Crystal structure, far-infrared spectroscopy, and microwave dielectric properties of two novel vanadates CaRECeV3O12 (RE = Nd, Sm)

Two novel low-& epsilon;r CaRECeV3O12 (RE = Nd, Sm) microwave dielectric ceramics were prepared to utilize the solid-state method. According to XRD and Raman spectroscopy data, the CaRECeV3O12 (RE = Nd, Sm) ceramics had a tetragonal zircon-type with an I41/amd space group. Dense CaNdCeV3O12 and CaSmCeV3O12 ceramics sintered at 1225 degrees C and 1200 degrees C showed & epsilon;r-11.85 & PLUSMN; 0.1 and 11.33 & PLUSMN; 0.1, Q x f-40,100 & PLUSMN; 500 GHz and 43,290 & PLUSMN; 500 GHz, & tau;f --27.2 & PLUSMN; 0.5 ppm/degrees C and-22.4 & PLUSMN; 0.5 ppm/degrees C, along with & alpha;L of 9.4 ppm/degrees C and 8.5 ppm/degrees C, respectively. The measured & epsilon;r and corrected & epsilon;r(corr) values were larger than & epsilon;r(C-M) (9.41 and 9.47) in CaN-dCeV3O12 and CaSmCeV3O12 due to the cations being, on average, under-bonded and the overall structures being in a slightly expanded state. The slightly higher |< d > | value of CaNdCeV3O12 led to its higher & epsilon;r(corr) value, even though it had a lower & alpha;D/Vm value. The sign and magnitude of & tau;f values for CaNdCeV3O12 and CaSmCeV3O12 were mainly determined by their positive temperature coefficients of dielectric polarizability & tau;& alpha;m of +36.2 ppm/ degrees C and +32.1 ppm/degrees C, respectively. The inherent dielectric constant and dielectric loss were examined using far-infrared reflectivity spectra, Raman spectra, and the packing fraction.

Automated summary

Two novel low-εr CaRECeV3O12 (RE = Nd, Sm) microwave dielectric ceramics were prepared via the solid-state method. XRD and Raman spectroscopy data confirmed the tetragonal zircon-type structure of the ceramics with dense CaNdCeV3O12 and CaSmCeV3O12 ceramics exhibiting superior dielectric properties compared to the predicted values. The temperature coefficients and dielectric loss were mainly influenced by the temperature coefficients of their polarizability, and the slight structural variations led to higher dielectric constants in CaNdCeV3O12.