Search

Nanocomposite thin films (NCTF) of low-dimensional ZnSe and copper doped ZnSe integrated poly(vinylidene fluoride) (PVDF) polymer were developed via simple solution casting method. Herein, ZnSe and Cu:ZnSe nanoparticles were synthesized through the chemical reduction technique. The obtained low-dimensional nanoparticles and NCTFs were characterized by XRD, SEM/EDS, TEM, and FTIR analysis. Room temperature dielectric and ferroelectric characteristics of PVDF/ZnSe flexible NCTF exhibited superior dielectric and ferroelectric behavior with a high coercive field of 15.6 V. Whereas, the dielectric and ferroelectric characteristics were greatly diminished in the PVDF/Cu:ZnSe flexible NCTF was due to the conducting behavior of copper ions at the interface of the polymer network. These results indicated that the PVDF/ZnSe flexible NCTF will be a potential candidate for advanced electrical applications and device fabrication. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44983.

Cu90Co10 and Cu85Co10Ni5 soft magnetic alloys were obtained by non-equilibrium phase synthesis. Elemental powder mixtures were mechanically alloyed in a planetary mill to disperse ultrafine Co and (Co,Ni) particles in the copper matrix. Thus, it was possible to modified magnetic properties of these materials. Resulting powders were characterised as a function of milling time by means of X-ray diffraction, SEM, high resolution transmission electron microscopy and electron probe microanalysis. The variation of magnetic properties and its dependence on the structure/precipitation change with milling time for each alloy are discussed. Magnetic properties of Cu‐Co and Cu‐Co‐Ni powders reached their optimum values after milling for 60 h. On the other hand, superparamagnetic behaviour was observed at 300 K in the Cu‐Co‐Ni alloys. Both alloys were consolidated after 60 h milling by cold compaction and sintering at 973 K for 1 h. Although this treatment is performed at high temperature, precipitation and coalescence of Co particles on the Ni5CoXCu95−X system was retarded by the presence of Ni in solid solution in Cu matrix.

This paper highlights the dielectric, pyroelectric, and resistivity studies of Ba1.45Sr2.4Dy0.1LixNa2−xNb10O30 (x = 0 ≤ x ≤ 1.0) tungsten–bronze-structured ceramics. X-ray diffraction studies indicated single orthorhombic (mm2) phase supported by tolerance factor and average electronegativity difference. The lattice parameters, unit cell volume, axial ratio, and densities are calculated from XRD studies. The experimental densities obtained are about 95% to that of theoretical values. It is found that the unit cell volume enhanced up to Li0.8. The effect of Li modification and Dy doping on eRT, $$ \varepsilon_{{{\text{T}}_{\text{c}} }}, $$ and Tc in BSNN system are discussed. D.C. resistivity studies indicated the positive temperature coefficient of resistivity (PTCR) response in these compositions.

The influence of Ba doping in 0.5PMN-0.5PLZT composition is investigated for microstructure and nanostructure, dielectric and ferroelectric properties near morphotropic phase boundary (MPB). Lead magnesium niobate (PMN)–lead lanthanum zirconate titanate (PLZT) nano-ceramics were synthesized through two stage calcination process namely columbite precursor method. XRD studies revealed that incorporation of Ba and PMN in PLZT perovskite resulted in pseudocubic phase with reduced pyrochlore phase. The isovalent additive Ba2 + influenced the microstructure and densification in the nano-ceramics where Ba concentration increased to 1.5 mol% Ba. The grain growth (3.17 μm) inhibited while apparent density (7.72 gm/cm3) remarkably enhanced, respectively. TEM studies revealed an average particle size ranging from 24 to 78 nm. The room temperature dielectric response (eRT = 2409 and e Tc = 21641) increased up to 1 mol% Ba with decreasing dielectric loss (TanδRT) and Curie temperature (Tc) throughout the series. Ba su...

In this investigation, (Pb 0.988 − y Sr 0.012 Ba y )(Zr 0.51 Ti 0.47 Nb 0.02 )O 3 (PSBZTN) where y = 0, 0.5, 1.0 and 1.5 mole% crystalline solid solutions have been fabricated by solid-state reaction method. A ferroelectric phase change occurred from rhombohedral to tetragonal MPB of (Pb1 − x − y Sr x Ba y )(Zr1 − z − k Ti z Nb k )O3was observed for y = 0.5 mole% Ba and further Ba increment resulted in strong tetragonality. Microstructure studies reveal that grain growth inhibited while the density profile showed the inter-diffusion between multiple ions and promoted densification. The isovalent substitutions of Ba 2 + and Sr 2 + cations at the Pb site and donor pentavalent Nb 5 + at Zr/Ti site enhanced the dielectric constant (ϵ RT = 2384) while decreasing the phase transition temperature (Tc). The substitution of 1.5 mole% Ba for Pb evidently increased (Pr = 32.46 μ C/cm 2 ) and (Ps = 38.44 μ C/cm2) with relatively decreasing coercive field.

Ba modified (Pb,La,Ag)(Zr,Ti)O3 ceramics synthesized by conventional mixed-oxide method with chemical formula [Pb0.983 − zLa0.012Ag0.005Baz] [(Zr0.52Ti0.48)0.99825]O3 were investigated for ferroelectric and piezoelectric properties. XRD studies indicate that increment of Ba concentration resulted in strong tetragonality in the ceramics. Grain growth (3.08 μ m) inhibited and apparent density (7.54 gm/cm3) enhanced up to 1.5 mole% Ba respectively. As Ba content increased dielectric properties showed maximum values (eRT = 2347, eTc = 23449) while Tc constantly decreased. The remanent (Pr = 34.72 μ C/cm2) and spontaneous polarization (Ps = 41.84 μ C/cm2) were optimum in 1 mole% Ba respectively while Ec showed increasing trend throughout the series. Piezoelectric properties attained maximum values of d33 = 438 pC/N in 1.5 mole% Ba while kp = 0.533 and kt = 0.412 in 1 mole% Ba doped (Pb,La,Ag)(Zr,Ti)O3 ceramics respectively.

[Pb0.961La0.012Ba0.015Sr0.012][Zr0.53Ti0.47]0.967-(h/2)Nb0.02Zn0.01MnhO3 (PLBSZZMNT) nano-ceramics where h = 0, 0.5. 1 and 1.5 mol% fabricated through solid state reaction method has been investigated for phase formation, microstructure, density, dielectric and piezoelectric properties. X-ray diffraction studies indicated that all the samples exhibited a single-phase perovskite tetragonal structure which had strongly intensified due to the acceptor Mn content increment in the series. Our investigation with reference to isovalent (Ba2+ and Sr2+) on the A-site, pentavalent donor (Nb5+) and acceptor (Zn2+ and Mn4+) dopants on the B-site in PLZT perovskite with the stoichiometric compositional formulation tailored for dielectric and piezoelectric properties has been clearly explained. As Mn concentration increased, the grain growth enhanced, and the inter-diffusion between multiple ions promoted densification in the PLBSZZMNT nano-ceramics. TEM studies revealed an average particle size ranging from 20 to 72 nm. Dielectric characterization revealed that the eRT enhanced till 1.5 mol% Mn (2946) while the Curie temperature and dielectric loss at room temperature (Tc and TanδRT) decreased, respectively. Mn doping in PLBSZZNT induced the piezoelectric parameters (kp = 0.567) and (d33 = 486 pC/N) till 1.5 mol% Mn. Thus, 1.5 mol% Mn modified PLBSZZNT exhibits optimum dielectric and piezoelectric properties, which are suitable for possible sensor and actuator applications.

Dielectric, ferroelectric and piezoelectric properties of xPb(Mg1/3Nb2/3)O3–(1-x)(Pb0.988 La0.012)(Zr0.535Ti0.465)O3 ceramic system synthesized through columbite precursor method are investigated. X-ray diffraction patterns of ceramics indicated pseudocubic phase formation with pyrochlore phase. Grain growth (4.47 μ m) and apparent density (7.68 gm/cm3) enhanced remarkably in 0.8PMN-0.2PLZT composition, respectively. Increasing PMN content remarkably increased both room temperature dielectric permittivity (eRT = 2316) and dielectric maximum (eTc = 24747) in 0.6PMN-0.4PLZT composition, respectively. PMN substitution in PLZT system enhanced the ferroelectric remanent (Pr = 28.4 μ C/cm2) and spontaneous (P s = 31.2 μ C/cm2) polarization while coercive field (Ec) continuously decreased in xPMN-(1-x)PLZT system. PMN modification in PLZT system influenced piezoelectric properties (d33, kp and kt) throughout the PMN-PLZT system.

The ceramic compositions (1 − x)Pb0.9875Sr0.0125(Zr0.53Ti0.47)O3 –xBaTiO3 where x = 0.2, 0.4, 0.6 and 0.8, fabricated through solid state reaction method were investigated for phase formation, microstructure, density, dielectric and piezoelectric properties. The X-ray diffraction patterns indicated that introduction of BaTiO3 in isovalent donor Sr modified PZT lattice, diminished the tetragonality. All the specimens were homogenous in nature due to the coarse grains of BaTiO3, which had undergone inter-granular growth and were homogeneously distributed within the PSZT–BT lattice. Introduction of BaTiO3 in PSZT perovskite lattice resulted in enhanced grain growth till x = 0.6 (2.03 μm). Dielectric properties (eRT, Tanδ and T c) were influenced by both BaTiO3 and Sr. The maximum eRT = 1588 and eTc = 10478 were found in 0.2PSZT–0.8BT ceramic system. The optimum dielectric permittivity at room temperature with a low Curie transition temperature was found in 0.2PSZT–0.8BT composition. Piezoelectric properties are very sensitive to isovalent substitutions, where isovalent donor Sr modification and BT concentrations in PZT, affected the piezoelectric properties (k p and d 33) in the ceramic system. Thus, the series PSZT–BT compositions could be ideal candidates for capacitors and suitable sensor applications.

The influence of multiple doping (A-site modifiers: La, Ba and Pb(Mg 1/3 Nb 2/3 )O 3 ) on dielectric, ferroelectric and piezoelectric properties of Pb(Zr 0.55 Ti 0.45 )O 3 solid solutions synthesized through mixed oxide and columbite precursor methods, respectively were investigated. La and Ba introduction in Pb(Zr 0.55 Ti 0.45 )O 3 resulted in rhombohedral (FE RH ) to tetragonal (FE TET ) phase change whereas PMN and La modified Pb(Zr 0.55 Ti 0.45 )O 3 attained pseudocubic phase with reduced pyrochlore phase. The A-site modification in PZT inhibited the grain growth while density enhanced. The increasing Ba2+ content in PLZT and La 3+ content in PMN-PZT remarkably enhanced ϵ RT and ϵ Tc , respectively. The optimum ferroelectric and piezoelectric properties were observed in 5 mole% Ba doped PLZT and 1.2 mole% La doped 0.3PMN-0.7PZT, respectively.

The morphotrophic phase boundary compositions of Ba doped Pb 1 − 3x/2 La x Δ x (Zr y Ti 1 − y )O 3 (1.2/55/45) ceramics are synthesized for x = 0 to 6 mole% by mixed-oxide method and characterized for phase formation, microstructure, dielectric and relaxor studies. Density of ceramics is increased as Ba concentration is increased. Coexistence of rhombohedral and tetragonal phases is strong in 5 mole % Ba doped PLZT composition near morphotrophic phase boundary of PLZT phase diagram. Scanning electron micrographs indicate the grain size control as Ba concentration increases in PLZT system. ϵ rt and Tanδ are increased up to 4 mole% Ba doped PLZT system. Dielectric maximum (ϵ Tc ) is decreased to 4 mole% Ba and increased to 6 mole% Ba. Curie temperature (T c ) decreased substantially with increase of Ba concentration in PLZT system. Relaxor behavior of the system is characterized over range of 200 kHz.