The full-width-at-half maximum (FWHM) of rhombohedral (002)_(R) x-ray diffraction peak as a function of particle size in Pb(Zn_(1/3)Nb_(2/3))O_(3)-(6,7)PbTiO_(3) PZN-(6,7)PT solid solutions has been investigated. The sharpest (002)_(R) peak, which has a FWHM of 0.10°-0.12°, was obtained from powder samples of intermediate particle sizes of about 120 μm. The broad (002)_(R) peak typically observed in PZN-PT single crystal plates and coarse powder samples is the result of trapped metastable phases and, to a lesser extent, the transformation stresses/strains in the material. The increased FWHM at particle sizes <60 μm, on the other hand, can be attributed to crystal defects and, possibly, freshly formed metastable phases induced by the sample pulverization process.
展开▼
