X-Ray Study of Thermal Parameters of NH₄H₂PO₄and ND₄D₂PO₄in the Paraelectric Phase

Chemical bond analysis of the crystal growth of KDP and ADP

“…The crystallographic structures of KDP and ADP crystals have been well examined by X-ray analysis and neutron diffraction experiments at different temperatures and pressures [13][14][15][16][17][18]. Until phase transition occurs, the variance of cell parameters is very small.…”

“…Therefore, these two crystals may be good instances to validate our present method, i.e., to predict the crystal morphology by calculating the bond strength through BVM. Moreover, as two excellent piezoelectric and nonlinear optical crystals, the structures of both KDP and ADP crystals and their growth in aqueous solution are studied in great detail; therefore, much essential structure information about the crystals, clusters and crystal surfaces in solution are provided for understanding the growth process and morphology evolution [11][12][13][14][15][16][17][18][19].…”

Phase Transition Dielectric Properties in Order-disorder Antiferroelectric NH4(H2PO4) (ADP) Crystal

“…The (H 2 PO 4 ) −1 network in which each phosphate group is linked by O-H-O bonds to a tetrahedral arrangement of phosphate group neighbours. The lattice parameters in the antiferroelectric phase (II) are a = b = 7.473 (1) A • and c = 7.551 (2) A • at 152K 6 . The lattice parameters in the paraelectric phase (I) are a = 7.526 (1) A • , b = 7.551 (1) A • and c = 7.464 (1) A •7 .…”

Neutron Diffraction Study of Ferrielectric Phase Transition in Monoclinic RbD2PO4

“…The crystals of KH 2 PO 4 , RbH 2 PO 4 and NH 4 H 2 PO 4 belong to the tetragonal system, whereas the crystals of CsH 2 PO 4 , TlH 2 PO 4 , (CH 3 ) 2 NH 2 H 2 PO 4 to the monoclinic one. [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.…”