Effect of Sm substitution on microwave dielectric properties of Nd(Mg0.5Sn0.5)O3 ceramics

The microwave dielectric properties of Nd_(1?x)Sm_x(Mg_0.5Sn_0.5)O₃ ceramics were examined with a view to their exploitation in mobile communication. The Nd_(1?x)Sm_x(Mg_0.5Sn_0.5)O₃ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd_0.98Sm_0.02(Mg_0.5Sn_0.5)O₃ ceramics revealed no significant variation of phase with sintering temperatures. A density of 6.87 g/cm³, a dielectric constant (ε _r ) of 19.2, a quality factor (Q × f) of 104,300 GHz, and a temperature coefficient of resonant frequency (τ _f ) of ?57 ppm/°C were obtained for Nd_0.98Sm_0.02(Mg_0.5Sn_0.5)O₃ ceramics that were sintered at 1,550 °C for 4 h.     

Influence of Ba2+ substitution on the microwave dielectric properties of Nd(Mg0.5Sn0.5)O3 ceramics

The microwave dielectric properties of Nd(Mg_0.5?xBa_xSn_0.5)O₃ ceramics were examined with a view to their exploitation in mobile communication. The Nd(Mg_0.5?xBa_xSn_0.5)O₃ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd(Mg_0.47Ba_0.03Sn_0.5)O₃ ceramics revealed no significant variation of phase with sintering temperatures. A density of 6.91 g/cm³, a dielectric constant (ε _r ) of 19.14, a quality factor (Q × f) of 97,500 GHz, and a temperature coefficient of resonant frequency (τ _f ) of ?65.4 ppm/°C were obtained for Nd(Mg_0.47Ba_0.03Sn_0.5)O₃ ceramics that were sintered at 1,600 °C for 4 h.     

Improved microwave dielectric properties of Nd(Mg0.5Sn0.5)O3 ceramics with Ni2+ substituting

This study elucidates the microwave dielectric properties and microstructures of Nd(Mg_0.5?xNi_xSn_0.5)O₃ ceramics with a view to their potential for microwave devices. The Nd(Mg_0.5?xNi_xSn_0.5)O₃ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd(Mg_0.43Ni_0.07Sn_0.5)O₃ ceramics revealed no significant variation of phase with sintering temperatures. A dielectric constant ( $ \varepsilon_{r} $ ) of 19.3 and a quality factor (Q × f) of 93,400 GHz and a temperature coefficient of resonant frequency ( $ \tau_{f} $ ) of ?66 ppm/ °C were obtained for Nd(Mg_0.43Ni_0.07Sn_0.5)O₃ ceramics that were sintered at 1,550 °C for 4 h.     

Microwave dielectric properties of (1 − y)Nd(1−2x/3)Bax(Mg0.5Sn0.5)O3–yCa0.8Sr0.2TiO3 ceramic

The (1 ? y)Nd_(1?2x/3)Ba_x(Mg_0.5Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramics were prepared by the conventional solid-state method. The X-ray diffraction patterns of the Nd_(1?2x/3)Ba_x(Mg_0.5Sn_0.5)O₃ ceramics revealed that Nd_(1?2x/3)Ba_x(Mg_0.5Sn_0.5)O₃ is the main crystalline phase, which is accompanied by a little Nd₂Sn₂O₇ as the second phase. An apparent density of 6.89 g/cm³, a dielectric constant (ε _r ) of 19.1, a quality factor (Q × f) of 212,000 GHz, and a temperature coefficient of resonant frequency (τ _f ) of ?68 ppm/°C were obtained when the Nd_2.94/3Ba_0.03(Mg_0.5Sn_0.5)O₃ ceramics were sintered at 1,550 °C for 4 h. The temperature coefficient of resonant frequency (τ _f ) increased from ?68 to +55 ppm/°C as y increased from 0 to 0.7 when the (1 ? y)Nd_2.94/3Ba_0.03(Mg_0.5Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramics were sintered at 1,600 °C for 4 h. 0.4Nd_2.94/3Ba_0.03(Mg_0.5Sn_0.5)O₃–0.6 Ca_0.8Sr_0.2TiO₃ ceramic that was sintered at 1,600 °C for 4 h had a τ _f of ?7 ppm/°C.     

Microstructures and microwave dielectric properties of (1 − y)Nd1−xYbx(Mg0.5Sn0.5)O3–yCa0.8Sr0.2TiO3 ceramics

The (1 ? y)Nd_1?xYb_x(Mg_0.5Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramics were prepared by the conventional solid-state method. The X-ray diffraction patterns of the Nd_1?xYb_x(Mg_0.5Sn_0.5)O₃ ceramics revealed that Nd_1?xYb_x(Mg_0.5Sn_0.5)O₃ is the main crystalline phase, which is accompanied by a little Nd₂Sn₂O₇ as the second phase. An apparent density of 6.87 g/cm³, a dielectric constant (? _r ) of 19.48, a quality factor (Q × f) of 117,300 GHz, and a temperature coefficient of resonant frequency (τ _f ) of ?61 ppm/°C were obtained when the Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃ ceramics were sintered at 1,600 °C for 4 h. The temperature coefficient of resonant frequency (τ _f ) increased from ?61 to ?3 ppm/°C as y increased from 0 to 0.6 when the (1 ? y)Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramics were sintered at 1,600 °C for 4 h. 0.4Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic that was sintered at 1,600 °C for 4 h had a τ _f of ?3 ppm/°C.     

Improved microwave dielectric properties of La(Mg0.5Sn0.5)O3 ceramic with Ba2+ substitution

The microwave dielectric properties of La(Mg_0.5?xBa_xSn_0.5)O₃ ceramics were examined with a view to their exploitation for wireless communications. The La(Mg_0.5?xBa_xSn_0.5)O₃ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The La(Mg_0.5?xBa_xSn_0.5)O₃ ceramics contained La₂Sn₂O₇. An apparent density of 6.54 g/cm³, a dielectric constant ( $ \varepsilon_{r} $ ε r ) of 20.1, a quality factor (Q  $ \times $ ×  f) of 51,600 GHz, and a temperature coefficient of resonant frequency ( $ \tau_{f} $ τ f ) of ?82 ppm/°C were obtained for La(Mg_0.43Ba_0.07Sn_0.5)O₃ ceramics that were sintered at 1,550 °C for 4 h.     

Influence of B2O3 on microstructure and microwave dielectric properties of 0.4Nd0.96Yb0.04(Mg0.5Sn0.5)O3–0.6Ca0.8Sr0.2TiO3 ceramic system

The effect of B₂O₃ on the microstructure and microwave dielectric properties of the 0.4Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic system were investigated with a view to their use in microwave devices. A B₂O₃-doped 0.4Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic system was prepared by the conventional solid-state method. The X-ray diffraction patterns of the B₂O₃-doped 0.4Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic system did not significantly vary with sintering temperature. A 1.25 wt% B₂O₃-doped 0.4Nd_0.96Yb_0.04(Mg_0.5Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic system that was sintered at 1,525 °C for 4 h had a dielectric constant of 38.0, a quality factor (Q × f) of 68,600 GHz, and a temperature coefficient of resonant frequency of 2 ppm/°C.     

Microwave dielectric properties and microstructures of Nd(Mg0.5?xCoxSn0.5)O3 ceramics

This study elucidates the microwave dielectric properties and microstructures of Nd(Mg_0.5?xCo_xSn_0.5)O₃ ceramics with a view to their potential for microwave devices. The Nd(Mg_0.5?xCo_xSn_0.5)O₃ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd(Mg_0.45Co_0.05Sn_0.5)O₃ ceramics revealed no significant variation of phase with sintering temperatures. A dielectric constant (? _r ) of 19.2, a quality factor (Q?×?f) of 68,900?GHz, and a temperature coefficient of resonant frequency (τ _f ) of ?67?ppm/°C were obtained for Nd(Mg_0.45Co_0.05Sn_0.5)O₃ ceramics that were sintered at 1,550?°C for 4?h.     

Tuning the microwave dielectric properties of La0.97Sm0.03(Mg0.5Sn0.5)O3 by adding Ca0.8Sm0.4/3TiO3

The influence of sintering temperature on the microwave dielectric properties and microstructure of the (1 ? y)La_0.97Sm_0.03(Mg_0.5Sn_0.5)O₃–yCa_0.8Sm_0.4/3TiO₃ ceramic system were investigated with a view to their application in microwave devices. The (1 ? y)La_0.97Sm_0.03(Mg_0.5Sn_0.5)O₃–yCa_0.8Sm_0.4/3TiO₃ ceramic systems were prepared using the conventional solid-state method. The X-ray diffraction (XRD) patterns of the (1 ? y)La_0.97Sm_0.03(Mg_0.5Sn_0.5)O₃–yCa_0.8Sm_0.4/3TiO₃ ceramic system did not significantly vary with sintering temperature. The XRD patterns of the (1 ? y)La_0.97Sm_0.03(Mg_0.5Sn_0.5)O₃–yCa_0.8Sm_0.4/3TiO₃ ceramic system shifted to higher angle as y increased. A dielectric constant of 37.5, a quality factor (Q × f) of 40,300 GHz, and a temperature coefficient of resonant frequency of 2.4 ppm/°C were obtained when the 0.425La_0.97Sm_0.03(Mg_0.5Sn_0.5)O₃–0.575Ca_0.8Sm_0.4/3TiO₃ ceramic system was sintered at 1,600 °C for 4 h.     

Improvement microwave dielectric properties of Zn2SnO4 ceramics by substituting Sn4+ with Si4+

The microwave dielectric properties of Zn₂(Sn_(1?x)Si_x)O₄ ceramics were examined with a view to their exploitation for mobile communication. The Zn₂(Sn_(1?x)Si_x)O₄ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Zn₂(Sn_(1?x)Si_x)O₄ ceramics revealed no significant variation of phase with sintering temperatures. A maximum density of 6.24 g/cm³ was obtained for Zn₂(Sn_0.93Si_0.07)O₄ ceramic, sintered at 1,175 °C for 4 h. Dielectric constant (? _r ) of 8.12, quality factor (Q × f) of 55,500 GHz, and temperature coefficient of resonant frequency (τ _f ) of ?119.3 ppm/°C were obtained for Zn₂(Sn_0.93Si_0.07)O₄ ceramics that were sintered at 1,175 °C for 4 h.     

Structure and microwave dielectric characteristics of lithium-excess Ca0.6Nd0.8/3TiO3/(Li0.5Nd0.5)TiO3 ceramics

Compositions based on (1−x)Ca_0.6Nd_8/3TiO₃−x(Li_1/2Nd_1/2)TiO₃ + yLi (CNLNTx + yLi, x = 0.30–0.60, y = 0–0.05), suitable for microwave applications have been developed by systematically adding excess lithium in order to tune the microwave dielectric properties and lower sintering temperature. Addition of 0.03 excess-Li simultaneously reduced the sintering temperature and improved the relative density of sintered CNLNTx ceramics. The excess Li addition can compensate the evaporation of Li during sintering process and decrease the secondary phase content. The CNLNTx (x = 0.45) ceramics with 0.03 Li excess sintered at 1190 °C have single phase orthorhombic perovskite structure, together with the optimum combination of microwave dielectric properties of ɛ_r = 129, Q × f = 3600 GHz, τ_f = 38 ppm/°C. Obviously, excess-Li addition can efficiently decrease the sintering temperature and improve the microwave dielectric properties. The high permittivity and relatively low sintering temperatures of lithium-excess Ca_0.6Nd_0.8/3TiO₃/(Li_0.5Nd_0.5)TiO₃ ceramics are ideal for the development of low cost ultra-small dielectric loaded antenna.     

Improvement in microwave dielectric properties of La(Mg0.5Sn0.5)O3 ceramics by applying ZnO–B2O3–SiO2

The microwave dielectric properties of ZnO–B₂O₃–SiO₂ (ZBS)-doped La(Mg_0.5Sn_0.5)O₃ ceramics were investigated with a view to their application in microwave devices. ZBS-doped La(Mg_0.5Sn_0.5)O₃ ceramics were prepared by the conventional solid-state method. The X-ray diffraction patterns of ZBS-doped La(Mg_0.5Sn_0.5)O₃ ceramics exhibited no significant variation of phase with sintering temperature. By adding 2.0 wt% ZBS, a dielectric constant of 19.14, a quality factor (Q × f) of 35,800 GHz, and a temperature coefficient of resonant frequency τ _f (?86 ppm/°C) were obtained when La(Mg_0.5Sn_0.5)O₃ ceramics were sintered at 1,400 °C for 4 h.     

Microwave dielectric properties of La1−xBix(Mg0.5Sn0.5)O3 ceramics

The La_1−xBi_x(Mg_0.5Sn_0.5)O₃ ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the La_0.97Bi_0.03(Mg_0.5Sn_0.5)O₃ ceramics revealed no significant variation of phase with sintering temperatures. An apparent density of 6.50 g cm⁻³, a dielectric constant (?_r) of 20.2, a quality factor (Q × f) of 58,100 GHz and a temperature coefficient of resonant frequency (τ_f) of −84.2 ppm °C⁻¹ were obtained for La_0.97Bi_0.03(Mg_0.5Sn_0.5)O₃ ceramics that were sintered at 1550 °C for 4 h.     

Effect of TiO2 and Al2O3 doping on sintering behavior and microwave dielectric properties of Ba4(Sm0.5Nd0.5)28/3Ti18+xO54+2x ceramics

The effects of TiO₂ and Al₂O₃ doping on the phase formation, the microstructure and microwave dielectric properties of Ba_6?3x (Sm_1?y ,Nd _y )_8+2x Ti₁₈O₅₄ (x = 2/3 and y = 0.5; BSNT) ceramics were investigated. X-ray diffraction patterns showed that the main crystal phase of BSNT + xTiO₂ (x = 0–2) ceramics sintered at 1,280 and 1,300 °C for 5 h was Ba(Sm, Nd)₂Ti₄O₁₂, accompanied by a small number of second phases: Ba₂Ti₉O₂₀ and TiO₂ (x ≥ 1.0), while the new phase BaAl₂Ti₅O₁₄ appeared and the two phases Ba₂Ti₉O₂₀ and TiO₂ disappeared in BSNT ? 2TiO₂ ceramic doped with ≥2 wt% Al₂O₃ successively as identified by scanning electron microscopy and energy dispersive spectroscopy analysis. The TiO₂ and Al₂O₃ working as sintering aids conduced effectively to promote the densification and grain growth, and thus decreasing the sintering temperature, so when the amounts of TiO₂ was increased, Q × f and τ _f values increased continuously. The BSNT ? 2TiO₂ ceramics doped with y wt% Al₂O₃ decreased the density and dielectric constant, increased the Q × f value remarkably and the τ _f values was adjusted from 25.3 to ?7.3 ppm/ °C. When doped with 1.5 wt% Al₂O₃ sintered at 1,260 °C for 5 h, the ceramics obtained the excellent microwave dielectric properties: ε _r  = 74.3, Q × f = 11,928 GHz, and τ _f  = +5.39 ppm/ °C.     

Enhancement microwave dielectric properties of La(Mg0.5Sn0.5)O3 ceramics by Substituting Mg for Co

The microwave dielectric properties of La(Mg_0.5−xCo_xSn_0.5)O₃ ceramics were examined with a view to exploiting them for mobile communication. The La(Mg_0.5−xCo_xSn_0.5)O₃ ceramics were prepared using the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the La(Mg_0.4Co_0.1Sn_0.5)O₃ ceramics revealed that La(Mg_0.4Co_0.1Sn_0.5)O₃ is the main crystalline phase, which is accompanied by small extent of La₂Sn₂O₇ as the second phase. Formation of this Sn-rich second phase was attributed to the loss of MgO upon ignition. Increasing the sintering temperatures seemed to promote the formation of La₂Sn₂O₇. An apparent density of 6.67 g cm⁻³, a dielectric constant (?_r) of 20.3, a quality factor (Q.F.) of 70,500 GHz, and a temperature coefficient of resonant frequency (τ_f) of −77 ppm °C⁻¹ were obtained for La(Mg_0.4Co_0.1Sn_0.5)O₃ ceramics that were sintered at 1550 °C for 4 h.     

Tuning the microwave dielectric properties of La(Mg0.4Sr0.1Sn0.5)O3 by introducing Ca0.8Sr0.2TiO3

The influence of sintering temperature on the microwave dielectric properties and microstructure of the (1 ? y)La(Mg_0.4Sr_0.1Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramic system were investigated with a view to their application in microwave devices. The (1 ? y)La(Mg_0.4Sr_0.1Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramic systems were prepared using the conventional solid-state method. The X-ray diffraction patterns of the (1 ? y)La(Mg_0.4Sr_0.1Sn_0.5)O₃–yCa_0.8Sr_0.2TiO₃ ceramic system shifted to higher angle as y increased. A dielectric constant of 41.2, a quality factor (Q × f) of 56,900 GHz, and a temperature coefficient of resonant frequency of ?6 ppm/ °C were obtained when the 0.4La(Mg_0.4Sr_0.1Sn_0.5)O₃–0.6Ca_0.8Sr_0.2TiO₃ ceramic system was sintered at 1,550 °C for 4 h.     

Effect of Zr substitution on microwave dielectric properties of Zn2SnO4 ceramics

The microwave dielectric properties of Zn₂(Sn_(1?x)Zr_x)O₄ ceramics were examined with a view to their exploitation for mobile communication. The Zn₂(Sn_(1?x)Zr_x)O₄ ceramics were prepared by the conventional solid-state method with various amount of Zr substitution. The diffraction peaks of Zn₂(Sn_(1?x)Zr_x)O₄ ceramics did not vary significantly as x varied. A density of 6.10 g/cm³ was obtained for Zn₂(Sn_0.99Zr_0.01)O₄ ceramic, sintered at 1,225 °C for 4 h. Dielectric constant (? _r ) of 9.6, quality factor (Q × f) of 87,000 GHz, and temperature coefficient of resonant frequency (τ _f ) of ?51 ppm/°C were obtained for Zn₂(Sn_0.99Zr_0.01)O₄ ceramics that were sintered at 1,225 °C for 4 h.     

Influence of Ca0.8Sr0.2TiO3 on the microstructures and microwave dielectric properties of Nd(Mg0.4Zn0.1Sn0.5)O3 ceramics

The influence of Ca_0.8Sr_0.2TiO₃ on the microstructures and microwave dielectric properties of Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ ceramics were investigated by the conventional solid-state method. The X-ray diffraction peaks of (1 − x)Nd(Mg_0.4Zn_0.1Sn_0.5)O₃–xCa_0.8Sr_0.2TiO₃ ceramic system shifted to higher angles as x increased. The dielectric constant increased from 31.8 to 47.7, the quality factor (Q × f) decreased from 54,200 to 42,800 GHz, and the temperature coefficient of resonant frequency (τ _f ) increased from −43 to +41 ppm/°C as x increased from 0.5 to 0.7 when (1 − x)Nd(Mg_0.4Zn_0.1Sn_0.5)O₃–xCa_0.8Sr_0.2TiO₃ ceramic system sintered at 1,600 °C for 4 h.     

Composite dielectrics (1−x)(Mg0.97Zn0.03)2(Ti0.95Sn0.05)O4−xCaTiO3 suitable for microwave applications

(Mg_0.97Zn_0.03)₂(Ti_0.95Sn_0.05)O₄ ceramics by adding CaTiO₃ have been prepared via the solid-state reaction method. The microstructures of samples are systematically studied in order to establish the effects of sintering temperature and additives on microwave dielectric properties of (Mg_0.97Zn_0.03)₂(Ti_0.95Sn_0.05)O₄ ceramics by X-ray diffraction and scanning electron microscopy. A fine combination of microwave dielectric properties (ε_r = 14.57, Q × f = 183,468 GHz, τ_f = ?43.7 ppm/°C) was achieved for (Mg_0.97Zn_0.03)₂(Ti_0.95Sn_0.05)O₄ ceramics sintered at 1,390 °C for 4 h. CaTiO₃, as a τ_f compensator, was added to form a temperature-stable ceramic system. For (1?x) (Mg_0.97Zn_0.03)₂(Ti_0.95Sn_0.05)O₄?xCaTiO₃ system, 0.93(Mg_0.97Zn_0.03)₂(Ti_0.95Sn_0.05)O₄?0.07CaTiO₃ ceramic sintered at 1,390 °C had optimal dielectric properties (ε_r = 18.32, Q × f = 94,715 GHz, τ_f = ?4.1 ppm/°C) which satisfied microwave applications in resonators, filters and antenna substrates.     

Effect of Sb5+ substitution on the dielectric properties of Ba3LiTa3Ti5O21 ceramics

The effects of substitution Sb for Ta on the sintering behavior and the microwave dielectric properties of Ba₃LiTa₃Ti₅O₂₁ ceramic were studied. Single-phase polycrystalline microwave dielectric ceramics Ba₃LiTa_3?x Sb _x Ti₅O₂₁(x = 0–3) were prepared by the solid-state reaction method. The sintering behavior and microwave dielectric properties of Ba₃LiTa_3?x Sb _x Ti₅O₂₁ ceramics were found to be affected by Sb substitution for Ta. With the increasing Sb content, the densified (>95 % of their theoretical X-ray density) temperatures of Ba₃LiTa_3?x Sb _x Ti₅O₂₁ ceramics increased from 1,160 to 1,220 °C, the dielectric constant (ε _r ) decreased from 55.5 to 27, and the Q × f value enhanced significantly from 18,480 to 29,400 GHz, with τ _f improving from 70 to ?25 ppm/°C. A near zero τ _f value could be obtained by carefully adjusting the Sb content.