화학공학소재연구정보센터
Advanced Functional Materials, Vol.14, No.2, 169-173, 2004
On the feasibility of growing Pb[(Zn1/3Nb2/3)(0.91)Ti-0.09]O-3 single crystals
Pb[(Zn1/3Nb2/3)(0.91)Ti-0.09]O-3 (PZNT91/9) single, crystals were grown,by two methods: from solution using PbO as a self-fluxing agent (SC method) and directly from the melt without fluxing (MC method). In both growth methods, an allomeric Pb[(Mg1/3Nb2/3)(0.69)]Ti-0.31]O-3 (PMNT69/31) single crystal Was used as a seed. X-ray diffraction patterns of, ground, crystals showed that phase-pure perovskite PZNT91/9 single crystals were, successfully fabricated by the above two methods. The composition of the crystals obtained by both the SC and MC methods was analyzed using X-ray fluorescence, which confirmed that the crystal composition is close to the nominal value, although volatilization of PbO and segregation during crystal growth are inevitable. MC PZNTT91/9 crystals exhibit excellent piezoelectric properties, with the piezoelectric constant, d(33), in the range of 1800-2200 pCN(-1). This value is comparable to that-of the SC crystals. However, the MC crystals show an abnormal dielectric behavior. In contrast with the SC crystals, in the MC crystals a much broader dielectric peak appears in the dielectric response curves, accompanied by a much lower peak temperature of around 105 degreesC. Furthermore, frequency dispersion is apparent over a much wider temperature range (even more apparent than in pure relaxors), where a large, ie. about 70 degreesC, full Width at half maximum (FWHM) for the dielectric peaks-is observed, in the dielectric response. It is speculated that such an unusual phenomenon correlates with defects, microinhomogeneities; and polar regions in the as-grown MC crystals, The origins of this abnormality have not been interpreted in detail until now. However, optical observation of the domain structure confirms that both the SC and MC crystals possess complex structural states.