Abstract
The unit cell parameters of KTiOPO4 and KTiOAsO4 single crystals are measured in the temperature range from room temperature to 20 K. It is found that the unit cell volume of the single crystals changes smoothly. With a decrease in temperature, the c parameter remains almost unchanged. In a certain temperature range, the linear temperature dependence of the a and b parameters is violated. An X-ray diffraction study of KTiOAsO 4 single crystals is performed at T = 293 and 30 K. With a decrease in temperature, the electron density in the channels of the structure undergoes a redistribution, suggesting that at room temperature the state of the potassium ions is characterized by the dynamic and static disordering. The nonuniformity of the distribution of the electron density at the junctions of TiO6 octahedra and AsO4 tetrahedra is significantly enhanced in relation to that at the corresponding junctions in the KTiOPO4 structure. It has been experimentally established that the geometry of the tetrahedral anions makes a decisive contribution to the nonlinearity of KTiOAsO4 single crystals.
Original language | English |
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Pages (from-to) | 412-423 |
Number of pages | 12 |
Journal | Crystallography Reports |
Volume | 55 |
Issue number | 3 |
DOIs | |
State | Published - May 2010 |