Dielectric relaxation in ferroelectric (CH₃)₂NH₂H₂PO₄and its isotope effect

Abstract

The temperature dependences of the real and imaginary parts of the complex dielectric constant of (CH3)2NHZH2P04 and its partially deuterated crystal, (CH3)2N(HI -,Dx)2(H~-,D,)2P04, were measured in a frequency range between I MHz and 1 GHz. The results obtained in the present study indicate that the crystal of (CH3)2N(H1-,DX)2(H1 _xD,)zP04 exhibits remarkable dielectric relaxation in the microwave frequency range, and exhibits critical slowing-down near T,. It is therefore concluded that the ferroelectric phase transition is of order-disorder type, and the transition temperature and the relaxation time are enhanced by the increase of the deuterium concentration.

Synthesis and Structure of Supramolecular Compound with Ethyl 2‐(4‐Aminophenoxy)acetate Based on 18‐Crown‐6

“…Owing to their widespread applications in resonators, filters, and other key components in microwave communication systems, much attention has been devoted to the preparation of suitable materials displaying excellent dielectric constant. [1,2] The temperature-dependent dielectric response, especially in relatively high frequency range, is very useful in searching for phase transitions materials. [3,4] There are only a limited number of materials which approximately meet the stringent dielectric constant requirements.…”

Neutron Diffraction Study of Ferrielectric Phase Transition in Monoclinic RbD2PO4

“…[1][2][3][4][5][6][7] The tetragonal and monoclinic AH 2 BO 4 -type crystals differ extremely in the physical properties associated with the phase transition, for example the dielectric and thermal properties and the pressure effect. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] The RbH 2 PO 4 crystal undergoes the ferroelectric phase transition at 147 K. 24) The space group changes from the tetragonal I 4 42d of the paraelectric phase to the orthorhombic Fdd2 of the ferroelectric phase. The tetragonal RbH 2 PO 4 crystal is characterized by a three-dimensional network of the hydrogen-bond chains linking the PO 4 tetrahedra.…”

Synthesis, structure and dielectric deuterated effect of a novel organic–inorganic hybrid compound

“…(18-crown-6)·H 2 PO 4 − ·2H 3 PO 4 ·2.5H 2 O (1), (EB-NH 3 + = 4-ethoxybenzenammonium; 18-crown-6=1, 4, 7, 10, 13, 16-hexaoxacyclo-octadecane) and its deuterated compound (2) have been synthesized and structurally characterized. In the structure of 1, organic (EB-NH 3 + )(18-crown-6) supermolecular cation sheet related by C-H…π and N-H…O hydrogen bond interactions and inorganic phosphate anion sheet linked by O-H…O hydrogen bonds arrange alternately.…”

“…DEF of inorganic phosphate can be studied with these active hydrogen atoms easily deuterated. As a continuation of our systematic studies of dielectric and ferroelectric materials[9], we herein report the crystal structure, thermogravimetric analysis, dielectric property and of dielectric permittivity DEF of (EB-NH 3 + )(18-crown-6)·H 2 PO 4 − ·2H 3 PO 4 ·2.5H 2 O (1) and its deuterium compound (2).…”

“…Dielectric studies on organic-inorganic hybrid material, which posses the excellent properties of both organic and inorganic compounds, are recently extensively investigated. A large number of organic-inorganic isomorphous compounds, like (CH 3 ) 2 NH 2 H 2 PO 4 [2], (CH 3 ) 2 NH 2 H 2 AsO 4 [3,4], β-NH 3 (CH 2 ) 2 NH 3 HPO 4 [5] and (NC 4 H 4 NH 2 )·H 3 PO 4 [6], belonging to the widely described family of AH 2 BO 4 type (where A = K, Cs, NH 4 and B = P, As), which are obtained by substitution of potassium by organic ammonium cations, have also been found to display excellent dielectric property. Crown ether is a kind of typical subject molecule of organic-inorganic hybrid that arouses our interest [7], where interesting H-bond interactions and supramolecular packing structures result in the motion space for organic cation and phase transition.…”