Na_<1-x>Nb_xZr_<2-x>(PO_4)_3系低熱膨張セラミックス

概要

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The synthesis of near-zero-expansion ceramic from Na_<1-x>Nb_xZr_<2-x>(PO_4)_3 was investigated. The replacement of Zr^<4+> and Na^+ by Nb^<5+> decreased the thermal expansion of the c-axis. The thermal expansion of the a-axis was negative. Consequently the average thermal expansion exhibited zero expansion at x≒0.75. Thermal expansion coefficients of Na_<9・25>Nb_<9・75>Zr_<1・25> (PO_4)_3 are α_a= -3.4X10^<-6>/℃,α_c=+6 OX10^<-6>/℃ α^^-_<avg>=-0.3 X 10^<-6>/℃, Thermal expansion coefficients of Nb Zr(PO_4)_3 which does not contain Na^+ ion are α_a=-3.4×10^<-6>/℃, α_c=+1.2×10^<-6>/℃, α^^-_<avg>=-1.9×10^<-6>/℃ with less thermal expansion anisotropy. The dense ceramics were fabricated by sintering at 1200°-1400℃ for 10-60 min with MgO as sintering aids. The linear thermal expansion coefficient of the sintered ceramics was near zero.
1988-10-01