New,thermally stable Gd<Subscript>11</Subscript>(GeO<Subscript>4</Subscript>)(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>O<Subscript>10</Subscript>-based upconversion phosphors

A series of Gd_11–x–y Yb _x Er _y GeP₃O₂₆ germanate phosphates differing in the ratio of the Yb³⁺ and Er³⁺ active ions have been synthesized, and their luminescence spectra have been measured. According to X-ray diffraction characterization results, all of the synthesized germanate phosphates are single-phase and have a triclinic structure (sp. gr. P1). We have measured upconversion luminescence spectra due to the Er^{3+ 2}H_11/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 radiative transitions in the synthesized gadolinium ytterbium erbium germanate phosphates and determined the luminescence upconversion energy yield (B _en) in Gd_11–x–y Yb _x Er _y GeP₃O₂₆. The effects of the concentrations and ratio of the dopants in the Gd₁₁(GeO₄)(PO₄)₃O₁₀ germanate phosphate host on B _en and the ratio of the luminescence intensities in the red and green spectral regions (R/G) have been assessed.     

Luminescence performance of Eu<Superscript>3+</Superscript>-doped lead-free zinc phosphate glasses for red emission

In this study, the luminescence performance of zinc phosphate glasses containing Eu³⁺ ion with the chemical compositions (60–x)NH₄H₂PO₄-20ZnO-10BaF₂-10NaF–x Eu₂O₃ (where x = 0.2, 0.5, 1.0 and 1.5 mol%) has been studied. These glasses were characterized by several spectroscopic techniques at room temperature. All the glasses showed relatively broad fluorescence excitation and luminescence spectra. Luminescence spectra of these glasses exhibit characteristic emission of Eu³⁺ ion with an intense and most prominent red emission (614 nm), which is attributed to ⁵D₀ → ⁷F₂ transition. Judd-Ofelt (Ω₂, Ω₄) parameters have been evaluated from the luminescence intensity ratios of ⁵D₀ → ⁷F_J (where J = 2 and 4) to ⁵D₀ → ⁷F₁ transition. Using J-O parameters and excitation spectra, the radiative parameters are calculated for different Eu³⁺-doped glasses. Effect of γ-irradiation at fixed dose has been studied for all the Eu³⁺-doped glass matrices. The lifetimes of the excited level, ⁵D₀, have been measured experimentally through decay profiles. The colour chromaticity coordinates are calculated and represented in the chromaticity diagram for Eu³⁺-doped zinc phosphate glasses for all concentrations.     

Tunable luminescence of Sr<Subscript>5(1−x)</Subscript>Ba<Subscript>5x</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>Cl:Eu<Superscript>2+</Superscript> (0 ≤ x ≤ 100%) phosphors from different Eu<Superscript>2+</Superscript> centers

In this paper, a series of Eu²⁺ activated Sr_5(1?x)Ba_5x(PO₄)₃Cl (0?≤?x?≤?100%) phosphors were prepared by solid-state reaction method, and their luminescence properties under near-ultraviolet excitation were investigated. For Eu²⁺-activated Sr₅(PO₄)₃Cl, a strong emission band located at 445 nm is observed upon 365 nm excitation, which could be attributed to the 4f ⁶5d ¹–4f ⁷ transition of different Eu²⁺ centers. When the Ba²⁺ is introduced into the Sr₅(PO₄)₃Cl:Eu²⁺, the emission band of Eu²⁺ is broadened largely. The fluorescence lifetimes for different Eu²⁺ centers were determined by the decay curves and time-resolved spectra. The excitation spectra of the as-prepared samples cover a wide wavelength range from 240 to 420 nm, which can well match the emission wavelength of the near ultraviolet LED chip. The investigation of the thermal luminescence stability reveals that the introduction of Ba²⁺ could improve the thermal quenching properties.     

New NaSrPO<Subscript>4</Subscript>:Sm<Superscript>3+</Superscript> phosphor as orange-red emitting material

Sm³⁺-activated NaSrPO₄ phosphors could be efficiently excited at 403 nm, and exhibited a bright red emission mainly including four wavelength peaks of 565, 600, 646 and 710 nm. The highest emission intensity was found for NaSr _1?x PO₄: xSm³⁺ with a composition of x = 0.007. Concentration quenching was observed as the composition of x exceeds 0.007. The decay time values of NaSr_1?x PO ₄ : xSm³⁺ phosphors range from around 2.55 to 3.49 ms. NaSr_1?x PO₄: xSm³⁺ phosphor shows a higher thermally stable luminescence and its thermal quenching temperature T ₅₀ was found to be 350°C, which is higher than that of commercial YAG:Ce³⁺ phosphor and ZnS:(Al, Ag) phosphor. Because NaSr_1?x PO₄: xSm³⁺ phosphor features a high colour-rendering index and chemical stability, it is potentially useful as a new scintillation material for white light-emitting diodes.     

Enhancement of Pinning Role by Nonstoichiometry in YBa2Cu3O7−y Superconductors

Considerably improved flux pinning and critical current density Jc values have been achieved in Y-deficient Y-123 superconductors by directional solidification in air. In comparison with the regular Y-123 composition, Y-deficient one also has an orthorhombic structure and Y-123 main crystal phase remains in it. Whereas with the shortage of Y, Y_1?xBa₂Cu₃O_7?y can be regarded as (YBa₂Cu₃)_1?xO_7?t(Ba₂Cu₃) _x O_t?y or (YBa₂Cu₃O_7?z)(□ _x ^YO_z?y), so there may develop several kinds of microstructure defects as pinning sites in the system, such as highly dense, fine-scale, and faultlike defects, as well as localized superstructure, which are able to induce the increasing in flux pinning and Jc values in higher external magnetic fields. This kind of simple nonstoichiometric route could lead to a commercial technique for flux-pinning enhancement in Y-123 bulk materials.     

Tunable luminescence properties and energy transfer of single-phase Ca<Subscript>4</Subscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>O: Dy<Superscript>3+</Superscript>, Eu<Superscript>2+</Superscript> multi-color phosphors for warm white light

The novel Ca_4?x(PO₄)₂O: xDy³⁺ and Ca_4?x?y(PO₄)₂O: xDy³⁺, yEu²⁺ multi-color phosphors were synthesized by traditional solid-state reaction. The crystal structure, particle morphology, photoluminescence properties and energy transfer process were investigated in detail. The X-ray diffraction (XRD) results demonstrate that the products showed pure monoclinic phase of Ca₄(PO₄)₂O when x < 0.1. The scanning electron microscopy (SEM) indicated that the phosphors were grain-like morphologies with diameters of ~ 3.7–7.0 μm. Under excitation of 345 nm, Dy³⁺-doped Ca₄(PO₄)₂O phosphors showed multi-color emission bands at 410, 481 and 580 nm originated from oxygen vacancies and Dy³⁺. Interestingly, Ca₄(PO₄)₂O: Dy³⁺, Eu²⁺ phosphors exhibited blue emission band at 481 nm and broad emission band from 530 to 670 nm covering green to red regions. The energy transfer process from Dy³⁺ to Eu²⁺ was observed for the co-doped samples, and the energy transfer efficiency reached to 60% when Eu²⁺ molar concentration was 8%. In particular, warm/cool/day white light with adjustable CCT (2800–6700 K) and high CRI (R_a > 85) can be obtained by changing the Eu²⁺ co-doping contents in Ca₄(PO₄)₂O: Dy³⁺, Eu²⁺ phosphors. The optimized Ca_3.952(PO₄)₂O: 0.04Dy³⁺, 0.008Eu²⁺ phosphor can achieve the typical white light with CCT of 4735 K and CRI of 87.     

Phase structure evolution and chemical durability studies of Gd<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Yb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>PO<Subscript>4</Subscript> ceramics for immobilization of minor actinides

Rare earth phosphates (REPO₄) are considered as promising materials to immobilize the high-level radioactive waste. In the paper, Gd_1?xYb _x PO₄ (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8 and 1.0) series were prepared via the solid-state reaction using Gd as the surrogate for minor actinide Am and Cm, and the structure, phase transformation and morphology were characterized by XRD, Raman, TEM and SEM. With the calcination temperature ranging from 1200 to 1500 °C, the coexisted phases of monazite- and xenotime-type structure are observed in Gd_0.9Yb_0.1PO₄. The monophasic xenotime-type Gd_0.9Yb_0.1PO₄ is obtained at 1600 °C. The monazite → xenotime transformation of Gd_1?xYb _x PO₄ depends on the substitution of Gd³⁺ by Yb³⁺ ions. With the decrease in Gd³⁺ content, the gradual changes of FWHM and the hypsochromic shift of P-O symmetrical stretching vibration (Vs) are observed in the Raman spectra, indicating that the distortion of PO₄ tetrahedra occurs during the phase transformation process. The chemical durability test is measured by the ASTM product consistency test leaching method, and the normalized mass loss (NL_Gd) of Gd and (NL_Yb) of Yb is extremely low and shown in the order of 10^?6–10^?7 g/m² for all the ceramics.     

Photoluminescence and electrical properties of Eu3+-doped Na0.5Bi4.5Ti4O15-based ferroelectrics under blue light excitation

Na_0.5Bi_4.5?x Eu _x Ti₄O₁₅ (NBT- _x Eu³⁺) ceramics with x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu³⁺ ceramics show the strongest red and orange emissions corresponding to the ⁵D₀ → ⁷F₂ (617 nm) and ⁵D₀ → ⁷F₁ (596 nm) transitions, respectively. The strongest excitation band around 465 nm matches well with the emission wavelength of commercial InGaN-based blue LED chip, indicating that Eu³⁺-doped NBT ceramics may be used as potential environmental friendly red-orange phosphor for W-LEDs application. As an inherent ferroelectric and piezoelectric material, the electrical properties of this potentially multifunctional electro-optical material have been also studied. The introduction of Eu³⁺ distinctly increased the Curie temperature (T _C ) of NBT- _x Eu³⁺ ceramics from 640°C to 711°C as x ranges from 0 to 0.40. For higher temperature applications, the electrical conductivity was also investigated. The conduction of charge carriers in high-temperature range originates from the conducting electrons from the ionization of oxygen vacancies. High T _C and low tanδ makes Eu³⁺-doped NBTceramic also suitable for high temperature piezoelectric sensor applications and electro-optical integration.     

Sr<Subscript>3</Subscript>GdLi(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>F: Sm<Superscript>3+</Superscript> phosphor: preparation and luminescence properties evaluation

A series of Sr₃Gd_1?xLi(PO₄)₃F: xSm³⁺ (x?=?0.02, 0.04, 0.06, 0.08) phosphors were synthesized by a high-temperature solid state method. The Sm³⁺ activated Sr₃GdLi(PO₄)₃F phosphors can be efficiently excited by the wavelengths in the range from 350 to 450 nm, which matches perfectly with that of the commercial near-UV LED chips. The optimal doping concentration of Sr₃Gd_1?xLi(PO₄)₃F: xSm³⁺ phosphors was determined to be x?=?0.04, corresponding to the quantum efficiency of 2.23%, and the CIE chromaticity coordinates (x?=?0.5172, y?=?0.4641). The concentration quenching mechanism of Sm³⁺ in Sr₃GdLi(PO₄)₃F host is mainly attributed to the dipole–dipole interaction, which was confirmed by the fluorescent lifetimes. The effect of temperature on the photoluminescence property of Sr₃GdLi(PO₄)₃F: Sm³⁺ was investigated. 90% of the intensity is preserved at 150 °C. In addition, a white light emitting diode (WLED) lamp was fabricated by a 405 nm n-UV LED chip coated with Sr₃Gd_0.96Li(PO₄)₃F:0.04Sm³⁺ phosphor and commercial yellow phosphor (YAG: Ce³⁺) of a certain mass ratio. The present work indicates that the Sr₃GdLi(PO₄)₃F: Sm³⁺ orange–red-emitting phosphors tend to be potential application in n-UV WLED.     

Synthesis and luminescence spectra of (Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–YOF):Ln(III) composites

Sols were prepared by reacting yttrium, europium, and terbium trifluoroacetates with thioacetamide in ethyl acetate. The Eu³⁺ and Tb³⁺ concentrations in the sols were 0.10 to 10 wt % relative to yttrium, which corresponded to 0.061 (0.059) to 6.1 (5.9) at % Eu (Tb). The sols were converted into a gel-like state by slowly evaporating the solvent. After ripening, the gels were heat-treated at a temperature of 800°C. X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and IR spectroscopy results showed that the resultant composites consisted predominantly of a mixture of Y₂O₃ and YOF. The Eu³⁺ and Tb³⁺ ions were shown to substitute for Y³⁺ ions in the crystal lattices of the yttrium oxide and yttrium oxyfluoride. The formation of the (Eu_0.6Y_0.4)₂O₃, Eu₂O₃, and EuOF phases was demonstrated. We determined the types and parameters of the crystal lattices of the synthesized materials in relation to activator concentrations. The luminescence of the composites is due to the ⁵ D ₀ → ⁷ F _j and ⁵ D ₄ → ⁷ F _j electronic transitions of the Eu³⁺ and Tb³⁺ ions and depends on the host and activator compositions, the excitation wavelength, and other factors.     

Recombination luminescence of activated CaI<Subscript>2</Subscript> crystals

Data are presented on the recombination luminescence of CaI₂:Eu²⁺, CaI₂:Gd²⁺, CaI₂:Tl⁺, CaI₂:Pb²⁺, and CaI₂:Mn²⁺ crystals grown by the Bridgman-Stockbarger method. It follows from their photostimulated luminescence, roentgenoluminescence, and thermostimulated luminescence spectra that the activation of CaI₂ with Gd²⁺, Eu²⁺, Tl⁺, Pb²⁺, and Mn²⁺ cations, which produce anion defects, leads to the formation of defect complexes which act as electron traps and determine the 90-K photostimulation spectra of the crystals. The observed effect of the nature of the dopant on the photostimulation spectrum indicates that the doped calcium iodide crystals contain near-activator F- and F _A -type electron centers. Under x-ray and optical excitation, the trapping levels in the crystals are filled mainly by charge carriers delocalized from hydrogen- and oxygen-containing centers. The activation increases the decay probability of impurity-bound excitons.     

Stability region of Eu<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript>x</Subscript>O<Subscript>3+δ</Subscript> solid solutions in air

The homogeneity range of EuMnO₃ has been determined using x-ray diffraction analysis of single-and mixed-phase Eu_2?x Mn_xO_3+δ samples (0.90≤x≤1.20, Δx = 0.02) prepared from oxide mixtures by solid-state reactions in air between 900 and 1400°C. The results have been used to construct a partial phase diagram of the Eu-Mn-O system in air. The dependences of unit-cell parameters on x and synthesis temperature are presented for the samples synthesized at 1100 and 1400°C and for EuMnO₃, respectively. The solubility of europium oxide in EuMnO₃ is tentatively attributed to structural defects, and that of managanese oxides is interpreted in terms of structural defects, oxygen nonstoichiometry of europium manganite, the disproportionation reaction 2Mn³⁺ = Mn²⁺ + Mn⁴⁺, and partial substitution of the resulting Mn²⁺ for Eu³⁺ on the cuboctahedral site of the perovskite-like structure. To check these assumptions, systematic studies of the oxygen nonstoichiometry and structure of Eu_2?x Mn_xO_3+δ solid solutions synthesized at different temperatures are needed.     

Synthesis and photoluminescence study of narrow-band UVB-emitting LiSr<Subscript>4</Subscript>(BO<Subscript>3</Subscript>)<Subscript>3</Subscript>:Gd<Superscript>3+</Superscript>, Pr<Superscript>3+</Superscript> phosphor

A series of Pr³⁺, Gd³⁺ and Pr³⁺–Gd³⁺-doped inorganic borate phosphors LiSr₄(BO₃)₃ were successfully synthesized by a modified solid-state diffusion method. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. Surface morphology of the sample was studied by scanning electronic microscopy (SEM). The optimal concentrations of dopant Gd³⁺ ions in compound LiSr₄(BO₃)₃ were determined through the measurements of photoluminescence (PL) spectra of phosphors. Gd³⁺-doped phosphors LiSr₄(BO₃)₃ show strong band absorption in UV spectral region and narrow-band UVB emission under the excitation of 276 nm was only due to ⁶P _J → ⁸S_7/2 transition of Gd³⁺ ions. The effect of Pr³⁺ ion on excitation of LiSr₄(BO₃)₃:Gd³⁺ was also studied. The excitation of LiSr₄(BO₃)₃:Gd³⁺, Pr³⁺ gives a broad-band spectra, which show very good overlap with the Hg 253.7 nm line. The photoluminescence spectra of LiSr₄(BO₃)₃ with different doping concentrations Pr³⁺ and keeping the concentration of Gd³⁺ constant at 0.03 mol have also been studied. The emission intensity of LiSr₄(BO₃)₃:Pr³⁺–Gd³⁺ phosphors increases with increasing Pr³⁺ doping concentration and reaches a maximum at 0.01 mol. From the photoluminescence study of LiSr₄(BO₃)₃:Gd³⁺, Pr³⁺ we conclude that there was efficient energy transfer from Pr³⁺→ Gd³⁺ ions in LiSr_4?x?y Pr _x Gd _y (BO₃)₃ phosphors.     

A new yttrium oxysulfide-based multispectral IR phosphor activated with Nd<Superscript>3+</Superscript> and Yb<Superscript>3+</Superscript> ions

We have identified the main general trends of variations in the spectral and kinetic properties of the Nd³⁺ and Yb³⁺ IR luminescence bands in (Y_0.99–xNd_0.01Yb_x)₂O₂S solid solutions under excitation at wavelengths of 0.810 and 0.940 µm. Using these results, we have developed the first multispectral IR phosphors with various relative intensities of the IR luminescence bands in the ranges 0.88–0.94, 0.94–1.06, 1.06–1.12, and 1.35–1.42 µm under excitation with 0.810-µm light and bright IR luminescence in the range 0.94–1.06 µm under excitation with 0.940-µm light.     

Spin Gap Characteristic of Y(Ba1−<Emphasis Type="Italic">x</Emphasis>Gd<Emphasis Type="Italic">x</Emphasis>)2Cu3O7−δ

Y(Ba_1?xGd _x )₂Cu₃O_7?δ compounds with x = 0 ～ 0.15 are prepared using the solid reaction technique. With structure analysis by Rietveld refinement of x-ray diffraction, we find that Gd³⁺ ions prefer to occupy Y sites within lighter doping x ≤ 0.08 due to ion size effects, then begin partially to occupy Ba sites with doping content increasing, which gives vital influence on superconductivity and spin-gap properties. The magnetic doping effects of Gd³⁺ ions on spin-gap properties are investigated in detail by contrast of the distinguished behaviors between T* and T_c, indicating that spin-gap temperature is not completely determined by the carrier density, but strongly dependent on the strength of interplane antiferromagnetic coupling. Finally, we propose an expression of in-plane resistivity dependent on the maximal width of spin-gap Δ₀ to derive their values for different samples, which almost keep constant with the increase of Gd doping contents.     

Structure and Magnetic Properties of Ce-Substituted Yttrium Iron Garnet Prepared by Conventional Sintering Techniques

Y_3?xCe _x Fe₅ O ₁₂ (CeYIG) ceramics, with x = 0, 0.15, 0.25, 0.35, 0.45, and 0.5, were fabricated by a conventional ceramic sintering technique. We studied the structures and magnetic fields of a series of CeYIG ceramics using X-ray powder diffraction, a scanning electron microscope, and a superconducting quantum interference device magnetometer. Findings showed that the substitution limit of the concentration of Ce³⁺ ions in the yttrium iron garnet structure was approximately x = 0.25. An extra CeO₂ phase was detected in the ceramic when the addition of CeO₂ content overtook the limit. The lattice constants and relative densities increased by increasing the Ce³⁺ contents in the ceramics. First, the saturation magnetization increased gradually with increases in the substitute concentration of Ce³⁺ ions and then decreased gradually when x = 0.35, 0.45, and 0.5. Overall, this study showed that the Y_3?xCe _x Fe₅ O ₁₂ material with x ≤ 0.15 exhibited excellent magnetic properties. Hence, the material show promise for magneto-optical and microwave communication applications.     

Critical Temperature of Smart Meta-superconducting MgB<Subscript>2</Subscript>

Enhancing the critical temperature (T _C ) is important not only to widen the practical applications but also to expand the theories of superconductivity. Inspired by the meta-material structure, we designed a smart meta-superconductor consisting of MgB₂ microparticles and Y₂O₃/Eu³⁺ nanorods. In the local electric field, Y₂O₃/Eu³⁺ nanorods generate an electroluminescence (EL) that can excite MgB₂ particles, thereby improving the T _C by strengthening the electron–phonon interaction. An MgB₂-based superconductor doped with one of four dopants of different EL intensities was prepared by an ex situ process. Results showed that the T _C of MgB₂ doped with 2 wt% Y₂O₃, which is not an EL material, is 33.1 K. However, replacing Y₂O₃ with Y₂O₃/Eu³⁺II, which displays a strong EL intensity, can improve the T _C by 2.8 to 35.9 K, which is even higher than that of pure MgB₂. The significant increment in T _C results from the EL exciting effect. Apart from EL intensity, the micromorphology and degree of dispersion of the dopants also affected the T _C . This smart meta-superconductor provides a new method to increase T _C .     

Phosphors based on NaZr2(PO4)3-type calcium and strontium phosphates activated with Eu2+ and Sm3+

Ca_0.5Zr₂(PO₄)₃:Eu²⁺, Sr_0.5Zr₂(PO₄)₃:Eu²⁺, and Ca_0.5Zr₂(PO₄)₃:Eu²⁺, Sm³⁺ orthophosphates prepared through precipitation using sol-gel processes are analogs of NaZr₂(PO₄)₃ (NZP) and crystallize in space group R $\bar 3$ . Their crystallographic parameters determined by X-ray diffraction are consistent with the interatomic distances extracted from EXAFS data. Their luminescence spectra obtained under excitation in the range 300?C400 nm contain emission bands between 425 and 525 nm. Substitution of the larger sized cations Eu²⁺ and Sm³⁺ for Ca²⁺ shifts the emission bands to shorter wavelengths and reduces their width because of the decrease in the effect of the crystal field. Analysis of the spectra indicates that Eu²⁺ occupies two types of crystallographic sites (independent interstitial sites of different sizes and shapes in the NZP framework structure). Codoping with Eu and Sm has ensured luminescence with chromaticity coordinates approaching those of white light: (x = 0.27, y = 0.34).     

Luminescence Spectra of Poly(methylmethacrylate)/ZnS:Eu(III),Tb(III) Composites

Colloidal zinc sulfide solutions have been prepared by reacting zinc trifluoroacetate and thioacetamide in methyl methacrylate as a reaction medium, and europium and terbium salts have been added to the solution. Using methyl methacrylate block polymerization, we have synthesized PMMA/ZnS, PMMA/ZnS:Eu(III), PMMA/ZnS:Tb(III), and PMMA/ZnS:Eu(III),Tb(III) composites. The luminescence of the composites is due to charge recombination at energy levels of structural defects and impurities in ZnS and also to ⁵D₀ → ⁷F _j and ⁵D₄ → ⁷F _j electronic transitions of the Eu³⁺ and Tb³⁺ ions. It depends on the composition and structure of the composites, excitation wavelength, and other factors. The mutual effects of the ZnS and the Eu³⁺ and Tb³⁺ ions show up as changes in the position and relative intensity of luminescence bands in the spectra of the composites.     

Visible quantum cutting through downconversion in Eu3+-doped K2GdZr(PO4)3 phosphor

K₂Gd_1?xZr(PO₄)₃:Eu_x³⁺ (0.02 ≤ x ≤ 0.1, x is in mol.%) were prepared by solid-state reaction method and their photoluminescence properties were investigated in ultra-violet (UV) and vacuum ultra-violet (VUV) region. The phenomenon of visible quantum cutting through downconversion was observed for the Gd³⁺–Eu³⁺ couple in this Eu³⁺-doped K₂GdZr(PO₄)₃ system. Visible quantum cutting, the emission of two visible light photons per absorbed VUV photon, occurred upon the 186 nm excitation of Gd³⁺ at the ⁶G_J level via two-step energy transfer from Gd³⁺ to Eu³⁺ by cross-relaxation and sequential transfer of the remaining excitation energy. The results revealed that the efficiency of the energy transfer process from Gd³⁺ to Eu³⁺ in the Eu³⁺-doped K₂GdZr(PO₄)₃ system could reach to 155% and K₂GdZr(PO₄)₃:Eu³⁺ was effective quantum cutting material.