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The solid-state sintering route was employed for the production of (1-x)Bi2(Li0.5Ta1.5)O7-xTiO2 (x = 0, 0.02, 0.04, 0.06, 0.08) ceramics. The phase, microstructure and microwave dielectric properties of each ceramic composition were determined via X-ray diffraction, scanning electron microscopy and Haki Colmon resonator technique, respectively. The dielectric constant, tan δ and AC conductivity were also determined for the composition of x = 0.04. The TiO2 addition developed new phases of Bi3Ti4O12 and Bi3TaTiO9 for x = 0.04 along with Bi2(Li0.5Ta1.5)O7 phase which disappeared for x = 0.08. The τf of Bi2(Li0.5Ta1.5)O7 was tuned through zero by TiO2 addition and good microwave dielectric properties er~67.2, Qufo13,767 GHz and τf ~ −1.45 ppm/°C can be obtained for the composition of x = 0.04 sintered at 1050 °C for 2 h. This ceramic composition is a suitable candidate for 5G cellular base station resonator application.

Sr0.6Ca0.4LaAlO4 ceramic was fabricated via solid-state sintering route and the effect of TiO2 addition on its microwave dielectric properties was investigated. Sr0.6Ca0.4LaAlO4 formed as the major phase along with LaAlO3 as a minor phase at 1400 °C. However, the concentration of LaAlO3 phase increased with increase in the sintering temperature and it became a major phase at 1475 °C. Maximum density was obtained for the composition with x = 0 (i.e., Sr0.6Ca0.4LaAlO4 ceramics) sintered at 1450 °C for 4 h. The TiO2 addition lowered the maximum densification temperature to 1400 °C from 1450 °C. The microwave dielectric properties varied linearly with increasing the volume fraction of TiO2 (x value). Relative permittivity (er) increased from 20.7 to 31.1, Qufo decreased from 95,250 to 65,000 GHz, and τf was tuned through zero and increased from − 29.5 to + 25.4 ppm/°C with increase in the x value from 0 to 0.2. In the present study, er ≈ 24.8, Qufo ≈ 83,500 GHz, and a near-zero τf ≈ − 2.5 ppm/°C was obtained for the composition with 10wt% addition of TiO2.

Mg0.95Ni0.05Ti0.98Zr0.02O3 and CaTiO3 were prepared separately using solid state reaction method. The effect of CaTiO3 addition on the microwave dielectric properties of Mg0.95Ni0.05Ti0.98Zr0.02O3 was investigated to get low loss and temperature stable ceramics in (1 – x)Mg0.95Ni0.05Ti0.98Zr0.02O3-xCaTiO3 series. Mg0.95Ni0.05Ti0.98Zr0.02O3 formed as the major phase along with Mg0.95Ni0.05Ti2O5 phase that formed as minor secondary phase for the composition with x = 0. Microwave dielectric properties ∈r ~ 17.1, Qufo of 195,855 GHz and τf of –46.3 ppm/°C were obtained for the composition with x = 0. The positive τf value of CaTiO3, tuned the τf value of Mg0.95Ni0.05Ti0.98Zr0.02O3 through zero and ∈r ~ 28.4, Qufo ~ 108,775 GHz and τf ~ 3.1 ppm/°C were attained for x = 0.15 in this study. This composition is the best choice for high frequency applications.

The ceramics in Sr5−xBixTi1+xNb4−xO17 (x = 4, 3) series were prepared using solid state sintering method. The phase and microwave dielectric properties were investigated. The parent phase Sr2Bi3Ti4NbO17 and SrBi4Ti5O17 phases did not formed along the Sr5−xBixTi1+xNb4−xO17 series for the compositions with x = 3 and 4. The SrBi4Ti4O15 phase formed as the major phase along with some secondary Bi2Ti2O7 and SrTiO3 phases for the composition with x = 4 in Sr5−xBixTi1+xNb4−xO17 series. For the composition with x = 3 in Sr5−xBixTi1+xNb4−xO17 series, Nb based Bi2Ti2O7 pyrochlore phase formed as the major phase along with SrBi3Ti2NbO12 phase as a secondary phase. In this study, good combination of microwaves dielectric properties i.e., er ~ 166, Qufo 8888 GHz and τf ~ 3.4 ppm/°C is obtained for the compositions with x = 4 sintered at 1200 °C and er ~ 88, Qufo~ 12,500 GHz and τf ~ − 9.36 ppm/°C is obtained for the composition with x = 3 sintered at 1200 °C.

The effects of dwell sintering time on the densification and microwave dielectric properties of Sr0.5Ca0.5La4Ti5O17 ceramic were investigated. The ceramic was fabricated using the conventional solid-state mixed oxide route using high-purity raw materials which was characterized using X-ray diffraction, scanning electron microscopy and vector network analyzer for phase, microstructure and microwave dielectric properties analysis, respectively. The XRD findings showed single-phase ceramics for all sintered samples. The microstructure was observed to be comprised of compacted elongated plate like grains. The grain size was observed to increase with increase in sintering time from 2 to 7 h. Abnormal grain growth is observed for sintering time > 5 h. Thus, the dwell sintering times effected the density, and hence the microwave dielectric properties of Sr0.5Ca0.5La4Ti5O17 ceramic. er ~ 57.1, Qufo ~ 13,250 GHz and τf ~ 5.1 ppm/°C were obtained for Sr0.5Ca0.5La4Ti5O17 ceramic sintered at 1550 °C for 5 h in the present study.

Solid-state sintering method was used for the synthesis of Mg1−xCoxSiO3 (x = 0–0.25) ceramics. Phase, microstructure and microwave dielectric properties of the ceramics were investigated. With increase in Co2+ content, the increase was observed in the lattice parameters. The Qufo value of MgSiO3 was enhanced from 103,453 to 145,846 GHz with increasing the value of x content from 0 to 0.15. The Co2+ substitution also led to an obvious decrease in the sintering temperature by ~ 100 °C. Clino-enstatite phase formed for the composition with x = 0 while Proto-enstatite formed as the major along with minor clino-enstatite phase for the compositions with x > 0. Good dielectric properties at microwave frequencies i.e. er ~ 8.11, Qufo ~ 145,846 GHz and τf ~ − 12 ppm/°C were obtained for the composition with x = 0.15 sintered at 1350 °C for 9 h. This is suggested to be a very favorable dielectric material for millimeterwave applications.

Solid-state reaction (SSR) was used to synthesize samples of (Zn1–xInx)O, with x = 0.05, 0.02, 0.01, 0.005 and 0.00 respectively. All compositions were sintered in an argon atmosphere and their thermoelectric properties, phase constituents, and microstructures were investigated. Single-phase ceramic was formed for each composition with dense microstructure. In3+ doping lowered the electrical resistivity of ZnO and in the present study, lower value of electrical resistivity ρ ~ 1.884 mΩ·cm and highest power factor (P.F) ~ 4.660 × 10−4 WK−2 m−1 at 693.4 °C respectively are obtained for the composition with x = 0.02. The electrical resistivities (ρ) of all compositions were regulated. The tuned and regulated (ρ) are expected to be helpful for future thermoelectric devices.

In this study the synthesis of bi-phase nanoparticles of Fe1.46Zn0.5La0.04Cu0.5O4 (FZLCs) ceramics were first carried out by Sol-gel method and then nanocomposites of FZLCs with polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyethylene oxide (PEO) were prepared by one-pot blending technique. XRD, FT-IR, TG/DTA and SEM techniques were applied for complete characterization of composites. Rheological and dielectric properties of all nanocomposites were studied in detail for their comparative performance. TGA results reveal the highly thermal stability for all nanocomposites in this order i.e. FLZCs/PEO > FLZCs/PVA > FZLCs/PVP > FZLCs/PEG. Rheological properties show that these materials are rigid, pseudo plastic and non-Newtonian in nature. The increase in values for storage modulus (G′) and loss modulus (G′′) with increasing angular frequency owed to the shear thinning behavior of these nanocomposites. Dielectric properties show good agreement to that of energy storage substances which means that these materials have potential to be applied in storage devices.

The compositions in Sr2Ca3Ta4Ti1−xZrxO17 (0 ≤ x ≤ 0.12) series were designed and fabricated by solid state sintering method. All the compositions formed single phases and crystallized in an orthorhombic crystal structure. Zr substitution led to the enhancing of the microwave dielectric properties by tuning the τf value through zero and increased the Qufo value from 12,540 to 14,970 GHz with a slight decrease in er. In the present study, a good combination of er ~ 51, Qufo ~ 145,43 GHz and τf ~ 3 ppm/°C were obtained for Sr2Ca3Ta4Ti0.90Zr0.1O17 ceramic sintered at 1575 °C for 4 h.

(1-x)K0.5Na0.5NbO3-xBi (Li0.5Ta0.5)O3 (x = 0, 0.05, 0.10, 0.15, 0.20) ceramics were processed using a solid-state sintering route. All the sintered samples were characterized in terms of phase, microstructure, dielectric, ferroelectric, and energy storage characteristics. A structural variation from orthorhombic to pseudo-cubic was observed with an increase in x from 0 to 0.20. At x ≥ 0.10, in addition to the parent phase, the formation of a secondary phase was also observed. The grain size decreased with an increase in x value to 0.15 and then increased, for example, at x = 0.20. A charged energy density (Ws) of ∼1.99 J/cm3 along with a recoverable energy density (Wrec) of ∼1.10 J/cm3 was obtained for the x = 0.15 composition. Moreover, the composition with x = 0.15 exhibited high stability of dielectric constant at temperatures ranging from 30 to 371 °C.

The phase, microstructure, and microwave dielectric properties of Sr2-x(Ca1-yMgy)xCe2Ti5O16 (x=0, and 2 with y=0 and 1) ceramics prepared via mix oxide route were investigated. For x=2, y=1, CeO2 apparently formed as the major phase along with a second phase identical to MgTi2O5. In the present study, τf of Sr2Ce2Ti5O16 ceramic was tuned through 0 ppm/°C at the cost of a decrease in er from 109 to 23.1 and an increase in the Q u f o value from 13452 to 22450 GHz. In the present study, er~23.1, Q u f o ~22450 GHz and τf~−30.4 ppm/°C was achieved for the composition with x=2, y=1 (i.e., CeO2 and MgTi2O5 mixture) sintered at 1250°C/4h.

The ceramics in (1 − x) CaLa4Ti5O17-xTiO2 (0 ≤ x ≤ 0.1) series were fabricated via conventional solid-state mix oxide sintering route. Their phase and microwave dielectric properties were investigated. Ca0.1La0.60TiO3 formed as the major phase while CaLa4Ti5O17 formed as secondary phase for the composition with x = 0. The addition of TiO2 content suppressed the formation of the parent CaLa4Ti5O17 phase that finally disappeared and Ca0.1La0.60TiO3 was formed as the only phase. The addition of TiO2 increased er, Q u f o and τf values. In the present study, e r ~ 155, Q u f o ~ 12678 GHz and τ f ~ 8.9 was achieved for the composition with x = 0.1 sintered at 1450 °C for 4 h.

This study focuses on the investigation and characterization for adsorption property of the clay sample collected from river Kasho of district Bannu, Khyber Pakhtunkhwa, Pakistan. The as received clay was investigated via a series of characterization techniques such as XRD, TG-DSC, XRF, FT-IR and SEM-EDS. The characterization of raw sample revealed the presence of clay as well as non-clay accessory minerals. In this study, low cost adsorbent (clay) used for the removal of a cationic dye (methylene blue) as the model pollutant from aqueous solution. For adsorption performance, batch adsorption technique was utilized at various conditions such as initial dye concentration (50–300 mg/L), contact time (10–380 min), solution pH (2–10), and temperature (25–45 °C). Kinetic study exhibited that experimental data were fitted well Pseudo second order (PSO) model and intra-particle diffusion (IPD) as the rate determining step. Equilibrium isotherm data were described well using Langmuir model by giving a maximum capacity of adsorption ( q m = 270 mg/g). Thermodynamic study exhibited that the adsorption process shows spontaneity. The results indicate that the clay could be employed in waste-water treatment for the removal of cationic pollutants and dyes.

Bi0.4806-xYbxNa0.4606Ba0.0588Ti0.98Al0.02O3 (x = 0.0, 0.005, 0.01, 0.05) ceramics were processed using a solid state sintering route. Highly dense microstructure with maximum apparent density was obtained for the composition of x = 0.005. The polarization versus electric field (P-E) loop got relatively slimmer and remnant polarization decreased with an increase in x content. A maximum recoverable energy density of 0.69 J/cm3 at a DBS of 95 kV/cm was obtained at x = 0.005 with its dielectric constant satisfying the condition of Δer/er200°C ≤ ±15 % in a working temperature range of 97–383 °C having

Ca substituted Sr5Ta4TiO17 ceramics were fabricated via solid state mixed oxide route. For all the investigated compositions, single phase was obtained. All the investigated ceramics crystallized into an orthorhombic crystal structure with space group Pnnm. Sr5Ta4TiO17 exhibited lower τf (~180 ppm/°C) and higher Q u f o (~8500 GHz) than its Nb analog compound (Sr5Nb4TiO17). The Ca substitution for Sr tuned the τf of Sr5Ta4TiO17 ceramics through zero and enhanced the Q u f o value at the cost of a decrease in er value. A good combination of microwave dielectric properties i.e. er ~49, Q u f o ~13560 GHz and τf ~−9 ppm/°C was achieved for SrCa4Ta4TiO17 ceramics sintered at 1575 °C for 4 h respectively.

Sr5Nb4 − xTaxTiO17 (0 ≤ x ≤ 4) ceramics were fabricated via solid state mixed oxide sintering rout. Single phase formation was observed for each composition within the in-house XRD detection limit in the entire range of compositions. All the investigated ceramics crystallized into an orthorhombic crystal structure with space group Pnnm. A highly dense microstructure comprised of alongated plate shaped grains was observed for each ceramics. Ta substitution for Nb improved the \({{Q}_{u}}{{f}_{o}}\) and τf values at the cost of slightly decrease in er. Optimum microwave dielectric properties i.e. er ~ 66, \({{Q}_{u}}{{f}_{o}}\) ~ 8500 GHz and τf ~ 180 ppm/°C was achieved for Sr5Ta4 TiO17 ceramics sintered at 1550 °C for 4 h respectively.

The ceramics (1−x)SrTiO3-x (0.93Bi0.5Na0.5TiO3-0.07Ba0.94Sm0.04Zr0.02Ti0.98O3) abbreviated as ((1−x) ST -x (BNT-BSmZT)) (x = 0, 0.1, 0.2, 0.3) were synthesized via solid-state sintering route. The phase structure, microstructure, electrical properties and energy storage performances of the outlined compositions were investigated using X-ray diffraction, electron microscopy, and dielectric measurement techniques. The X-ray diffraction results reveal structural phase transformation from a perfect cubic structure to a rhombohedral structure as the x value increased from 0 to 0.3. The submicron grain size of ∼0.71 μm was obtained for x = 0.1. The rest of the parameters such as breakdown strength (BDS), energy storage performance, charge-discharge efficiency (η), discharging time, dielectric loss and electrical conductivity were observed to be affected by the homogeneous, compact microstructure and grain size. Herein we report an innovative ST-based lead free ceramics capacitor with the highest breakdown strength (BDS) of 420 kV/cm, an impressive recoverable energy density (Wrec) of 1.93 J/cm3, simultaneously with high efficiency (η) of 80.0%, moreover, low dielectric loss, low electrical conductivity ∼4.7 × 10−8 S/m at 100 °C and a fast discharge time (∼0.18 μs) in x = 0.1. Our findings in this work suggest that the obtained ceramics system might be a promising candidate for pulsed power technology.

SrLa4Ti5−xSnxO17 (0 ≤ x ≤ 2) ceramics were fabricated through solid state ceramic route and their microwave dielectric properties were investigated in an attempt to tune their temperature coefficient of resonant frequency (τf) to zero. The compositions were sintered to single phase SrLa4Ti5O17 and SrLa4Ti4.5Sn0.5O17 ceramics at x = 0 and x = 0.5, and SrLa4Ti4−xSnxO17 along with a small amount of La2Ti2O7 at x = 1. The major phase observed at x = 2 was La2Ti2O7 but along with SrLa4Ti4SnO17 and SrLa4Ti4O15 as the secondary phases. τf decreased from 117 to 23.0 ppm/°C but at the cost of dielectric constant (εr) and quality factor multiplied by resonant frequency (Qufo) which decreased from 65 to 33.6 and 11150 to 4191 GHz, respectively. The optimum microwave dielectric properties, i.e. τf = 38.6 ppm/°C, εr = 45.5 and Q u fo = 7919 GHz, correspond to the SrLa4Ti5−xSnxO17 composition with x = 1.

Ca1−xBaxLa4Ti5O17 (0 ≤ x ≤ 0.2) compositions were fabricated via a solid-state mixed oxide route and their phase, microstructure and microwave dielectric properties were investigated. All the compositions formed single phase in the Ca1−xBaxLa4Ti5O17 (0 ≤ x ≤ 0.2) solid solutions within the detection limit of in-house X-ray diffraction. The sintered microstructure of these ceramics comprised densely packed elongated and plate-like grains. The dielectric properties varied linearly with increasing x content. Relative permittivity (e r ) increased from 53.2 to 56.6, Q u f o decreased from 14,600 to 12,630 GHz and τ f was tuned through zero and increased from −33.6 to 1.4 ppm/°C with increase in x value from 0 to 0.2. In the present study, er ≈ 56.6, Q u f o ≈ 12,630 GHz and a near zero τf ≈ 1.4 ppm/°C was achieved for Ba0.2Ca0.80La4Ti5O17 (x = 0.2) ceramics.

Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics was prepared via conventional solid-state mixed-oxide route. The phase, microstructure and microwave dielectric properties of the sintered samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vector network analyzer. The microstructure comprised of circular and elongated plate-like grains. The semi quantitative analysis (EDS) of the circular and elongated grains revealed the existence of Mg0:95Ni0:05T2O5 as a secondary phase along with the parent Mg0:95Ni0:05Ti0:98Zr0:02O3 phase, which was consistent with the XRD findings. In the present study, εr ~17.1, Qufo~195855 ± 2550 GHz and τf ~ -46 ppm/K was achieved for the synthesized Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics sintered at 1325 °C for 4 h.