For the purpose of the developing Pb-free piezoelectric ceramics, the dielectric and piezoelectric properties of two series of KNbO 3 -NaNbO 3 -LiNbO 3 -SrTiO 3 (KN-NN-LN-ST) perovskite ceramics, namely 0.47KN-0.47NN-(0:06 À x)LN-xST (0 x 0:06) and 0.45KN-0.45NN-(0:10 À y)LN-yST (0:02 y 0:10) were investigated as functions of composition. In both series, the orthorhombic perovskite phase formed at lower temperatures, and was transformed to tetragonal form and then cubic form with increasing temperature. The orthorhombic-tetragonal transition temperature (T ot ) and tetragonal-cubic transition temperature (Curie temperature, T c ) gradually shifted toward lower temperatures with increasing ST content. For the 0.47KN-0.47NN-(0:06 À x)LN-xST series, the T ot ¼ 100 C and T c ¼ 500 C for x ¼ 0, and the T ot ¼ À20 C and T c ¼ 220 C for x ¼ 0:06. For the 0.45KN-0.45NN-(0:10 À y)LN-yST series, T ot ¼ À30 C and T c ¼ 450 C for y ¼ 0:02, and T ot ¼ À60 C and T c ¼ 330 C for y ¼ 0:05. Among the ceramics obtained, the 0.45KN-0.45NN-0.06LN-0.04ST composition showed relatively good piezoelectric properties, k p ¼ 0:33 and d 33 ¼ 120 pC/N, which are comparable to those of Pb-free piezoelectric ceramics previously reported.

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Ta(V) oxynitride (TaON) powders for new pigments were prepared by heat-treatment for mixed powders of Ta(V) oxide, nitrides and alkaline fluorides in nitrogen atmosphere without flowing ammonia. This synthetic method is an eco-friendly and costeffective way suitable for an industrial scale production of the powder containing TaON with the color of yellow as compared to the conventional method such as ammonolysis with flowing large amounts of ammonia. They have a potential to be employed as non-toxic pigments, and to substitute pigments containing harmful elements. In this study, influence of nitrides as the agent for nitridation of tantalum oxide on the formation of TaON in the synthetic method was examined. It has become apparent that the formation of TaON was promoted by using silicon nitride (Si 3 N 4 ) for nitridation of tantalum oxide. Inorganic pigments serve the purpose of imparting color to various compounds. In comparison with organic pigments, inorganic pigments are generally better able to withstand the influence of sunlight and chemical exposure. However, most inorganic pigments contain transition metals or heavy metals such as Cd, Cr, Pb, Sb, Se and V. The use of them containing such toxic elements is restricted in many countries to protect human health and the environment.Tantalum(V) oxynitride (TaON) is generally obtained as a yellowish powder by ammonolysis of tantalum oxide (Ta 2 O 5 ) powder with ammonia containing a little moisture.

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