A low‐permittivity microwave dielectric ceramic BaZnP₂O₇ and its performance modification

Abstract

The past few decades have witnessed an ever-growing scholarly interest in microwave dielectric ceramics with the rapid development of telecommunication. [1][2][3][4] Recently, there is a strong ongoing search for dielectric ceramics with a dielectric constant (ε r ) less than 15, a low dielectric loss (tan δ = 1/Q), and a near-zero temperature coefficient (τ f ) to meet the demands for microwave substrate applications. 5,6 Although traditional inorganic substrates such as Al 2 O 3 possess excellent dielectric properties, the exploration for novel materials with superior dielectric properties and sintering behaviors continues today.Pyrophosphates belong to typical low-permittivity compounds, in which M 2 P 2 O 7 possesses two kinds of structure according to the ionic radius of M that is a divalent cation. 7 The structure is recognized as thortveitite-type if the M ionic radius is less than 0.97 Å (M = Mn, Mg, Zn), while the structure converts to dichromate-type if the M ionic radius is larger than 0.97 Å (M = Ca, Sr, Ba). The dependence of dielectric properties on the phase composition of M 2 P 2 O 7 (M = Ca, Sr, Ba, Mn, Mg, Zn) was investigated by Bian et al. 8 and dielectric properties were ε r = 6.1~8.4, Qf = 12300~53500 GHz, and τ f = −23~−746 ppm/°C. Sutapun et al. 9 studied the substitution effect of Zn 2+ at the Mn site of Mn 2 P 2 O 7 , and found that the dopants of Zn 2 P 2 O 7 were diffused completely into the Mn 2 P 2 O 7 structure, forming solid solutions.In recent years, many compounds with the general formula of M2M1P 2 O 7 have been reported with excellent microwave dielectric properties and low sintering temperatures. Complex pyrophosphates compounds M2M1P 2 O 7 (M2 = Ca, Sr; M1 = Zn, Cu) were investigated as low temperature cofired ceramic (LTCC) materials due to their intrinsic low sintering temperatures. 10 In the past, the work of BaZnP 2 O 7 was mainly focused on the luminescence properties. 11,12 In 2016, Xie et al. 13 prepared BaZnP 2 O 7 ceramics through solid-state reaction and reported its dielectric properties: ε r = 8.4, Qf = 27925 GHz, and τ f = −56.7 ppm/°C. However, there are

Perfect absorption based on a ceramic anapole metamaterial

“…Appropriate dielectric properties of ceramics are the premise behind the performance and also determine the characteristics of temperature robustness of a metamaterial perfect absorber. [64][65][66][67] Here, the modification of BENT-AG ceramics is done for hightemperature stable perfect absorption. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) are presented in the ESI † (in Fig.…”

The lattice vibration and microwave dielectric properties of BaZnP2−xNbxO7 ceramics for microwave substrates

“…A 2 P 2 O 7 , A 1 A 2 P 2 O 7 (A = Ca, Ba, Sr, Mg, Mn, Zn; A 1 = Ca, Sr, Ba; A 2 = Cu, Zn, Mg), and LiMPO 4 (M = Mg, Zn) [13][14][15][16][17][18][19][20][21][22][23][24][25][26] are some of the hot studied phosphate microwave dielectric ceramics as they possess low dielectric constants, high quality factors, and low sintering temperatures (<950 • C) that meet the LTCC processes. Various reports on LiMPO 4 can be found in the literature, 13,14 and the later studies have mainly focused on ionic substitution to improve the microwave dielectric properties of ceramics [15][16][17][18][19][20] ceramics have superior properties compared to some of the LiMPO 4 ceramics.…”

“…Xie et al 25 initially reported that the microwave dielectric properties of BaZnP 2 O 7 are (ε r = 8.4, Q × f = 27 925 GHz and τ f = −56.7 ppm/ • C). Then Chen et al 26 substituted Mg 2+ for Zn 2+ to improve the microwave dielectric properties of ceramics, and based on the P-V-L theory, the relationship between the chemical bond characteristics and performance was analyzed. The excellent performance was realized for the sample BaZn 0.98 Mg 0.02 P 2 O 7 with ε r = 8.21, Q × f = 84 760 GHz and τ f = −21.9 ppm/ • C. However, as can be seen from previously reported works, there are few relevant studies on the spectral and vibrational properties of BaZnP 2 O 7 .…”

“…initially reported that the microwave dielectric properties of BaZnP 2 O 7 are ( ε r = 8.4, Q × f = 27 925 GHz and τ f = −56.7 ppm/°C). Then Chen et al 26 . substituted Mg 2+ for Zn 2+ to improve the microwave dielectric properties of ceramics, and based on the P–V–L theory, the relationship between the chemical bond characteristics and performance was analyzed.…”

Nearly stoichiometric BN fiber with high crystallinity achieved by boron trichloride assisted curing process

“…10 Therefore, controlling the near-stoichiometric ratio of BN elements, reducing crystal defects, and improving BN fiber's crystallization and orientation are beneficial to further increase the fiber strength, thermal stability, and transparent properties. [11][12][13][14] However, according to the previous research on the synthesis of precursor polymers and pyrolysis mechanism, most polyborazine precursors are nitrogen-rich, and a large number of N elements will be excessive in the process of carbon removal in an ammonia atmosphere and crystallization in a nitrogen atmosphere, resulting in the content of boron and nitrogen deviating from stoichiometry. 11,[15][16][17] Thus, many B vacancy defects are produced in the crystallization process, which destroys the crystal structure of the fiber and reduces the strength of the fiber.…”