Phase evolution, crystal structure, and microwave dielectric properties of gillespite‐type ceramics

Abstract

A gillespite‐structured MCuSi4O10 (M = Ba1‐xSrx, Sr1‐xCax) ceramics with tetrahedral structure (P4/ncc) were prepared by solid‐state reaction method. X‐ray diffraction and thermogravimetry with differential scanning calorimetry (TG‐DSC) were employed to study the phase synthesis process of BaCuSi4O10. Pure BaCuSi4O10 phase was obtained at 1075°C and decomposed into BaSiO3, BaCuSi2O6, and SiO2 when calcined at 1200°C. The relationships between the crystal structure and microwave dielectric properties of MCuSi4O10 ceramics were revealed based on the Rietveld refinement and P‐V‐L complex chemical bond theory. The dielectric constant (εr) decreased linearly with decreasing total bond susceptibility and ionic polarizability. Quality factor (Q × f) was closely dependent on bond strength and lattice energy. The temperature coefficient of resonant frequency (τf) was controlled by the stability of [CuO4]6− plane in MCuSi4O10. Optimum microwave dielectric properties were obtained for SrCuSi4O10 when sintered at 1100°C for 3 hours with a εr of 5.59, a Q × f value of 82 252 GHz, and a τf of −41.34 ppm/°C. Thus, SrCuSi4O10 is a good candidate for millimeter‐wave devices.

Crystal structure and enhanced microwave dielectric properties of the Ce2[Zr1−x(Al1/2Ta1/2)x]3(MoO4)9 ceramics at microwave frequency

“…The optimal values are obtained at 850 ℃. Densification and a relatively uniform microstructure are the main reasons for optimizing the quality factor; the decline of Q × f values at a higher sintering temperature can be attributed to intrinsic loss [24,25].…”

“…The optimal values are obtained at 850 ℃. Densification and a relatively uniform microstructure are the main reasons for optimizing the quality factor; the decline of Q × f values at a higher sintering temperature can be attributed to intrinsic loss[24,25].In recent years, Mo-based microwave dielectric ceramics were studied in depth, as shown in Fig. 8[10,[17][18][19][20][21][26][27][28][29][30][31][32].…”

Preparation, properties and applications of near-infrared fluorescent silicate nanosheets

“…49,57 Alternatively, flux-less solid-state synthesis is usually less timeconsuming and can lead to lower amounts of glassy matrix surrounding the crystals, however they require higher temperatures and tend to produce smaller crystallites. 52,[57][58][59][60][61][62][63] Synthesis in molten carbonates has proven so far inefficient, resulting in the production of e.g. azurite and malachite.…”

“…[50][51][52][53]95,[112][113][114] However, exciting speculations about the employment of bulk EB, HB and HP in diverse technological fields have been made, including telecommunications, lasers, sensing/labelling for bioimaging, component of cool roofing and facades, luminescent solar concentrators and more. 50,55,58,59,66,69,91,95,97 With regards to the down-sized EB, HB and HP, several applications for photonics have been theorized and demonstrated (Tables 1-3). For example, Borisov et al have showcased applications of ball-milled EB, HB and a strontium homologue (SrCuSi 4 O 10 , SC) as optical chemosensors.…”

Structure and Microwave Dielectric Properties of Gillespite-Type ACuSi4O10 (A = Ca, Sr, Ba) Ceramics and Quantitative Prediction of the Q × f Value via Machine Learning

“…130) materials CaCuSi 4 O 10 and BaCuSi 4 O 10 , known as cuprorivaite and effenbergerite, respectively, have been fabricated and used as blue pigments on frescoes and faience since ancient times . Recently, excellent microwave dielectric properties (ε r = 4.0 and tan δ = 1.1 × 10 –3 at 5 GHz) of SrCuSi 4 O 10 (wesselsite) are of interest to researchers in the field of functional ceramics ,− (Table S1). Layered copper silicates ACuSi 4 O 10 , where the A-site element is alkaline earth elements Ca, Sr, or Ba, are formed by a double-layered puckered silicon–oxygen framework (Figure ).…”