  Using the high-resolution x-ray diffraction (XRD) analysis, scanning electron
microscopy (SEM), and the temperature-dependent microwave resonator
characterization, structural properties, phase assemblage and dielectric
properties of La(Mg1/2Ti1/2)O3 (LMT) and Nd(Mg1/2Ti1/2)O3 (NMT) ceramics
prepared via the mixed oxide route were investigated in this study.
Single-phase ceramics were synthesized for both LMT and NMT at sintering
temperatures from 1250 degree C to 1675 degree C. On the basis of the XRD
analysis we have found that the LMT and NMT compounds have cubic and monoclinic
crystal structures, respectively. We have also observed that the relative
densities of LMT and NMT vary between about 93 and 99% of the theoretical
density, depending on the sintering temperature. Finally, concerning the
dielectric properties of the microwave resonators made of LMT and NMT compounds
we have measured their temperature coefficient of the resonant frequency
({\tau}f) and the quality factor (Q). It is interesting to notice that
({\tau}f) in the case of the NMT compound (-16 ppm 1/K) is essentially smaller
than in the case of the LMT compound (-72 ppm 1/K), therefore proving a better
stability against temperature variations in the NMT based resonators. On the
other hand, the Q values are very similar, being 34000 at the resonance
frequency of 8.07 GHz and 38000 at the resonance frequency of 9.76 GHz in the
LMT and NMT cases, respectively.
  Keywords: dielectric properties; microstructure-final: grain growth; single
phase Ln(Mg0.5Ti0.5)O3 (Ln=Nd,La); Lanthanum magnesium titanium oxide.
