The effect of MgO and the non-stoichiometric ratio of La3+ on microwave dielectric properties of pyrochlorite La2Zr2O7 ceramics

In this work, the pyrochlorite structure ceramic La2Zr2O7 microwave dielectric ceramics were prepared using the solid-state reaction method. The dielectric properties of La2Zr2O7 ceramics were improved by adding MgO, and the effect of the La3+ non-stoichiometric ratio on microwave dielectric properties of the La2Zr2O7–MgO ceramics was studied. Combined with XRD patterns, it was confirmed that the formation of the second phase La2MgZrO6 was inhibited with the decrease of La3+ content. And the content of La2MgZrO6 ceramic decreased with the decrease of La3+ content. The dielectric constant (εr), Quality factor (Q × f), and temperature coefficient of resonant frequency (τf) were changed correspondingly with the La3+ content. Proper reduction of La3+ content enhanced the dielectric properties of La2Zr2O7–MgO ceramics. After sintered at 1650 °C for 4 h, the La2−xZr2O7−1.5x–MgO ceramics with x = 0.16 exhibited excellent microwave dielectric properties: εr = 22.9, Q × f = 59,200 GHz and τf = − 44.6 ppm/°C.