Investigation of Zirconium Phosphate Zr3(PO4)4 during Heating

Zirconium phosphate Zr-3(PO4)(4) has been synthesized by the sol-gel technique and investigated using X-ray powder diffraction, IR spectroscopy, and differential scanning calorimetry. It has been established that the symmetry of the unit cell, R (3) over barc, which is characteristic of the NaZr2(PO4)(3) (NZP) family, is lowered to. The behavior of the zirconium phosphate during heating has been examined using high-temperature X-ray diffraction at temperatures ranging from 25 to 575 C. It has been revealed that the structure of the zirconium phosphate is hardly subjected to expansion due to heating in the temperature ranges 25-125 degrees C (alpha(a) < 1 x 10(-6) K-1, alpha(c) < 1 x 10(-6) K-1, Delta alpha < 1 x 10(-6) K-1) and 325-575 degrees C (alpha(a) =-1.4 x 10(-6) K-1, alpha(c) < 1 x 10(-6) K-1, Delta alpha <-2.4 x 10-6 K-1). In the temperature range 125-325 degrees C, the synthesized compound undergoes a second-order phase transition (upon heating), which is accompanied by the contraction of the structure along all crystallographic directions. Upon cooling in the range from 75 to 25 C, the phase transition is accompanied by the expansion of the structure.