностi реплiчно-симетричного розв'язку).…”