Textured Microstructure and Dielectric Properties Relationship of BaNd₂Ti₅O₁₄ Thick Films Prepared by Electrophoretic Deposition

Abstract

An alternative approach to tailor the temperature coefficient of permittivity (TCεr) of high Q dielectric BaO–Re2O3–TiO2 (Re: rare earth elements) thick films is presented. 10‐ to 80‐µm‐thick BaNd2Ti5O14 (BNT) films are fabricated by electrophoretic deposition on Pt foils under different processing conditions. Observed anisotropic grain growth is facilitated by constrained sintering. The increase of the sintering temperature increases markedly the aspect ratio of the grains, decreases the dielectric permittivity and TCεr changes from −114 to +12 ppm °C−1. By controlling the sintering temperature, near‐zero TCεr, high Q thick films can be fabricated with 45 < εr < 70. These findings are of technological relevance since they demonstrate that control of substrate constraint and sintering conditions can be used to control grain anisotropy and thus microwave properties of the BaO–Re2O3–TiO2. The thick films facilitate scaling to small device sizes for high frequency operation. Similar observations are expected in other microwave systems thus opening further technological opportunities.

Dielectric response and thermally stimulated depolarization current analysis of BaNd1.76Bi0.24Ti5O14 high-temperature microwave capacitors

“…The theoretical density of specimen is calculated from the theoretical density of BaNd 2 Ti 5 O 14 (5.643 g/cm 3 ) and Bi content. The ceramic specimens of Bi-BNT exhibit excellent microwave dielectric properties: the dielectric permittivity e r value of 88, the Qf value of 8800 GHz, and the s f value of ?6.9 ppm/°C [12][13][14][15]. The good microwave dielectric properties indicate the absence of secondary phases such as BaTi 4 O 9 and TiO 2 even in minor quantity, since such secondary phases can significantly change microwave dielectric properties.…”

“…[16][17][18][19][20][21][22][23][24]. TSDC may also be used to evaluate the activation energy of relaxation, relaxation time and the defect concentration, which enables a better understanding of the physical phenomena related to such defects [10,11,[15][16][17][18]. TSDC is frequently used to analyze polymer materials; however, TSDC is yet to be extensively employed on microwave dielectrics [16][17][18][19][20][21][22][23][24].…”

“…Future power electronics modules also require that electronic components can work at ambient temperature higher than 150°C without external cooling, which is critical for applications in automotive, oil and gas, aerospace, and energy generation industries [12]. Many types of microwave dielectrics have been investigated to meet the demand of commercial microwave applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. It is desired that Microwave dielectrics possess high dielectric constant, low dielectric loss and near-zero temperature coefficient of resonant frequency [3][4][5][6][7][8][9][10].…”

“…It is desired that Microwave dielectrics possess high dielectric constant, low dielectric loss and near-zero temperature coefficient of resonant frequency [3][4][5][6][7][8][9][10]. Tungsten bronze-type BaO-Ln 2 O 3 -TiO 2 (Ln = rare earth) ceramics with superior microwave dielectric properties have been extensively investigated and widely utilized for microwave resonators and filters [3][4][5][6][7][8][10][11][12][13][14][15]. In 1980s, Kolar et al reported the synthesis and crystal chemistry of the ternary compounds BaNd 2 Ti 3 O 10 (BaONd 2 O 3 -TiO 2 , 1:1:3) and BaNd 2 Ti 5 O 14 (1:1:5) with a tungsten bronze phase structure [3].…”

Tuning dielectric properties in ceramics with anisotropic grain structure: The effect of sintering temperature on BaLa4Ti4O15

“…MW ceramics with high contribute to the miniaturization of devices, which include COG multilayer capacitors (thick films) and dielectric resonators, antennas and filters (bulk) [1][2][3][4][5]. Materials with > 40 and close to zero, such as CaTiO 3 14 (BNT) [6][7][8][9][10][11], have potential to be used as resonators or dielectric substrates for antennas either as bulk ceramics or thick films [12]. BLT is a single-phase compound with hexagonal perovskite structure.…”