The phase transitions of tin-modified zirconium titanate and microwave dielectric properties were investigated using DTA, DSC, high temperature X-ray, electrical conductivity and TEM. In low concentration of Sn (x<0.2) in $Zr_{1-x}Sn_xTiO_4$, the thermal expansion, the satellite reflections, dielectric anomalies, thermal anomalies, specific heat anomalies and unit cell parameters clarified that the successive phase transitions of normal high temperature phase to incommensurate intermediate phase occurred around the temperatures of 1117℃ and 1125℃ on cooling and heating run, respectively. Furthermore, intensity of satellite reflections was proportional to specific heat capacity, enthalpy, and c-axis lattice parameter, while inversely proportional to cooling rate and to Sn (x) contents. The kinetics of phase transitions of the commensurate to incommensurate were sluggish. For the composition of $Zr_{0.8}Sn_{0.2}TiO_4$, the phase transitions were completely inhibited.
On the other hand, the incommensurete deviation δ were measured by X-ray scattering and TEM. With decrease of cooling rate, the phase transition sequences observed in $ZrTiO_4$ are as follows: high temperature disordered normal phase (N) - incommensurately modulated ordered phase (IC) - commensurately ordered phase (C). With the decrease of the incommensurate deviation δ, quality factor (Q) increased with the decrease of the incommensurate deviation δ.
Through the melting process, the transparent X-ray amorphous ceramics were obtained. For pure $ZrTiO_4$, as-quenched X-ray amorphous ceramics undergoes three successive phase transitions; X-ray amorphous ceramic to cubic, cubic to tetragonal, and tetragonal to orthorhombic, with increase of annealing time at 1300℃. The microwave quality factor (Q) increases in that order of the incommensurate intermediate phase, normal high temperature phase and commensurate low temperature phase.
An X-ray study of the effect of the pressure and electric field on the commensurate phase transition in $ZrTiO_4$ was performed in order to obtained the information concerning the nature of the competing force that give rise to a structural instability. It was found that an increase in pressure and electric field shifts the normal to incommensurate transiton temperature $(T_i)$ to a lower and higher value, respectively:$(dT_i/dP_i \cong -6.9K/bar and dT_i/dE_i \cong +1.7 degㆍcm/kV, respectively)$. The pressure and electric field dependence of the incommensurate to commensurate transition ($T_c$) was also investigated $(dT_c/dP_c \cong -9.0K/kbar and dT_c/dE_c \cong +1.5 degㆍcm/kV, respectively).$
