Dielectric dispersion in ferroelectric (CH₃)₂NH₂Ga(SO₄)₂. 7H₂O crystal

Dielectric Dispersion Studies in (CH3)2NH2Ga(SO4)2- 6H2O(DMAGaS) Crystal

“…The obtained diagrams are typical semicircles with β parameter practically equal to 1 and we deal with a single relaxational process. We did not observe any additional contribution to permittivity and dispersion as it was presented in [3].…”

“…Dielectric dispersion in DMAGaS crystal has been already studied [3]. However, the strange behaviour of dispersion as a very large contribution to the permittivity at low frequency range was found.…”

“…So far, this subfamily consists of two crystahs, namely: DMAAS -(CΗ 3 ) 2 ΝΗ 2 Αl(SO4 ) 6 . 6H2O and DMAGaS -(CR3 ) 2 ΝΗ 2 Ga(SO 4) 6 .6Η2O [1][2][3]. DMAAS undergoes continuous para-ferroelectric phase transition of Τc = 153 I{ and DMAGaS undergoes two successive phase transitions at Τc 1 = 136 I{ and at Tc2 = 118 K [4,5].…”

“…The phase transition at Τc 2 is stronghy of the first-order. At T c 1 para-ferroelectric phase transition of the order-disorder type is connected with an ordering of the dimethylammonium cations [3][4][5][6][7]. At T c2 a rearrangement of dimethylammonium cations takes place and ferroelectric properties disappear [7].…”

“…The phase transition at Tc1 is a first-order one and close to tricritical point [3,6]. The crystal belongs to monoclinic system with point group symmetry 2/m above Τc 1 and m below Τc [6].…”