Effect of Zn2+ substitution on the microwave dielectric properties of LiMgPO4 and the development of a new temperature stable glass free LTCC

The LiMg(1-x)ZnxPO4 ceramics have been prepared by the solid state ceramic route. The LiMg(1-x)ZnxPO4 ceramic retains the orthorhombic structure up to x = 0.2. The compositions with 0.3 <= x <= 0.8 exist as a mixture of orthorhombic and monoclinic phases. When Mg2+ is fully replaced with Zn2+ (x = 1.0) complete transition to monoclinic phase occurs. The ceramic with x = 0.1 (LiMg0.9Zn0.1PO4) sintered at 925 degrees C exhibits low relative permittivity (epsilon(r)) of 6.7, high quality factor (Q(u) x f) of 99,700 GHz with a temperature coefficient of resonant frequency (tau(f)) of -62 ppm/degrees C. The slightly large tau(f) is adjusted nearly to zero with the addition of TiO2. LiMg0.9Zn0.1PO4-TiO2 composite with 0.12 volume fraction TiO2 sintered at 950 degrees C shows good microwave dielectric properties: epsilon(r) = 10.1, Q(u) x f = 52,900 GHz and tau(f) = -5 ppm/degrees C. The ceramic is found to be chemically compatible with silver. (C) 2012 Elsevier Ltd. All rights reserved.