Effects of (Mg1/3Sb2/3)4+ substitution on the structure and microwave dielectric properties of Ce2Zr3(MoO4)9 ceramics

Abstract

Ce2[Zr1−x(Mg1/3Sb2/3)x]3(MoO4)9 (0.02 ⩽ x ⩽ 0.10) ceramics were prepared by the traditional solid-state method. A single phase, belonging to the space group of $$R⩈erline 3 c$$ R 3 ¯ c , was detected by using X-ray diffraction at the sintering temperatures ranging from 700 to 850 °C. The microstructures of samples were examined by applying scanning electron microscopy (SEM). The crystal structure refinement of these samples was investigated in detail by performing the Rietveld refinement method. The intrinsic properties were calculated and explored via far-infrared reflectivity spectroscopy. The correlations between the chemical bond parameters and microwave dielectric properties were calculated and analyzed by Phillips-van Vechten-Levine (P-V-L) theory. Ce2[Zr0.94(Mg1/3Sb2/3)0.06]3(MoO4)9 ceramics with excellent dielectric properties were sintered at 725 °C for 6 h (εr = 10.37, Q×f = 71,748 GHz, and τf = −13.6 ppm/°C, εr is the dielectric constant, Q×f is the quality factor, and τf is the temperature coefficient of resonant frequency).

Principal element design of garnets to access structure stability and excellent microwave dielectric properties

“…As illustrated in Figure 6, to speculate the intrinsic contribution of dielectric properties, IR reflection spectra of Ca 3 BTiGe 3 O 12 (B = Mg, Zn) ceramics in the range of 100–1000 cm −1 were recorded and reflectance data were fitted with the Lorentz oscillator model and Fresnel formula: $$\begin{equation}{\varepsilon ^*}\left( \omega \right) = {\varepsilon _\infty } + \sum\nolimits_{j\ = \ 1}^n {\frac{{\omega _{pj}^2}}{{\omega _{oj}^2 - \ {\omega ^2} - j\omega {\gamma _j}}}} = \varepsilon ^{\prime}\left( \omega \right) - i\varepsilon ^{\prime\prime}\left( \omega \right)\end{equation}$$ $$\begin{equation}R\left( \omega \right) = {\left| {\ \frac{{1 - \sqrt {{\varepsilon ^*}\left( \omega \right)} }}{{1 + \sqrt {{\varepsilon ^*}\left( \omega \right)} }}\ } \right|^2}\end{equation}$$where ε *( ω ) represents a complex dielectric function, $${\varepsilon _\infty }$$ is the permittivity caused by the electronic polarization at optical frequencies, n refers to the order of transverse polar‐phonon modes, ω pj , ω oj , and γ j are the plasma frequency, eigen frequency, and damping constant of the j th mode, respectively. The real part ( ɛ ′( ω )) of microwave relative permittivity and loss tangent (tan δ ) can be evaluated as follows 30,39 : …”

“…As illustrated in Figure 6, to speculate the intrinsic contribution of dielectric properties, IR reflection spectra of Ca 3 BTiGe 3 O 12 (B = Mg, Zn) ceramics in the range of 100-1000 cm −1 were recorded and reflectance data were fitted with the Lorentz oscillator model and Fresnel formula: (9) where ε*(ω) represents a complex dielectric function, 𝜀 ∞ is the permittivity caused by the electronic polarization at optical frequencies, n refers to the order of transverse polar-phonon modes, ω pj , ω oj , and γ j are the plasma frequency, eigen frequency, and damping constant of the jth mode, respectively. The real part (ɛ′(ω)) of microwave relative permittivity and loss tangent (tanδ) can be evaluated as follows 30,39 :…”

Temperature Stability of Li2TiO3‐Zn2SiO4 Microwave Dielectric Ceramics

“…[4,6] However, the disadvantages of pure Li 2 TiO 3 ceramics, such as positive τ f value and high sintering temperature (1300 °C), are detrimental to its practical applications. [1] Generally, there are two methods to design a material with good microwave dielectric properties: [10][11][12] (1) Formation of composite materials. The sintering temperature of Li 2 TiO 3 was successfully reduced by adding ZnO-B 2 O 3 glass frit as sintering aid, and 2.5 wt % ZnO-B 2 O 3 glass frit doped Li 2 TiO 3 ceramic exhibits the best Qf value of 32,300 GHz, ɛ r = 23.06 and τ f = 35.79 ppm/°C.…”

Novel Tri-rutile Ni0.5Ti0.5TaO4 Microwave Dielectric Ceramics: Crystal Structure Chemistry, Raman Vibration Mode, and Chemical Bond Characteristic In-Depth Studies

“…In the emerging 5G communication era, microwave dielectric ceramics (MWDCs) have been widely used in resonators, filters, dielectric antennas, dielectric guided wave loops, and other microwave components. − On top of that, there is increasing demand for microwave equipment miniaturization, and the size of the resonator is inversely proportional to the square root of the dielectric constant of a dielectric material. − Therefore, it is urgent to develop medium and high dielectric constant materials with good microwave properties.…”