Order–disorder and displacive components in the ferroelectric–paraelectric phase transition of potassium titanyl phosphate KTiOPO4

Abstract

In situ neutron powder diffraction analysis from 297 to 1358 K indicates the experimental evidence of the coexistence of order-disorder and displacive nature in the ferroelectric-paraelectric phase transition of potassium titanyl phosphate (KTiOPO(4), KTP).

Understanding the Behavior of the Above-Room-Temperature Molecular Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted Distortion Mode Analysis

“…It is associated with a variety of technological applications such as memories, modulators, and energy harvesting devices. [1][2] Extensively studied ferroelectrics include inorganic materials such as BaTiO3 [3][4] , PbTiO3 5-8 PZT [9][10][11][12] , KDP and similar [13][14][15][16][17][18][19] , KTP [20][21][22][23][24] and Rochelle salt [25][26][27][28][29] . In recent years there has been significant interest in organic ferroelectrics which offer the advantages of being light-weight, flexible and non-toxic.…”

A neutron total scattering study of local coordination in KTiOPO4from room temperature to 900 °C

“…The ferroelectric to paraelectric phase transition of the KTP family is described as being of continuous second order and is both displacive and of order-disorder nature [13]. Recently, Yashima & Komatsu have reported [14] a high-temperature neutron powder diffraction study of KTP up to 1085°C, which briefly describes a Rietveld refinement of the structure of the Pnan phase. The structural model includes split K + sites as evidence of the order-disorder nature, with the high-temperature position of the K + being divided over two sites equivalent by nglide symmetry and each having approximately 50% occupancy.…”

Structural Reasons for the Nonlinear Optical Properties of KTP Family Single Crystals

“…In situ neutron powder diffraction analysis from 297 to 1358 K [28] indicated the largest average displacements of K + and P 5+ cations during the transition from paraelectric (space group Pnna in the authors' set) to ferroelectric (space group Pna2 1 ) phase. The average values of the displacements at 297 K were 0.16, −0.59, 0.04 and 0.14 Å for O 2− , K + , Ti 4+ , and P 5+ ions, respectively.…”