Ni-rich Compositions Research Articles

Development of a ReaxFF Reactive Force Field for the Pt-Ni Alloy Catalyst.

We developed the ReaxFF force field for Pt/Ni/C/H/O interactions, specifically targeted for heterogeneous catalysis application of the Pt-Ni alloy. The force field is trained using the DFT data for equations of state of Pt3Ni, PtNi3 and PtNi alloys, the surface energy of the PtxNi1-x(111) (x = 0.67-0.83), and binding energies of various atomic and molecular species (O, H, C, CH, CH2, CH3, CO, OH, and H2O) on these surfaces. The ReaxFF force field shows a Pt surface segregation at x ≥ 0.67 for the (111) surface and x ≥ 0.62 for the (100) surface in vacuum. In addition, from the investigation of the preferential alloy component of the adsorbates, it is expected that H and CH3 on the alloy surface to induce a segregation of Pt whereas the oxidation intermediates and products such as C, O, OH, H2O, CO, CH, and CH2 are found to induce Ni segregation. The relative order of binding strengths among adsorbates is a function of alloy composition and the force field is trained to describe the trend observed in DFT calculations, namely, H2 < H2O < CH3 ≈ O2 ≈ CO < OH < CH2 < C ≈ CH on Pt8Ni4, H2 < H2O < CO ≈ O2 < CH3 < OH < CH2 < CH < C on Pt9Ni3, and H2 < H2O < O2 < CO < CH3 < OH < CH2 < C ≈ CH on Pt10Ni2. Using this force field, we performed the grand-canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations for a Pt3Ni slab and a truncated cuboctahedral nanoparticle terminated by (111) and (100) faces, to examine the surface segregation trend under different gas environments. It is found that Pt segregates to the alloy surface when the surface is exposed to vacuum and/or H2 environment while Ni segregates under the O2 environment. These results suggest that the Pt/Ni alloy force field can be successfully used for the preparation of Pt-Ni nanobimetallic catalysts structure using GCMC and run MD simulations to investigate its role and the catalytic chemistry in catalytic oxidation, dehydrogenation and coupling reactions. The current Pt/Ni force field still is found to have difficulties in describing the observed segregation trend in Ni-rich alloy compositions (x < 0.6), suggesting the need for additional force field training and evaluation for its application to describe the characteristics and chemistry of Ni-rich alloys.

High-Throughput Combinatorial Analysis of Mechanical and Electrochemical Properties of Li[NixCoyMnz]O2 Thin Film Battery Material

Lithium-ion battery cathode material has been the subject of much research in both academia and industry in order to improve its electrochemical properties and cyclability. A prime candidate for replacing the relatively expensive and unstable LiCoO2, is the Lil[NiCoMn]O2 cathode material. Being a ternary material, the Li[NiCoMn]O2 has ample room for composition optimization. As such, extended investigations have been conducted to optimize the electrochemical properties of Li[NiCoMn]O2. However, there arose a need for the evaluation of the mechanical properties of Li[NiCoMn]O2 in order to remedy the deterioration of cathode cycle life due to stress development during repeated charge/discharge cycles. In this study, an efficient and high throughput combinatorial methodology is developed using sputter deposition technique and applied to the characterization of mechanical properties degradation of Li[NiCoMn]O2 as a result of repeated charge/discharge cycling. Co-sputter deposition of LiCoO2, LiNiO2, and LiMn2O4 compound targets was carried out in order to create the necessary concentration gradient to efficiently fabricate a Li[NiCoMn]O2 composition library. EDS analysis confirmed that the fabricated composition library encompassed a broad composition range of 20~80 at. % Ni content, 3~44 at. % Co content, and 5~50 at. % Mn content. XRD analysis confirmed a layered α -NaFeO2 (R3-m) structure for all compositions. Mechanical properties characterization by nanoindentation was carried out pre and post five charge/discharge cycles conducted via voltammetry sweep cycles between 2.5V and 4.5V at a scan rate of 1mV/s. Elastic modulus and hardness values pre and post charge/discharge cycles were found to both exhibit a strong composition dependency; Ni-rich compositions exhibited highest hardness values of 12GPa and Mn-rich compositions exhibited highest modulus values of 170GPa pre charge/discharge cycling. However, post charge/discharge cycling nanoindentation results indicated that Mn-rich compositions were characterized to have highest retention of its mechanical properties whereas the properties degraded more significantly for Ni-rich and Co-rich compositions. Electrochemical performance was analyzed at Ni-rich Li[Ni0.80Co0.10Mn0.10]O2, Co-rich Li[Ni0.40Co0.50Mn0.10]O2, and Mn-rich Li[Ni0.60Co0.03Mn0.37]O2, Li[Ni0.45Co0.10Mn0.45]O2­, and Li[Ni0.33Co0.30Mn0.37]O2 compositions. Overall, a strong correlation for enhanced mechanical properties retention leading to superior discharge capacity retention was found with high Mn compositions demonstrating both superior mechanical properties retention and discharge capacity retention. Li[Ni0.33Co0.30Mn0.37]O2 composition, which retained 50% and 38% of its hardness and elastic modulus after cycling, demonstrated 90.61% discharge capacity retention after 20 cycles at 1C rate. Our results, obtained via the developed high throughput and efficient combinatorial analysis, indicate that the manganese rich compositions, which were characterized to have superior mechanical properties, demonstrate the best discharge capacity retention capability even after multiple charge/discharge cycles.

Re-heating effect of Ni-rich cathode material on structure and electrochemical properties

The re-heating effect for Ni-rich Li[Ni0.7Mn0.3]O2 is investigated because the process is required in surface modification and removal of adhered water molecules. A representative binary Ni-rich Li[Ni0.7Mn0.3]O2 (in which cationic distribution in Li layers is not affected by heteroelements) is selected and synthesized via co-precipitation. The as-synthesized Ni-rich Li[Ni0.7Mn0.3]O2 is re-heated at 200 °C, 400 °C, and 600 °C, so that the resulting structural and electrochemical properties are compared by means of X-ray diffraction, transmission electron microscopy, time of flight-secondary ion spectroscopy, thermogravimetric analysis, high temperature X-ray diffraction, and electrochemical tests. Raising the re-heating temperature increases the occupancy of Ni2+ in Li layers and accelerates the aggregation of lithium-related compounds such as Li2CO3 and LiOH towards the particle surface. Among the several conditions tested, re-heating at 200 °C results in a negligible change in the crystal structure; specifically, Ni2+ occupation in Li layers, higher capacity with good reversibility upon cycling tests, better rate capability, and thermal properties. Therefore, re-heating of cathode active materials, in particular Ni-rich compositions, should be considered to stabilize both electrode performances and thermal properties.

Thermal Stability of Materials for Thin-Film Electrochemical Cells Investigated by Thin-Film Calorimetry

ABSTRACTPhase transformation enthalpies are determined using the recently developed measurement technique Thin-Film Calorimetry (TFC), which is based on piezoelectric resonators vibrating in thickness shear mode. They are applicable up to at least 1000 °C. To the best of our knowledge, no comparable TFC systems for such high temperatures exist.The experimental part is divided into two subsections. The first is addressed to a thermodynamic investigation on piezoelectric langasite crystals (LGS, La3Ga5SiO14) which are the key component of the TFC system. The specific heat capacity is measured on LGS crystals of three different manufacturers. It ranges from about 0.45 J g-1 K-1 at 40 °C to about 0.60 J g-1 K-1 at 1000 °C. Thereby, deviations of up to 5 % between the different crystals are detected. Thermal diffusivity data for Y-cut LGS crystals are determined as well. Here, a constant decrease with temperature is detected ranging from 0.48 mm2 s-1 at room temperature to 0.38 mm2 s-1 at 700 °C.The second part presents thin-film calorimetric investigation on thin films of the family Li-Ni-Mn-Co-Al-Oxide (NMC/NMCA). These cathode materials are investigated and compared when annealed in ambient air or 0.5 % H2/Ar up to 860 °C. Three stoichiometries are chosen: Li(Ni1/3Mn1/3Co1/3)O2, Li(Ni0.6Mn0.2Co0.2)O2, and Li(Ni0.6Mn0.2Co0.15Al0.05)O2. The samples show three or four phase transformations. In air, the samples crystallize in the range of 250-350 °C. In 0.5 % H2/Ar, the transformations occur at higher temperatures. Especially in air, stoichiometric NMC crystallizes at lower temperatures compared to Ni-rich compositions. Additional doping with Al enhances the thermal stability which shifts all phase transformations to higher temperatures in both atmospheres.

Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries

In technologically important LiNi1−x−yMnxCoyO2 cathode materials, surface reconstruction from a layered to a rock-salt structure is commonly observed under a variety of operating conditions, particularly in Ni-rich compositions. This phenomenon contributes to poor high-voltage cycling performance, impeding attempts to improve the energy density by widening the potential window at which these electrodes operate. Here, using advanced nano-tomography and transmission electron microscopy techniques, we show that hierarchically structured LiNi0.4Mn0.4Co0.2O2 spherical particles, made by a simple spray pyrolysis method, exhibit local elemental segregation such that surfaces are Ni-poor and Mn-rich. The tailored surfaces result in superior resistance to surface reconstruction compared with those of conventional LiNi0.4Mn0.4Co0.2O2, as shown by soft X-ray absorption spectroscopy experiments. The improved high-voltage cycling behaviour exhibited by cells containing these cathodes demonstrates the importance of controlling LiNi1−x−yMnxCoyO2 surface chemistry for successful development of high-energy lithium ion batteries. Advanced batteries require careful control over the interfacial properties of their constituent materials. This study designs hierarchically structured cathode materials that are resistant to surface reconstruction, leading to improved cycling performance.

On the widths of the hysteresis of mechanically and thermally induced martensitic transformations in Ni–Ti-based shape memory alloys

Abstract It is well known that a good crystallographic compatibility between austenite and martensite in Ni–Ti-based shape memory alloys results in narrow thermal hystereses (e.g. Ball and James, Arch. Ration. Mech. Anal., 1987). The present work suggests that a good crystallographic fit is moreover associated with a small mechanical hysteresis width, observed during a forward and reverse stress-induced transformation. Furthermore, shape memory alloys with a good crystallographic fit show smaller transformation strains. The results obtained in the present study suggest that these correlations are generic and apply to binary Ni–Ti (with varying Ni contents) and quaternary Ni–Ti–Cu–X (X = Cr, Fe, V) alloys. For binary Ni–Ti, it was observed that Ni-rich compositions (good lattice fit) show a lower accummulation of irreversible strains during pseudoelastic cycling.

Hardening behavior and phase decomposition in very Ni-rich Nitinol alloys

A series of Ni-rich Nitinol compositions spanning from 53NiTi to 58NiTi (at%) have been solutionized at 1050°C and aged at 400°C, 625 °C, and 750°C for varying times to determine the correlation between microstructure and hardenability. Compositions of 55NiT, 56NiTi, and 57NiTi displayed peak hardness values near 650 VHN upon quenching, which are on par with tool steels. Upon aging at 400°C, all but the 55NiTi and 56NiTi compositions exhibited a decrease in hardness initiating, between 1 and 10h for the lower Ni alloys and after 100h for the highest Ni containing alloys. The high hardness, including the solution treated condition, was attributed to the precipitation of a large volume fraction of nanoscale Ni4Ti3 platelets that resulted in narrow B2 NiTi matrix channels. These channels provided a microstructure-driven strengthening morphology. Upon increasing Ni content to greater than 56NiTi and increasing the aging time and temperature, the Ni4Ti3 phase decomposed to either Ni3Ti2 and/or Ni3Ti with a subsequent loss in hardness. The decomposition morphology between the precipitates was characterized by serial sectioning showing that Ni4Ti3 platelets acted as a heterogeneous nucleation site and subsequent Ni-reservoir during the growth of globular Ni3Ti precipitates.

Structural and magnetic aspects of La4(Co1−xNix)3O10+δ (0 ≤ x ≤ 1)

The Ruddlesden–Popper (RP3) type oxides, La4Co3O10+δ and La4Ni3O10+δ, form a complete solid solution. Powder X-ray and neutron diffraction data show that La4(Co1−xNix)3O10+δ is isostructural to the monoclinic La4Co3O10+δ structure (P21/a) described for all compositions without any further structural distortions as suggested in the literature. A slight elongation of the Co/Ni–O bonds facing the rock salt interlayer occurs for Ni-rich compositions. The magnetic properties of the solid solution series are mapped in the temperature range from 4 to 300 K, and the results are presented in a magnetic phase diagram. Three regimes with antiferromagnetic order (AF) exist at low temperatures, TN < 10 − 30 K. For x = 0.00, the AF is ascribed to Co(II), whereas a broader AF regime around x = 0.50 is ascribed mainly to Ni(II). Pauli paramagnetism is observed close to metallic La4Ni3O10+δ, x > 0.80. The possibility to tune the oxidation state of the transition metal atoms is demonstrated for La4Co3O10+δ, and exemplified by weakening of a temperature-induced spin transition at around 480 K.

First principles simulations of elastic properties of radiopaque NiTiPt

Ternary NiTiPt is of great interest in the biomedical industry with the potential to replace binary NiTi in implanted devices due to the alloy’s compatibility with medical imaging techniques and higher radiopacity. Cohesive and elastic properties are important for the processability and formability of materials using various hot and cold work methods. First principles simulations using density functional theory are reported here to determine the theoretical cohesive and elastic properties of NiTiPt with particular focus on nickel-rich stoichiometry. It has been found that Ni-rich NiTiPt alloy can form energetically stable cubic B2 phase, but only up to a platinum content of around 18.75at.%. On the other hand, the titanium-rich composition can keep the B2 symmetry throughout the 0–50at.% Pt range. Based on the observed trend in the elastic moduli cubic → orthorhombic → monoclinic phase transition has been suggested for both Ni-rich and Ti-rich compositions. With increasing platinum content the nickel-rich alloy becomes stiffer compared to the binary alloy. In contrast, the titanium-rich alloy exhibits a decrease in the Young’s modulus as the platinum concentration increases. While both compositions suffer from elastic instability beyond certain amount of Pt addition, the ratio between the bulk modulus to the shear modulus indicates that they both should be reasonably ductile within the elastically stable range of Pt concentrations.

Ab initiostudy of point defects in NiTi-based alloys

Changes in temperature or stress state may induce reversible B2$\leftrightarrow$(R)$\leftrightarrow$ B19' martensitic transformations and associated shape memory effects in close-to-stoichiometric nickel-titanium (NiTi) alloys. Recent experimental studies confirmed a considerable impact of the hydrogen-rich aging atmosphere on the subsequent B2 austenite $\leftrightarrow$ B19' martensite transformation path. In this paper, we employ Density Functional Theory to study properties of Ar, He, and H interstitials in B2 austenite and B19' martensite phases. We show that H interstitials exhibit negative formation energies, while Ar and He interstitials yield positive values. Our theoretical analysis of slightly Ni-rich Ni--Ti alloys with the austenite B2 structure shows that a slight over-stoichiometry towards Ni-rich compositions in a range 51--$52\,\text{at.%}$ is energetically favorable. The same conclusion holds for H-doped NiTi with the H content up to $\approx6\,\text{at.%}$. In agreement with experimental data we predict H atoms to have a strong impact on the martensitic phase transformation in NiTi by altering the mutual thermodynamic stability of the high-temperature cubic B2 and the low-temperature monoclinic B19' phase of NiTi. Hydrogen atoms are predicted to form stable interstitial defects. As this is not the case for He and Ar, mixtures of hydrogen and the two inert gases can be used in annealing experiments to control H partial pressure when studying the martensitic transformations in NiTi in various atmospheres.

Isothermal B2–B19′ martensitic transformation in Ti-rich Ni–Ti shape memory alloy

The athermal/isothermal nature of the B2↔B19′ martensitic transformation was investigated by means of electrical resistance measurements in a Ni49.5Ti50.5 alloy that has elevated transformation temperatures as compared with the near-equiatomic or Ni-rich compositions studied previously. The direct B2–B19′ martensitic transformation shows a clear time dependence, whereas isothermal effects are not revealed for the reverse B19′–B2 transition. The applicability of the C-shaped time–temperature–transformation diagram to interpret the experimental results is discussed.

NixPd1−x (x = 0.98, 0.93, and 0.58) nanostructured catalysts for ammonia electrooxidation in alkaline media

The effect of Pd atomic content in NixPd1−x (x=0.98, 0.93 and 0.58) nanometer-sized catalysts synthesized with modified polyol method is investigated for the electrooxidation of ammonia in alkaline media. Physicochemical characterization by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray diffraction (XRD) are carried out to identify the sizes, shapes, chemical and structural features of the catalysts. Both synthesized Ni98Pd2 and Ni93Pd7 are composed of large 50–100nm Ni particles coated with finer Pd ones in the 5–20nm range. The Ni58Pd42 catalyst has smaller and narrower size distribution in the 20nm size range, indicating that Pd stabilizes the particle size of Ni. According to XRD, Ni and Pd form two separate face-centred cubic phases with traces of β-Ni(OH)2. Before ammonia electrooxidation reaction, the catalysts were subjected to an electrochemical treatment that consisted of 200 potential cycles in NaNO3 at pH 10.5 to build a layer of Ni(OH)2. Ammonia electrooxidation proceeds on NiOOH phase and follows the direct pathway at low concentrations and indirect pathway at higher concentrations where NiOOH is reducing and NH3 is oxidizing. It was found that the Ni-rich compositions have higher activity towards the degradation of ammonia.

Unusual magnetization characteristics of Fe-Ni films with graded composition

Thin films of Fe-Ni with graded composition have been deposited on a Si (001) substrate at room temperature by co-sputtering of Fe and Ni with variable rates of the constituting elements. The composition of the films was changing linearly across the thickness from Fe80Ni20 to Fe6Ni94. Five samples were studied with the thickness of 30, 50, 100, 150, and 200 nm. The hysteresis loops measured with the field applied in the film plane had square shape and the coercivity was varying from 11 to 22 Oe. However, the loops for the field perpendicular to the film plane displayed unusual shapes consisting of a double-step hysteresis loop at low fields and unhysteretic part at higher fields. The size of the steps varied with the thickness of the film. The most likely source of the double step hysteretic curves was identified as magnetostrictive stresses at the film/substrate interface. This was evidenced by the disappearance of the second hysteresis step after annealing at 200 °C for 1 h and significant changes of the hysteresis loops when the same structure was deposited starting from Fe-rich or Ni-rich compositions at the substrate.

Cell-constrained melt-quench simulation of d-AlCoNi: Ni-rich versus Co-rich structures

Complex crystalline ground state structures may be obtained by direct (simulated) quenches from the melt for systems of up to a few hundred atoms, given the constraint of a fixed unit cell, coupled with use of (i) replica-exchange Monte Carlo, and (ii) realistic empirical interaction pair potentials. We applied this procedure to decagonal approximants of Al72Co8Ni20 and Al73Co27, obtaining the best energies seen to date for d-AlCoNi models (respectively +20 meV/atom and +9 meV/atom above the tie-plane of competing phases). We elucidated the reasons why different decagonal structures are associated with the Ni-rich and Co-rich compositions. We found a cell doubling to c = 8 Å due to layer puckering not only in the Co-rich structure, but (locally) in the nominally c = 4 Å Ni-rich structure.

Local transformation strain measurements in precipitated NiTi single crystals

The objective of this work was to determine the effect of composition on the local transformation strain in NiTi single crystals. Using in situ digital image correlation to obtain full-field strain measurements, we revealed that increasing Ni concentration and precipitate volume fraction results in smaller local transformation strains. Comparison of the local strain measurements to theoretical calculations indicated that detwinning strains are limited in Ni-rich compositions. It was also found that the Ni-rich compositions displayed a more homogeneous transformation.

Epitaxial FexNi1 − x Thin Film Contacts to GaAs via Electrochemistry

The galvanostatic electrodeposition of epitaxial films on n-GaAs(001) substrates from aqueous metal ammonium sulfate solutions is reported. Structural measurements using X-ray diffraction and transmission electron microscopy indicate that the films have single crystalline or highly oriented body-centered cubic (bcc) or face-centered cubic (fcc) structure at Fe and Ni-rich compositions, respectively. The preparation of the substrate surface via ammonium hydroxide as well as the usage of an ammonium sulfate electrolyte buffer facilitates the initial nucleation of aligned metal islands on GaAs. The ratio of the Fe atomic concentration in the fcc films to that in the electrolyte is close to unity (1.1), whereas a preferential incorporation occurs for the bcc phase such that this ratio increases linearly with Fe atomic composition at a rate of 3.7. bcc diodes have uniform Schottky barrier heights as measured by current-voltage measurements independent of Fe composition consistent with a high interfacial state density. The observed magnetic properties of are consistent with single crystalline material with distributed inhomogeneities. The epitaxy via electrodeposition suggests the importance of ammonium sulfate for technical applications.

Combinatorial fabrication and high-throughput characterization of a Ti–Ni–Cu shape memory thin film composition spread

The phase transformation properties of Ti–Ni–Cu shape memory thin films prepared in the form of a continuous composition spread were investigated. The thin film materials library was fabricated from elemental targets using an ultra-high vacuum combinatorial magnetron sputter-deposition system. Alternating wedge-type layers of Ti, Ni, and Cu were deposited on a thermally oxidized Si wafer and subsequently annealed at 500 °C for 1 h in situ. Automated temperature-dependent resistance measurements ( R( T)), energy dispersive X-ray analysis and X-ray diffraction measurements revealed the compositional region in the ternary phase diagram where thermoelastic transformations occur. The transformation temperatures and the thermal hysteresis were determined from R( T) measurements. Within the composition spread an extended transformation region was found. For Ni-rich compositions, a two-stage B2 → R → B19′ phase transformation was observed. Among others, compositions of Ti 51Ni 49− x Cu x (at.%) show a single-stage transformation for a Cu-content <6.5 at.% (B2 → B19′) and >14 at.% (B2 → B19). In the intermediate composition range two-stage transformations (B2 → B19 → B19′) were found. The dependency of the thermal hysteresis on the Cu-content as described in the literature was confirmed.

Shape memory effect and superelastic behavior of TiNi shape memory alloy processed by vacuum plasma spray method

Machining of TiNi shape memory alloy into a complicated three-dimensional (3D) shape is quite difficult, thus a near-net shape forming of 3D shaped TiNi alloy is attractive and cost-effective. Vacuum plasma spray (VPS) process is one of such near-net shape forming processes. In this paper, two kinds of thick TiNi layer, Ni-rich and Ti-rich compositions, were fabricated by VPS process and their shape memory effect (SME) and superelastic (SE) behaviors were characterized. As-VPS processed Ni-rich TiNi which was subjected to homogenization at 1163 K for 7.2 ks and subsequent aging at 773 K for 18 ks exhibited good martensitic transformation behavior. The recoverable strain of the TiNi alloys due to SME and SE behavior were measured to be 2.4% and 5.0%, respectively. The Ti-rich TiNi alloy also exhibited good martensitic transformation behavior and SME in the as-homogenized state.

Crystal chemistry and electrochemical characterization of layered LiNi 0.5− yCo 0.5− yMn 2 yO 2 and LiCo 0.5− yMn 0.5− yNi 2 yO 2 (0 ≤ 2 y ≤ 1) cathodes

The crystal chemistry and electrochemical performance of the layered LiNi 0.5− y Co 0.5− y Mn 2 y O 2 and LiCo 0.5− y Mn 0.5− y Ni 2 y O 2 oxide cathodes for 0 ≤ 2 y ≤ 1 have been investigated. Li 2MnO 3 impurity phase is observed for Mn-rich compositions with 2 y > 0.6 in LiNi 0.5− y Co 0.5− y Mn 2 y O 2 and 2 y < 0.2 in LiCo 0.5− y Mn 0.5− y Ni 2 y O 2. Additionally, the Ni-rich compositions encounter a volatilization of lithium at the high synthesis temperature of 900 °C. Compositions around 2 y = 0.33 are found to be optimum with respect to maximizing the capacity values and retention. The rate capabilities are found to bear a strong relationship to the cation disorder in the layered lattice. Moreover, the evolution of the X-ray diffraction patterns on chemically extracting lithium has revealed the presence of Li 2MnO 3 phase in addition to the layered phase for the composition LiNi 0.25Co 0.25Mn 0.5O 2 with an oxidation state of manganese close to 4+, which results in a large anodic peak at around 4.5 V due to the extraction of both lithium and oxygen.

Dielectric and ferroelectric properties of Pb(Ni 1/3Nb 2/3)O 3–Pb(Zn 1/3Nb 2/3)O 3–PbTiO 3 ternary ceramics

Ternary ceramics with the type of (1 − x)(0.64PNN–0.36PT)– x(0.91PZN–0.09PT) ( x = 0–0.82) were synthesized by the columbite precursor method. X-ray diffraction results demonstrate that all the samples lie within the morphotropic phase boundary (MPB) region in the pure perovskite structure except for the composition with x = 0.82. The dielectric and ferroelectric properties of compositions with x = 0–0.75 were investigated in detail. All the tested compositions show dielectric behaviors of frequency dispersion and diffuse phase transition. The Ni-rich compositions exhibit superior dielectric and ferroelectric properties to those of Ni-poor ones. The composition with x = 0.15 has the maximum peak dielectric constant (23,410) at 1 kHz and the maximum remnant polarization (14.8 μC/cm 2) with the driving electric field at 10 kV/cm. The variation of peak dielectric constant with x can be explained in terms of the product rate of the polar microregion in the materials.