(PLZT)Lead lanthanum zirconate titanate ceramics
Lead lanthanum zirconate titanate ceramics (PLZT) are of lead zirconate titanate PZT piezoelectric ceramics. Is Haertling GH in 1970 with milling and hot pressing process for the preparation of transparent optical ceramic PLZT.
A ferroelectric ceramics optoelectronic materials. The optical field, or characteristics may be changed by stretching or compressing. For a variety of optical memory and display devices. Also known as doped lanthanum zirconate [acid lead] lead titanate.
PLZT belongs ABO3 perovskite structure, cubic crystal lattice parameters a = 4.078 & Aring;, A ions (Pb2 + or La3 +) in a cube of eight corner on top; B ion (Ti4 + or Zr4 +) in the body-centered position; O2- ions located in the six position of the center plane together form an oxygen octahedron. B ions in octahedral centers. Zr4 + (or Ti4 +) - 8 {111} planes O2- octahedra are perpendicular to the <111> axis. As shown in FIG.
Figure: Schematic cubic α-phase PLZT
Figure PLZT system temperature phase diagram
In PLZT in, A Bit by Pb2 + and La3 + ions fill, according to the neutral condition, the B bit (Ti4 + or Zr4 +) form a vacancy to compensate for the charge, every permutation into four La4 +, produces a vacancy in the B position. Thus, PLZT ceramic material of the formula Pb1- X La X (ZrYTi1-Y) 1-X / 4O3.
PLZT system phase diagram at room temperature. Seen from the figure, PLZT maintaining each phase PbTiO3-PbZrO3 ceramics at room temperature. With increasing amount of La, so that the anti-ferroelectric phase (AFE) and tetragonal ferroelectric phase (FETet) expand, relatively speaking, rhombohedral ferroelectric phase (PERh) decreases. Due to the composition of point closer paraelectric phase (FECub), La visible increase, reducing the Curie temperature TC. Regional cross the line shown in the phase diagram for rhombohedral ferroelectric (PERh), tetragonal ferroelectric (FETet), orthogonal antiferroelectric phase (AFE), cis electric phase (FECub) coexistence metastable zone, in the phase the composition has the electro-optical properties. Down to room temperature and the Curie point, the maximum dielectric constant, the phase becomes a diffusion phase change even in the TC above a certain temperature, the stress will be induced by applying an electric field, or ferroelectric.
