Preparation, characterization and electrical conductivity studies of NdYb1−xGdxZr2O7 (0 ≤ x ≤ 1.0) ceramics

Several compositions of NdYb_1−xGd_xZr₂O₇ (0 ≤ x ≤ 1.0) ceramics were prepared by pressureless-sintering method at 1973 K for 10 h in air. The relative density, microstructure and electrical conductivity of NdYb_1−xGd_xZr₂O₇ ceramics were analyzed by the Archimedes method, X-ray diffraction, scanning electron microscopy and impedance plots measurements. NdYb_1−xGd_xZr₂O₇ (0 ≤ x ≤ 0.3) ceramics have a single phase of defect fluorite-type structure, and NdYb_1−xGd_xZr₂O₇ (0.7 ≤ x ≤ 1.0) ceramics exhibit a single phase of pyrochlore-type structure; however, the NdYb_0.5Gd_0.5Zr₂O₇ composition shows mixed phases of both defect fluorite-type and pyrochlore-type structures. The measured values of the grain conductivity obey the Arrhenius relation. The grain conductivity of each composition in NdYb_1−xGd_xZr₂O₇ ceramics gradually increases with increasing temperature from 673 to 1173 K. NdYb_1−xGd_xZr₂O₇ ceramics are oxide-ion conductor in the oxygen partial pressure range of 1.0 × 10⁻⁴ to 1.0 atm at all test temperature levels. The highest grain conductivity value obtained in this work is 1.79 × 10⁻² S cm⁻¹ at 1173 K for NdYb_0.3Gd_0.7Zr₂O₇ composition.     

Preparation and microstructural characterization of (Nd1−xGdx)2(Ce1−xZrx)2O7 solid solutions

(Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ (0 ≤ x ≤ 1.0) powders with an average particle size of 100 nm were synthesized with chemical-coprecipitation and calcination method, and were characterized by X-ray diffractometry and scanning electron microscopy. The sintering behaviour of (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ powders was studied by pressureless sintering at 1600–1700 °C for 10 h in air. The relative densities of (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ solid solutions increase with increasing the sintering temperature, and gradually decrease with increasing the content of neodymium and cerium at identical temperature levels. (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ solid solutions have a single phase of defect fluorite-type structure among all the composition combinations studied. The lattice parameters of (Nd_1−xGd_x)₂(Ce_1−xZr_x)₂O₇ solid solutions agree well with the Vegard's rule.     

Preparation, structure and electrical conductivity of pyrochlore-type Gd1−xEu2xSm1−xZr2O7 ceramics with a constant lattice parameter

A novel series of Gd_1−xEu_2xSm_1−xZr₂O₇ (x = 0, 1/3, 1/2, 2/3, 1) ceramics with a constant lattice parameter are prepared by solid-state reaction, and are then evaluated as possible solid electrolytes. The microstructure and electrical properties of Gd_1−xEu_2xSm_1−xZr₂O₇ ceramics have been investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance analysis. Gd_1−xEu_2xSm_1−xZr₂O₇ ceramics exhibit a single phase of pyrochlore-type structure. The total conductivity of Gd_1−xEu_2xSm_1−xZr₂O₇ ceramics obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173 K. At 973–1173 K, the composition has little effect on electrical conductivity of Gd_1−xEu_2xSm_1−xZr₂O₇ ceramics. Gd_1−xEu_2xSm_1−xZr₂O₇ ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10⁻⁴ to 1.0 atm at all test temperature levels. The maximum total conductivity of Gd_1−xEu_2xSm_1−xZr₂O₇ ceramics is about 1.01 × 10⁻² S cm⁻¹ at 1173 K in air.     

Microwave dielectric properties of Ba3Ti4−x(Zn1/3Nb2/3)xNb4O21 for low temperature co-fired ceramics

The effects of substitution of (Zn_1/3Nb_2/3) for Ti on the sintering behavior and microwave dielectric properties of Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (0 ≤ x ≤ 4) ceramics have been investigated. The dielectric constant (?_r) and the temperature coefficient of the resonant frequency (τ_f) of Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ ceramics decreased with increasing x. However, the Q × f values enhanced with the substitution of (Zn_1/3Nb_2/3) for Ti. It was found that a small amount of MnCO₃-CuO (MC) and ZnO-B₂O₃-SiO₂ (ZBS) glass additives to Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (x = 2) ceramics lowered the sintering temperature from 1250 to 900 °C. And Ba₃Ti_4−x(Zn_1/3Nb_2/3)_xNb₄O₂₁ (x = 2) ceramics with 1 wt% MC and 1 wt% ZBS sintered at 900 °C for 2 h showed excellent dielectric properties: ?_r = 53, Q × f = 14,600 GHz, τ_f = 6 ppm/°C. Moreover, it has a chemical compatibility with silver, which made it as a promising material for low temperature co-fired ceramics technology application.     

The effect of co-doping with MgO and Yb2O3 on the structure and electrical conductivity of the Sm2Zr2O7 pyrochlore

SmYb_1−xMg_xZr₂O_7−x/2 (0 ≤ x ≤ 0.15) ceramics are pressureless-sintered at 1973 K for 10 h in air. The structure and electrical conductivity of SmYb_1−xMg_xZr₂O_7−x/2 ceramics are investigated by the X-ray diffraction, scanning electron microscopy and impedance spectroscopy measurements. SmYb_1−xMg_xZr₂O_7−x/2 ceramics exhibit a defect fluorite-type structure. The measured electrical conductivities of SmYb_1−xMg_xZr₂O_7−x/2 ceramics obey the Arrhenius relation, and electrical conductivity of each composition increases with increasing temperature from 673 to 1173 K. At identical temperature levels, the electrical conductivity of SmYb_1−xMg_xZr₂O_7−x/2 ceramics gradually increases with increasing magnesia content. SmYb_1−xMg_xZr₂O_7−x/2 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10⁻⁴ to 1.0 atm at all test temperature levels. The electrical conductivity obtained in SmYb_1−xMg_xZr₂O_7−x/2 ceramics reaches the highest value of 2.72 × 10⁻³ S cm⁻¹ at 1173 K for the SmYb_0.85Mg_0.15Zr₂O_6.925 ceramic.     

Electrical conductivity of samarium-ytterbium zirconate ceramics

(Sm_1 − xYb_x)₂Zr₂O₇ (0 ≤ x ≤ 1.0) ceramic powders were prepared by chemical-coprecipitation and calcination method, and were pressureless-sintered at 1973 K for 10 h to fabricate dense bulk materials. (Sm_1 − xYb_x)₂Zr₂O₇ has a single phase with a pyrochlore or defect fluorite structure, depending mainly upon the Yb content. They are found to be pyrochlores for 0 ≤ x ≤ 0.1, and defect fluorites for 0.3 ≤ x ≤ 1.0. The electrical conductivity of (Sm_1 − xYb_x)₂Zr₂O₇ was investigated by complex impedance spectroscopy over a frequency range of 200 Hz to 20 MHz from 723 to 1173 K in air. The measured electrical conductivity obeys the Arrhenius relation. The grain conductivity of (Sm_1 − xYb_x)₂Zr₂O₇ ceramics gradually increases with increasing temperature. A decrease of about one order of magnitude in grain conductivity is found at all temperature levels when the Yb content increases from x = 0.1 to x = 0.3. The electrical conductivities of defect fluorite-type materials are lower than those of pyrochlore-type materials in (Sm_1 − xYb_x)₂Zr₂O₇ system, whereas activation energies for the conduction process increase monotonically as the structure becomes disordered.     

Structural anomaly and electrical relaxation in (Na2/3Pb1/3)(Mn1/2Nb1/2)O3 ceramics

The X-ray diffraction patterns of (Na_2/3Pb_1/3)(Mn_1/2Nb_1/2)O₃ ceramics were measured within 15–850 K temperature range. The anomaly in the thermal expansion temperature dependence occurred in 250–365 K range. The generalised Cole–Cole model was proposed to describe the measured effective electric permittivity influenced by high electric conduction and the coexistence of two contributions ?*(T,f) = ?*_lattice + ?*_carriers was considered. The analysis of the electric permittivity and conduction exhibited two relaxation processes. The electric conduction relaxation characteristic time values indicated the small polaron mechanism with τ₀ ≈ 10⁻¹³ s occurring in 240–345 K range and the ionic mechanism with τ₀ ≈ 10⁻¹¹ s involved in the other relaxation occurring in the 320–510 K range. The ionic relaxation process was ascribed to a subsystem of defects, which was weakly interrelated to the anomaly in thermal expansion of the (Na_2/3Pb_1/3)(Mn_1/2Nb_1/2)O₃ ceramics. The Gate model was proposed to describe the ionic relaxation mechanism.     

Electrical Conductivity Improvement of Nd2Ce2O7 Ceramic Co‐doped with Gd2O3 and ZrO2

(Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ (0 ≤ x ≤ 0.5) ceramic powders synthesised by the chemical‐coprecipitation and calcination method were pressureless‐sintered at 1,973 K for 10 h in air. The structure and electrical conductivity of (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ ceramics were investigated by the X‐ray diffraction and impedance spectroscopy measurements. (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ (0 ≤ x ≤ 0.5) ceramics exhibit a single phase of defect fluorite‐type structure. The electrical conductivity of (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ ceramics increases with temperature in the range 623–1,173 K following an Arrhenius law. At identical temperature levels, the measured electrical conductivity of (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ ceramics varies with doping different Gd₂O₃ and ZrO₂ contents and exhibits a maximum at x = 0.1.     

Dielectric and ferroelectric properties of Ba0.8Sr0.2Ti1−5x/4NbxO3 ceramics

Ba_0.8Sr_0.2Ti_1−5x/4Nb_xO₃ ceramics, x = 0, 0.01, 0.05, 0.10, were fabricated by conventional solid-state reaction. With increasing niobium content the ferroelectric phase transition temperature decreases linearly, and the dispersivity of the transition increases. Niobium B-site decreases transition temperature more pronounced than Sr²⁺ at A-site. The heterovalent substitution of Nb⁵⁺ in low content causes local defect dipole, while more substitutions introduce disorder to disturb the long-range dipole correlation. Ba_0.8Sr_0.2Ti_1−0.5/4Nb_0.1O₃ ceramic shows weak ferroelectric loop at room temperature far from its transition temperature, 153 K.     

Oxygen and chlorine evolution on RuO2 + TiO2 + CeO2 + Nb2O5 mixed oxide electrodes

A systematic investigation was conducted on the mechanism and electrocatalytic properties of O₂ and Cl₂ evolution on mixed oxide electrodes of nominal composition: Ti/[Ru_(0.3)Ti_(0.6)Ce_(0.1−x)]O₂[Nb₂O₅]_(x) (0 ≤ x ≤ 0.1). For the oxygen evolution, a 30 mV Tafel slope is obtained in the presence of CeO₂, while in its absence a 40 mV coefficient is observed. The intrinsic electrocatalytic activity is mainly due to electronic factors, as result of the synergism between Ru and Ce oxides. For chlorine evolution, the Tafel slope (30 mV) is independent on oxide composition. The best global electrocatalytic activity for ClER was observed in the absence of Nb₂O₅ additive. Variation of the voltammetric charge throughout the experiments confirms high CeO₂ content compositions are fragile, due mainly to the porosity caused by CeO₂ presence. On the other hand, Nb₂O₅ addition decreases considerably this instability.     

Marked reduction in the thermal conductivity of (La0.2Gd0.2Y0.2Yb0.2Er0.2)2Zr2O7 high-entropy ceramics by substituting Zr4+ with Ti4+

The (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂(Zr_1-xTi_x)₂O₇ (x = 0–0.5) high-entropy ceramics were successfully prepared by a solid state reaction method and their structures and thermo-physical properties were investigated. It was found that the high-entropy ceramics demonstrate pure pyrochlore phase with the composition of x = 0.1–0.5, while (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂Zr₂O₇ shows the defective fluorite structure. The sintered high-entropy ceramics are dense and the grain boundaries are clean. The grain size of high-entropy ceramics increases with the Ti⁴⁺ content. The average thermal expansion coefficients of the (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂(Zr_1-xTi_x)₂O₇ high-entropy ceramics range from 10.65 × 10^?6 K^?1 to 10.84 × 10^?6 K^?1. Importantly, the substitution of Zr⁴⁺ with Ti⁴⁺ resulted in a remarkable decrease in thermal conductivity of (La_0.2Gd_0.2Y_0.2Yb_0.2Er_0.2)₂(Zr_1-xTi_x)₂O₇ high-entropy ceramics. It reduced from 1.66 W m^?1 K^?1 to 1.20 W m^?1 K^?1, which should be ascribed to the synergistic effects of mass disorder, size disorder, mixed configuration entropy value and rattlers.     

Dielectric properties of Sm, Nd and Fe doped Bi1.5Zn0.92Nb1.5O6.92 pyrochlores

New pyrochlore ceramics have been produced by doping Sm and Nd into the Bi site and Fe into the Nb site in the Bi_1.5Zn_0.92Nb_1.5O_6.92 (BZN) pyrochlore. Doped pyrochlore ceramics were produced by conventional solid state mixing of oxides at different doping levels using the compositions of Bi_1.5−xSm_xZn_0.92Nb_1.5O_6.92, Bi_1.5−xNd_xZn_0.92Nb_1.5O_6.92 and Bi_1.5Zn_0.92Nb_1.5−xFe_xO_6.92−x. The solubility limit of cations was determined as x = 0.13, 0.18 and 0.15 for Sm, Nd and Fe, respectively. While Sm and Nd increased the dielectric constant (?), Fe doping led a decrease in ?. Dielectric constant of Sm and Nd doped BZN increased to 199 at x = 0.13 (Sm) and to 219 at x = 0.18 (Nd). At low Fe dopings (x = 0.05), the dielectric constant of BZN increased to 242 but decreased to 211 at x = 0.15. The dielectric losses were lower for Sm and Nd dopings than Fe but in all cases it was lower than 0.006. The dielectric constant of Sm, Nd and Fe doped BZN ceramics was nearly independent of frequency within the frequency range between 1 kHz and 2 MHz, but decreased considerably with temperature between 20 and 200 °C. Temperature coefficient of Sm doped BZN (−354 ppm/°C) was lower than Nd and Fe doped BZN ceramics at solubility limits (−538 ppm/°C for Nd and −565 ppm/°C for Fe).     

Co-doped ceria-based solid solution in the CeO2-M2O3-CaO, M = Sm, Gd system

The Pechinni method (A) as well as hydrothermal treatment (B) of co-precipitated CeO₂-based gels with NaOH solution were used to synthesise pure CeO₂, and CeO₂-based solid solutions with formula Ce_1−xM_xO₂, Ce_1−x(M_0.5Ca_0.5)_xO₂ M = Gd, Sm for 0.15 < x < 0.3 nanopowders. The thermal evolution of CeO₂-based precursors during heating them up to 1000 °C was monitored by thermal (TG, DTA) analysis and X-ray diffraction method. All nanopowders and samples sintered were found to be pure CeO₂ or ceria-based solutions with fluorite-type structure. The microstructure of CeO₂-based sintered samples at 1500 °C (A) or 1250 °C (B) was observed for 2 h under the scanning electron microscope. The electrical properties of singly Ce_1−xM_xO₂ or doubly doped CeO₂-based samples with formula Ce_1−x(M_0.5Ca_0.5)_xO₂, M = Gd, Sm, 0.15 < x < 0.30 were investigated by means of the ac impedance spectroscopy method throughout the temperature range of 600-800 °C. It has been stated that partial substitution of calcium by samarium or calcium by gadolinium in the Ce_1−x(M_0.5Ca_0.5)_xO₂, M = Gd, Sm solid solutions leads to ionic conductivity enhancement comparable with only samaria- or gadolina-doped ceria. The CeO₂-based samples with small-grained microstructures obtained from powders synthesised by hydrothermal method exhibited better ionic conductivity than samples with the same composition obtained from powders synthesised by the Pechinii method. The stability of the electrolytic properties of selected co-doped ceria sinters in fuel gases (H₂, CH₄) as well as exhaust gases from diesel engine was also investigated. The co-doped Ce_0.8(Sm_0.5Ca_0.5)_0.2O₂ or Ce_0.85(Gd_0.5Ca_0.5)_0.15O₂ dense samples would appear be to more adequate oxide electrolytes than Ce_1−xM_xO₂, M = Sm, Gd and x = 0.15 or 0.2 for electrochemical devices operating at temperatures ranging from 600 to 700 °C.     

Fabrication and characterisation of Cr and Co doped Bi1.5Zn0.92Nb1.5O6.92 pyrochlores

Cr and Co doped Bi_1.5Zn_0.92Nb_1.5O_6.92 pyrochlore ceramics were produced by solid state mixing of oxides. Cr and Co were doped into the Nb and Nb-Zn sites considering the compositions of Bi_1.5Zn_0.92Nb_1.5−xCr_xO_6.92−x, (Bi_1.5Zn_0.46)(Zn_0.46−3x/6Nb_1.5−3x/5Cr_x)O_6.92−x/2 for Cr doping and Bi_1.5Zn_0.92Nb_1.5−3x/5Co_xO_6.92, (Bi_1.5Zn_0.46)(Zn_0.46−3x/6Nb_1.5−3x/5Co_x)O_6.92−x/2 for Co doping. The solubility limit of Cr in BZN was higher than that of Co and the solubility limit increased when doping was made both into Nb and Zn sites. The second phases appeared when x > 0.2 for Cr and x > 0.15 for Co doping into the Nb-Zn sites. Simultaneous Cr doping into the Nb- and Zn-sites of BZN pyrochlore gave higher dielectric constant than doping into the Nb-site of pyrochlore. However, Co doping into the Nb- and Zn-sites and only into the Nb-site of BZN gave identical dielectric results in the range of 202-218. The temperature coefficient of dielectric constant decreased with Cr doping and increased with Co doping.     

Solid-state electrochromic devices with Nb2O5:Mo thin film and gelatin-based electrolyte

A gelatin-based electrolyte has been developed and characterized by impedance spectroscopy, X-ray diffraction, UV-vis-NIR spectroscopy and atomic force microscopy (AFM). The heat treatment temperature was found the key factor affecting its ionic conductivity that increases from 1.5 × 10⁻⁵ S/cm to 4.9 × 10⁻⁴ S/cm by heating from room temperature up to 80 °C. The temperature dependence of the ionic conductivity exhibits an Arrhenius behavior. EC-devices with the configuration K-glass/Nb₂O₅:Mo EC-layer/gelatin-based electrolyte/(CeO₂)_x(TiO₂)_1−x ion-storage (IS) layer/K-glass, have been assembled and characterized. They show a good long time cyclic stability, but the change of the optical density measured at 550 nm after 25 000 cycles was only 0.13.     

Effect of Ti substitution for Nb in double perovskite-type Ba3CaNb2O9 on chemical stability and electrical conductivity

This paper reports the synthesis, structure, chemical stability and electrical transport properties of Ti substituted Ba₃CaNb₂O₉ (BCN) to develop electrolytes for proton conducting solid oxide fuel cells (H-SOFCs). The powder X-ray diffraction (PXRD) of Ba₃CaNb_2−xTi_xO_9−δ (x = 0.1, 0.15, 0.2, 0.25 and 0.3) and Ba₃Ca_1.18Nb_1.82−xTi_xO_9−δ (x = 0.15 and 0.25) showed formation of double perovskite-like structure with lattice constant comparable to that of Ba₃Ca_1.18Nb_1.82O_9−δ (BCN18). Scanning electron microscopy (SEM) showed dense and pore-free microstructure for Ba₃CaNb_1.75Ti_0.25O_8.875. PXRD and Fourier transform infrared (FTIR) spectroscopy data confirmed long-term stability of Ba₃CaNb_2−xTi_xO_9−δ and Ba₃Ca_1.18Nb_1.82−xTi_xO_9−δ in boiling H₂O and in CO₂ at elevated temperatures. The AC impedance investigation showed contribution due to bulk, grain-boundary and electrode effect at low temperatures. The electrical conductivity of studied materials were measured in different medium including dry air, dry H₂, wet H₂, wet N₂ and D₂O. Increase in conductivity in wet N₂ and decrease in conductivity in D₂O confirmed the proton conduction in Ba₃CaNb_1.75Ti_0.25O_9-δ. Among Ti-substituted compounds investigated in this study, Ba₃Ca_1.18Nb_1.57Ti_0.25O_8.605 showed the highest conductivity of 3.5 × 10⁻⁴ S cm⁻¹ at 400 °C in wet N₂ (3%H₂O), which is comparable to reported values of Ba₂Ca_0.79Nb_0.66Ta_0.55O_6−δ and BCN18.     

Relationship between glass network structure and conductivity of Li2O-B2O3-P2O5 solid electrolyte

Solid state glass electrolyte, xLi₂O-(1 − x)(yB₂O₃-(1 − y)P₂O₅) glasses were prepared with wide range of composition, i.e. x = 0.35 - 0.5 and y = 0.17 - 0.67. This material system is one of the parent compositions for chemically and electrochemically stable solid-state electrolyte applicable to thin film battery. Lithium ion conductivity of Li₂O-B₂O₃-P₂O₅ glasses was studied in the correlation to the structural variation of glass network by using FTIR and Raman spectroscopy. The measured ionic conductivity of the electrolyte at room temperature increased with x and y. The maximum conductivity of this glass system was 1.6 × 10⁻⁷ Ω⁻¹ cm⁻¹ for 0.45Li₂O-0.275B₂O₃-0.275P₂O₅ at room temperature. It was shown that the addition of P₂O₅ reduces the tendency of devitrification and increases the maximum amount of Li₂O added into glass former without devitrification. As Li₂O and B₂O₃ contents increased, the conductivity of glass electrolyte increased due to the increase of three-coordinated [BO₃] with a non-bridging oxygen (NBO).     

Compositional dependence of phase structure and electrical properties in (K0.50Na0.50)0.97Bi0.01(Nb1−xZrx)O3 lead-free ceramics

(K_0.50Na_0.50)_0.97Bi_0.01(Nb_1-xZr_x)O₃ (KNBNZ) lead-free ceramics were prepared by the conventional solid-state sintering process. Their phase structure is dependent on the Zr content in the investigated range, and the ceramics endure a phase transition from pseudocubic to orthorhombic with increasing Zr content. Improved piezoelectric properties have been observed when the poling temperature is located at ~100 °C because of the coexistence of orthorhombic and tetragonal phases. Their dielectric and piezoelectric properties were enhanced by doping Zr, the ceramic with x=0.02 showing optimal electrical properties, i.e., d₃₃~161 pC/N, k_p~0.41, Q_m~81, T_c~370 °C, and T_o−t~130 °C. These results show that the KNBNZ ceramic is a promising lead-free piezoelectric material.     

Garnet-based red emitting phosphors Li6MLa2Nb2O12: Eu (M=Ca,Sr, Ba): Photoluminescence improvement by changing crystal lattice

A series of novel red emitting phosphors Li₆M(La_1−xEu_x)₂Nb₂O₁₂ (M=Ca, Sr, Ba; 0≤x≤0.3) were synthesized by solid state reaction, and their structures and photoluminescence properties were investigated in detail. The excitation spectrum of Li₆M(La_1−xEu_x)₂Nb₂O₁₂ revealed two mainly excitation bands at 393 nm and 464 nm, which match well with the two popular emissions from near-UV and blue LED chips. Upon the 464 nm light excitation, Li₆MLa₂Nb₂O₁₂:Eu³⁺ phosphors exhibit a red emission centered at 608 nm, originated from the ⁵D₀–⁷F₂ transition of Eu³⁺ ions. The Eu³⁺ surrounding crystal lattice environment in the garnet-based host was changed by altering the c sites element with different radii alkaline earth Ba, Sr, and Ca. The evident photoluminescence enhancement was observed in Li₆M(La_1−xEu_x)₂Nb₂O₁₂ phosphors with the decreasing of the c sites ionic radius. The emission intensity of the optimized Li₆Ca(La_0.8Eu_0.2)₂Nb₂O₁₂ (λ_exc=464 nm) phosphor is about two times higher than that of Y₂O₃:Eu³⁺ (λ_exc=467 nm) under blue light excitation. In addition, the quenching mechanism and the relationship between the structure and photoluminescence property were also discussed.