Thermal properties of PZT95/5(1.8Nb) and PSZT ceramics.

Abstract

Thermal properties of niobium-modified PZT95/5(1.8Nb) and PSZT ceramics used for the ferroelectric power supply have been studied from -100 °C to 375°C. Within this temperature range, these materials exhibit ferroelectric-ferroelectric and ferroelectric-paraelectric phase transformations. The thermal expansion coefficient, heat capacity, and thermal diffusivity of different phases were measured. Thermal conductivity and Grüneisen constant were calculated at several selected temperatures between -60°C and 100°C. Results show that thermal properties of these two solid solutions are very similar. Phase transformations in these ceramics possess first order transformation characteristics including thermal hysteresis, transformational strain, and enthalpy change. The thermal strain in the high temperature rhombohedral phase region is extremely anisotropic. The heat capacity for both materials approaches to 3R (or 5.938 cal/(g-mole*K)) near room temperature. The thermal diffusivity and the thermal conductivity are quite low in comparison to common oxide ceramics, and are comparable to amorphous silicate glass. Furthermore, the thermal conductivity of these materials between -60°C and 100°C becomes independent of temperature and is sensitive to the structural phase transformation. These phenomena suggest that the phonon mean free path governing the thermal conductivity in this temperature range is limited by the lattice dimensions, which is in good agreement with calculated values. Effects of small compositional changes and density/porosity variations in these ceramics on their thermal properties are also discussed. The implications of these transformation characteristics and unusual thermal properties are important in guiding processing and handling procedures for these materials.

Processing and properties of hafnium‐doped tin‐modified lead zirconate titanate 95/5 ceramics

“…Additionally, Nb 5+ acts as a donor dopant, reducing the coercive field (a “soft” PZT), improving breakdown strength, and improving aging characteristics 3 . Modification by tin (Sn) has been shown to stabilize the AFE phase, enhance densification, and reduce the strain associated with the R3c‐R3m and R3m‐Pm$$\overline 3 $$m phase transitions 12–16 . PZT95/5 is typically doped with Nb or codoped with Sn 4+ and Nb 5+ to tailor the electrical properties and pressure‐induced FE‐AFE phase transition response in these materials 4,6,13,14,17 …”

Processing and properties of PSZT 95/5 ceramics with varying Ti and Nb substitution

“…3 Modification by tin (Sn) has been shown to stabilize the AFE phase, enhance densification, and reduce the strain associated with the R3c-R3m and R3m-Pm3m phase transitions. [12][13][14][15][16] PZT 95/5 is typically doped with Nb or co-doping the of Sn4+ and Nb5+ to tailor the electrical properties and pressure-induced FE-AFE phase transition response in these materials. 4,6,13,14,17 Berlincourt and Krueger proposed a pseudo-binary phase diagram for the Pb 0.995 [(Zr 0.85 Sn 0.15 ) 1-x Ti x ] 0.99 Nb 0.01 O 3 system, showing a near vertical morphotropic phase boundary for a Ti concentration of ∼4.5% (Figure 1).…”

“…Additionally, Nb 5+ acts as a donor dopant, reducing the coercive field (a “soft” PZT), improving breakdown strength, and improving aging characteristics 3 . Modification by tin (Sn) has been shown to stabilize the AFE phase, enhance densification, and reduce the strain associated with the R3c‐R3m and R3m‐Pm3m phase transitions 12–16 . PZT 95/5 is typically doped with Nb or co‐doping the of Sn4+ and Nb5+ to tailor the electrical properties and pressure‐induced FE‐AFE phase transition response in these materials 4,6,13,14,17 .…”