(Sr_0.4Ce_0.4)_1-xNd_xTi_0.8Mg_0.2O₃ [(SC)NdTMgO₃, x = 0.1–0.4] non-stoichiometric system were obtained through conventional solid-state synthesis technique. All perovskite peaks were attributed to either single (x ≤ 0.3) and/or mixed (x = 0.4) like phases. A solid solution of cubic structure was obtained for x ≤ 0.2, however, for x ≥ 0.3, the (SC)NdTMgO₃ compound, exhibits structure instability and (200)/(310) peaks splitting. The peaks splitting indicates cubic (C-phase) to tetrogonal (T-phase) structure phase transition. All ceramic samples appear nearly dense, presenting a non-uniform grain size distribution. The observed trend of the microwave dielectric properties (ε_r, τ_f, Q × f) is mainly related to the formation of structure phase transition, packing fraction, relative density and ionic polarizability. A key microwave (MW) dielectric properties of ε_r = 53, Q × f = 26,700 GHz and τ_f = +2.8 pmm/°C could be obtained for composition with x = 0.4.

（Sr _0.4 Ce _0.4）_{1- x} Nd _x Ti _0.8 Mg _0.2 O ₃ [（SC）NdTMgO ₃，x  = 0.1-0.4]非化学计量体系是通过常规固态合成技术获得的。所有钙钛矿的峰归因于任一单一的（X  ≤0.3）和/或混合（X  = 0.4）等相。为得到立方结构的固溶体X  ≤0.2，但是，对于X  ≥0.3，则（SC）NdTMgO ₃化合物显示结构不稳定性和（200）/（310）峰分裂。峰分裂表明立方（C相）到四方（T相）结构相变。所有陶瓷样品看起来几乎都是致密的，呈现出不均匀的粒度分布。观察到的微波介电特性（_εr，_τf，Q×f）的趋势主要与结构相变的形成，堆积分数，相对密度和离子极化率有关。一个关键的微波（MW）的介电特性ε _{- [R}  = 53，Q×F = 26700 GHz和τ _˚F  = 2.8 PMM /℃可以用于与组合物获得X  = 0.4。